ReliaEng2008
Mechanical
- Mar 5, 2021
- 22
I want to start this post by saying that I value safety, and I am not looking to cut any corners. The decision of not installing a PSV will only be made if it is safe to do so, and if permitted in my jurisdiction (Texas).
I heard that Texas is a non-code state for pressure vessels before, but it's my first time digging into what that means exactly. I checked the NBBI website, especially NB-370, which is a compilation of jurisdiction laws, rules, and regulations as reported to the National Board by jurisdictional authorities (here) and it looks like, for Texas, only boilers need to follow the requirements of ASME BPV Code:
"OBJECTS SUBJECT TO RULES FOR CONSTRUCTION AND STAMPING
All boilers, except the following:"
I also checked Texas Administrative Code and it does not mention pressure vessels, just boilers.
If I am interpreting this correctly, it means that, in Texas, an owner/operator can have pressure vessels that are not built per the ASME Code, or in my specific case, that do not have the protection (PSV) as per the Code requirements.
Now to my specific case: A new Unit is under construction. There is a pressure vessel that has been built and stamped per ASME Section VIII, and I just received the U1 form. This pressure vessel is for the sole purpose of storing water at high pressure - MAWP=125 psig / MAWT=240F. It was brought to my attention that the design for this system did not consider any protection (PSV) for this vessel. The question at hand is, do I need to stop the work and modify the design to include a PSV for this vessel, or can I move ahead with the current design, since the requirements from the Code does not apply to pressure vessels in Texas?
Considering the above, I can come to one of the three "solutions" below:
(1) Texas is a non-code state and we do not need to meet the requirements from ASME BPVC for pressure vessels - continue with current design.
(2) Consider that since this vessel was built per ASME BPVC Section VIII, and stamped, and has a national board number, this ship has sailed already and I need to comply with the Code requirements.
(3) The Code does not apply to a vessel containing water under pressure, including those containing air the compression of which serves only as a cushion, when the design pressure is less than 300 psi and the design temperature is less than 210°F (see ASME BPVC Section VIII, U-1 (c)(2)(-f)). My vessel does not meet this exemption because the MAWT is 240°F. I don't need the MAWP to be this high, in fact, the spec sheet called for a design temperature of 140°F. If I rerate the MAWP of this vessel from 240°F to less than 210°F, the vessel would fall outside the scope of the Code, and also outside of the scope of API510. Therefore I would not need to provide the protection per the Code.
Your consideration of this topic would be greatly appreciated.
I heard that Texas is a non-code state for pressure vessels before, but it's my first time digging into what that means exactly. I checked the NBBI website, especially NB-370, which is a compilation of jurisdiction laws, rules, and regulations as reported to the National Board by jurisdictional authorities (here) and it looks like, for Texas, only boilers need to follow the requirements of ASME BPV Code:
"OBJECTS SUBJECT TO RULES FOR CONSTRUCTION AND STAMPING
All boilers, except the following:"
I also checked Texas Administrative Code and it does not mention pressure vessels, just boilers.
If I am interpreting this correctly, it means that, in Texas, an owner/operator can have pressure vessels that are not built per the ASME Code, or in my specific case, that do not have the protection (PSV) as per the Code requirements.
Now to my specific case: A new Unit is under construction. There is a pressure vessel that has been built and stamped per ASME Section VIII, and I just received the U1 form. This pressure vessel is for the sole purpose of storing water at high pressure - MAWP=125 psig / MAWT=240F. It was brought to my attention that the design for this system did not consider any protection (PSV) for this vessel. The question at hand is, do I need to stop the work and modify the design to include a PSV for this vessel, or can I move ahead with the current design, since the requirements from the Code does not apply to pressure vessels in Texas?
Considering the above, I can come to one of the three "solutions" below:
(1) Texas is a non-code state and we do not need to meet the requirements from ASME BPVC for pressure vessels - continue with current design.
(2) Consider that since this vessel was built per ASME BPVC Section VIII, and stamped, and has a national board number, this ship has sailed already and I need to comply with the Code requirements.
(3) The Code does not apply to a vessel containing water under pressure, including those containing air the compression of which serves only as a cushion, when the design pressure is less than 300 psi and the design temperature is less than 210°F (see ASME BPVC Section VIII, U-1 (c)(2)(-f)). My vessel does not meet this exemption because the MAWT is 240°F. I don't need the MAWP to be this high, in fact, the spec sheet called for a design temperature of 140°F. If I rerate the MAWP of this vessel from 240°F to less than 210°F, the vessel would fall outside the scope of the Code, and also outside of the scope of API510. Therefore I would not need to provide the protection per the Code.
Your consideration of this topic would be greatly appreciated.
