Thrust Blocks Required ?

[hgordon]

Hi there,

I am looking to install a 150 PE main underground with heat-fused welded joins , the PE elbows up at both ends and termiantes near ground level.
Then a flanged connection will join steel pipe from a pump at one end to a valve room at the other end.
I am wondering if I need to concrete any of the pipe for thrust force protection?
I understand that welded PE pipe is monolithic and should not need thrust blocks on its underground elbows, however the steel pipe flange connection is that restrained enough?
Also the steel pipe to steel flange adapter is a viatulic grooved coupling - not welded.
Please refer to attached PDF.

Thanks!

 

[LittleInch]

I don't think so. The steel flame adaptor isn't under axial stress so should be ok.

You can also get pe flanges which have better axial connection.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[hgordon]

Awesome,

What about a fire pipe system downstream of a pump. We try to manage thrust forces (above ground) with wall/floor braces on pipe elbows and other direction changes.
The worst of the thurst force comes from the hydrostatic pressure acting at the bends - acting to push the bend fitting off the pipe. But vitaulic grooved couplings are restrained connections, holding the bend in place , when some flow is added, typically no more than 4-5m/s the hydrodynamic forces contribute to the pressure thrust forces but almost insignificantly.
Hence with restrained grooved couplings pipe runs, I do not see any need for thrust bracing?? So long as the pipe weight is being supported/hung properly?
But seismic bracing is another story..
I suppose my confusion is does thrust forces in a pipe run act to move the pipe as a whole or act to push the pipe apart?

 

[hgordon]

I think fire pump discharge pipe movement/shaking/vibration is not so much thrust forces (except for pump initial startup to pressurize the pipework) but more to do with the turbulence the elbows see during flow conditions - with higher velocities creating more shaking.
Because the grooved couplings prevent thrust forces having any affect, i.e. I have never seen pressurized, no flow pipework shake...