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CLH showing different cold setting values after hydrotest

CLH showing different cold setting values after hydrotest

CLH showing different cold setting values after hydrotest

(OP)
Hi

I have a peculiar problem. I have a pipe with some 10 CLHs. Before hydrotest of line, they were all checked for load and cold setting value and found to be OK? Now hydrotest is done and water is removed. Half of the CLH are showing different cold setting and load is original?

What may be the reason and what can be done to set it right?

RE: CLH showing different cold setting values after hydrotest

It was the first time they were loaded, and they just "settled in". Don't let it worry you; the 'Cold' setting is a 'best guess' that tries to put the pipe support onto the 'Hot' setting when the system is running at temperature. As soon as your new piping is in normal operating conditions, you need to inspect the CLH's and see if they are at [or very nearly at - these are Constant Load Supports] their 'Hot' settings. If any are significantly off the HOT, adjust them as needed.

RE: CLH showing different cold setting values after hydrotest

Please don't double post - you should know better than that.

As the other response says, if you didn't lock your supports during the hydrotest (you don't say if you did or didn't) then the supports will have been maxed out and the piping moved all over the place. However so long as it is still in the range then you are probably OK, but you may need to re-adjust some of them and double check loads and movements on any critical nozzles or rotating machinery.

If you put locks in, make sure you relieve the pressure first and don't hammer them out like one guy did on me.... Took another day to get the piping all lined up again after the pipe maxed out the hanger

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: CLH showing different cold setting values after hydrotest

(OP)
Hi...
The hydrotest was done with locks in place.
Dont know what happened during the hydrotest..


RE: CLH showing different cold setting values after hydrotest

Well even with locks in place, the pipework has been subject to lot more weight and stress than before and has simply moved about a bit. As dueweh 6 says, just run it up and if it is wildly out then adjust it.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: CLH showing different cold setting values after hydrotest

This type behavior from the piping and spring hangers can be expected in case the piping and/or hangers was not designed for the hydrostatic test on steam and gas lines, or required temporary supports were not used if assigned. Therefore the pipe can change the shapes between spans and unload some hangers while loading more the others during the hydrostatic test.

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