Double Walled Pressuer Vessel Certification
Double Walled Pressuer Vessel Certification
(OP)
Dear All;
I have successfully designed a Jet-A SS double walled pressure vessel and hydrotested. The internal vessel is the main vessel. The outside vessel is for leak detection as well as will work as a standby vessel in case of the failure of the internal vessel till the maintenance or replacement of the internal vessel. Hence, I have designed both internal and external vessels for the same conditions. I have not applied the internal pressure of the outside vessel as external pressure for the internal vessel. As per my understanding, they will not operate independently as expressed in UG-99 (e)(1). There is no inlet and outlet nozzles for the external vessel, liquid will fill-up only from the leakage of the internal vessel, if happens. In addition, UG-19 (a) says:
"Each element including the common elements, shall be designed for at least the most sever condition of coincident pressure and temperature expected in normal operation."
I have stated the operation scenario in the MDR. But, Is there any special requirements to be marked in nameplate in order to avoid full pressurizing the outside vessel where as the inside vessel is atmospheric? Could a caution similar to the one required for Heat Exchanger be sufficient? If common element marking is required, then the entire inside vessel is a common element. Could you please advise what to do, the vessel is waiting only for nameplate attachment and ASME Stamp application.
Best Regards,
M.Salaheldin
I have successfully designed a Jet-A SS double walled pressure vessel and hydrotested. The internal vessel is the main vessel. The outside vessel is for leak detection as well as will work as a standby vessel in case of the failure of the internal vessel till the maintenance or replacement of the internal vessel. Hence, I have designed both internal and external vessels for the same conditions. I have not applied the internal pressure of the outside vessel as external pressure for the internal vessel. As per my understanding, they will not operate independently as expressed in UG-99 (e)(1). There is no inlet and outlet nozzles for the external vessel, liquid will fill-up only from the leakage of the internal vessel, if happens. In addition, UG-19 (a) says:
"Each element including the common elements, shall be designed for at least the most sever condition of coincident pressure and temperature expected in normal operation."
I have stated the operation scenario in the MDR. But, Is there any special requirements to be marked in nameplate in order to avoid full pressurizing the outside vessel where as the inside vessel is atmospheric? Could a caution similar to the one required for Heat Exchanger be sufficient? If common element marking is required, then the entire inside vessel is a common element. Could you please advise what to do, the vessel is waiting only for nameplate attachment and ASME Stamp application.
Best Regards,
M.Salaheldin
Regards,
M.Salaheldin
Static Equipment Mechanical Design Engineer





RE: Double Walled Pressuer Vessel Certification
RE: Double Walled Pressuer Vessel Certification
RE: Double Walled Pressuer Vessel Certification
I have filled the MDR for Multi-walled vessels. I have used Items 6~11 for the outside vessel & Items from 14~18 for the outside vessel. MDR for me is filled satisfactory, however, only nameplate marking I'm still doubtful. The 3 lines suggested by @GenB is not sufficient as per my understanding. It means the outside vessel can be pressurized independently from the inside vessel which is not considered as well as not applicable in the operation. Commonly if we have differential pressure for the common element, it has to be marked in the nameplate, but, for the current case the entire internal vessel is a common element!! I'm really confused :)
Regards,
M.Salaheldin
Static Equipment Mechanical Design Engineer
RE: Double Walled Pressuer Vessel Certification
Cheers,
gr2vessels
RE: Double Walled Pressuer Vessel Certification
Regards,
M.Salaheldin
Static Equipment Mechanical Design Engineer
RE: Double Walled Pressuer Vessel Certification
1. All the inlet outlet nozzles must be in the top of vessel, fitted with anti-siphon valve, to prevent accidental siphoning of the fuel on the ground. There must be a form of overfilling protection, typically you use a standard mechanical float valve designed for fuel tanks. You can use level controllers, linked to the filling control panel.
2. You must protect the tank during filling with a relief valve fitted with a flame arrester. Also, you need an oversized emergency relief valve, with no flame arrester, for fire case.
3. You need to vent the interstitial space of the double skin, in case of breach of the inner shell. I would also put a small 1" drain valve just in case...
4. Again, safety is your main concern, any design which cannot prevent the fuel spill is wrong!
Cheers,
gr2vessels
RE: Double Walled Pressuer Vessel Certification
RE: Double Walled Pressuer Vessel Certification
Thanks to all.
Regards,
M.Salaheldin
Static Equipment Mechanical Design Engineer