I need to design a Y fitting that acts as a nozzle to connect two pressure vessels. All 3 sections of the Y is to be made of 2" SS304 pipe. Which part of the ASME code should I use to do the design calculations for this Y ?
The design pressure of the fitting is 240 psi and design temperature is 80f. Our aim is not to connect the tubes in series, so we cannot use a 180 elbow. We can only use a Y joint in our application.
since it's size on size, if I'm understanding correctly, it's outside VIII-1. Appendix 1-7 only covers a ratio of RN/R of 0.7 or less. As I stated before, U-2(g), and do a burst test to UG-101(m). Or do an FEA.
As it is with the Y connection there will not be any flexibility between the vessels.
In case one vessel moves differentially then the other one the Y nozzle will be overloaded/overstressed, and perhaps will fail. As it is the supports are opposing each other, vessels will grow towards each other under thermal load and this will create additional bending stresses on Y legs. In case the system is not small and identically supported I would suggest to create loop which includes a T connection with flange as suggested. Everything depends on the thermal loading, if any in the system, differential expansion/contraction and the supporting system.
A solution is CC202. It may imply you have to use a casting or forging, but hey, if you need to comply with B31.3, at least you have an option that (to me) sounds better than FEA or burst testing. Why take all the hassle of 304.7.2?
Huub
- You never get what you expect, you only get what you inspect.