“Four Common Misconceptions About Specifying No-Hub Fitting Restraints”

Not using no-hub fitting restraints can lead to lawsuits and property damage, which ultimately can be more costly than installing a proper restraint system at the get-go.

by Jim LeStage

Holdrite no-hub fitting restraintsIf you were to visit commercial job sites—like parking structures or the garages of high-rise buildings—that were built during the last decade, you’d probably notice exposed no-hub cast iron waste piping, but chances are you wouldn’t see any restraint systems in place.

When designing aboveground cast iron hubless piping systems, many engineers are held back by their preconceived notions about using no-hub fitting restraints, which can lead to potentially disastrous circumstances. Instead, it’s important to understand the most common misconceptions to inform your decisions for future builds.

Following are four of the most common misconceptions about no-hub fitting restraints and the reasons why they are inaccurate.

Misconception #1: Building Codes Don’t Require Them

In the past, no-hub fitting restraints weren’t specifically addressed by the International Plumbing Code (IPC). The code simply directed installers to follow the manufacturer’s installation requirements. Since 2009, however, the IPC has stated in Section 308.7.1 that a cast iron soil pipe greater than 4 inches shall be restrained at all changes of pipe diameter greater than two pipe sizes and at all changes of direction with braces, blocks, rodding, or other suitable methods as specified by the coupling manufacturer. Unfortunately, even with the update to the IPC more than 10 years ago, some inspectors still don’t know the requirements for restraints, leading to building code violations and costly mistakes.

Misconception #2: They’re Too Costly to Install

It’s too costly not to install them. Fitting restraints keep the pipe together under thrust conditions. If restraints aren’t present in a no-hub system and thrust force increases to more than 10 feet of head, the pipe is at high risk of separating from the fitting. If that happens, it can cause expensive property damage.

The Indianapolis Colts’ new stadium was widely regarded as a marvel in design when it was unveiled for public use in 2008 but has since become a prime example of how failure to properly install no-hub systems can prove disastrous. While working on the stadium, a series of delays forced the plumbing contractor to rush completion. A major rainstorm hit just after expensive IT equipment had been moved into the stadium’s basement, and three of the rainwater leader system’s 15-inch no-hub cast iron rain leader joints failed, flooding the basement and ruining the valuable equipment.

Similarly, the University of Pennsylvania Health System’s Translational Research Center was hit with a massive rainstorm that dropped about 5 inches of rain per hour. This deluge caused significant head pressure in the piping systems, and without no-hub fitting restraints in place, a section of the system buckled. An unrestrained section of 12-inch rainwater drain piping separated at a double-offset fitting, fell through the ceiling in the fifth-floor stairwell, and caused the building to flood.

In both instances, the lack of no-hub fitting restraints led to lawsuits and property damage, which was ultimately more costly than installing a proper restraint system at the get-go.

Misconception #3: They Don’t Need to Be Included in Specifications

Because the IPC does not specify exactly how pipes and fittings need to be restrained, many installers get creative. For example, riser clamps are commonly used in field-devised restraint systems for hubless pipes and fittings. However, these clamps are not designed as a thrust restraint. The do-it-yourself approach uses untested methods and materials, and the reliability of these rigs can be difficult or even impossible to assess.

Before the issue of using field-devised methods was addressed in the IPC, some plumbers only restrained the pipe and fitting during system testing. Once the system passed the test and the inspector was satisfied with the installation, they would pull the plug, get rid of the shackling, and assume the system was complete.

Unfortunately, many installers still rig a restraint system until the test is over today. The only thing worse than a field-devised restraint is no restraint at all—which is what you get when the field-devised restraint is treated as a temporary measure.

Misconception #4: Engineered Restraints Are Time-Consuming for the Installer 

It can take anywhere from 30 minutes to an hour or more to measure, cut, and fabricate a field-devised system. If a plumber is taking the time to fabricate a do-it-yourself restraint system for each coupling on a 20-floor building, the installation cost can be significant.

Contractors can save 30 to 50 percent in total installed costs by opting for engineered solutions, such as HoldRite’s engineered #117 series restraints. Instead of creating a makeshift pipe restraint, this solution installs in minutes without any onsite cutting, bending, measuring, or modifications. It provides a convenient, lab-tested, third-party engineer-certified solution that has made makeshift field-devised pipe restraints completely unnecessary.

With a better understanding of the common misconceptions around no-hub fitting restraints, more engineers and contractors can finish jobs on budget, on time, in code, and with minimal risk.

To learn more about HoldRite’s engineered #117 series restraints, please visit holdrite.com.

About the Author

Jim LeStage is the Specification Sales Manager at RWC—a market leader and manufacturer of water control systems and plumbing solutions for residential, commercial, and industrial applications.

The opinions expressed in this article are those of the author and not the American Society of Plumbing Engineers.

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