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U stamp for jacketed vessel 2
- Thread starter jtk921
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chaulklate
Mechanical
Depends on the pressure of the jacket. If it exceeds 15 psig, I would think 'yes'.
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2
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The vessel itself won't require a U stand as it will not be a coded vessel. The jacket will require the stamp if its design pressure exceeds 15 psig. The jacket will then also have a PSV. The vessel manufacturer must know what this PSV setting is so they can take this into account when determing the vessel wall thickness that is surrounded by the jacket. Remember, even though the vessel won't be a pressure vessel, it still must be designed to handle the high external pressure of the jacket.
gr2vessels
Mechanical
Guys,
Would you be kind to point me out to the ASME VIII clause which stipulates mandatory U stamp on pressure vessels subject to design pressure above 15 psig.
Best regards,
gr2vessels
Would you be kind to point me out to the ASME VIII clause which stipulates mandatory U stamp on pressure vessels subject to design pressure above 15 psig.
Best regards,
gr2vessels
chaulklate
Mechanical
pleckner,
I disagree. If the jacket has an internal pressure greater than 15psig, then the vessel itself has an external pressure equal to the jacket internal pressure (greater than 15 psig) and will be subject to code rules, ergo registration required.
gr2vessels,
Refer to U-1(c)(2) and U-1(c)(2)(h)(1). This area indicates the exceptions to registration, pressure can be higher in water service, read all of U-1(c)(2) to get the big picture.
I disagree. If the jacket has an internal pressure greater than 15psig, then the vessel itself has an external pressure equal to the jacket internal pressure (greater than 15 psig) and will be subject to code rules, ergo registration required.
gr2vessels,
Refer to U-1(c)(2) and U-1(c)(2)(h)(1). This area indicates the exceptions to registration, pressure can be higher in water service, read all of U-1(c)(2) to get the big picture.
jtk921,
"U" stamp is not always required. The Jurisdiction, where your vessel will be installed, will tell you if a "U" stamp is mandatory. Some Jurisdictions do not require stamping.
gr2vessels,
I think UG-116(a) is the clause in ASME VIII-1 which stipulates mandatory "U" stamp. But I believe this is overruled by U-1(c)(1). This is just my interpretion. I might be wrong.
"U" stamp is not always required. The Jurisdiction, where your vessel will be installed, will tell you if a "U" stamp is mandatory. Some Jurisdictions do not require stamping.
gr2vessels,
I think UG-116(a) is the clause in ASME VIII-1 which stipulates mandatory "U" stamp. But I believe this is overruled by U-1(c)(1). This is just my interpretion. I might be wrong.
ASME Section VIII, Division 1 Scope can be very confusing and will generate many responses, and disagreements, to this question.
The definition of MAWP and Design Pressure (Mandatory Appendix 3, Definitions) references to the top of a vessel positioned in its expected operating orientation. In other words, if I have a vertical, cylindrical vessel, the design pressure stated would be what I would expect at the top of the vessel when it is properly erected into operating position, not laying on its side. The manufacturer is to then take into consideration static head and other forces on the vessel when designing.
Now, if I have an atmospheric tank but put a pressure jacket on it, the implication is that as long as my design pressure at the top of the vessel is less than 15 psig, this tank will not fall under the scope of ASME Section VIII, Division 1 [U-1(c)(2)]. Therefore, it does not require the stamp.
If the pressure jacket goes around the top, then I guess it would then be within the scope and need to be stamped.
I will not claim that I've been able to follow EVERY strand of the spaghetti of Section VIII, Division 1 so if anyone finds something I've missed, please let me know.
The definition of MAWP and Design Pressure (Mandatory Appendix 3, Definitions) references to the top of a vessel positioned in its expected operating orientation. In other words, if I have a vertical, cylindrical vessel, the design pressure stated would be what I would expect at the top of the vessel when it is properly erected into operating position, not laying on its side. The manufacturer is to then take into consideration static head and other forces on the vessel when designing.
Now, if I have an atmospheric tank but put a pressure jacket on it, the implication is that as long as my design pressure at the top of the vessel is less than 15 psig, this tank will not fall under the scope of ASME Section VIII, Division 1 [U-1(c)(2)]. Therefore, it does not require the stamp.
If the pressure jacket goes around the top, then I guess it would then be within the scope and need to be stamped.
