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

 

[LittleInch]

Are you sure it's a Pressure vessel at that design pressure?

All design calcs are undertaken using design pressure

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

 

[muruep00]

Are you sure it's a Pressure vessel at that design pressure?

All design calcs are undertaken using design pressure

It is a pressure vessel with design pressure of 0.05MPa internal. But client states that test pressure is 0.15MPa internal.

Where does ASME state that nozzles should not be dimensioned for test pressure?

 

[LittleInch]

0.5 bar / 7 psi is not normally considered a Pressure Vessel.

If the client insists on a 1.5 bar pressure test, then set the design pressure to 1 bar?

I'm no expert on ASME VIII, but no other code requires you to design for pressure test pressures, only check that you're not exceeding yield. All the margins in the design parameters include and allow for the increase in pressure in a pressure test which is applied according to the code, which is 1.5 x DP / MAWP. Why the client has set the TP to be 3 x DP is not clear and should be addressed to them.

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

 

[muruep00]

0.5 bar / 7 psi is not normally considered a Pressure Vessel.

If the client insists on a 1.5 bar pressure test, then set the design pressure to 1 bar?

I'm no expert on ASME VIII, but no other code requires you to design for pressure test pressures, only check that you're not exceeding yield. All the margins in the design parameters include and allow for the increase in pressure in a pressure test which is applied according to the code, which is 1.5 x DP / MAWP. Why the client has set the TP to be 3 x DP is not clear and should be addressed to them.

I also calculate for external pressure FV (1 bar).

Why set the design internal pressure to 1 barg?

What if DP=0.5 barg and MAWP=0.5 barg? Then, test pressure of 1.5 barg would make sense according to 1.5 x DP/MAWP.

 

[LittleInch]

Errrr 1.5 x 0.5 is 0.75....

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

 

[muruep00]

Errrr 1.5 x 0.5 is 0.75....

1.5 x DP / MAWP

1.5 x 0.5 / 0.5 = 1.5

 

[LittleInch]

DP/MAWP means one or the other, not one divided by the other....

sorry if that caused confusion, but otherwise all test pressures would be 1.5 barg.... as DP and MAWP are always pretty close to each other if not equal.

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

 

[muruep00]

DP/MAWP means one or the other, not one divided by the other....

All right. Still, my test pressure exceeds 1,5 x DP.

 

[LittleInch]

EXACTLY.

That's your issue so you need to address that somehow - either raise your design pressure to be 2/3 of the test pressure or lower the test pressure.

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

 

[XL83NL]

Just guessing here - but could it be the client might specify a (mandatory) low pressure leak test or soap test on repads, for which case they specify a test pressure of 1.5 bar(g)?

Huub
- You never get what you expect, you only get what you inspect.

 

[muruep00]

Just guessing here - but could it be the client might specify a (mandatory) low pressure leak test or soap test on repads, for which case they specify a test pressure of 1.5 bar(g)?

My design inputs of client just state: hydraulic test pressure of 0.15MPa

 

[LittleInch]

The its time for a TQ / RFI to sort that out as the two at the moment don't add up

DP 0.5 barg
Test pressure 1.5 barg

One of them needs to change.

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

 

[LittleInch]

It's 0.05 MPa - I just like working in bar so I changed that to 0.5 bar. My fault.

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

 

[david339933]

1.3 x DP for hydro.
See UG-99 all will be revealed.

 

[SnTMan]

LittleInch, more properly MY fault for not confirming units before blabbing, but thanks

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

1,3 DP at least.
The Code does not specify an upper limit for hydrostatic test pressure.

Regards

 

[muruep00]

Client insists on hydro test pressure to be 3 times the design pressure

 

[XL83NL]

Client insists on hydro test pressure to be 3 times the design pressure

Wow. Has the client considered the potential (though maybe not likely for this case) of going beyond yield?

Huub
- You never get what you expect, you only get what you inspect.

 

[muruep00]

Wow. Has the client considered the potential (though maybe not likely for this case) of going beyond yield?
Huub

I dont know that.

But since test is performed right after assembly, there is no corrosion yet. I calculate nozzle pads and thicknesses with 3mm corrosion, so I believe Im on the safe side. Still, I would like to know if I have to justify the calculations with test pressure in ASME.