Ditch Doctor Archive

DEAR FAILING,

First, let me reassure you that you're not the only one being "bucked" by this misunderstanding. Some other contractors have contacted me about not being allowed to even drop a single PSI in pressure during their hydrotest! Yup, you heard that right — held to a "zero pressure drop" requirement, which is not in line with nor supported by the actual industry standard being incorrectly imposed upon you. But I've got good news for you! For most people, at any time in their lives, "losing 6 pounds or more" is generally considered a good thing, especially if it is based upon advice from your actual doctor. But not so in a pipeline hydrotest.

As held in the governing standards, the original rules used a combination of pressure drop and recovery volume as a two-pronged gauge of a pipeline's fitness for service. Of course, if the line falls to 0-psi, you have a leak somewhere, the test has failed and corrective action is needed. The 5-psi pressure loss restriction was introduced and used as a guide to indicate that your filling and flushing process has removed all the "meaningful" air out of the pipeline. Air compresses, but water does not. That's a critical difference to keep in mind. When you turn the pump off during a pressure test, any trapped air, no matter how small or large the bubble, will expand and reflect on the gauge as a pressure loss. Stay within 5-psi of the target pressure for your test, and obviously, most, if not all, of the air has been exhausted prior. A loss of more than 5-psi IS AN INDICATOR but not a ruler or decider. In some pipelines, a small amount of trapped air, no bigger than a football in total size, can cost you 25 or 30-psi on a gauge. But is it only trapped air causing this loss? That's the question ultimately answered by the recovery volume, in ounces or gallons, used to regain the lost pressure.

So, here's the good news — in realized recognition of the ongoing confusion often caused by "trapped air" — in 2017, the AWWA standard addressing hydrotesting was revised to read, "Test pressure shall be maintained within this tolerance [+/- 5 psi] by adding makeup water through the pressure test pump into the pipeline. The amount of makeup water added shall be accurately measured (in gallons or liters per hour) using suitable methods. It shall not exceed the applicable testing allowance as specified." So yes, you can flick the pump on and off as many times as needed during the time frame of your test to stay within 5-psi of the target pressure, keeping track of the total water used, and use that total volume as the ULTIMATE JUDGE of your pipeline. The point is that no pipeline of any size or length will stay within its computed recovery volume limit if it has an active leak. Plain and simple.

The hydrotest accounts for the water tightness of an assembled pipeline, and the recovery volume incorporates things that happen to a newly pressurized pipeline, like pipeline growth at the joints under pressure and water absorbing into the concrete lining, to name two considerations. And don't panic if you get a 30 or 40-psi drop in your first pressurization; just an inch or two of total growth in length due to pressure forces can easily cause such a drop. Only worry if your pipeline drops to zero. And then call someone for assistance. As a contractor, you should NOT BE good at finding or fixing leaks. If you are, that's a whole 'nother concern for me to write about. And that one would not be "good news!" And "zero pressure drop" test requirements? Don't get me started!!

Sincerely,

The Ditch Doctor

Dear Zinced,

The factory-applied zinc coating on the barrel exterior of Ductile iron pipe is applied by vaporizing zinc wire with a significant electric arc inside special machinery, so it becomes a permanently affixed portion of the non-flyable metal surface. There is no potential nor fear to be had of fluids or other corrosives migrating under the zinc at a cut end, as can be the case with most paints or some epoxies. The zinc coating itself is not a stand-alone corrosion prevention mechanism on DI pipe. It works best with appropriate polyethylene pipe encasement, like antibacterial ointment under a Band-Aid on your skin! There is no need to "re-zinc" or otherwise coat the vertical surface of the cut end as it becomes an "interior surface" in the joint, not subject to the corrosive mechanisms that might want to attack the outside of the pipe. So that you know, the inside surfaces of the bell section on DI pipes are not zinc-coated. Doing so could affect the dimensional needs of the joint, and there truly is no purpose to it, as, again, inside surfaces are coated with other special linings if a corrosive fluid service is anticipated. That's a whole different discussion we could have at another time. So, for your question here … cut and move on. No worries. But I must also tell you, in all sincerity and experience, the time to question or amend project specifications is BEFORE you begin installation, not DURING. Most authorities avoid discussing changes during the construction, and it is difficult to change their minds at that point. Talk first, cut second. Always a good plan.

Sincerely,

The Ditch Doctor

Dear Annoyed,

Tiger stripes, zebra stripes, roadway stripes, candy stripes and even barcode stripes … all have a purpose, and each is different. The same goes for the stripes at the end of a Ductile iron pipe spigot. Tyton® joint pipe has two stripes around the barrel near the beveled spigot end as received from the factory. These indicate the portion of that pipe end that will be homed (inserted to the stripes) of the bell section of another DI pipe of the same diameter. They are circumferentially parallel to each other and approximately ½ inch apart. When the spigot is homed correctly, you'll hear the "thump" during assembly. The second stripe, the one furthest from the bell being inserted into, finishes in a position flush or thereabouts with the entry lip of the bell. Anything near that is fine. When you deflect a joint in any direction post-assembly, a portion of this same second stripe — and often the first stripe — will be exposed to the outside radius of the offset joint. Again, common by design. So, seeing at least one of the stripes when set straight in is like knowing a tiger by its stripe, which is perfectly normal. Truthfully, these spigot stripes are most useful as an "alignment gauge" BEFORE you push the pipe home. Simply compare the spigot stripes to the face of the bell it is entering as you set the spigot gently on the bell lip, and if they look like train tracks, parallel to each other from any direction you view them, PUSH the pipe home and get you your traditional THUMP of completion. "Over-homing" is NOT a concern with DI pipe. So yes, it is not a problem. It's a Ductile iron pipe design feature! And much less dangerous than encountering the stripes of a tiger in person!

Sincerely,

The Ditch Doctor

Dear Inquisitive,

What you can expect from Ductile iron pipe is STABLE SUCCESS FOR CENTURIES! Seriously. Regardless of variant temperatures bearing upon it, of all the common utility piping materials available today, Ductile iron is the least affected by temperature, inside or out. It remains strong from -40o F to 212o F and beyond. In terms of thermal expansion and contraction, the entirety of a 1,000-foot string of Ductile iron pipe exposed to a 10o F temperature change would shrink or grow only 0.75 inches overall. As-cast longitudinal restrained joints are usually required for aerial installations, and each joint can typically provide approximately 0.50 inches of expansion/contraction. With 50 to 55 such joints in a 1,000-foot DI pipe string, that equates to 25 inches of "play" available. Simply put, DI pipelines breathe along comfortably with most, if not all, ambient conditions. Another beautiful truth of Ductile iron pipe, given its superior strength, the "desire" to shrink or grow is generally muted by the pipes' physical strengths in that — let's say — it has already fully expanded (from internal pressure or other means prior). The material wants to expand slightly more due to the thermal effects described above … it just won't. The same goes for contraction. Trust me, that's just the nature of our beautiful beast known as DI. Let me know if this clears it up for you. If not, reach out at any time and be sure to cut out and save the helpful Bridge Crossing Checklist found on the reverse side of this page. Be sure to check out this helpful tip sheet about bridge installation:

Sincerely,

The Ditch Doctor

Dear Worried,

What you describe is not uncommon. Nothing to worry about … yet. You see, buried pipelines can routinely expand slightly in length when first pressurized as they settle into their home within the trench. With some basic math, you can "see" where "all that water" went. The answer is NOWHERE. You simply created more (overall) pipe length with the initial pressurization. Each lineal foot of 24-inch DI pipe contains 25 gallons of water. Even with fittings in your 3,000-foot pipeline, at least 150 pushon joints are likely involved. If each of these push-on joints were to expand just one-eighth of an inch, which can occur even in consolidated trenches, that equates to (0.125 x 150) 18.75 inches (1.56 feet) of "new pipe volume" created by the push of the initial pressurization, which equals 39 gallons of "space." This minor "setting into its surrounds" and minor growth of the pipeline occurs slower than pumping to a designated pressure, which is why it seems to you above ground that something adverse is happening to the pipe. If the pipeline drops below adjacent static pressure or near 0-psi, we could now say, "Yup, you've got a leak." Pump to desired pressure again, or even a third time, to gauge whether the recovery volume decreases or worsens. That will be a better read of what is going on below ground. If it persists, contact your pipe supplier immediately for support and guidance. Oh, by the way, I haven't even mentioned that on the initial fill, the standard cement lining slowly absorbs some of the water volume you used to fill it. That's another thing that can cause questions on the first fill, just so you know. Be sure to check out this helpful tip sheet on preparing for a hydrostatic pressure test:

