steris
Mechanical
- Nov 7, 2007
- 171
Hi Everyone,
I know the topic of pressure part versus nonpressure part has been asked before and these are good threads:
Additionally, I have reviewed UG-4(a) & (b) regarding the definition of pressure part to be any part that sees stress as a result of pressure. We are looking at a design where a sealing mechanism may require metal shims underneath locking elements in order to obtain a proper seal. These shims are external to the pressure retaining surfaces and do not directly see pressure. However, as pressure is increased, these shims will see a greater load. The shims will be loaded in compression only and will transfer the load to more structural elements (ie. not shims) that are pressure retaining parts. Because of the nature of the design, we are looking at using sheet metal to make up the small distance where the shims would be installed.
On the surface, it seems obvious that these shims would be pressure retaining since they see stress as a result of pressure. However, somewhere in the back of my head, I have this nagging thought parts that are under compression loads and that are not a pressure retaining surface could be treated as nonpressure parts. Am I making this up? The reason I care, is that I would love to use stock sheet metal for these shims and not have to worry about the extra work that comes with items classified as pressure parts.
I've asked our AI, and they don't have an opinion. Can anyone shed any light on this one way or the other?
Thanks for the help!
-Steris
I know the topic of pressure part versus nonpressure part has been asked before and these are good threads:
Additionally, I have reviewed UG-4(a) & (b) regarding the definition of pressure part to be any part that sees stress as a result of pressure. We are looking at a design where a sealing mechanism may require metal shims underneath locking elements in order to obtain a proper seal. These shims are external to the pressure retaining surfaces and do not directly see pressure. However, as pressure is increased, these shims will see a greater load. The shims will be loaded in compression only and will transfer the load to more structural elements (ie. not shims) that are pressure retaining parts. Because of the nature of the design, we are looking at using sheet metal to make up the small distance where the shims would be installed.
On the surface, it seems obvious that these shims would be pressure retaining since they see stress as a result of pressure. However, somewhere in the back of my head, I have this nagging thought parts that are under compression loads and that are not a pressure retaining surface could be treated as nonpressure parts. Am I making this up? The reason I care, is that I would love to use stock sheet metal for these shims and not have to worry about the extra work that comes with items classified as pressure parts.
I've asked our AI, and they don't have an opinion. Can anyone shed any light on this one way or the other?
Thanks for the help!
-Steris