Pressure Containing vs Pressure Retaining Parts
Pressure Containing vs Pressure Retaining Parts
(OP)
May I know what does it mean by "pressure containing parts"? And What does it mean by "pressure retaining parts"? What is the difference between "pressure containing parts" and "pressure retaining parts"? Very appreciate if anyone can help.





RE: Pressure Containing vs Pressure Retaining Parts
Pressure Containing Part: Withstanding or "containing" a (internal) pressure without leakage, as would a pressure pipe, valve body or pressure tank.
Pressure Retaining Part: Holding a pressure, but without actually "containing", or stopping flow entirely, as would a stuffing box or a labyrinth seal. Also it might be a part that could hold pressure under, inside, or to one side of it after an external, body, or primary pressure had been released.
http://virtualpipeline.spaces.msn.com
RE: Pressure Containing vs Pressure Retaining Parts
I buy some Coriolis flow measurement instruments that include secondary containment. The secondary containment lacks the full ASME flange pressure and temperature rating. However, upon a rupture of the element it may prevent a spill or release up to a pressure well below the body rating.
RE: Pressure Containing vs Pressure Retaining Parts
jt
RE: Pressure Containing vs Pressure Retaining Parts
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: Pressure Containing vs Pressure Retaining Parts
I would like to understand the terms apply on valve. Thank you
RE: Pressure Containing vs Pressure Retaining Parts
I know of no document that makes a distinction between "pressure-retaining" and "pressure-containing" parts and I agree with jte's last sentence. In the real world these terms are used interchangeably.
In theory, if you have a section view of a valve assembly that is internally pressurized, any part that you erase that would allow the pressure to escape would be considered and pressure-containing part.
Having stated this, some parts, such as bodies, bonnets, cover flanges etc. are strictly governed by design codes and standards published by the ASME/ANSI (or agencies in other countries). Some parts that may be cosidered pressure-containing, such as stems, shafts, packings and seals may not be covered by any design standards.
This can be a complex issue depending upon the valve style and the applicable codes and standards. If you have a specific question please add some details and we will attempt to answer your question.
Hope this helps.
ABScott
RE: Pressure Containing vs Pressure Retaining Parts
And "retaining" parts are the bolting, studs, nuts, clamps etc. holding the containing parts together.
RE: Pressure Containing vs Pressure Retaining Parts
RE: Pressure Containing vs Pressure Retaining Parts
To retaining, I would add bonnets.
Paul Ostand
www.ostand.com
RE: Pressure Containing vs Pressure Retaining Parts
JAC
RE: Pressure Containing vs Pressure Retaining Parts
Clause 1.4.1 7 A pressure-containing part is a part that acts as a barrier between processo r motive fluid and thea tmosphere. Such parts include, but are not necessarily limited to the liquid cylinder, the discharge manifold, the suction manifold, the stuffing box, cylinder plugs and covers (when in contact with process fluid), valve seats (when a portion is in contact with the atmosphere), the gas cylinder, the gas cylinder head, the valve chest, and the valve chest cover and heads.
Clause 1.4.1 8 A pressure-retaining part is a part whose failure
would allow process or motive fluid to escape to the atmosphere. In addition to the pressure-containing parts listed in 1.4.17, pressure-retaining parts include, but are not necessarily limited to, liquid and gas cylinder bolting, stuffing box bolting, gland bolting, glands, and covers that constrain plugs and valve stops. Not included in pressure-retaining parts are parts such as packing, gaskets, pistons, plungers, piston rings, rods, valves, seats (when completely surroundbeyd pressurecontaining
parts), and internal bolting.
Does anyone have an ASME reference for the above definitions, having just hit the wall with a fabricator refusing to accept this definition not sourced from the Code, but a standard only...
gr2vessels
RE: Pressure Containing vs Pressure Retaining Parts
I checked API 579 - fitness for service uses examples but no real definition. API RP 582 Welding Guidelines includes the following:
"Pressure-containing equipment (such as pressure vessels,
heat exchangers, tankage, piping, heater tubes, pressure
boundaries of rotating equipment, and attachments welded
thereto)."
API RP 582 uses the phrase pressure retaining without a definition.
RE: Pressure Containing vs Pressure Retaining Parts
Quoted, "Those parts whose failure to function as intended would result in a release of retained fluid to the atmosphere. Examples are valve bodies, bonnets, and stems.", Unquoted.
The above is not direct response to this thread. So, I would add my own response below,
"containing parts" and "retaining parts" are to be understood as same meaning at the viewpoint whether or not, a failure of parts (e.g., body, bonnet, cover, seat ring & closure member <-- if valves used as dead-end service) results in releasing pressurized service fluid outside of spoken pressure unit (e.g., valve, pump, vessel).
However, gaskets and seals should be exempted from those terms, by their nature. These parts are produced to act against "pressure", thus unnecessary to be categorized into "containing parts" nor "retaining parts" again.
I hope that I am not far a way from others in interpretation.
monofm4m
RE: Pressure Containing vs Pressure Retaining Parts
i have neither with me at the moment but I know that in sorting out test results and quality assurance issues with the National Board they make specific reference to portions of a Safety Relief Valve as pressure containing, and others as pressure retaining. Much like the post from No Soup above.
There is also "pressure defining element" in a B & PV Sense but thats another can of worms.