Constant Spring Hanger Setting During Commissioning 3

[adam08285]

Hi guys,

For constant spring hanger (lug attached to a structure case), we will carry out cold setting as per stress designed during cold condition before the piping is put in service. In commissioning stage, which by right the locking pin has been removed, the supported pipe will travel up to a certain level.Based on my understanding, if the travel point is till lower the hot point, we will not do anything to the spring and leave it as it is. My question is, what should we do if the indicator go beyond the hot point? I mean exceeded the hot marking of the spring hanger. Hope anybody can give me some lights on this matter.

 

[europipe]

adjust the rod, so that the indicator is in the middle.
It is a constant load support, so the force remains the same.

 

[XL83NL]

- check if there sufficient travel left in the hanger. if there's too little travel left, the pipe may want to move up but is jammed. so hold periodic inspections to see how the travel evolves over time.
- review your stress analysis. your design may be wrong, or other supporting structures may cause negative influence. find out the causes, and adjust accordingly.

 

[racookpe1978]

Good points above. Follow them. In operation, at nominal hot temperatures of everything, the constant force hanger should be "near middle" of the hanger movement.

Almost all of the time, the pipe hangers are sized and positioned so no hanger is "bottomed out" nor "top crushed" when shutdown. Not always, but almost always. If you are seeing that, check everything as mentioned above: This kind of finding is why they call it "testing" and "commissioning" rather than "startup" 8<)

You may have to replace a hanger, or adjust a hanger upstream of downstream of the one being crushed too tight. I had one case where the hangers were fine, but the structural steel I-beam between the hangers bent.

 

[adam08285]

Thanks guys for your knowledge and experience sharing.
It would be helpful for me and others as well.