One fundamental aspect of fluid movement is thrust force, which is created when a flow path bends, tees, wyes, dead ends, or reduces. In order to counter the unbalanced forces that are created at these locations, the pipe and fittings must be mechanically restrained from separating, welded together, or otherwise fixed from movement.
Push-On Underground Joints
One popular method of preventing pipe separation for underground pipe is gasketed push-on joints for underground pipe that do not have special locking devices, but permit pipe to be installed in any direction and at any point along the path.
Role of Thrust Blocks
In order to prevent the internal pressure from forcing the pipe and fittings to separate, blocking (or "thrust blocks") provide stability and allow the surrounding soil to accept the thrust force from the pipe assembly.
Soil conditions vary in its ability to handle forces. Thrust blocks allow a narrow point force to be spread and distributed across larger areas of soil down to a pressure that the soil can bear.
Thrust blocks take the point force created from the change in direction of the water (static and dynamic)
and distribute that force to the soil.
The tool below is an early part of a larger effort to determine the thrust block detailing. In the coming weeks, I would like to add block height, width, volume and visualizations to detail the parameters.
Don't see the tool below? Click here.
For those who work routinely with thrust block and their calculations under NFPA 13, what else could I add to this tool to be more useful? Comment here or email me at email@example.com if you have any ideas.
The Toolkit - Launches Next Week
The long-awaited Toolkit launches next week - complete with this and other tools in a downloadable software package. Be the office hero with quick and printable tools, as well as access to the Sprinkler Database and the ability to post questions to users on the Daily Discussion forum.
Look out for news regarding the launch next week.
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Joseph Meyer, PE, is a Fire Protection Engineer in St. Louis, Missouri. See bio on About page.