Sincerely,

The Ditch Doctor

Dear Blown By The Weather,

Sorry to hear you forgot a jacket. Hopefully, you can warm up with a hot cup of coffee. It always makes my day better. I am also glad you are thinking about winter. You're on the right track there. Proper storage of accessories is essential all year round, and some additional recommendations for cold weather months exist. I’m glad you have reservations about using a blow torch to heat gaskets. Gaskets should be stored in a warm, dry place, and heating the gaskets just before installation is definitely a good idea, but not with a blow torch! Placing the gaskets in a heated truck cab or heated job site trailer is best. One unique idea I've seen is a crew that placed a heater in a toolbox and mounted the toolbox on the side of the trench box. Rather ingenious. Pipe lube should be stored in the same manner as the gaskets. Pipe lube supplied by your pipe supplier can be used in subfreezing temperatures but should not be allowed to freeze. Reviewing the product's installation guide and MSDS is also a good recommendation. Go to the McWaneDuctile.com Learning Center tab for Installation Guides and Downloadable Tip Sheets Like Gasket Storage Tip Sheet:

Sincerely, The Ditch Doctor

Dear Lost Without Lube,

I feel ya, bro. I can't wait for some Saturday afternoon football myself. I've been working hard all week and will be ready to relax! To address your first issue, which isn't the point of your inquiry but should be noted, the person who received and signed for the materials at your job site should have verified that ALL materials were received and properly staged for the project. That would have eliminated the root cause of your lack of lube. In response to your three suggestions, none of which are exceptionally good, here's what the Ditch Doctor would recommend: If considering using older lube, you must determine the brand, the age of the lube and how well it has been stored. Is it the brand recommended by the pipe supplier? If you can’t verify this, don’t use it. Does the lube look separated, oily, puttied, or hard from old age or poor storage? If so, chuck it! Purchasing lube from a local distributor is a better option than using old lube, but a word of caution: There are pipe lubes out there that work very well with the product it was intended for, but not for others — and cooking oil? Seriously? This is definitely a bad idea as seemingly safe, slippery stuff such as Crisco, Vaseline and common greases often contain ingredients harmful to rubber, such as petrolatums. So, what does this boil down to? Using the pipe lube the pipe supplier provides is always the best option. Who wants to have difficulty passing a hydrostatic test due to using unproven accessories? McWane Ductile ships pipe lubricant with every load of pipe. Currently, lubricants approved by McWane Ductile include Phoenix XL-27 and Black Swan. These products have been thoroughly tested for their effectiveness in our Universal Test Facility located in Ohio. If you are in dire need, contact your local McWane Ductile representative, and let’s work together to expedite the resolution of your situation. Then we'll all go watch some football!

Sincerely,

The Ditch Docter

Dear Wondering,

It appears you’re asking if a plain Tyton spigot (no weld bead on it) can be used reliably in a TR Flex bell. That answer is simply and reliably “YES.” Just push the pipe fully home until the spigot bottoms out against the shoulder in the rear of the bell. Both spigot stripes will disappear well into the as-cast extended TR Flex bell cavity, and that’s OK. The rubber-gasketed joint within is just as watertight as any other Tyton Joint assembly. No concerns there; it just is not “restrained.”

Simply put, the back half of a TR Flex bell is merely a fully conformant Tyton joint bell cavity. The front half of a TR Flex bell contains the restraining segments, in their dedicated channel, against the welded bead of a fabricated TR Flex spigot. No segments used = no restraint provided. While the bell is cast as a one-piece unit, the front and back sections operate independently, serving individual purposes. Watertight in the back, restraint in the front … it’s basically the MULLET of PIPE!! Sincerely, The Ditch Doctor

Dear Bemused,

Here’s the first truth about Ductile iron pipes … they don’t rust; they oxidize. Rust is a structural issue; oxidation is cosmetic only. Ductile iron pipes actually begin to oxidize during production. This oxide layer remains microscopically thin on all pipe surfaces and reliably protects the underlying metal wall from further degradation. Now, this innate protective layer will not stall any actively corrosive environment the pipe might be placed in; other simple protections are available to do that. Yet certainly, snow ... especially your clean mountain variety, is not corrosive to Ductile iron pipe or fittings. The “melt” might reveal more of the oxidation than you saw before (as it can dilute the waterbased asphaltic sealcoat on the pipe), yet there is no cause for concern or need to address or replace the pipe condition. Ductile is sturdy. Ductile is resilient. Ductile is “the pickup truck of pipe”… tiny dings and scratches do not diminish its value, fitness for service, designed lifetime or warrantability. In four simple words, much ado about nothing!!

Sincerely, The Ditch Doctor

Dear Wondering,

While regardless of brand, the locking gaskets you have inquired about are designed and proven to be a standard condition performative equal to their full-fledged integral cast restrained joint counterparts, such as TR Flex®. And while these gaskets serve wonderfully for the impressive internal pressure ratings and external load handling capabilities of Ductile iron pipe, there is one general caveat to heed. These steel-segmented locking gaskets should not be used in above-ground installations where excessive or repetitive vibrations are likely to occur over time. While there is little, if any, evidence of joint separation ever occurring, the theory is that such oscillation forces could adversely affect the engagement of the locking segments into the pipe surface.

These gaskets are also not recommended for areas of unseen potential adverse engagements, such as in horizontal directional drilling installations. Pulled through a relatively flat casing is fine, but not for severely deflected, relatively uncontrolled dragging through a radius. As for the actual assembly of locking gaskets, I would suggest your on-site inspectors and the contractors themselves take a gander at the proper assembly techniques outlined in a recent YouTube video from a pipe manufacturer … just search “Install Sure Stop gaskets” and follow along for success every time! Also check out this tip sheet about gasket storage: 

Sincerely, The Ditch Doctor

You are NOT wrong, not at all. In fact, you nailed it with your succinct and sharp retort. Unlike most other alternate pipe materials in our industry, where their concerns probably developed, Ductile iron is NOT affected in any meaningful way by temperatures that we commonly encounter on earth. Ductile iron remains stable and strong from minus 40°F to well beyond the boiling point of water, 212°F. Exceptions from standard cement-lined pipe to accommodate temperature limitations of the asphaltic paint (typically applied or specialized epoxy linings, both restricted to 125°F in-service) or other items such as rubber-compound gaskets that top out near 300°F. Other materials are often structurally weakened by temperatures far less extreme.

When I tell you that the melting point of Ductile iron is 2,100°F, suddenly, the desire to laugh begins about the concerns raised by others! A tremendous amount of helpful information is available online by searching "Cold Weather" on the McWane Ductile website at McWaneDuctile.com.

Sincerely, The Ditch Doctor

Well, Rita, sounds like Clyde is good at picking up lunch. Regarding corrosion, not so much. Resistivity is not defined as the ability of a metal or iron to “resist” corrosion. Resistivity is defined as a measure of the resisting power of a specified material to the flow of electric current.  All metal pipe materials possess a certain amount of current. Extremely small, but present. That said, resistivity is defined in this case as the ease with which the current may flow or travel from the metallic product through the soil. A soil resistivity of <500 ohm-cm is considered a corrosive environment, and steps should be taken to mitigate corrosion which in many cases involves the installation of polyethylene encasement.

Sincerely,

Ditch Doctor

Walter,

I was too young to remember a wiggle dance from the 60s.  I do, however, possess extensive installation knowledge. I can assure you that your operator’s wiggle dance will eventually (if not already) cause an issue for YOU. When installing a restrain gasket in our Tyton® joint pipe, the pipe must be in straight alignment with the existing pipe using a straightforward push from the bell end to home the pipe. 

Wiggling the pipe during insertion will increase the potential to snag a tooth and damage the gasket.  This is not a difficult process but one that must be done properly. McWane Ductile places handy installation tip sheets in each bag of Sure Stop 350® gaskets. This information is also available on our website @ McWaneDuctile.com, keywords – SURE STOP. To ensure you’re no longer wondering and wobbling about, I’ll even provide jobsite training which also includes a free McWane Ductile feeler gauge used to verify proper installation if you prefer. Just no dance lessons, please! Also check out this tip sheet about sure stop installation:

Sincerely,

         Ditch Doctor

Dear Living Within,

Through the years, I’ve heard of and seen many different attempts to solve your concern in the field, and here is the best and most reliable suggestion I can offer, with no “measuring” needed! Regardless of pipe diameter and joint configuration, restrained or not, when the pipe you just assembled and are now shifting in any direction begins to move the pipe it is inserted to…you’ve reached maximum recommended deflection. This indicates that the first opportunity for metal-to-metal contact within the body of the joint has been met. It’s OK for that first joint away from you to actually move a tiny bit in the trench, Ductile iron pipe is incredibly strong and resilient. You would need to place excessive force on the pipe past this initial point of “contact movement” to affect the joint adversely. And by that, I mean purposely using a good portion of the excavators’ hydraulic capacity. Don’t do that, and all will be just fine!

 Sincerely,

The Ditch Doctor.

