Hi all,

Please show me how to calculate or find hydro-test load for spring support (variable hanger, contant hanger).

BR
HOKI

During the hydrotest,the spring hanger is locked therefore is like any other rigid support.

As a thumb rule, Hydro test load is load is taken as 1.5 times of operating load.But this may not hold always true due to system imbalance & hydro load may exceed this value.

Spring vendor needs to be informed about this load so that he can design travel stops accordingly. If this is not possible, then there are other options like replacing spring by temporary support during hydro-test etc etc.

Hope this helps.

SJ,

I do not agree with your statement in the first paragraph. However it is correct for the hydrotest pressure. I guess you meant for that.

Everything depends on SG of the contents. If you run piping with law SG (steam or gas) you need to consider the test liquid SG into consideration, and spring hangers need to be gagged as you expained in the second paragraph. However replacing the spring hanger with a rigid support is not economical, may be left as it is without noticing during the commissioning, and therefore is not preferable.

In case the SG of the content is almost equal to/larger than the SG of test liquid this will be considered in the analysis within the displacement/load acceptable limitation in accordance with the code, so you do nothing for the spring hangers.

Regards,

Ibrahim Demir

Ibrahim,

You're right in your own way...!!! But what I meant to say was the test load is considered generally 1.5 times the Normal/Rated Load of springs (though this varies from vendor to vendor)!!

I guess I should've used the word Normal in lieu of Operating load.

Say for eg; Carpentar & Paterson Springs are normally designed to take care of test load upto twice the normal/rated load. If this limit is exceeded, then special design is required for Test load.

Anyway , thanks for highlighting this!!

Dear sirs, as Ibrahim wrote, normally codes states that pressure in hydrotest is about 1.43 or 1.5 design pressure.
SJ is right as well, but please be carefull about considering loads on hydropressure 1.5 times loads on operating condition.

Let's make an example. The weight of 1 meter of 24" pipe sch. std, without insulation is about 141 kg with gas, 415 kg with water. So in this case we have the hydrotest loads 3 times the ope loads.

The bigger is the pipe, the bigger is the difference between weight of pipe full of gas and full of water.

Of course remember that when you consider weight under hydrotest, insulation should be removed.

Corrado Vannella

Mr. Richard Ay and Forum members,

Please tell me where i can find the option to "lock the spring support in the hydrostatic case" in Caesar-II load case.

here

Thankyou Danb...