Oxygen Service PZV 1

[Nasim12345]

Dears
Is it mentioned anywhere in the International Standards (ASME/API) that, don't use Grease or Molykote on PSV Internals and threads. If yes, can you pls share the same

I have read on safety bulletins that special lubricants, which are exclusively made of Oxygen service can be used.

Thanks
Nasim

 

[The Obturator]

It's engineering common sense not to use grease for oxygen applications. The attachment you present is one such example.

As regards oxygen service Pressure-relief Valves, most manufacturers (and end users), have their own standards for oxygen service should it be made clear in the clients enquiry.

Generally, carbon steel is not to be used. Stainless steel is generally used for the entire valve construction. The valve components are first degreased in a controlled environment before assembly and special lubricants are used during valve assembly. Depending on the severity of the application, the valves may even be built in an isolated 'clean room' by the assembler wearing special clothing. The test medium may even be of a controlled 'clean' nature. Once tested, the valves will be tagged as for 'Oxygen Service', then bagged up and sealed to a defined procedure.

The above can be one such procedure which may differ between manufacturers and the end users own requirements.


*** Per ISO-4126, the generic term
'Safety Valve' is used regardless of application or design ***

*** 'Pressure-relief Valve' is the equivalent ASME/API term ***

 

[Nasim12345]

Thanks for your reply

 

[shvet]

Grease can be used if it is proven compatible with oxygen enriched fluids. Some brief view in a vast world of O2 and cryo fluids can be found in NFPA 53, ASTM G88, G128 and EIGA IGC 13. All of those contain prohibitions to use not-certified materials in contact with an oxygen enriched fluid. More info can be found in references in those.

Note that if outlet nozzle of a valve is connected to a piping that is proven for non-oxygen enriched service then it is overkill to provide oxygen design for downstream parts of valve internals. If this situation is valid for your PSV then answer is - any grease can be used for low-pressure side of PSV.

Note that it is prohibited by para. 5.3.5 EIGA IGC 13 to use non-compatible greases even for valve parts not in contact with a fluid for instance for gear box and wheel in manual operated valves.

 

[FacEngrPE]

ASTM-G88 › Standard Guide for Designing Systems for Oxygen Service
ASTM-G128 › Standard Guide for Control of Hazards and Risks in Oxygen Enriched Systems
are highly useful and recommended references.
MIL-STD-1330D, MILITARY STANDARD: PRECISION CLEANING AND TESTING OF SHIPBOARD OXYGEN, HELIUM, HELIUM-OXYGEN, NITROGEN, AND HYDROGEN SYSTEMS has a useful explanation of oxygen clean.