Dear Worried,

 No need to worry if you use Ductile iron pipe and the appropriate gaskets! Unlike some alternate materials available in the utility marketplace, Ductile iron pipe is impermeable to exterior pollutants typical to contaminated soils, including hydrocarbons. The gasketed joint resists up to 430-psi of external fluid pressure in all circumstances, so infiltrating the pipeline would require damage or destruction of the rubber gasket itself to occur from said potential pollutants. Fortunately, the Ductile iron industry has extensively researched and made available a wide array of specialized rubber compounds for decades for one to select as the gasket material. From seawater to dilute acids or alkalis, oils, hydrocarbons, chemicals, refined petroleum, solvents, and even aromatic hydrocarbons; we’ve got a compound to cover you! Styrene-Butadiene Rubber (SBR) is the default gasket material provided with Ductile iron pipe and fittings, with Ethylene Propylene Diene Monomer (EPDM), Nitrile (NBR), Neoprene (CR), and Fluorocarbon (Viton) gaskets rounding out the advanced gasket options. If or when the surrounding soils or the contaminants they may contain could be deemed corrosive, there are proven exterior protection options available as well, from enhanced polyethylene film encasement (V-Bio®) to specialized exterior coatings designed specifically for Ductile iron pipe. You can Google “DIPRA gasket options” for more detail.

 Sincerely,

The Ditch Doctor

Dear Harried,

Glad to hear of your experienced confidence in constructing things! Let me try to help you with things your suffering past that. First rule of success in hydrostatic testing of Ductile iron pipelines is operating in strict adherence to a few basic rules: (1) Fill from the lowest point, bleed air from the highest point. Not the “close to” each, but at each location. (2) Fill slow, and let it blow. Filling too fast (turbulent flow) or not having an appropriately sized air-release mechanism at the high end virtually guarantees you will trap air pockets within the pipeline, even if it’s laid “flat and straight.” (3) Never fill from the high side. That is a guaranteed air-trapping invite, and often creates hardships far beyond the norm that we’d have to cover in a different discussion. (4) Losing more than 5-psi is not the end of it all. While this would disqualify you from “passing the test,” it likewise alone offers you no insight as to what’s really going on. For that you need to go “diagnostic,” and there’s an easy way to do that. A simple Google search for “McWane Double Bump” will put you on the right path. You’ll even find a handy tip sheet and data tracking form there.

 Lastly, and certainly on all inclined installations, it is wildly helpful to place a pressure gauge at both the low point (from where you’re pumping) and the high point (where you’re blowing air out of the pipeline). Doing so, and knowing the relationship of a water column vs. pressure created (0.433-psi per vertical foot of water), you can compare the pressure values top and bottom to gauge if the pipeline is hydraulically tight despite the pressure drop experienced.

 Much like a balloon will not stay inflated if it has even a microscopic pinhole, or a thermometer won’t stay red if there’s a hole in the tube, a pipeline with a true leak – especially an inclined one – will typically drop to zero pressure in as short a period as an overnight sit. If it stays at let’s say 64-psi overnight, then at least we know there’s no need to check for leaks below an elevation of 148 feet above the lower gauge’s location. That part is leak-free, i.e. the red part of a thermometer doesn’t lie! So, there’s a few TRICKY TREATS to help you through, reliable and proven, just like Ductile iron is made to be! Be sure to check out this helpful tip sheet about hydrostatic pressure testing: 

 Sincerely,

 The Ditch Doctor

Dear Roger,

Not certain I can help you with the giggles and snakes, and I hope the fight with snakes is in the figurative sense. As for the wiggle, I can actually help with that, and I’m not talking about my dance moves from the ‘80s. I was the bomb diggity dance machine! Back to the wiggle. Straight is great, man. No “wiggling” permitted. And yes, it does take more energy to home a joint when restraint gaskets are used compared to a standard gasket. Let’s do the math. The restraint gasket contains metal as well as the rubber. I’ll give you an example: Some operators use a spud bar to home 6-inch and 8-inch pipe when using standard gaskets. Not many operators, if any, can home an 8-inch restraint gasket joint using a spud bar. Kind of doubt Judd would use a spud. Last thing, white gloves and taking it easy may be a requirement when installing PVC pipe to prevent over belling. No worries here with Ductile iron. Shove that pipe home and get the job done.

Good luck and stay safe,

Ditch Doctor

Dear Rick,

Well, Rick, good to hear you are looking out for your little brother. Sounds like Ron is heading down the road of despair. First, there is typically a good reason why a specification is written. Every job is different, and what works in one situation may not be a wise choice for a different application. It would be a bad day if Ron had to redo the HDD portion of the project after choosing to use something other than specified. Second, Sure Stop® gaskets are an excellent form of restraint. However, they are not recommended for HDD applications. Stick to the plan, man! Also check out is helpful tip sheet about sure stop joint assembly:

Thanks for watching out for your bro,

Ditch Doctor

Dear Harry,

Good to hear you are concerned because your concerns are justified. What’s not good to hear is the words Tyton and Fast-Grip in the same sentence. The pull-out is much less than 1.5 inches per joint. Therefore, STOP. Fast-Grip gaskets do not fit in Tyton bells. You must re-install all joints in question. One other small detail that has HUGE ramifications is to use a simple paper clip as a feeler gauge to check the joints for proper installation. You or Brent would have detected an issue on the first joint had you followed this simple step. Now re-install the joints then schedule on-site training with a McWane Ductile Professional. Less stress, better eats, buddy. Be sure to check out this helpful tip sheet about specialty gasket material properties: 

Later man,

Ditch Doctor

Dear Cindy,

Well Cindy, I don’t get it either. Measuring the OD takes less than a minute, yet I have seen the same thing you have noticed on numerous occasions. So, here is the skinny on the fat pipe: the maximum OD for a 24-inch pipe is 25.85 inches. The minimum inside diameter (ID) for a retainer gland is 25.87 inches. Wow, .02 inches difference. Not much, and those components are rather heavy, so yes, frustration can quickly rise. Now, if the operator was to measure and cut a pipe with an OD of 25.79 inches (which is within specification), there is now .08 difference between the OD & ID. You may think that doesn’t sound like much, but hey, you just more than doubled the difference between the two. The installation will now go much better. I would ask the operators a similar question, “Do you take the time to measure the length of pipe needed to fit between two fittings?” Be sure to check out this helpful tip sheet about using O.D tape:

Happy cutting, Cindy,

Ditch Doctor

Well, Pepper Pete,

I would love to say you’re going to be okay, but this just isn’t one of them. You are about to set yourself up for failure, and that keeps me up at night. You say you have 7 inches of clearance, but actually, the OD of the flange is more than the 6-inch pipe. Therefore, your 7 inches is now 5 inches. The next problem is the MJ bell depth, the width of the gasket, and the width of the retainer gland, which in total is approximately 9.5 inches prior to assembly. Somewhat difficult to install over 9 inches of products in a 5-inch space. The last major issue you are facing is the probability of a leak at the welded outlet. The welded outlet may be damaged when the retainers on the gland are tightened to the 36-inch pipe due to the proximity. So, sorry my friend, but the answer you don’t want to hear is the best one: order a new pipe. Be sure to check out this helpful tip sheet about cutting ductile iron pipe:

Later man,

Ditch Doctor

Dear Freez’n,

Easy bro. There are options and you are correct. The bell restraint harnesses are cumbersome and do take a considerable amount of time to install. I feel for ya there. A great option is to switch out the Tyton® pipe (with restraint harnesses) with TR Flex® pipe. Installation time for a 30- inch TR Flex® Joint is less than five minutes. You already know the installation time for a 30” Tyton® joint with a bell restraint harness can take over one hour. Let’s get your project back on schedule so you’ll have more time to get that firewood cut and keep the house warm.

Stay warm,

Ditch Doctor

Dear Unique,

Your situation is not as uncommon as you may think. Fires are a problem from coast to coast. Fortunately, you have Ductile iron in your system. Unfortunately, you also have PVC in your system. There are two big concerns with your situation. First, PVC will burn. Don’t be misled and think the pipe is okay just because it is buried. PVC pipe burns and melts, therefore, no water. Second problem is PVC is subject to surge pressures and cyclic loading. Say the power does go out and you actually have to pump water from the 14-inch Ductile line to the 8-inch PVC line. Is someone going to run out there and make sure all the operators and fire fighters take their time and slowly open and close the valves or make sure there are no interruptions with the pumping truck? Let’s face it, these folks need to trust the equipment they use so they can focus on putting out the fire. You have a potential problem all right, but it is not your 40- to 50-year-old Ductile iron pipe. Be sure to check ou tthis helpful tip sheet about PVC vs. Ductile Iron pipe: 

Sincerely,

The Ditch Doctor

Dear Miffed,

First thing, take a nice relaxing deep breath, and gently exhale. You've done nothing wrong. All that's happened is what's expected to happen in such a scenario. Internal pressure creates a pushing force, even with "static" water. This force is equal to the product of the internal pressure in pounds per square inch (psi) times the available area (square inches) on the dead-end surface.