I will not claim that I've been able to follow EVERY strand of the spaghetti of Section VIII, Division 1 so if anyone finds something I've missed, please let me know.
gr2vessels
Mechanical
I'm not disputing the ASME VIII-1, clause UG-116.
I know, however, that I can have a vessel fully compliant with ASME code, but without stamp simply because the reputed fabricator does not have U-stamp.
Also, apparently pressure vessels cannot be fabricated to the ASME VIII requirements by any fabricator lacking the U stamp, because he is unable to comply with UG-116. Right? I guess docky you are right.
Back to jtk921 post;- If the jacket is pressurised over 15 psi, the non-pressure vessel becomes pressure vessel and the user becomes liable for the legal use of a pressure vessel (in accordance with the local legislations). The U-stamp is then only subject of the local legislation requirements, not a mandatory code requirement because of operating pressure above 15 psi.
Cheers
gr2vessels
I know, however, that I can have a vessel fully compliant with ASME code, but without stamp simply because the reputed fabricator does not have U-stamp.
Also, apparently pressure vessels cannot be fabricated to the ASME VIII requirements by any fabricator lacking the U stamp, because he is unable to comply with UG-116. Right? I guess docky you are right.
Back to jtk921 post;- If the jacket is pressurised over 15 psi, the non-pressure vessel becomes pressure vessel and the user becomes liable for the legal use of a pressure vessel (in accordance with the local legislations). The U-stamp is then only subject of the local legislation requirements, not a mandatory code requirement because of operating pressure above 15 psi.
Cheers
gr2vessels
BRAVO.... pleckner....BRAVO..!!!
I truly appreciate your "strand of spagetti" comments about the ASME Code.
I think that this dicussion only verifies what i have suspected all along.....the rules should be made more simple.
I have often wondered why there were not more comparsions by reasonable engineers between the IRS tax Code ( all 44,000+ pages) and the confusing, convoluted "mess of spagetti that is ASME VIII and I...
Both systems were borne of old, well-paid men from entrenched, aging bureaucracies. The difference, of course, is that one group are all accountants and the other is all engineers...
My opinion only,
-MJC
I truly appreciate your "strand of spagetti" comments about the ASME Code.
I think that this dicussion only verifies what i have suspected all along.....the rules should be made more simple.
I have often wondered why there were not more comparsions by reasonable engineers between the IRS tax Code ( all 44,000+ pages) and the confusing, convoluted "mess of spagetti that is ASME VIII and I...
Both systems were borne of old, well-paid men from entrenched, aging bureaucracies. The difference, of course, is that one group are all accountants and the other is all engineers...
My opinion only,
-MJC
MJC-
Its easy to take potshots at the "old, well-paid men from entrenched, aging bureaucracies." Just curious: Have you volunteered your time to help clarify the codes? Being on a code committee is not an insubstantial commitment.
I haven't seen the VIII Div 2 rewrite, but there's at least a bit of hope since the ASME chose to not further evolve the existing code, but to start from scratch when writing it. Hopefully it will be a bit more straightforward to understand and apply.
jt
Its easy to take potshots at the "old, well-paid men from entrenched, aging bureaucracies." Just curious: Have you volunteered your time to help clarify the codes? Being on a code committee is not an insubstantial commitment.
I haven't seen the VIII Div 2 rewrite, but there's at least a bit of hope since the ASME chose to not further evolve the existing code, but to start from scratch when writing it. Hopefully it will be a bit more straightforward to understand and apply.
jt
Thank you MJC.
gr2vessels:
I don't know if I fully understand what you said. Quoting:"The U-stamp is then only subject of the local legislation requirements, not a mandatory code requirement because of operating pressure above 15 psi."
In the U.S. there are only two states that don't accept ASME Section VIII, Div 1 as law, one is Texas and I think the other is Louisiana. In all other states (and I pray these two states come to their senses soon), ASME is law. So unless this particular vessel is in these two rouge states, if the vessel is a pressure vessel, it must be stamped. Now, when you said, "...because of operating pressure ABOVE 15 psi", did you really mean "BELOW" 15 psig?
