Below are some of the frequently asked questions and answers regarding our Ductile iron pipe products. If you need more product information, or would like to speak to a specialist, please submit a request.

  • What is the difference between Thickness Class and Pressure Class Ductile Iron Pipe?

    The basic difference is a change in terminology in how Ductile Iron is classified under the specifications. The design and manufacturing requirements have not changed since 1976. The difference between the two is the thickness classes have no particular meaning, while the pressure classes define the actual working pressure of the pipe. This allows the end user to specify a pipe that meets the design requirements of a given pipeline. Ductile Iron is still the most conservatively designed pipe in the water works industry.

  • What is gauged pipe?

    All pipes are checked to insure that the spigot end, bell, and socket comply with requirements of AWWA C151/A21.51. Gauged pipe is pipe which has physically been checked to insure the entire length, to within 2 feet of the bell, falls below the maximum O.D. This allows for easier installation of fittings on this pipe. We mark this pipe with a green mark on the bell of the pipe. It is recommended that all pipes be checked in the field with an O.D. tape prior to cutting any pipe.

  • Are all Ductile Iron Pipe push-on joint gaskets interchangeable?

    No. There are two types of joint design for ductile iron, Tyton® and Fastite®. You should verify the manufacturer of the pipe and use gaskets provided by the manufacturer.

  • How much deflection is allowed for ductile iron per joint?

    The allowable defection varies from 2 to 5 degrees depending on the size and type of joint used. See our deflection charts for more information by clicking here.

  • Are small cracks in the cement lining normal?

    Yes. These cracks (sometimes resembling a spider web) are caused by the fact that iron and cement have different thermal expansion coefficients. As the temperature changes prior to installation these cracks can occur. These cracks are normal and are of little concern due to a process called autogenous healing. Simply stated, autogenous healing is the ability of cement to heal itself. In the presence of moisture, cement extrudes calcium hydroxide which, upon exposure to the atmosphere, is converted to calcium carbonate which seals the crack. These calcium carbonate crystals are formed when the carbon dioxide in the air and water carbonates the free calcium oxide in the cement and the calcium hydroxide liberated by the hydration of the tricalcium silicate of the cement.

  • How do you repair cement lining in Ductile Iron Pipe?

    Cement mortar lining can be repaired following the instructions in ANSI/AWWA C104/A21.4 "Cement-Mortar Lining for Ductile-Iron Pipe and Fittings for Water". To make the repair first the damaged lining needs to be removed to the metal leaving the edges perpendicular to the pipe wall. Second, prepare a stiff mortar that is one part cement to two parts sand. Third, trowel the mortar over the repair area so it is smooth with the existing lining. Fourth, keep the repaired area moist by applying seal coat over the repaired area.

  • When is it required to use Polyethylene encasement?

    In most soils Ductile Iron needs no additional corrosion protection. However, polyethylene encasement should be used when the soils on the project are determined to be corrosive to Ductile Iron Pipe using the ten point soil evaluation procedure. This procedure is included in the Appendix to ANSI/AWWA C105/A21.5. For assistance with this procedure please contact your local sales representative or DIPRA.

  • How much pipe is a truckload quantity?

    The number of pipe per truckload varies depending on the size and class of pipe. See this helpful blog for more information.

  • When bronze wedges are used, how many are used per joint?

    When bronze wedges are specified you use 2 per joint on 3" through 12" pipe and 4 per joint on larger diameters. Each wedge is driven into the opening between the plain end and the bell until snug. When four wedges are used, they are inserted side by side, in pairs.

The Ditch Doctor

FALL 2022

Dear Ditch Doctor,

I read a previous “Ditch Doctor” and now understand that Resistivity generally has more influence on corrosion than pH levels. Clyde says the definition of resistivity is one pipe is more “resistive” to corrosion than another. This sounds good, but I’m not convinced Clyde is 100% accurate, although Clyde does know the quickest route to the local sub-shop.


Rita from Rialto

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.


Ditch Doctor

Dear Ditch Doctor,

We are installing restrain gaskets in our Tyton® joints when restraint is required. My operator is telling me that “wiggling” the pipe when he is pushing/homing the pipe is the best way to install the pipe.  Sounds like some dance from the ’60s.  This wiggling has me wondering and wobbling about.

Whoooo, help please. 

Walter from Winnemucca


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 @, 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!


