Spring hangers hot load adjustment

[uaepiping]

Dear Experts,
In an existing piping system having three generators, structural brackets supporting spring hangers failed. Stress analysis was done again and some new supporting points were identified for providing spring hangers. The system works on two generators running and one standby. Also the generators have working cycle of 36 hours whereby temperature ranges from ambient to 280 °C. We have received the new spring hangers. Maintenance team has already installed the new structural members and put the spring hangers in place. Now the question is how to adjust their hot loads on these variable spring hangers?
Should we wait for the one generator (at a time) to reach maximum temperature and then adjust the hot loads for piping connected to that generator? Then should we adjust the cold loads on spring hangers on the piping connected to standby system?
How to go for it?
Any suggestions please from your experience?

 

[racookpe1978]

My experience says you MUST get an EXPERIENCED spring support technician in (from your spring supplier) to LOK AT each spring and each generator BEFORE you adjust anything.

DO NOT DO THIS YOURSELF, if you're not going back to the original weights, pre-stresses, and final stresses on your high pressure pipe drawings.

 

[saplanti]

You have mentioned that you have done a stress analysis and identified new supporting points with spring hangers.

To be able to buy spring hangers you need the following for each hanger:

1. Spring rate (or travel from cold installation location to hot operating location - the travel shall be 25% of the maximum allowable travel of the selected spring hanger in accordance with the code)
2. Hot operating load
3. Cold installation load

If one of them is missing you cannot buy the correct spring hanger.

If you have not given all these you need to ask the pipe stress analyst to provide the information if you have bought the right spring hanger (sometimes spring hanger supplier takes the ancillary weights into consideration and change the spring characteristics. In this case the stress analyst shall be informed about the changes for the acceptance of these changes).