ASME VIII - Div. 1 UG-37 with hydraulic test pressure?

[muruep00]

I am doing reinforcement pad calculations for nozzles with 0.05MPa design internal pressure with ASME VIII - Div. 1 2017.

My input data from client specifies a test pressure requirement of 0.15MPa internal pressure (I know its hydraulic test).

Should I consider 0.15MPa or 0.05MPa in UG-37 reinforcement pad calculations?

Thanks

 

[r6155]

See special test in UG-99(c)

Regards

 

[muruep00]

See special test in UG-99(c)

But it doesnt say if I must use the test pressure for nozzle thickness and pad calculations.

 

[LittleInch]

Design for the design pressure.

Then check at this ridiculous x 3 DP hydrotest pressure to see if you're overstressed.

Does the client do this for everything? So if you have a 50 bar vessel and then you teat at 150bar?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[r6155]

Please, read again UG-99(c) and try to understand.
I recommend this special test as best practice. Always.

Regards

 

[LittleInch]

This might help?

https://www.eng-tips.com/viewthread... hydrotest,calculated for all pressure parts.

Not quite sure how you do the reverse calculation bit, but then I guess that's up to the designer.... or his software.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[david339933]

Your vessel must be awfully thin or huge diameter to need a repad for 7psi.

 

[muruep00]

Please, read again UG-99(c) and try to understand.
I recommend this special test as best practice. Always.

I read UG-99 and still don't known whether if I should use design or test pressure in UG-37 / UG-45 when test pressure is 3 times the design pressure as stated by client.

Design for the design pressure.

Then check at this ridiculous x 3 DP hydrotest pressure to see if you're overstressed.

Does the client do this for everything? So if you have a 50 bar vessel and then you teat at 150bar?

Yes, UG-37 requirements of nozzle thickness are greater for test pressure than design pressure.

Yes, that's the client requirement.

Your vessel must be awfully thin or huge diameter to need a repad for 7psi.

Yes, its over 1 meter diameter.

 

[LittleInch]

"Huge is over 5m....

How big?

So what's the impact of designing for 1.5 bar vs 0.5 bar?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[muruep00]

"Huge is over 5m....

How big?

So what's the impact of designing for 1.5 bar vs 0.5 bar?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

Four meters. The impact is an increase in nozzle required nozzle thickness as per UG-37.

The question is simple, should I use design or test pressure in UG-37 / UG-45 when test pressure is 3 times the design pressure as stated by client?

 

[r6155]

Let your computer work.
Use pressure test in UG-37 with corrosion = 0 and check if the nozzle is reinforced.
If yes, use a design pressure as test pressure/ 1,3.

This check is for all the pressure parts.

Regards

 

[LittleInch]

And try to educate the client that TP of DP*3 is a bit high and results in increased cost for no benefit.

Also if you set the DP to be higher than 0.5 bar, will the client just keep increasing the TP?
Or has he set a TP of 1.5 bar?

I've learnt that ASME VIII has no upper test pressure limit which I didn't know before and looks like you're suffering the consequences of that.

So you're in a strange place and therefore r6155 suggestion of design to PT pressure with no corrosion looks to me the best one. But you will also need to do that for the whole vessel and its components / shell design etc. Could make a big difference or no difference. Depends on what the calculation spits out.

Please let us know.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[r6155]

Example:
1)Required thickness (design pressure): 2.5mm
Allowable corrosion: 2 mm
Actual thickness: 9.5 mm.
9.5/2.5= 3.8
2) DP x 1.3= test pressure is insignificant
This pressure tickles the equipment.

Regards