ASME ôU Stampö for Acrylic Pressure Vessels? 1

[scott1971]

Hi friends,

According to this web page, pressure vessels conforming to Section VIII may incorporate acrylic cylinders and be U-stamped. The page goes on to say "The American Society of Mechanical Engineers (ASME) has now approved the use of acrylic in the construction of pressure vessels under ASME Boiler and Pressure Vessel Code PVHO-1." Aren't BPVC and PVHO completely separate and independent of each other?

I have read "PVHO Case 14" (found here), which states that acrylic tubes without UV inhibitors can be used in PVHO's, but does this have anything to do with BPVC? Does this automatically mean that a vessel compliant with all other requirements of the BPVC, but which includes a PVHO-1 compliant acrylic tube, can carry a "U" stamp? What am I missing?

Thanks,
Scott

Scott
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[CodeRef]

My experience of the PVHO Code is limited and I do not claim to be an authority in any way. However, here is my opinion.

Aren't BPVC and PVHO completely separate and independent of each other?

No, The General Requirements Section of PVHO-1 states the following:
1.2 General
1.2.1 The PVHO’s shall be designed, fabricated,
inspected, tested, marked, and stamped in accordance
with the requirements of this Standard and Section VIII
of the Code. The user, or the user’s agent, shall specify
which Division of Section VIII of the Code shall
be used.
1.2.2 PVHO manufacturers shall hold a valid Certificate
of Authorization for use of the ASME U or U2
Code Symbol Stamp, and shall complete Form PVHO-1
, Manufacturer’s Data Report for Pressure Vessels for
Human Occupancy, to certify that each PVHO meets
the requirements of this Standard and the applicable
Division of Section VIII of the Code.
1.2.3 PVHO window fabricators shall complete Form
PVHO-2, Fabrication Certification for Acrylic Windows,
to certify that each window meets the requirements of
this Standard

Does this automatically mean that a vessel compliant with all other requirements of the BPVC, but which includes a PVHO-1 compliant acrylic tube, can carry a "U" stamp?

No, not any pressure vessel. Only those constructed to the ASME PVHO Standard.

 

[CodeRef]

Perhaps I should stay current.
The Gen Reqt's above were taken from the PVHO-1-2002
This is from the PVHO-1-2007.

1-1 INTRODUCTION
This Standard defines the requirements that are applicable
to all Pressure Vessels for Human Occupancy
(PVHO’s) fabricated to this Standard and shall be used in
conjunction with specific requirements in other Sections
and mandatory appendices of this Standard.
PVHO’s shall be designed, fabricated, inspected,
tested, marked, and stamped in accordance with the
requirements of this Standard and of the ASME Boiler
and Pressure Vessel Code (Code), Section VIII unless
otherwise permitted within this Standard.
In-service requirements for PVHO’s are found in
ASME PVHO-2.
1-2 SCOPE
1-2.1 Application
This Standard applies to all pressure vessels that
enclose a human within its pressure boundary while
under internal or external pressure exceeding a differential
pressure of 2 psi. PVHO’s include, but are not limited
to, submersibles, diving bells, personnel transfer capsules;
and decompression, recompression, hypobaric,
and hyperbaric PVHO’s.


I expect many changes to PVHO Code as shown by this most recent Case.

 

[scott1971]

CodeJackal,

Thank you very much for your valuable input! I don't have access to PVHO at the moment, and the information you provided definitely put things into perspective.

Scott

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[CharlesUK]

Scott,

The primary objective of ASME PVHO-1 Case 14 was to extend the use of acrylic chromatography column tubes to ASME specified bio-pharmaceutical production plant.

By removing the UV inhibitors, the acrylic is can be made USP Class VI compliant and tests have been conducted that demonstrate that the acrylic material is not degraded over time (aging) by the removal of UV inhibitors.

ASME PVHO-1 is the only ASME standard that covers acrylic materials for pressure rated applications and has been applied to Pressure Vessels for Human Occupancy (submarimes, diving systems, hyperbaric chamabers, hypobaric chambers, etc) for many years. Case 14 effectively extends the application of acrylic materials to pressure vessels (e.g. chromatography column tubes) that have humans in close proximity.

By having a 'U Stamp', the material is certified as a pressure rated material by complying to ASME PVHO-1 and, through association, BPVC Section VIII.

Charles

 

[scott1971]

Thanks Charles,

I'm involved in that very industry and discussed this further with Guy R and John D at the recent BPE meeting in Dublin (John and I work for the same company). I appreciate your comments and they will certainly add value to the thread. I was just looking for third-party opinions before the trip.

Cheers,
Scott

Scott
======================================
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