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Combination of thrust block and restraint thrust system

Combination of thrust block and restraint thrust system

Combination of thrust block and restraint thrust system


thread164-292032: Why both restraints and thrust blocks?: Why both restraints and thrust blocks?

Reference to the previous thread and subsequent discussions regarding concrete thrust blocks with thrust restraint design and the inputs from waterpipe, I am interested in knowing about the design details related to using a combination of thrust blocks and restrained joint system, as mentioned in Unified Approach to Thrust Restraint Design, JOURNAL OF TRANSPORTATION ENGINEERING, ASCE / JANUARY 2007.

The piping system we are constructing is Ductile Iron push on type. we have separate designs for thrust blocks and restraint design but it would be interesting to know how a combination of these both can be utilized.

RE: Combination of thrust block and restraint thrust system

I didn't see it mentioned in the other thread, but on a 6 inch hydrant and lead replacement (including hydrant isolation valve, hydrant replacement and lead to the main tee) use of both thrust blocks and restraints can be a benefit as you can (with peace of mind and confidence) pressure test, flush and sample the hydrant that day rather than (with no restraints) waiting until tomorrow after the thrust block has set up enough. For the price of the restraints, it saves some time and provides extra confidence in the quality of the build (eg. no leaks). If this asset was being replaced in the event of an emergency water leak, then it might save a day on your boil water advisories process and inconveniences to the system customers as it may apply.

I would think on vertical bends (especially on larger mains) both restraints and thrust block would be utilized for that extra "confidence" as well.

RE: Combination of thrust block and restraint thrust system

Thrust blocks and restrained joints are alternative methods of providing thrust restraint.

Thrust blocks are no longer considered to be good piping practice. This is because thrust blocks are normally paired with undetermined soil properties and poor construction techniques. These uncertainties lead to unknown performance parameters for the piping system.

The reasons for not using thrust blocks are explained here:


The use of mechanical restrained joints instead of thrust blocks would provide an easier, more predictable and safer installation.

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