Can Service Pressure Exceed Design Pressure?

[LS_SMS]

I'm using ASME, year 2023. In Sec. III and Sec. VIII vessel design, is there ever a situation where the service pressure of a defined load case may exceed the design pressure? For example, if design pressure is 100 psi, can I have a service load case that is defined at 150 psi? Please provide citations to the code paragraphs.

A colleagues is referencing ASME Sec. III, NCA-3211.40 where it's insinuated that service loads may exceed design loads. This doesn't seem rational.

 

[GD2]

ASME Section III defines different service levels (A, B, C, D) that represent varying levels of loading and stress. Service level A (which is normal operating condition) occurs most frequently while level D occurs least frequently.

Consider a piping system designed for a specific operating pressure and temperature. During startup or shutdown procedures, the pressure and temperature may vary rapidly, potentially exceeding the design values. However, if the resulting stresses remain within the allowable limits for the appropriate service level, the piping system is still considered to meet the requirements of ASME Section III.

 

[TGS4]

As noted by GD2, these limits are specific to Section III Construction. Such service levels do not exist in Section VIII construction (at least in Division 1 and 2). So, for Section VIII, Division 1 and 2, the internal pressure is not permitted to exceed the Design Pressure / MAWP.

 

[LS_SMS]

Thank you both! That makes sense for Sec. III.

@TGS4, can you provide a Sec. VIII code citation where I can read it? My colleague prefers to see an actual statement from the code.

 

[TGS4]

Your colleague will need to read the Code themselves. Might find a thing or two interesting while in there.

 

[LS_SMS]

Hmm, fair enough. But I myself do not know either. Yes, I already looked but came up with nothing. And that's why I came here for some enlightening. I think that's the point of these forums. Otherwise, I could just cancel my user name and stop trying to learn from others here.

Would you mind sharing please?

 

[Geoff13]

I believe ASME Section VIII Division 1 clause UG-21 makes it clear that the specified design pressure must be greater than any possible operating condition.

 

[r6155]

See the calculated pressure in UG-99(c)
with corrosion zero.

 

[GD2]

Hmm, fair enough. But I myself do not know either. Yes, I already looked but came up with nothing. And that's why I came here for some enlightening. I think that's the point of these forums. Otherwise, I could just cancel my user name and stop trying to learn from others here.

Would you mind sharing please?

OP,
Your question only applies to ASME Sec III, not Sec VIII. Design criteria for both Sections are different.

 

[LS_SMS]

OP,
Your question only applies to ASME Sec III, not Sec VIII. Design criteria for both Sections are different.

My apologies, but I think you misunderstood my question. In fact, my question applies to both Sec. III and Sec. VIII. Regardless, thanks for sharing. I now realize that both sections have different criteria.