For any diameter of Ductile iron pipe, the force required to home the joint during assembly is no more than what it takes to move the dead-weight of the pipe itself. The pipe barrel does all the work of compressing the gasket to make it watertight, simply by moving across it. This should work the same in reverse then, right? And it does. To separate the joint requires no more than moving the dead weight of the pipe in the opposite direction of assembly. And for any diameter of Ductile iron pipe, the combined force on all the square inches of dead-end surface area will begin to "walk the joint apart" at or about 50 psi of internal water pressure. So how is the Ductile iron pipe "rated" to 350 psi? Once assembled the compressed rubber gasket is designed and reliable to 1,000 psi of internal water pressure, 430 psi of external (groundwater) pressure and/or a negative 14 psi vacuum. Pretty sturdy to say the least. But as you've seen, and as we're talking about here, the "grip" of the rubber gasket itself is nowhere near as great. So, to keep the joints together past 50 psi requires the combined efforts of the weight of the pipe, the weight of the backfill upon it, and the frictional grip of the pipe with the soil around it. Any "remaining" push force needs to be zeroed out through the use of strategically located restrained joints, such as TR Flex® pipe or restraining gaskets in standard Ductile iron pipe, "rubber gaskets with stainless steel teeth inserts," such as Sure Stop 350 gaskets from McWane.

There is easy-to-use Ductile iron pipe restrained joint calculators available online, and experienced professionals available to consult with at each Ductile iron pipe manufacturer to help you along. But for now, it remains a requirement to hydrotest the pipe before burying it. I would suggest you replace the standard rubber gasket in any Ductile iron pipe joint that "walks" with a restraining gasket. Or install external restraining harness assemblies across each joint first before re-pressurizing the pipeline. Why? Because if you're testing to even just 150 psi water pressure, that same 12-inch pipe we discussed earlier would now generate 18,000 pounds of push force on that same dead-end ... that's nearly 10 tons! And that'll move a bunch of pipes, for sure. Be sure to check out this helpful tip sheet on hydrostatic testing:

Here for You Always,

The Ditch Doctor

Dear Stopped,

Yes, a fabricated TR Flex® spigot end can be successfully mated with a Tyton® joint bell. In fact, a TR Flex® bell is simply an as-cast, single-pour extension of the bell to house the fabricated spigot end plus the restraining segments that longitudinally lock the otherwise still-flexible joint. There is a full-capacity Tyton® joint portion of the bell behind this integrally cast extension, where the exact same watertight radial-compression of the rubber Tyton® gasket occurs by insertion of the pipe spigot across it. By design, the weld-bead on the fabricated end (which works with the restraining segments in a true TR Flex® joint) lands just outside of the Tyton® joint bell-face, whether inside a TR Flex® joint or not. So yeah, no harm, no foul and no restriction created on the deflection of the joint. Just wasted fabrication dollars for the spigot end, as the weld-bead will not serve its purpose in a Tyton® joint assembly. More concerning, as you know, is that each and every fabricated spigot is sent to the site as a planned companion for a TR Flex® bell. And robbing from the "restrained" to pay the "non," for whatever reason you need now could create a complicated shortfall later in your pipeline construction.

It would not be a good day if next week or later you reach for a critical piece of restrained joint pipe when needed ... and it's not there ... because you used it here. So please, advise and coordinate any substitutions with your pipe provider so that replacement or other options can be employed, before it's a shutdown crisis. That's the worst for everybody! And one last note ... the spigot stripes on a fabricated TR Flex® end are applied at a point on the barrel exterior to align with the extended as-cast TR Flex® bell. So, don't freak out when they land a few inches or more from the Tyton® bell you've pushed it into. The reassuring "thump" sound made when the spigot end homes into the bell shoulder is all you need to know all is well. Hope this gets you back to laying pipe, making good money and quality water supply or sewer management as designed!

Sincerely,

Ditch Doctor

Dear Miffed,

The spigot stripes are applied during the process of pipe manufacturing at a location on the barrel exterior where, ideally, the leading stripe is not visible. The trailing stripe is planned to be visible yet flush with the bell face in a completed push-on Ductile iron pipe joint assembly. During post-assembly joint deflection, the leading stripe can become completely visible on the outside edge of the deflected joint as you approach maximum recommended deflection limits for the joint. Either way, or in a joint, such as with a field-cut and re-beveled pipe, where there are no spigot stripes involved, maximum deflection of a Tyton® joint (5 degrees for 3-inch to 36-inch Ductile iron pipe) equates to 1-inch of offset for each laying foot of pipe away from the bell face (i.e., 10 inches total for a 10-foot spool piece), and serves as the point when metal computes to contacting metal within the joint.

The machine operator, or trenchman with a push-bar, will certainly feel it when, or if, it occurs. And with Ductile iron pipe it takes significant force to deflect any further. Minor visible variations of this ideal are not necessarily a cause for concern, within reasonable limits. In a completed fully homed Tyton® joint, the ultimate end of the spigot lands nearly two inches past the compressed gasket. So, unless the stripes appear that far off the front edge of the bell itself ... no worries. In truth, the spigot stripes serve best as an alignment guide during joint assembly. If the spigot stripes are visually parallel to the bell face as the spigot approaches and inserts into the joint, you are doing it right, and chances to displace the gasket are minimized, for any diameter. The "thump" home is the next best indicator of a proper joint assembly. In a restrained joint assembly, such as TR-Flex®, when the joint is manually extended as described in the installation procedure, or upon initial hydrostatic pressurization, the joint will reliably expand to a point where both spigot stripes are visible in full. All diameters of TR Flex® pipe are designed to provide expansion of between 1/2 to 3/4 of an inch, depending on diameter. On the other hand, Tyton joint assemblies are/must be controlled to not expand upon filling and pressurization by thrust blocking or other measures available. So yes, the position of the stripes, down to a minimal level at which yours are being judged, really is much ado about nothing. Now, get back to work!

Sincerely,

Ditch Doctor

Wyatt,

Sounds like the guy who taught you and the guy who educated him were good guys and most likely knew what they were doing. 1983 was an awesome year for music, but technology has changed. There are many new products and techniques that were not around in the mullet days — not that I would know anything about mullets. There are many shows and conferences that are available for you to expand your knowledge, but I have one even better for ya. Contact your local McWane Ductile representative and schedule a Lunch & Learn or Day of Water event. Scores of industry members, from engineers to installers, are currently taking advantage of services from the McWane Ductile professionals who will provide up-to-date training on numerous subjects at no cost to you. And while you’re at it, check out the numerous educational blogs and videos McWane Ductile has produced for water professionals such as yourself.

Go to McWaneDuctile.com/blog. Sincerely, Ditch Doctor Dear Ditch Doctor, we found some old water pipe and don’t know what material it is. Clifford tells me to tap the pipe with a metal hammer and he can tell by the “ring.” Not certain I trust his hearing due to Clifford’s “lack-there-of” when it’s time to start working. Also, not sure where this scientific process originated from. How can I tell what kind of pipe this is? Thanks, Shane from Shamokin Shane, the good news is you have metal pipe — believe it or not, folks continue to find wood pipe in their systems. Clifford is correct as old timers did use the “ring test” to check grey iron. They did that on unlined products that were not installed. And hey, our hearing just isn’t what it used to be back in the day we were casting grey iron. The surface of grey iron is relatively smooth compared to ductile iron, which will have a dimple texture. The outside diameter of the grey iron is typically larger than ductile as well. Another good measuring tool if you have one is to check the metal thickness. Grey iron pipe was much thicker than ductile iron pipe. This may be checked with an ultrasound thickness device without cutting into the existing pipe. These methods are more reliable than the old ring test. Maybe someday we can all sit down and go through Clifford’s black and white photos from back in the day… Also be sure to check out this helpful training brochure: 

 Sincerely,

 Ditch Doctor

Dear Larry,

Discovering an installation error during the hydrostatic test is definitely a bad day. Realizing the owner is not about to listen to the “I think it will work” repair theory will make the bad day a really long, bad day. A good question would be why the joints were not double-checked prior to entering the casing. McWane Ductile qualified personnel would be happy to provide a job-start installation training for your crew in the future. As for the repair, follow the owner’s prescription and pull the pipe and repair, and for the love of Pete, check those joints! Remember, happy owner, happy life — well, you know what I mean.

Sincerely,

The Ditch Doctor

Dear Chuck,

Grandpa used to plow the fields with a team of horses. Then came the tractor. Now there are GPS controlled tractors that are extremely efficient and save an extraordinary amount of time. New boltless restraint systems are far more superior in effectiveness while greatly reducing installation time. Time is money. Unless, of course, Buzz wants to extend your current installation into the next decade. Just curious...does Buzz have a cell phone?

Sincerely,

The Ditch Doctor

Yup, That's in Michigan!

