Code Case 2211

[TangoCleveland]

Case 2211-1 says we can use system design in lieu of a relief valve to protect a pressure vessel if "The vessel is not exclusively in air, water, or steam service unless these services are critical to preventing the relase of fluids that may result in safety or environmental hazards."

We are looking at an air receiver designed to 150 psig being used in a system fed by a 40 psig centrifugal compressor with a 45 psig relief valve. The air is used as a utility. Since the vessel is exclusively in air service, it looks like CC2211 tells us we must have a relief valve. Is this correct?

Larry

 

[Ashereng]

Case 2211-1 says we can use system design in lieu of a relief valve to protect a pressure vessel

Larry, I am not familiar with Case 2211-1, but this passage seems to indicate using a HIPPS (High Integrity Pressure Protection System).

From a practical point of view, using a PRV on an instrument air receiver is most likely cheaper, and more common. I have not heard of a HIPPS on an air receiver.

Anyone else out there know of one?

 

[metengr]

No, net necessarily. I would discuss this with your local Jurisdiction or insurer because they are the ones that have to issue an operating permit, and their opinions are the only ones that count. I will tell you this, some Jurisdictions will adopt Code Cases, and others do not.

 

[TangoCleveland]

I checked for HIPPS and found IEC 61508, "FUNCTIONAL SAFETY OF ELECTRICAL/ELECTRONIC/PROGRAMMABLE ELECTRONIC SAFETY-RELATED SYSTEMS." This seems to relate to part of the intent of Code Case 2211-1, but the extra analysis and complexity seem to indicate that it's meant for more hazardous processes than just air systems. A PSV on our air vessel would be more economical. The two documents should probably refer to each other.

I'd still like to have a discussion about a pressure vessel in a system with a PSV on adjacent piping, though. Would 2211-1 apply to a case like that?

Our local jurisdiction is NASA, so that's another complication.....

Larry

 

[TangoCleveland]

I just took a closer look at Sec VIII. UG-125 says:

[tt]"UG-125 GENERAL
(a) All pressure vessels within the Scope of this
Division, irrespective of size or pressure, shall be
provided with pressure relief devices in accordance
with the requirements of UG-125 through UG-137."[/tt]

Our specific situation (not a receiver, but a compressor aftercooler) looks like it's covered by UG-125(g), so that our 150 psig shell fed by a 40 psig compressor with 50 psig PSV does not need its own relief valve:

[tt]"(g) The pressure relief devices required in (a) above
need not be installed directly on a pressure vessel when
the source of pressure is external to the vessel and is
under such positive control that the pressure in the
vessel cannot exceed the maximum allowable working
pressure at the operating temperature except as permitted
in (c) above (see UG-98)."[/tt]

I've used this provision to install filter vessels rated at 150 psig in a line protected by a 140 psig PSV on the compressor discharge - with no intervening valves.

Comments, please?

Larry