If the vessel "design" pressure is 15 psig or less the vessel is NOT a pressure vessel and does not fall within ASME Section VIII, Div. 1 scope and does not need a U stamp. Also, since this particular vessel is in low pressure service, unless the design pressure is greater than 15 psig (and the OP did not tell us this), it remains a non-pressure vessel even with the jacket. The jacket only forces the manufacturer to increase the metal thickness around the jacket to withstand the higher pressure of the jacket, it does not mean the vessel needs to be rated as a pressure vessel. As I showed in my post above, the design conditions are based on the top of the vessel. The vessel top head and nozzles will not have been fabricated for high pressure and don't need to be. As such, and with the above assumption, the vessel remains a low-pressure designed vessel and does not require a U stamp, no matter what state it is in.
gr2vessels:
I don't know if I fully understand what you said. Quoting:"The U-stamp is then only subject of the local legislation requirements, not a mandatory code requirement because of operating pressure above 15 psi."
In the U.S. there are only two states that don't accept ASME Section VIII, Div 1 as law, one is Texas and I think the other is Louisiana. In all other states (and I pray these two states come to their senses soon), ASME is law. So unless this particular vessel is in these two rouge states, if the vessel is a pressure vessel, it must be stamped. Now, when you said, "...because of operating pressure ABOVE 15 psi", did you really mean "BELOW" 15 psig?
If the vessel "design" pressure is 15 psig or less the vessel is NOT a pressure vessel and does not fall within ASME Section VIII, Div. 1 scope and does not need a U stamp. Also, since this particular vessel is in low pressure service, unless the design pressure is greater than 15 psig (and the OP did not tell us this), it remains a non-pressure vessel even with the jacket. The jacket only forces the manufacturer to increase the metal thickness around the jacket to withstand the higher pressure of the jacket, it does not mean the vessel needs to be rated as a pressure vessel. As I showed in my post above, the design conditions are based on the top of the vessel. The vessel top head and nozzles will not have been fabricated for high pressure and don't need to be. As such, and with the above assumption, the vessel remains a low-pressure designed vessel and does not require a U stamp, no matter what state it is in.
PVinspector
Industrial
Mandatory Appendix 9 is also important for determining when Vessel/Jacket is Code. See 9-1 Scope.
chaulklate
Mechanical
Hi again team.
I'm not trying to be argumentative, merely explore all sides of this coin so I have a better understanding. There is validity in what pleckner has put forth, but I feel it falls into a 'grey' area of the spaghetti...I mean Code. Also consider the following interpretation, I will reprint here for those that do not have access.
VIII-1-98-19
Question 1: A vessel is vacuum jacketed at full vacuum. The operating pressure in the vessel is less than 15 psig. Is the vessel outside the scope of Section VIII, Divsion 1?
Reply 1: No.
Qeustion 2: U-1(2)(c)(h) states vessels are outside the scope of Section VIII, Division 1 if the internal or external operating pressure does not exceed 15 psi. Is this provision based on "guage pressure" or "differential pressure"?
Reply 2: This provision is based on differential pressure.
Reply 1 indicates the vessel proper falls within the scope of the Code. I interpret that as to requiring registration. Reply 2 indicates the basis to be differential pressure. I know, the argument would still stand that the differential pressure at the top of the vessel is still 0, but how does a guage effectively measure external pressure anyway? I think in the end the jurisdiction will get the final say, but I'm doubtful that many jurisdictions will pass this.
I could be wrong.
I'm not trying to be argumentative, merely explore all sides of this coin so I have a better understanding. There is validity in what pleckner has put forth, but I feel it falls into a 'grey' area of the spaghetti...I mean Code. Also consider the following interpretation, I will reprint here for those that do not have access.
VIII-1-98-19
Question 1: A vessel is vacuum jacketed at full vacuum. The operating pressure in the vessel is less than 15 psig. Is the vessel outside the scope of Section VIII, Divsion 1?
Reply 1: No.
Qeustion 2: U-1(2)(c)(h) states vessels are outside the scope of Section VIII, Division 1 if the internal or external operating pressure does not exceed 15 psi. Is this provision based on "guage pressure" or "differential pressure"?
Reply 2: This provision is based on differential pressure.
Reply 1 indicates the vessel proper falls within the scope of the Code. I interpret that as to requiring registration. Reply 2 indicates the basis to be differential pressure. I know, the argument would still stand that the differential pressure at the top of the vessel is still 0, but how does a guage effectively measure external pressure anyway? I think in the end the jurisdiction will get the final say, but I'm doubtful that many jurisdictions will pass this.
I could be wrong.
chaulklate:
Good point about the interpretations. I will look further.
However, this interpretation does not clarify the vessel and jacket configuration (nor does the original post). Is the jacket completely around the vessel? Again, the design pressure is taken at the top of the vessel, not the bottom.