         Ditch Doctor


Dear Ditch Doctor,

 I’ve been having an ongoing “discussion” with both the onsite project inspector and my pipe crew. We are trying to establish a simple and reliable way of determining in the trench when the post-assembly deflection of a joint has reached the maximum recommended amount. It’s almost impossible to physically “measure” the amount applied, given the ever-changing geometry of a trench. We, of course, want to follow all guidelines and avoid creating any deficiencies in the finished pipeline, but this never-ending debate on deflection is becoming quite aggravating. Please, if you have any suggestions, share them with us!


Living Within Limits in Laconia

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!


The Ditch Doctor.

Dear Ditch Doctor,

 We have an upcoming pipeline project where it is very possible to encounter some polluted soils, mainly areas where old gas stations were demolished years ago. We are concerned that contaminants could somehow infiltrate the new waterline over time. Is there a way to reliably prevent this?


Worried in Walla Walla

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.


The Ditch Doctor

FALL 2021

Dear Ditch Doctor,

Out here in the western United States we wind up with a lot of pipelines installed up or down serious hills, dare I say mountains as well? We are good at the construction part, yet time after time we struggle with getting a satisfactory post-installation hydrostatic test on the pipeline, especially with inclined installations. Often the pipeline drops anywhere from 20 to 50-psi on the gauge and can do that several times or more until we take some sort of drastic re-do/re-start on the test procedures. 

Rarely is there ever a true leak involved, we just seem to “battle the gauge” with repetitive pumping, draining, refilling, blow-offs, and other stuff until somehow wham, it passes! Often the pipeline drops anywhere from 20 to 50-psi, far more than the 5-psi allowed by the AWWA standards, so we never even get the opportunity to check for “recovery allowance”, i.e. part 2 of the AWWA hydrotest. Is there a TRICK I’m missing, or is just that TREATS don’t exist in this line of work?


Harried Halloween in Hayden, CO

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!


 The Ditch Doctor


Dear Ditch Doctor,

Between fighting the snakes and rain, we are attempting to finish this job. I noticed the other day that my operator, Judd, appears to be using more force to push/home pipe when we are using Sure Stop® restraint gaskets. Judd says he could use less force if he wiggles the pipe as he is pushing home. Wiggles, giggles and snakes — I just want to get the work done! What do you think?

Roger from Rawlins

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 Ditch Doctor,

My little brother, Ron, will be installing a Horizontal Directional Drill section of a project. He says the spec calls for TR Flex® pipe, but he is about 400 feet short. Ron thinks he can use Sure Stop® gaskets for the remaining 400 feet, but I’m not so sure. Should I be concerned for my little bro?

Rick from Riner

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!

Thanks for watching out for your bro,

Ditch Doctor


Dear Ditch Doctor,

We are installing Tyton® pipe with restraint gaskets, following every detail for proper installation. We are supposed to pull out on each joint to lock in the restraint, correct? Is it okay if the pull-out is 1.5 inches before the gaskets lock? I also noticed some Fast-Grip® gaskets at the jobsite. Fast-Grip gaskets work in Tyton bells, right? Brent tells me to stop bugging him and go to lunch. I can’t possibly eat with this much stress. Help!

Harry from Hadley

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.

Later man,

Ditch Doctor

Dear Ditch Doctor,

Freddie continues to tell me his guys do not need to use an outside diameter (OD) tape to check pipe prior to cutting. Freddie says the pipe pieces marked green are the “super-duper good pipe” and his guys don’t need to waste time checking pipe. I just don’t get it. I have watched his guys spend close to 30 minutes cutting a 24-inch pipe and then see them struggling to assemble the pipe with a restraint gland & MJ 90. Am I missing something? If so, what? Because I just don’t understand. What kind of advice can you offer?

Cindy from Cimarron

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?”

Happy cutting, Cindy,

Ditch Doctor


Dear Ditch Doctor,

We have a situation. We need to field cut the bell from a 36-inch pipe, but there is a 6-inch welded flange outlet 7 inches from the cut location. We can cut the pipe and make a connection with an MJ valve, right?

Pepper Pete in Pottsville

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.

Later man,

Ditch Doctor

Dear Ditch Doctor,

Installation time for these 30-inch bell restraint harnesses is crazy long, man. It has been raining off and on for a month, and we are falling way behind on this project. I also can’t get the firewood cut at home when I’m working all this overtime! Is there a faster, easier, better product we can use to speed up this process?

Freez’n in Farmington

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