Hi Fellas,

I look forward to hear from people on their approach to install Spring hangers near strain sensitive equipment after hydro testing. Please note the springs has cold load as set load. Few points to touch would be when releasing the lock-nut, how do you make sure equipment is not damaged due to large transfer of forces and moments (if nozzle is loosely bolted for alignment checking). also how you do the cold load setting - using turnbuckle or nut above spring piston plate?
Would appreciate response from someone who has actually done it in the field, as already have heard different stories from design people (speculative but not firm)

Cheers,

1.If you are looking for someone who has field experience, asking support vendor would be better choice. some of the support companies provide field adjustment or inspection. You've already mentioned that you heard from other designer, so not going to write basic stuffs like alignment check etc.

2. Adjusting spring cold load, you should ask vendor too. The method may differ from vendors, and they usually provide manuals for that.

3. As you mentioned that using 'cold load' setting, I have a query regarding spring variability. Could you share how you determine the spring support's variability? Is it [(cold load-hot load)/cold load]?

Hi CaesarIII,

The vendor as usual has given a general procedure in a bid to push their ridiculous site assistance services costing us arm and leg. See attached procedure.
Yes as cold load is our base set load, we will use (cold-hot) / cold to calculate variability. At the moment we would be happy to keep it below 20% but may allow upto 25% inline with MSS-SP.

Yes, it's not that specific.

As far as I know, variable spring bottom type can be adjusted as turning the neck part and hanger type, turning turnbuckle do so.

For constant spring, there will be devices that can modify spring load. MSS SP-58 note that 10% of adjustment at site can be done.

Of course, stress engineer have to check its safety by comparing set load and vendor catalogue.

API RP 686 does state few practices for alginment, hope that helps.