Hello Livid,

Take a deep breath. You've done nothing wrong. In recent years, the vernacular has changed from saying "allowable leakage" to the more accurate term "testing allowance.” Never was it meant to mean "... oh, it's just a little leakage ... it will get better over time ... don't worry about it!” Real leaks never get better on their own. No level of prayer, dance, hope, or other intervention short of digging up and repairing it is the answer if, in fact, water is escaping the pipeline. The testing allowance is a practical representation of what happens to a ductile iron pipeline once it is buried and pressurized. The allowance represents a total measure of minor factors that could produce a small pressure drop in a pipeline segment without a loss of water involved.

Real things such as tiny pockets of trapped air, absorption of water into the cement mortar lining, and longitudinal growth of the pipeline from internal pressure of the water are some of these factors. The expression “minor” relates to the +/- 5 psi pressure change permitted during the length of your hydrotest. With any meaningful amount of trapped air or even the tiniest drip occurring anywhere in the pipeline, you will never remain within this 5 psi differential. If you’re not sure that you really have a leak, just pump the line up another 50 psi above your original test pressure, wait 30 minutes, and pump back up. If the recovery volume increases at all from prior, you've got a real leak, get to digging. But if it stays the same or gets better at a higher internal pressure, good news, it's just trapped air! Like a balloon, squish when compressed and expands when released. I hope this long proven reality eases the engineer’s mind and gets you back to working! Be sure to check out this helpful hydrostatic testing tip sheet:

Sincerely,

The Ditch Doctor

Dear Stopped,

Your inquiry is the ultimate example of one of my favorite sayings: "that which makes no difference is no difference." Think about it, and perhaps ask the question of the inspector onsite, "how's the water gonna know (what direction the bells are laying)?" The inside surface of a ductile iron pipe joint is a smooth continuation of the barrel on each side, even when the joint is deflected. So, what difference does the bell direction make? Absolutely none! If you look at the configuration of the bell, its leading lip and everything else about the design is designed to guide the spigot gently across the gasket while compressing it to a watertight finish, much like how a boat ramp protects the bow into and out of the water.

It goes without saying, yet I'm typing it here nonetheless because it’s so important: every job site decision should start and end with worker safety. The laying direction of the bells is quite often determined by what is safest for those installing the pipe, especially on slopes, and can actually change during the construction of a pipeline. And as for machine size needed (second most popular inquiry), if the machine can pick up the pipe, it is big and strong enough to assemble the joint. It's the dead weight of the pipe that makes the gasket compress, not the force of the push. You can’t “over-home” DIP, but why bring an elephant gun to a chicken fight? I can call the inspector directly if he or she requires any additional information. We are here to help, free of charge!

Sincerely,

The Ditch Doctor

Dear Feelin' It,

Field or foundry, makes no difference. Three hundred psi is nowhere near the limit for ductile iron pipe (DIP). In fact, every single piece of DIP, all sizes and every wall class, are hydrotested in the standard manufacturing process to a minimum of 500 psi internal water pressure. And that's barely halfway to the worry mark, as all DIP barrels are likewise rated to 350 psi, which when including the DIP standard 100 psi surge allowance and a safety factor of 2.0 actually equates to 900 psi on a gauge. Truth be told, we have tested many diameters of class 52 DIP restrained joints to well over 1,000 psi with some smaller diameters nearing 2,000 psi of internal water pressure.

Now while we did this in highly controlled and safety-conscious environments, nonetheless you can see that 300–400 psi should not be a threat to your installation. I couch it (as should be) because I'm operating under the presumption that any restraint considerations or thrust block designs were done with at least 400 psi as the guide. If the designer based the pipeline considerations on, let's say an original 150 psi post-installation test pressure, well, no, don't go to 400 psi ... for obvious reasons. Something is gonna separate somewhere. And “surprise” is the last word anyone wants to hear on a jobsite! I would suggest you check with the design engineer to confirm the proper design pressure was used. Or you can easily go to the McWane Pocket Engineer Thrust Restraint Calculator at pe.mcwane.com and compare the needs at 400 psi to what the plans show and/or what you actually installed. It's easy online! Be sure to check out this helpful tip sheet about hydrostatic testing:

Sincerely Not Sweating It,

The Ditch Doctor

Dear TOiT, you might quite like to hear this: no true limit! Have at it!

The practical answer is that the only guideline you need to follow are these simple two steps. One is based on experience and the other is plain common sense.

1. The combination of your selected tap size and the pipe wall involved should result to at least two full threads left in the wall by the tapping machine. Two full threads are long proven to contain 500 psi without leaking and resist more than 2 tons (4,000 lbs.) of pullout force on average. Typically, the copper pipe would separate from the brass corporation body before the threads would fail in the pipe wall (i.e., if copper or HDPE service line accidentally grabbed by a backhoe, etc.).

2. The spacing of side-by-side taps is controlled by the footing of the tapping machine you have. Clearly, you want to give yourself and others adequate room to work a wrench on the orp stop, no? Most people have seen the famous DIPRA photo where it looked more like an artificial tree trunk or old-school phone operators control board with so many outlets near each other around the entire circumference of the small diameter pipe. And none of them leaked when tested to 500 psi. You don't weaken DIP with multiple taps. It is beyond the resilience you need to connect a service line. Many service lines near each other is necessary.

If it makes you feel better, you can stagger the tap locations along and around the barrel just to make it feel like you're not creating a "perforation" line. You know, like in your childhood paper notebooks. (I just lost everyone under 30 who is reading this ... perforations, what? Paper?). Nonetheless, tap away to either your heart's content or everyone in the neighborhood has clean running water! Ductile iron is here to serve. Reliable, and without limits or restrictions seen with other pipe materials! #SratchesAndDingsMeanNothingToDuctileIron #IronStrong

Sincerely, Tap Master D

The Ditch Doctor

Dear Hyper,

To quote a popular "local guy" of yours, the great Aaron Rodgers — relax! Each and every piece of AWWA conforming ductile iron pipe, in every available thickness or pressure class, is rated from 700 to 900 psi of real fluid pressure contained within the pipeline, depending upon the diameter. Pretty impressive, huh? But wait, there's more! While that may sound extreme, it's not even close to alarm time. AWWA standards include a casting tolerance and service allowance built into every ductile iron pipe wall, which affords even greater pressure containment than the rating indicates. For example, if I read your sales order correctly, you ordered 24-inch pressure class 350 DIP and we shipped class 52 DIP.

This is not an uncommon practice when we have equal to or better than what you've ordered in stock (i.e., a slightly thicker pipe), and we can avoid you waiting to produce new pipe. The standard wall for PC 350 24-inch DIP is 0.43 inches and the standard wall for class 52 DIP is 0.44, so essentially, they are the same pipe. Maximum pressure held by 24" PC 350 computes to 1,400 psi while a TC 52 DIP has a maximum pressure value of 1,433 psi. Not that anyone would ever intentionally take a pipe to such internal pressures out in the field, but it sure is nice to know that DIP can handle it, regardless of minor wall class differences nonetheless, right? You breathing normal again yet? Also know that each and every pipe is hydrostatic tested to a minimum of 500 psi during the manufacturing & finishing process, so each pipe you receive has already experienced more pressure than your post-assembly testing or 100+ years of service life will ever put on them.

The beauty of ductile iron pipe begins with its strength and the bow on the package is its forever flexibility; it never gets weaker in service. And speaking of weak, it's fun to say, and it's true, that we can't make any ductile iron pipe weak enough to match other pipe materials! Building iron strong utilities for generations ain't just marketing brilliance. It is truth!

Sincerely Yours,

The Ditch Doctor

Dear Wondering,

No problem! Take a step back and think about this logically, and per your experience. What is the lubricant for? Where do you normally put it in every pipe joint? Correct, on the gaskets! Not that I'm saying pre-lubricating the gaskets was our intent or even a good idea, but it certainly did not contaminate the rubber gaskets. The gaskets themselves and the lubricant supplied by us, the pipe manufacturer, are each NSF-61 listed, which means certified safe for contact with potable water and not contaminating in nature or content at all. Plus, the lubricant is used to remove friction with the pipe exterior during the assembly process, minimizing the force needed to insert the pipe spigot across the gasket and into the bell, while maximizing the installer's margin for error at the same time. Here's the only true caution I will give you regarding your question.

We do want friction between the outside of the gasket and the inside of a pipe bell in a push-on pipe joint. This is important to keeping the gasket set in its seat during joint assembly. So while contamination from the lube is not a concern, because keep in mind, the approved pipe lubricant we provide is water soluble, it washes away, and that's what you should do for any gaskets to be used in a Tyton push-on DIP joint. Wash the stray lube away with lots of water and then use the gaskets as if nothing ever happened. All is good. If lube got on to mechanical joint ( MJ ) gaskets in any bag, that's different. No need to wash any of it away. Use those fitting gaskets pre-lubed as they are because any friction is always the enemy to the stuffing box design of ductile iron fittings. We want no friction in ductile iron mechanical joints. This helps the gasket set fully in its triangular recess of the joint, without complicating friction, and it will never loosen up if there's no original friction involved.

