Every piping designer has put in a y-strainer at some point, and if this is your first time, or you simply did it without knowing much about it - then here's some basic knowledge to help you out.
- "Y" strainers are not reducing. The bore is the same end to end.
- The top section is not a straight piece of pipe. The fitting is actually in a "Y" shape, hence the name. The shape allows fluid to flow down through a screen and then back up to the connecting pipe.
- The screen will catch any solid matter in the fluid and remain in the trap until cleaning.
- The bottom of the "Y" shape is often not a standard ASME flanged connection. I have seen rounded flanges, square flanges, threaded caps, and I'm sure there are other varieties. For this reason, you should avoid indicating a flange size/rating on your P&ID unless you know for sure what you are getting. You often don't know who the supplier is until late in the design, and sometimes you cannot confirm until the as-build stage. Call out only what you know.
- The "Y" strainer is somewhat of a custom fitting in that different suppliers/brands can have differing body shapes/sizes/dimensions. However, the face to face dimensions are somewhat standard from supplier to supplier.
- As a side note, basket strainers have the same function but are not dimensionally interchangeable. Best to know exactly what kind of strainer you are getting prior to piping it. Otherwise, you're place-holder may not be accurate.
When you are inserting a y-strainer into CADWorx or similar software, ask your PM for vendor information and obtain/verify the dimensions that you require for the strainer. Then make sure that your CADWorx component is modelled correctly before inserting. If you don't have accurate information, put in a place-holder spool and turn it red. Just make sure you don't forget to correct that piping prior to running spools.
Happy piping!
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