ASME Section 1 historical relief requirement

[AskOR]

Hello-
I am sizing relief devices for a client who has an ASME Section 1 boiler. Per the current code, if I set the valve at the MAWP, then my overpressure is limited to 6%.

My client wants to invoke relief requirements for equipment at the time of installation (not necessarily current code). The boiler in question was ASME code stamped in 1976. So, do you know if the relief requirements in 1976 were still at that 6% limit or was 10% allowed then?

Thanks!

 

[Latexman]

For a single PSV set at MAWP, the overpressure is limited to 3%.

For multiple PSVs, the 1st PSV can be set at MAWP with 3% overpressure. The 2nd PSV can be set at 1.03 x MAWP with a 3% overpressure. This gives about 6% accumulation for the 2nd PSV.

I do not know the history precisely, but it's been this way for quite a while.

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

 

[AskOR]

Thanks, but I need to dig a bit further. Do you know if the 6% rule on Section 1 has been in effect since at least 1976?

My client is trying to invoke a 10% over-pressure rule (116% for multiple devices), similar to an ASME Section VIII vessel. Their thinking is that the 6% rule was not in effect at the time of the equipment installation in 1976.

Thanks again-

 

[AskOR]

Oops - I think we were posting at the same time!

 

[Latexman]

Do you know if the 6% rule on Section 1 has been in effect since at least 1976?

I started work in 1979. I don't recall hearing about Section I ever having overpressure rules exactly like Section VIII. However, I have had very little experiences with Power Boilers over the years, and I don't know for sure. Your best bet here, is if don1980 knows and replies. If not, contact the ASME and/or NB with this historical question. They have a good many gray haired folks that probably know.



Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

 

[don1980]

I started work in 1980, about the same time as Latexman, but it wasn't until the 1990s that I started learning about pressure relief design. I don't know if the accumulation limit for Sec I boilers has changed since 1976. I doubt that it has, but I can't say for sure. The oldest Sec I edition that I have is 1989, and it has the same limits as today (6% above MAWP).

It's important to understand that Sec I boilers are regulated by the state, and these boilers require inspections by an independent boiler inspector. If the inspector finds that you're not in compliance with ASME boiler code, then they can deny an operating permit. Obviously, the client doesn't want that to happen, so explain to the client that they can't apply their own interpretation of code. Before making a decision to go beyond 6% accumulation (even if the 1976 code allowed a higher value) I would check with the inspector first. You'll find their contact info on the boiler certificate that is posted at the plant site.

 

[AskOR]

Thanks for the information. I had forgotten about considering the local codes and will definitely bring that up with my client.

On the other hand, and for reference if anyone else needs to know.....

I did find a copy of the 1971 ASME BPVC Section 1 code at my local University library. Not being a student, I couldn't check it out but was allowed to freely read. It does still have the 6% rule in effect as of 1971.

THanks everyone!