Sincerely Yours,

The Ditch Doctor

Dear Joe,

Sounds like you may be one of those guys who has put on a dress shirt and left half of it un-tucked. Not judging here but hey: Sloppy is as sloppy does, Joe. AWWA C105 Polyethylene Encasement for Ductile Pipe Systems clearly describes proper installation of poly wrap, including overlapping the poly and taping at both sides of the joint. This information is also backed up in the DIPRA publication for poly wrap installation. Furthermore, McWane Ductile and DIPRA recommend V-BIO Polyethylene Encasement. Let us use an analogy that is typically well understood during my corrosion discussions. Corrosion involves electric current. If you were to touch a live extension cord that is intact, you do not get shocked. However, if you touch a cord that has any kind of defect or exposed copper wire, you will likely get shocked. A corrosion cell involves millivolts and micro amps compared to the voltage and amperage of an electric cord. Therefore, leaving an exposed bell or joint area may result in a shock when someone receives a call at 3:00am to repair a water leak. The actual time required to properly install Polyethylene Encasement is minimal and the results of proper installation are, without a doubt, outstanding. My advice to you my friend: Do the job right today – sleep well tonight.

Later,

The Ditch Doctor

Dear Spinning,

Unfortunately, your situation is not so unusual these days. It seems with the growing use of internal inspection cameras on pipelines in the past decade or so, there is just as much misunderstanding of what people think they see versus what really is or is not there. The bright lights used by these cameras and the confined spaces in which they are used, along with curved surfaces everywhere, is a perfect recipe for the birth of unintentional misinformation. This is especially true with the small diameter pipes commonly used in many water and sewer systems. The bottom line is that many of the camera operators have little or no experience, from a manufacturing perspective, with the products they are inspecting, making it difficult for them to decipher real problems from false perception.

The "candy stripes" that you mentioned, also called spiraling in the paint or lining, are nothing more than the nature of the beast and can be seen in every centrifugally cement-lined pipe, given the right combination of lighting conditions and camera travel speed. You see, the cement lining is deposited in the pipe by a screw auger traveling the length of the interior while the pipe spins slowly. It is then set in place and smoothed out by rotating the pipe at much higher speeds once the cement delivery lance is removed. This compacts the cement lining to a fantastic degree, yet does not diminish the fact that it was originally placed "like a long ribbon". This is the same situation for the sealcoat inside and the pipe wall itself. Should a Ductile Iron Pipe ever fail (under ridiculously high pressure, etc.) it would fail on the helix (along its unseen seam), much like a Pillsbury dough cardboard container when you pop it along the visible seam. That's because the molten iron is delivered into the spinning mold inside a centrifugal casting machine. Don't even get me started on things some call "voids" or "misses" within a pipe that when they are dug up and examined are typically no more than meaningless surface variations in localized places along the lining, which cannot be avoided at times given the nature of the fluid cement when it is placed and set in the pipe.

To help your bottom line, and to preserve your working relationship with those who govern your projects, I would suggest involving an outside professional. Such assistance is typically available free of charge from the pipe or fitting manufacturer with whom you deal. That person can assist you in politely explaining the "that's not what you're seeing" situations to the inspector, to the engineer, or to others. Ask your salesman or supplying distributor. They can get you in touch with the person you need.

Sincerely,

The Ditch Doctor

Dear (You Should Be) Worried,

Where do I start on this? First off, 2-for-1 sales are not always a good buy, and that's exactly what would occur here (or anytime you go apples to oranges, plastic compared to iron). Iron pipes have proven their worth and beyond for centuries. Plastic pipe, at best, suggests less than a half-century of projected service life. So there alone "his" costs savings are going to cost "everyone" down the road, as this plastic pipe will need to be replaced at least once, if not twice, in the standard ductile iron pipe's life. Also, let's not overlook that replacement occurs underdeveloped areas and streets, which is costly by factors over initial installation conditions. That's just part of what's known as The Total Cost Equation when considering utility construction alternates. There's always a "hook" when the "price looks too good" to believe! As for the more specific parts of your inquiry; (yes) tapping for service connections will be more expensive with plastic pipe, due to the absolute need for saddles at each tap location. In addition, there are inherent risks of plastic pipe rupturing during tapping (even with saddles involved), based upon typical burial conditions. Methods and machinery for tapping plastic pipe are also different from that of relatively fail-proof ductile iron (no saddles required), which means that different training and equipment are required for plastic pipe. Oh, and did I mention the increased energy costs for pumping the same amount of water through plastic pipe versus ductile iron? For the average single mile of water delivery piping, in just the short 50-year anticipated service life of plastic pipe, a water company will spend more than $50,000 in extra energy costs as a result of using plastic pipe.

So yeah, the car that this developer wants to drive might be cheaper today, but who's paying for all that extra gas to drive it? It may not cost him, and for the moment it might not cost you. However, in the end, it costs everybody. So, thank you for bringing this to our attention, and hopefully the information provided in our response affords you a better argument than the weakest one of all (which is buying by price alone). BUILDING IRON STRONG UTILITIES FOR GENERATIONS is more than a phrase…it's the proven truth when using Ductile Iron Pipe and Fittings! Be sure to check out this helpful tip sheet about PVC vs. DI pipe:

Sincerely,

The Ditch Doctor

Dear Boring Bob,

I hear you; your time is precious. Let’s try some simple math. A 2800-foot project requires 70 joints of 40-inch HDPE. That could take up to 70 hours of cooling time alone, plus some additional time to fuse the joints. It takes roughly two weeks to assemble and pull HDPE, while Ductile Iron Pipe takes only two days. Computation of the extra pumping costs associated with using HDPE provides one example of the cost savings associated with using Ductile Iron Pipe. For instance, look at your crew cost per hour and the pumping costs per hour. The resulting comparative scenarios between HPDE and Ductile Iron Pipe should prove your theory to be absolutely correct.

That’s right…Ductile Iron Pipe is the cost-effective choice! Sincerely, The Ditch Doctor Dear Ditch Doctor, I wish I could bend Ductile Iron Pipe in the trench like we do with PVC pipe. When are you going to make a product with such attributes? Signed, Live Action Larry from Lucasville Dear Live Action, We already do…and never. Ductile Iron Pipe is deflected at the joints. Therefore, we do already manufacture pipe that deflects. Actually, standard Ductile Iron Joints deflect as much as 5 degrees, and specialty joints can deflect up to 15 degrees. Taking advantage of joint deflection may very well reduce the number of fittings and restraint required. Also, Ductile Iron does not bend like PVC does, which eliminates the potential for “hidden” stresses in a live Ductile Iron pipeline. Bent pipe, in combination with hidden stresses, can lead to very unstable infrastructure system. Consequently, I would suggest that you take the extra time to ensure that any PVC line is not bent prior to installing a live tap. Keep those questions coming, Live Action!

Sincerely,

The Ditch Doctor

Dear Billy,

I am glad you still have that ’78 pick-up. It sure has stood the test of time. Unfortunately, restrained gaskets are subject to vibration and will not last as well as a restrained joint will on a bridge crossing. Those gaskets will chew through the pipe faster than a beaver on steroids at a wood chopping convention. Be sure to check out this helpful tip sheet on bridge installations:

Happy Chopping!

The Ditch Doctor

Dear Larry,

Dude you crack me up. Why would you follow procedures underground but not above-ground? I have three questions for you: Is there expansion and contraction? Is there movement? Should you lube? I have three answers for you: yes, yes, and yes! If those were all cherries and we were in Vegas, we’d be rolling in the dough! Do the job right and maybe you will have some time to take a chance on the slots in Vegas.

The Ditch Doctor

Dear Inquisitor,

At first, I wanted to chuckle at your question. But, to be fair, it’s one that I get more often than you’d think. Overall, one thing really has nothing to do with the other. No, not your question and my laughter, but rather, psi and gpm. Internal pressure (expressed in pounds per square inch = psi ) and flow rate (expressed in gallons per minute = gpm) are essentially independent values. Furthermore, I can prove it in just two words …. HYDROSTATIC TESTING. Think about that. Anyone can attain high internal pressures with water that is absolutely standing still (i.e. static). Heck, all ductile iron pipe manufacturers do just that with every single piece of pipe during the manufacturing process (in accordance with the AWWA C151 standard) by pressure testing each piece to a minimum of 500 psi (contained internal water pressure) while the water is briefly static, thus not moving, through the pipe. Similarly, a 200 foot-tall water tower or tank would create 87 psi of pressure at its base, just due to the standing water column within it alone (computed at 0.433 psi per foot of standing water). Sure, that available psi would start to decrease as the water moves through pipes and away from the tower, due to friction of flow within the pipes and/or elevation changes along the way. This is why pumps are typically involved in order to “keep the pressure boosted”. Therefore, although a higher initial pressure would create a greater flow rate through any open orifice, the movement of water itself does not “create” pressure. What you should do to make sure that your pipes are sized correctly is go to: pe.mcwane.com (the McWane Pocket Engineer®) and use the Flow Calculator to keep operational velocities between 3.0 and 7.0 feet per second. That will ensure that everything the system owners and users want or need can be achieved for centuries to come.