What if I have a 40' vessel operating at atmospheric pressure but put a pressure jacket that extends up only 10'? Does this mean the whole vessel needs to be ASME stamped even though it is only operating at 0 psig? I would think not.
Another example, if I have a 50'vessel filled with 50%causitc at a design pressure of 14.9 psig, I think we would all agree that this does not fall within ASME Section VIII, Div. 1 scope. But the pressure at the bottom could exceed 15 psig when filled to the top. Does this make it a pressure vessel? I think not.
Good point about the interpretations. I will look further.
However, this interpretation does not clarify the vessel and jacket configuration (nor does the original post). Is the jacket completely around the vessel? Again, the design pressure is taken at the top of the vessel, not the bottom.
What if I have a 40' vessel operating at atmospheric pressure but put a pressure jacket that extends up only 10'? Does this mean the whole vessel needs to be ASME stamped even though it is only operating at 0 psig? I would think not.
Another example, if I have a 50'vessel filled with 50%causitc at a design pressure of 14.9 psig, I think we would all agree that this does not fall within ASME Section VIII, Div. 1 scope. But the pressure at the bottom could exceed 15 psig when filled to the top. Does this make it a pressure vessel? I think not.
Here is my two cents......following the "guru" deanc's constant advice.....,
Reading the "foreword" of ASME Sections I, IV and VIII you will find the following....
...............The Code Committee does not rule on whether a component shall or shall not be constructed to the provisions of the Code. The Scope of each Section has been established to identify the components and parameters considered by the Committee in formulating the Code rules.
Questions or issues regarding compliance of a specific component with the Code rules are to be directed to the ASME Certificate Holder (Manufacturer).
Inquiries concerning the interpretation of the Code are to be directed to the ASME Boiler and Pressure Vessel Committee. ASME is to be notified should questions arise concerning improper use of an ASME Code symbol.
So in effect, leave it to the Manufacturer and their AIA of record.
When reading the ASME Codes and Standards policy CSP-33.....Found Here...,
....."interpretations shall not revise existing requirements or establish new requirements"......,So, even interpretations are subject to interpretation if and when there is an identified need for a correction or clarification where factors such as (a) public health, safety, and welfare significance, (b) need for an accompanying standard revision, (c) elapsed time since publication of the interpretation, and (d) impact on continued compliance with the standard.
Additionally, the following was in the "foreword" of Sections I and IV but was located in paragraph U-1(c)(1) of Section VIII-1
"....Laws or regulations issued by municipality, state, provincial, federal, or other enforcement or regulatory bodies having jurisdiction at the location of an installation establish the mandatory applicability of the Code rules, in whole or in part, within their jurisdiction. Those laws or regulations may require the use of this Code for vessels or components not considered to be within its Scope or may establish additions or deletions in that Scope. Accordingly, inquiries regarding such laws or regulations are to be directed to the issuing enforcement or regulatory body......"
This should help make it simple for everyone!!
By the way, I agree with everyone here.....
There are three kinds of people in this world; those who can count and those who can't.
Reading the "foreword" of ASME Sections I, IV and VIII you will find the following....
...............The Code Committee does not rule on whether a component shall or shall not be constructed to the provisions of the Code. The Scope of each Section has been established to identify the components and parameters considered by the Committee in formulating the Code rules.
Questions or issues regarding compliance of a specific component with the Code rules are to be directed to the ASME Certificate Holder (Manufacturer).
Inquiries concerning the interpretation of the Code are to be directed to the ASME Boiler and Pressure Vessel Committee. ASME is to be notified should questions arise concerning improper use of an ASME Code symbol.
So in effect, leave it to the Manufacturer and their AIA of record.
When reading the ASME Codes and Standards policy CSP-33.....Found Here...,
....."interpretations shall not revise existing requirements or establish new requirements"......,So, even interpretations are subject to interpretation if and when there is an identified need for a correction or clarification where factors such as (a) public health, safety, and welfare significance, (b) need for an accompanying standard revision, (c) elapsed time since publication of the interpretation, and (d) impact on continued compliance with the standard.
Additionally, the following was in the "foreword" of Sections I and IV but was located in paragraph U-1(c)(1) of Section VIII-1
"....Laws or regulations issued by municipality, state, provincial, federal, or other enforcement or regulatory bodies having jurisdiction at the location of an installation establish the mandatory applicability of the Code rules, in whole or in part, within their jurisdiction. Those laws or regulations may require the use of this Code for vessels or components not considered to be within its Scope or may establish additions or deletions in that Scope. Accordingly, inquiries regarding such laws or regulations are to be directed to the issuing enforcement or regulatory body......"
