CrazyJ
Mechanical
- Feb 23, 2003
- 12
Perhaps the B31.1 experts can help me understand an issue regarding unions.
B31.1 106.3 states that Class 3000 steel pipe unions, constructed in accordance with MSS SP-83, may be used provided the system design conditions are within the standard's listed pressure-temperature ratings.
B31.1 114 Threaded Joints may be used within the limitations specified in Para 106 and within the other limitations specified herein.
B31.1 114.1 All threads on piping components shall be taper pipe threads in accordance with table 126.1 (MSS, ASTM, etc). Threads other than taper pipe threads may be used for piping components where tightness of the joint depends on a seal weld or a seating surface otehr than the threads, and where experience ot test has demonstrated that such threads are suitable.
B31.1 114.2.1(A) prohibits threaded connections in situations above 496C, severe erosion, shock, crevice corrosion, or vibration
B31.1 114.2.1(B) limits maximum size of threaded connections to 1200psi for 1" (along with other tabulated values), for (B1) steam/water above 105 C, (B2) flammable gases, etc.
I state all these to give some background.
At the plant where I'm employed, our original design standards prohibit unions for drains or condensate service, and there's no differentiation given for drain piping to ambient air (to tundishes), yet there are pipe unions everywhere. I feel that it may be commonly used by the designeres, just not documented in our standards.
What's the opinion of the piping experts? If draining to a tundish (after one or more isolation valves of course), is there a reason by code to disallow pipe unions on an open ended drain line?
B31.1 106.3 states that Class 3000 steel pipe unions, constructed in accordance with MSS SP-83, may be used provided the system design conditions are within the standard's listed pressure-temperature ratings.
B31.1 114 Threaded Joints may be used within the limitations specified in Para 106 and within the other limitations specified herein.
B31.1 114.1 All threads on piping components shall be taper pipe threads in accordance with table 126.1 (MSS, ASTM, etc). Threads other than taper pipe threads may be used for piping components where tightness of the joint depends on a seal weld or a seating surface otehr than the threads, and where experience ot test has demonstrated that such threads are suitable.
B31.1 114.2.1(A) prohibits threaded connections in situations above 496C, severe erosion, shock, crevice corrosion, or vibration
B31.1 114.2.1(B) limits maximum size of threaded connections to 1200psi for 1" (along with other tabulated values), for (B1) steam/water above 105 C, (B2) flammable gases, etc.
I state all these to give some background.
At the plant where I'm employed, our original design standards prohibit unions for drains or condensate service, and there's no differentiation given for drain piping to ambient air (to tundishes), yet there are pipe unions everywhere. I feel that it may be commonly used by the designeres, just not documented in our standards.
What's the opinion of the piping experts? If draining to a tundish (after one or more isolation valves of course), is there a reason by code to disallow pipe unions on an open ended drain line?
