Forged Branch Outlet Fittings

1. Basic knowledge of forged branch outlets

Just like reinforced pad and welding saddle, the forged branch outlet is a stub-in fitting which is most commonly used as an alternative to the reducing tee. A hole is bored into the run pipe(header). The branch outlet, which is used to connect the branch pipe, either 90 or 45 degree, is stubbed into the hole and then fillet welded to the header. One end of the branch outlet should be machined to the contour of the run pipe. The other end should be manufactured to match the end connection of the branch pipe. Hence it can be categorized according to its end connection:

1) Weld-Outlet(WeldOlet): buttwelding end finishes complying with the standard welding bevel and root face of ASME B16.25.

2) Thread-Outlet(ThreadOlet): Threads connection complying with ASME B1.20.1

3) Socket Weld-Outlet(SocketOlet): Socket weld end connection should meet the minimum socket depth, minimum socket wall thickness and socket diameter of ASME B16.11.

As a rule of thumb, the branch pipe can be the same pipe size or smaller as the run pipe. However, it can not be larger. A outlet should be welded at least 3 inches away from any other branches aside. According to MSS SP 97, The outlets shall be countoured to provide a good fit at the opening in the run pipe. The manufacturer can consolidate run sizes for a given branch size for economic reasons as long as the gap(crotch & skirt) distance between the run pipe radius and the fitting inlet radius does not exceed 1/16"(1.6mm).

In Hebei Metals' forging workshop, up to size 4", the outlets are manufactured the same on different run pipe sizes. For outlets sizes over 4", usually a specific radius is required for each run size.

Standard marking of outlets: Trademark + Material + Class + Size + SP 97 + Heat Number.

2. Advantages of using forged branch outlets

Compared with reducing tees, the branch outlets(either weldolet, threadolet or socketolet) reduce the welding cost and its related X-ray inspection cost. They also allow more flexible installation in practice. Besides, the run pipe having a branch connection is weakened by the hole bored in it. The forged high-yield branch outlet perfectly reinforces the opening and restore the original strength of the run pipe.

Compared with saddles and reinforcing pads, the forged branch outlets reduce fabrication cost. They avoid metal to metal lapped surfaces and improve the stress due to sharp conners. The contoured surface can fit the run pipe perfectly providing full fluid flow.

3. Materials for forged branch outlets

Forged branch outlets are available in an extensive range of materials:

1) Carbon Steel: ASTM A105(N), ASTM A694, ASTM A350

2) Low Alloy Steel: ASTM A182 F1, F11, F22, F5, F9, etc.

3) Stainless Steel: ASTM A182 F304(L), F316(L), F317, F321, F347, F904L, F51, etc.

4) Pure Nickel, Low Alloy Nickel, Ni-Cu Alloy, Ni-Mo Alloy, Fe-Ni-Cr Alloy, Ti, Colbalt, etc.

4. Size, Type and Class of forged branch outlets

Class of Outlets	Type	Branch Size	Pipe Wall Thickness
STD	WeldOlet	1/8" ~ 24"	STD
XS	WeldOlet	1/8" ~ 24"	XS
SCH 160	WeldOlet	1/2" ~ 6"	SCH 160
3000	ThreadOlet	1/8" ~ 4"	XS
6000	ThreadOlet	1/2" ~2"	SCH 160
3000	SocketOlet	1/8" ~ 4"	XS
6000	SocketOlet	1/2" ~2"	SCH 160

Views: Author：hbmetals Date:15/10/13