This should help make it simple for everyone!!
By the way, I agree with everyone here.....
There are three kinds of people in this world; those who can count and those who can't.
chaulklate
Mechanical
I'm still not trying to be argumentative, just continuing the discussion.
pleckner, you stated "Does this mean the whole vessel needs to be ASME stamped even though it is only operating at 0 psig?" I think it would be all or nothing, I don't think we can register 'part' of the vessel, and I'm still of the school that says 'register it'. Reply 2 indicates the provision to be for differential pressure (between chambers) and this won't necessarily be all measured at the top of the vessel if only the lower portion is jacketed. I could see measuring the differential pressure between the top of the vessel and top of the jacket...but that would be my interpetation.
One more interpretation to consider regarding type of jacket...
VIII-1-04-37
Question: Per U-1(c)(2)(h), is a jacket (Type 1 through Type 5 as defined in Appendix 9) within the scope of the Code when the inner chamber operates at 15 psi or less and the jacket is at full vacuum?
Reply: Yes. See Appendix 9, 9-1(c).
I think this also reinforces my position.
My apologies to jtk921 who obviously did not get a consensus to his question. Hopefully jtk921 will put this to his/her local AI and report back to us their final ruling.
pleckner, you stated "Does this mean the whole vessel needs to be ASME stamped even though it is only operating at 0 psig?" I think it would be all or nothing, I don't think we can register 'part' of the vessel, and I'm still of the school that says 'register it'. Reply 2 indicates the provision to be for differential pressure (between chambers) and this won't necessarily be all measured at the top of the vessel if only the lower portion is jacketed. I could see measuring the differential pressure between the top of the vessel and top of the jacket...but that would be my interpetation.
One more interpretation to consider regarding type of jacket...
VIII-1-04-37
Question: Per U-1(c)(2)(h), is a jacket (Type 1 through Type 5 as defined in Appendix 9) within the scope of the Code when the inner chamber operates at 15 psi or less and the jacket is at full vacuum?
Reply: Yes. See Appendix 9, 9-1(c).
I think this also reinforces my position.
My apologies to jtk921 who obviously did not get a consensus to his question. Hopefully jtk921 will put this to his/her local AI and report back to us their final ruling.
CodeJackel's statement, "...So, even interpretations are subject to interpretation " is a great one.
Chaulklate: I can see where it reads like I was asking if only part of the vessel was to be stamped and that was poor wording on my part. I think we all agree that it is all or nothing. Also, that last interpretation seems to be about the jacket and not the vessel. There is no confusion that the jacket needs to be stamped.
And I would like to second your statement to jkt921!
Codes are only meaningful if they can be interpreted by at the least learned engineers without the need to go to "higher" authorities to get these issues solved. The committee needs to do a better job than they are, which basically reiterates what MJC said above.
A thank you to all that participated in this discussion.
Chaulklate: I can see where it reads like I was asking if only part of the vessel was to be stamped and that was poor wording on my part. I think we all agree that it is all or nothing. Also, that last interpretation seems to be about the jacket and not the vessel. There is no confusion that the jacket needs to be stamped.
And I would like to second your statement to jkt921!
Codes are only meaningful if they can be interpreted by at the least learned engineers without the need to go to "higher" authorities to get these issues solved. The committee needs to do a better job than they are, which basically reiterates what MJC said above.
A thank you to all that participated in this discussion.
chaulklate
Mechanical
Ture that pleckner, all good feed back, thanks to everyone who contributed.
Hi folks, discussion is hot. Take it easy. Code books, may be, are not easy to interpret, but the issue of the infinite variaty of pressure equipment is not easy to descibe either. Did you ever read other national standards? ASME Code is the most complete and clear among all, and it is the first good reason for being the most applied in the world pressure vessel industry.
Did somebody think that when the inner chamber has no pressure, its shell is part of the shell of the outer chamber (the jacket)? Therefore the inner chamber may be non Code and have part of its shell Code because it is part of the jacket. KISS. Mauro.
Did somebody think that when the inner chamber has no pressure, its shell is part of the shell of the outer chamber (the jacket)? Therefore the inner chamber may be non Code and have part of its shell Code because it is part of the jacket. KISS. Mauro.
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