About hydra test

Dear all,

In one piping model, some part of the piping need hydra test, some part of the piping needn't hydra test, such as the pipe after bypass valve to condenser.

but in CII ,it seems that you can't set one part of the piping have hydra test, meanwhile let the else have no hydra test.

can CII modify to make it more easy to use in this aspect?

Best Regards,

The best way to accomplish this now is to set the "hydrotest pressure" to zero where you don't need it.

Assuming you adjust the fluid desity to suit?

Yes.

Richard

To set the hydra pressure to zero where i don't need it will not solve all the problem.

The software will still think there are water in all the piping, including the part where hydra pressure is zero,
so what changed after you set the hydra pressure to zero in one part of the piping:
1.the axial stress change to zero in this part.
2.the hoop stress change to zero in this part.
because this two stress are caused by water pressue.

what are still the same:
1.the bending stress in this part.
2,the restraint values in this part.
because this two are caused by weight of water .

Best Regard,

Which is why you set the fluid density to zero
for the portion which is empty.

(zero density=zero weight)

superpiper,

sorry ,i don't know what you mean.
fluid density? i think it means the density of the material which is transported in the piping.
my piping is a steam piping,so i let the fluid density blank.

I think the fluid density have no relation to hydro-test.
So ,i can't know your meaning, can you be kind to explain it more detailly ,
thanks!!

The 'Hydrostatic' test case is usually when we fill the pipe with water and pump it up to x bar to test for leaks.
So, normally, you would spade off equipment before doing so and test ALL the pipework.

Sometimes on long lengths, this is done in stages
between valves.

I can't think of a situation where 'some'of the pipework will not be tested except for atmospheric vents.

By the way, i usually assume density of 1SG for small steam pipes as these can backfill if valves close or because of low loads.

Dear superpiper,
you say there are no such situation:
some of the pipework do not need hydrotest.

Let me tell you an example:
In power plant which burning coal,
Usually the HP steam piping,
HP bypass to
CRH　steam piping and the CRH steam piping are modeled in one model,but the HP steam piping ususlly need hydro test, and To HP baypss piping,
the portion before HP bypass valve also need hydrotest, but the protion after the valve and the CRH steam piping usually do not need hydrotest because the diameter of CRH piping usually big,if do hydrotest, all the support need to be designed to satisfy the water weight, it will be a waste of steel.

Ok.
Save as seperate model (HP test only)and adjust fluid density to suit

Dear superpiper,

I still think the fluid density have nothing to do with hydro test.sorry!

If i have a steam piping ,fluid density is the density of steam,
why ajust the fluid density?
would you be kind to detail this,

Thank you very much!!!

whats your definition of a hydo test?

Hydro test:
As you have said:
fill the pipe with water and pump it up to x bar to test for leaks after installion.

yes,This is hydro test

Hydrotest use water, though the piping may transport gas or other material in normal operation. so in CII , we input fluid density ,
fluid density is the density of gas or other material which is transported.

Oh, I may finally get what you mean,
you may mean . ajust the fluid density to zero,
meanwhile set the HP pressure to zero,

then Load case:
L3:WW+HP(HYD)
L4:W+HP(HYD) ---- HP in some part is zero
if you want to see the stress and restaints in the portion which do not need hydro test.
,you see L4.

right?

Nearly


ok.
(language barrier besides!)

Hydo test for ceasar= hp+ww

1.save model as hydro test run,
2. adjust fluid density of model (ie when flooded or empty to suit situation) ie if full density=1sg
if empty, density=0
3.set HP pressure to suit above
3.run as W+HP (HYD)

Job Done.

Dear superpiper,

I should thank you for your continuous explaination,

Finally i got what you mean.

Though i think Caesar II should change to make things easy.

)))))))))
Best Regards

Well - yes and no.

You still have to be an "Engineer" and think about what you're doing. We will never be able to make CAESAR II think for you. All we can do is recommend things the way "we think" they should be and "alert you" to things "we think" are not normal. These assumptions are based on our experience. We still learn new things every day...

It's just a hope or advice from a user of this software, hope to make CII better use.
Accept or not is just the developer's own thing.