Manuel Sanchez is the utility supervisor for the Town of Gilbert, AZ, a town of just under 250,000 located southeast of Phoenix within the city’s metropolitan area. Gilbert has grown at an extremely high rate, growing at an average annual growth rate of nearly 13% from 1980 to 2010. The city’s water infrastructure is relatively new, featuring a variety of piping materials including PVC, AC and ductile iron ranging from 4 to 48 inches.

The Situation

While most of Gilbert’s fire hydrants have piping that is 3.5 feet underground, older fire hydrants have been buried closer to 6 feet. As the infrastructure for these hydrants deteriorated and needed to be replaced, the repairs presented safety issues given the depth of the pipe. 

Each time crews needed to reconnect the fire hydrant to the main line, shoring needed to be put in place to help prevent cave-ins. In addition, under-digging was needed to allow space for tightening the bolts given the small space. Sanchez was looking for a way to minimize time in the ditch and have the job done quickly so his crew could go home or move on to the next repair. Finding a way to make fire hydrant repairs quickly given the depth of the trench and the limited space became the primary challenge for the project.

The Solution

In Sanchez’s search to replace the fire hydrants quickly, he found the Hymax Grip. With only two bolts to tighten, he recognized the time savings it could have. 

“Reducing the number of bolts to tighten makes a huge difference in getting the job done quickly,” Sanchez said. “Also, when you don’t have to dig underneath to reach bolts close to the ground, it means that the ditch is more stable with a lower chance of cave-ins. The space needed to repair fire hydrants is relatively tight so anything that can make the job easier is a real plus.”

Three Reasons Why Hymax Was Picked

1. Ease of Installation

The unit features a radial closing mechanism that holds pipe tightly in place during installation to give the utility installers full control over the gap between pipes. Unlike wedge-style restraints that point-load and weaken the pipe, this restraint’s chain gave circular restraint around the pipe. As the pipe applies axial pressure, the Grip chain increasingly tightens around the pipe to prevent pullout.

It has a universal gripping system designed to restrain metal and plastic pipes and has a transition capability of up to 1.1 inches. This meant the utility had more flexibility to repair a variety of pipe sizes and pipe materials that could be found in the ground. 

“When you’re working with pipes and connections that can be decades old, it’s good to have the flexibility to fit and secure a coupling with whatever pipe sizes you might find,” Sanchez said.

2. Durability and Flexibility

The Hymax Grip also gave the utility installers the flexibility to connect to out-of-round pipe shape (up to 0.16 inches). The product’s radial closing design and sealing system provided room for the pipe and coupling to not be perfectly aligned while still ensuring a secure connection. 

“Having that room to make the connection without the pipe and coupling being perfectly aligned or round helped a great deal,” Sanchez said. “Again, the tight space leaves little room for error so any edge you can find makes a difference.”

The coupling’s dynamic deflection also reduced the risk of damage and cracking due to ground shifts. The patented gasket effectively transforms the pipe joint into a flexible connection and allows dynamic deflection of up to 4 degrees per side. The Grip is made of highly durable ductile iron and can withstand working temperatures of up to 125°F. It also meets or exceeds standards AWWA C219, NSF-61 and NSF-372. Overall, Sanchez found that the product’s features offered the utility a solution that would likely reduce future repairs and maintenance in the long term.

3. Advanced Anti-galling

The nuts and bolts for this system have advanced anti-galling using a dry treatment process with molecular anti-galling based on embedded zinc to prevent galling. This enables repeated bolt tightening and eliminates the need for grease, preventing dust and dirt build-up. The fusion-bonded epoxy coating also helps insulate against corrosion.

Conclusion

The town of Gilbert has installed more than 100 Hymax Grips in the last three years, and continues to use the product in any situation where pipes need to be restrained.

“It’s very convenient to have a product that has the restraining mechanism within the product ready to use,” Sanchez said. “For fire hydrants, this application is particularly valuable given that the work needs to be done within a trench with limited space. In these situations, it’s about getting the job done right and getting out so we can move on to the next job or send workers home.”

Author - Stan Pachorek is territory sales manager for Hymax, a Mueller brand.

Click here to read the full article in Water & Waste Digest