Cold Load for Spring Hanger

[marchieV]

Dear All,

​

I just want to know if an existing spring hanger can be reset with different cold load? Because the EXISTING cold load is 12978 N but upon changes in the line the spring cold load increases to 14653 N. I already checked the spring table and still the hot&cold load were within the allowable/range.

Thank you.

Sincerely,

marchie

 

[XL83NL]

I believe that when it's within the range of the hangers capabilities (travel range not exceeded etc.) then yes.

 

[marchieV]

XL83NL,

Yes, it is still within travel range/load. But I think the cold load was usually set upon installation. Please correct me if my information is incorrect.
What will be the purpose of cold load if it can be changed/reset? Aside from checking the range/variability(%).

Sincerely,

marchie

 

[XL83NL]

The purpose of having a changeable travel range of a spring hanger is that it allows to have only few hanger models for a large range of loads and travels, rather then a unique version for each travel/load combination. The cold load is indeed set before installation by a special device which the MFR uses for this purpose (some sort of pre-tensioning device).

 

[DSB123]

XL83NL,
I think you mean pre-compressing device!!!

 

[XL83NL]

Haha, yes, whoopsie

 

[Ehzin]

Marchie,

On that last question, the point of setting to the cold load is that when installed and chocks removed it will be at the conditions it was designed for, aside from minor adjustments. And it gives a marker on the plate to return to if minor adjustments were needed in the future.

If the preset cold load was at an arbitrary 50% mark of the total travel, in some cases you would have to overload/"oversupport" the pipe to properly remove the chocks and then loosen the load to reduce it back to the intended cold load for your service. This could possibly overstress connected equipment or connections during installation. Providing this to the vendor they set it exactly where needed to adequately support the deadweight of the pipe/components. When the pipe is supported by the hanger, if designed and specified properly, you should be able to easily remove the top chock from the hanger.

The last advantage of a preset cold load is that it is a calibrated value. That spring is exerting virtually that exact cold load when installed if no travel is observed. Any adjustments in the future are done somewhat relative to this calibrated value.

Thanks,
Ehzin