Sincerely,

The Ditch Doctor

Dear Confused, Don’t be confused. You’re actually way ahead of the game, in that you are considering today the potential effects of subsequent construction adjacent to or above the pipeline. That’s good planning (unlike my mullet for my Facebook profile pic), which leads to responsible and sustainable design! The backfill in the trench and/or the likely dirt in the dam’s earthen berm that could potentially be placed atop this pipe would weigh approximately 120 pounds per cubic foot. Water weighs 8.33 pounds per gallon and there are 7.48 gallons in a cubic foot of space, so it computes that water weighs just over 62 pounds per cubic foot. Therefore, let’s forget the water behind the dam (it’s too light and fluffy compared to dirt) and let’s concentrate on the effects of piled soil.

Using the McWane Pocket Engineer App (free to use at: pe.mcwane.com) the Thickness Calculator tells us that in a compacted backfill condition (Type 4 or 5 trench) which would be required to support the pending dam construction above it; at 5.0 feet of cover, you could use a (relatively thin-walled) pressure class 250 ductile iron pipe (nominal wall of 0.30 inches as manufactured) if that was the end of the construction story. But once you place the dam wall on top of it (no, I’m not cursing), the depth of cover now becomes as much as 55.0 feet, and the McWane PE Thickness Calculator (per its AWWA C150 standard conformance) now requires a pipe wall nominal metal thickness of 0.43 inches in the same max-compacted (Type 5) trench. This would equate to a Thickness Class 53 ductile iron pipe. Makes a difference. Makes it right. For generations. As manufacturers, we greatly appreciate people like you who take the long-term sustainable infrastructure view to all that they do. Especially since our product, ductile iron pipe, is among the most sustainable of all infrastructure materials, when properly incorporated into environmentally considerate designs. Thank you for this opportunity to explore these inherent virtues of DIP!

Sincerely,

The Ditch Doctor

Dear Wondering,

My first point of advice would be to pick ONE. Yep, just one…either cement OR epoxy. They typically serve very different purposes or design considerations. Also, most epoxies don’t stick very well to cement, especially to low aggregate, centrifugally-placed cement linings common with ductile iron pipe. In addition, if this is for a water line, then there are an even more limited number of epoxies that are NSF-61 certified as safe for contact with potable water. So long story short, the usual construct for ductile iron pipe and fittings is cement lining (with or without asphaltic sealcoat atop it…not epoxy!) for water service or any other fluid with a pH range between 4.0 and 12.0. It is generally understood that pH values below 4.0 speak to increased levels of septicity and fluid aggression, which require a specialized lining such as Type V sulfate-resistant cement, or yes, an epoxy. There are epoxies that will literally protect against superfund site fluids (ok, so I stretched that statement a touch, but you get the point) in that the first question you need answered is “what is this pipeline going to transport?” The second question to know, as you referenced in your inquiry, is “how warm is the transported fluid going to be?”

Standard asphaltic sealcoat used on cement linings, most epoxies, and regularly supplied rubber gaskets for pipe joints, each have a continuous service temperature limit of about 150 degrees Fahrenheit. If you need higher temperature resistance, there are readily available rubber compounds (such as neoprene ) that handle up to 200 degrees, and bare cement lining easily handles boiling water (212 degrees ). So in review: Don’t MIX…PICK! Don’t GUESS… ASK! From there, here’s how it works…you SAY, we SUPPLY. Done. Sound good? We look forward to hearing from you soon!

Sincerely,

The Ditch Doctor

Dear Peeved,

Well, I’m presuming that you followed the best course for filling and pumping a newly installed pipeline for the purposes of hydrostatic testing per AWWA C600, and by that I mean from the lowest point of the pipeline. So, if you’re standing at a gauge there at the bottom of the hill and it reads a steady 150 psi, that’s great. But the inspector is considering the hydraulic fact (discovered centuries ago by really smart, or at least highly observant, people) that standing water pressure will decrease by 0.433 psi for each foot of elevation against which it climbs. For example, let’s say that the hill you’re pumping up is 100 feet high at its crest, that the gauge at your level reads 150 psi, and that a gauge placed at the top of the hill would only read about 107 psi. I know…“toemayto/toemotto”, right? Be sure to check out this helpful tip sheet about hydrostatic testing: https://www.mcwaneductile.com/upl/downloads/tip-sheets/preparing-for-a-hydrostatic-pressure-test-tip-sheet.pdf

But seriously, may cities, authorities, or inspectors want the test pressure that they specify to be the MINIMUM pressure contained during the test, at any and every point of the pipeline. While this can lead to some interesting discussions onsite, such as the one you’ve obviously had so far with this inspector, it by no means creates any true difficulty or danger in your work. Ductile iron pipe involves a 100 psi surge allowance and a safety factor of 2.0 in its design. Therefore, a 350 psi rated pipe equates to 900 psi on a gauge before you should even care. So in your current case, when you see 193 psi on the gauge in front of you at your pumping location, the gauge at the top of the hill will be reading 150 psi. Case closed. Test passed. Inspector goes home. Also check out this helpful tip sheet about hydrostatic testing:

Sincerely,

The Ditch Doctor

Dear Tom,

I am sorry to hear that you are outnumbered and are really not getting good information. Ultraviolet rays are not just harmful to your skin. In fact, ultraviolet rays are also damaging to rubber gaskets, when exposed for long periods of time. Gaskets should be stored either inside or out of the elements. Consequently, the gasket shipping bags are opaque, and thus, do not allow exposure to sun. While plastic pipes like pvc and hdpe ARE corroded by exposure to sunlight McWane Ductile Pipe is not. As always, I recommend you take some time to look over the AWWA Standards. Gasket storage is addressed in AWWA C600 Installation of Ductile Iron Mains and Their Appurtenances. Good luck with your project and try to have your next discussion in the shade next time! Be sure to check out this helpful tip sheet about gasket storage: https://www.mcwaneductile.com/upl/downloads/tip-sheets/bridge-installations-tip-sheet.pdf

Sincerely,

The Ditch Doctor

Dear Lost,

The best advice I can give you is: DON’T BE A SLAVE TO THE GAUGE! Far too many contractors make that exact mistake over and over again, landing them right where you are now, which is frustrated and short of the goal. Forget the pressure drop. That can be very misleading. The pertinent issue here is: HOW MUCH WATER VOLUME it takes to recover the pressure loss that you describe. What you’ve done so far is nothing more than pet the same dog over and over again and wonder why all it does is wag its tail. I do not mean to oversimplify, but it’s true. We need to EXERCISE that dog and see how it reacts. When the standard “proof” test doesn’t work out, it’s time to go diagnostic.

The best way to do that is to IGNORE PRESSURE and TRUST VOLUME. Pumping the line to three different and increased pressure values, (perhaps 200 psi, 250 psi, and 300 psi), waiting 30 minutes at each pressure, then recording how much water volume it takes to recover each pressure loss, will absolutely and reliably tell you if you’ve simply got trapped air or a matter requiring additional attention (such as a leak). The relative difference of recovery volumes can help identify the problem and the best way to go about resolving it. Once you have those comparable recovery volume numbers, email or call me back and together we’ll take the next appropriate step. This diagnostic test is based in centuries-old reality, and the simple yet reliable physical properties of fluid, along with the knowledge that air is compressible while water is not. If you disagree with that fact, dig up Archimedes or Newton and argue with them. When it comes to successfully testing buried pipelines, PRESSURE LOSS is just a hint, while RECOVERY VOLUME is the truth. Trust it. Pump it. But only do so three times. THEN CALL ME BACK! In just two more hours of your work, we’ll know what’s up, and it shouldn’t be your BLOOD PRESSURE! Be sure to check out this helpful tip sheet about hydrostatic testing: https://www.mcwaneductile.com/upl/downloads/tip-sheets/preparing-for-a-hydrostatic-pressure-test-tip-sheet.pdf

Sincerely,

The Ditch Doctor

Dear Charles,

Good call my friend! Bells must be clean prior to installing gaskets. AWWA C600 paragraph 4.3.3.2 does not refer to ice in particular but does mention ALL debris. This does include ice. In fact, the ice will actually reduce the ID of the bell. Problem #2 will arise if the gasket is displaced during installation, causing a leak. Also, if problem #1 or #2 doesn’t bite you, Problem #3 likely will, which is that most ice contains dirt or debris frozen within it. So, if by luck the gasket does not displace due to a crowded bell condition, as soon as the ice melts (and trust me it will), the joint is now faulty due to dirt underneath the gasket. Ice may be good in your drinks, but it never helps in a pipe joint! It makes me feel good that you are paying attention to detail and eating a good breakfast as well. You know they say it is the most important meal of the day. Stay warm, my friend!

Sincerely,

The Ditch Doctor

Dear Wally,

Can I call you Wally for short? I am glad to offer my support, even if I don’t agree with you on this one :) First, I would like to suggest that a different “C” word be used towards at least this Inspector. Contrary to your characterization of him as “crazy”, I would prefer you call him what he is…which is CORRECT! A fundamental truth in all rubber-gasketed ductile iron pipe joints is that FRICTION IS THE ENEMY.

This is especially true in the mechanical joints used in pipe, fittings, and valve connections. In fact, the more AWWA-approved pipe lubricant you use, the better. Put enough on there to deepfry those bubbas! Any extra will squeeze out, without a problem. Also, the lube is water-soluble, so it will safely disappear into the water when you fill and flush the line. If you put mechanical joints together with a dry (non-lubricated) rubber gasket, half of what you feel through the wrench is friction being built-up, as opposed to the torque that you want to feel. The problem is that, friction releases (goes away overnight), when the next morning rolls around, you’ve got an argument between two guys like, “Why didn’t you tighten this yesterday?” Another complicating factor is that if you don’t happen to notice that the “nuts and bolts” have loosened, you will certainly notice when the joints leaks after filling and pressurizing the line.

This is the chief misconception about ductile iron assembly, that lubricant makes the joint loose and slippery, when in fact, it’s exactly the opposite. Lubricating all sides of the gasket before assembly makes the joint tighter and keeps the joint water-tight for its entire design life (more than 100 years, on average). Not bad, huh? In addition, remember that you only want to use lubricant that is consistent with AWWA standards and that carries the NSF-61 designation as safe for contact with potable water. Crisco, Vaseline petroleum jelly, PAM cooking spray, shotgun grease, or numerous other things that might be “slippery” do not qualify them as pipe gasket lubricant. Don’t worry, I won’t ever tell this Inspector what you first thought of him or her. It will remain our little secret, and your reflective lesson that sometimes CRAZY is just….RIGHT!

All the Best Wally,

The Ditch Doctor

Dear San,

CAN’T is such a strong word! To quote the great Yoda (yes, Star Wars Yoda): “DO or DO NOT…there is no TRY!“ With pipe through a casing, there are simple DOs and DON’Ts that are well worth following. Think of a ductile iron pipeline as a chain with 18-foot links. Now, who in his right mind would lay a chain on the ground and TRY to push it somewhere? Fortunately, ductile iron pipelines and the joints within them are more resilient than a common chain.

The design of the joint, the impressive natural strength of the material, and the use of friction-reducing casing spacers with nylon-tipped skids, all add up to success, whether you push or pull the pipeline through the casing. In fact, I have found through the years that a combination of PUSH and PULL (call it a friendly tug-ofwar upon the pipeline) is the most reliable method of successful assembly of a pipeline within a casing. There is one last point not to overlook. Without the aid of backfill inside the casing, and presuming you follow the advice of pulling the line to some extent, restrained joints are a must for the pipeline within the casing. Glad you reached out, and please tell the inspector I said “Thank You” for caring that it gets done right!

Sincerely,

The Ditch Doctor

Dear Anxious,

Ain’t construction fun? Ok, now that you’ve stopped screaming at my first thought, let me help you out. To begin with, “those gaskets with the metal teeth in them” are REAL RESTRAINED JOINTS. In fact, in terms of holding a joint together with nothing other than “the power of those teeth”, these gaskets are the exact equivalent of any as-cast and fabricated “real restrained joint”. Both types of restrained joints are typically rated to 350 psi, which means (with safety factors involved) this provides lasting joint stability at levels of anywhere from 700 psi to 900 psi of actual internal fluid pressure, depending upon pipe diameter.

That sounds very REAL to me, and I’m sure you that and he would both agree. In fact, the primary instance in which fabricated restrained joints are superior is when excessive end-pull forces are involved, such as in horizontal directional drilling installations or long pipelines on steep or vertical alignments. The end-pull rating for fabricated restrained joints is often 25% greater or more than “gaskets with teeth” and fabricated joints adapt better to the sometimes-twisting forces of these installations. “Gaskets with teeth” are also not recommended for installations where repetitive vibrations or oscillation can be anticipated, such as on bridges. On the bright side, however, for the wide array of standard and buried installation scenarios, there is no waiting on foundry fabrication or delivery schedules when using “gaskets with teeth”. Simply place a “restraining gasket” (ours are called Sure Stop 350) into the bell of any pipe. Instantly, your previously unrestrained Tyton® pipe is transformed into a quickly and reliably installed FULLY RESTRAINED PIPE FOR LIFE! I would be glad to meet with you and the engineer in question if more information or discussion is needed.

Sincerely,

The Ditch Doctor

Dear Spinning,

Unfortunately, your situation is not so unusual these days.  It seems with the growing use of internal inspection cameras on pipelines in the past decade or so, there is just as much misunderstanding of what people think seeing versus what really is or is not there.  The bright lights used by these cameras and the confined spaces in which they are used, along with curved surfaces everywhere, is a perfect recipe for the birth of unintentional misinformation.  This is especially true with the small diameter pipes commonly used in many water and sewer systems. 

The bottom line is that many of the camera operators have little or no experience, from a manufacturing perspective, with the products they are inspecting, making it difficult for them to decipher real problems from false perception.  The "candy stripes" that you mentioned, also called spiraling in the paint or lining, are nothing more than the nature of the beast and can be seen in every centrifugally cement-lined pipe, given the right combination of lighting conditions and camera travel speed.  You see, the cement lining is deposited in the pipe  by a screw auger traveling the length of the interior while the pipe spins slowly.  It is then set in place and smoothed out by rotating the pipe at much higher speeds once the cement delivery lance is removed. 

This compacts the cement lining to a fantastic degree, yet does not diminish the fact that it was originally placed "like a long ribbon".  This is the same situation for the sealcoat inside and the pipe wall itself.  Should a Ductile Iron Pipe ever fail (under ridiculously high pressure, etc.) it would fail on the helix (along its unseen seam), much like a Pillsbury dough cardboard container when you pop it along the visible seam.  That's because the molten iron is delivered into the spinning mold inside a centrifugal casting machine. 

Don't even get me started on things some call "voids" or "misses" within a pipe that when they are dug up and examined are typically no more than meaningless surface variations in localized places along the lining, which cannot be avoided at times given the nature of the fluid cement when it is placed and set in the pipe.  To help your bottom line, and to preserve your working relationship with those who govern your projects, I would suggest involving an outside professional.  Such assistance is typically available free of charge from the pipe or fitting manufacturer with whom you deal.  That person can assist you in politely explaining the "that's not what you're seeing" situations to the inspector, to the engineer, or to others.  Ask your salesman or supplying distributor.  They can get you in touch with the person you need.

Sincerely,

The Ditch Doctor

Joe,

Sounds like you may be one of those guys who has put on a dress shirt and left half of it un-tucked. Not judging here but hey: Sloppy is as sloppy does, Joe. AWWA C105 Polyethylene Encasement for Ductile Pipe Systems clearly describes proper installation of poly wrap, including overlapping the poly and taping at both sides of the joint. This information is also backed up in the DIPRA publication for poly wrap installation. Furthermore, DIPRA recommends V-BIO Polyethylene Encasement. 

 Let us use an analogy that is typically well understood during my corrosion discussions. Corrosion involves electric current. If you were to touch a live extension cord that is intact, you do not get shocked. However, if you touch a cord that has any kind of defect or exposed copper wire, you will likely get shocked. A corrosion cell involves millivolts and micro amps compared to the voltage and amperage of an electric cord. Therefore, leaving an exposed bell or joint area may result in a shock when someone receives a call at 3:00am to repair a water leak. The actual time required to properly install Polyethylene Encasement is minimal and the results of proper installation are, without a doubt, outstanding.

My advice to you my friend: Do the job right today – sleep well tonight.

Later,

Ditch Doctor

Jacked,

OH my!  Seriously…OH MY! He is correct about one thing: pressurizing that line to 800 psi will no doubt identify the weak link. Ductile Iron Pipe is typically not the weakest link in the system. Hopefully this project does not include a section of pvc. You most likely will not get close to 800 psi with pvc in the system. The first thing to consider is if 800 psi is reality and, thus, necessary. There is a good possibility that re-designing the project may reduce the working pressure.

Of course, the engineering tools are available on the McWane Ductile Pocket Engineer at pe.mcwane.com. Another thing to remember is that Ductile Iron Pipe design is the most conservative used in the market. Ductile Iron Pipe joints may operate at pressures much higher than the rated pressure, largely due to the 2 to 1 safety factor and 100 psi surge allowance utilized in the design. Also keep in mind that your local McWane Ductile representative is there to assist with design specifics. Have another conversation with your customer and bring the pressure rating and your blood pressure back to manageable levels.

Later,

Ditch Doctor