Weldolets

Size Range: 1/8" - 24" / DN6 - DN600

Branch pipe size range (NPS)½" ~ 24"
Header pipe size range (NPS)2" ~ 48"
Pressure Rating: STD, XS, SCH 160
Standard: MSS SP-97

Class: STD, XS, XXS, S160, 5S, 10S

A Weldolet is a forged branch outlet fitting used to create a reinforced branch connection on a run pipe.

Unlike a conventional tee, a Weldolet is installed at an opening made in the main pipe. Its forged body provides reinforcement around the branch connection.
The branch outlet has a butt-weld end. The branch pipe is aligned with the outlet and welded around the prepared end.
This design provides a compact branch connection while reducing the need for a fabricated branch fitting.
The main components are:
Run pipe — the main pipeline carrying the process medium.
Branch outlet — the smaller pipe connected to the main pipe.
Forged reinforcement — the integral body around the branch opening.
Butt-weld end — the prepared outlet connected to the branch pipe.
MSS SP-97 covers integrally reinforced forged branch outlet fittings, including butt-weld, socket-weld and threaded outlet types.

No.	Type	Code	Description	Branch Size Range	Pressure / Wall Rating	End Connection	Standard Materials (ASTM)
1	Weldolet	WOL	Forged integrally-reinforced buttweld branch outlet, 90° (optional 45°). Branch end beveled for direct buttweld to branch pipe. Eliminates reinforcing pad.	NPS 1/8" – 24" (DN6–DN600)	STD / XS / Sch160 / XXS (per ASME B31.3)	Buttweld (BW)	A105, A350 LF2/LF3, A694 F42–F70, A182 F11/F22/F91/F92, A182 F304/F304L/F316/F316L/F321/F347H, A182 F51(2205)/F53(2507), B366 N06625/N10276/N08825
2	Sockolet	SOL	Forged socket-weld branch outlet, 90° (optional 45°). Branch pipe inserts into socket bore, fillet-welded at socket shoulder. For small-bore high-pressure lines.	NPS 1/8" – 4" (DN6–DN100)	Class 3000# / 6000#	Socket Weld (SW)	A105, A350 LF2, A182 F11/F22, A182 F304/F316L, A182 F51/F53, B366 N06625/N10276
3	Threadolet	TOL	Forged threaded branch outlet, 90° (optional 45°). Branch end with internal NPT (or BSP) thread, no branch-side welding. For instrument tapping, vent & drain.	NPS 1/8" – 4" (DN6–DN100)	Class 3000# / 6000#	Threaded (NPT / BSP)	A105, A350 LF2, A182 F11/F22, A182 F304/F316L, A182 F51/F53, B366 N06625/N10276
4	Latrolet	LAT	Forged 45° offset branch outlet. Branch axis at 45° to run pipe, reducing flow resistance for inclined take-offs. Available in BW / SW / NPT ends.	NPS 1/4" – 12" (DN8–DN300)	BW: STD/XS/Sch160; SW/THD: 3000#/6000#	BW / SW / NPT	A105, A350 LF2, A182 F11/F22/F91, A182 F304/F316L, A182 F51/F53, B366 N06625/N10276/N08825
5	Nipolet	NIP	Forged branch outlet with extended short-nipple body. Integral spool eliminates separate nipple fitting, reduces weld joints. Length per order.	NPS 1/8" – 4" (DN6–DN100)	Class 3000# / 6000#	Plain / BW / Ext. Thread	A105, A350 LF2, A182 F11/F22, A182 F304/F316L, A182 F51/F53
6	Elbolet	ELB	Forged elbow-type branch outlet, branch tangential to run pipe. Flow-optimized curved take-off, available BW / SW / NPT ends.	NPS 1/4" – 2" (DN8–DN50)	Class 3000# / 6000#	BW / SW / NPT	A105, A350 LF2, A182 F11/F22, A182 F304/F316L, A182 F51/F53
7	Orificeolet	ORI	Special forged instrument branch outlet for orifice tap connections. Pre-machined tapping port for differential-pressure flow meters.	NPS 1/4" – 2" (DN8–DN50)	Class 3000# / 6000#	SW / NPT (instrument tap)	A105, A350 LF2, A182 F11/F22, A182 F304/F316L, A182 F51/F53
8	Flangeolet	FOL	Forged branch outlet with integral flange face (RF / RTJ per ASME B16.5). No separate flange required; branch bolts up directly.	NPS 1/2" – 24" (DN15–DN600)	Class 150# – 2500#	Flanged (RF / RTJ)	A105, A350 LF2, A182 F11/F22/F91, A182 F304/F316L, A182 F51/F53, B366 N06625/N10276

Standard	Scope
MSS SP-97	Integrally reinforced forged branch outlets (primary standard)
GB/T 19326-2022	Forged socket-weld, threaded & buttweld branch outlets (China)
ASME B16.9	Factory-made buttweld fittings (reference for BW ends)
ASME B16.11	Forged socket-weld & threaded fittings (reference for SW/NPT ends)
ASME B16.5	Pipe flanges (reference for Flangeolet flange faces)

1.Raw Material Selection
Select suitable carbon steel, stainless steel, or alloy steel according to the application and required standards.
2.Cutting and Forging
Cut the raw material and form the weldolet through hot forging to achieve the required shape and strength.
3.Machining
Machine the forged fitting to achieve accurate dimensions, branch outlet size, wall thickness, and surface finish.
4.Heat Treatment
Apply the required heat treatment to improve strength, toughness, ductility, and dimensional stability.
5.Welding Preparation
Clean and bevel the connection surfaces to ensure proper fit-up and weld penetration.
6.Finishing and Inspection
Finish the surface and inspect dimensions, appearance, and material quality. NDT methods such as UT, RT, or MT may also be performed when required.
7.Packaging and Delivery
After final inspection, pack the weldolets securely and prepare them for shipment.

Group	ASTM Grades
Carbon Steel	A105
Low-Temp Carbon Steel	A350 LF2, LF3
Line Pipe Steel	A694 F42 – F70
Cr-Mo Alloy Steel	A182 F5, F11, F22, F91, F92
Austenitic Stainless	A182 F304, F304L, F316, F316L, F321, F347H
Duplex / Super Duplex	A182 F51 (2205), F53 (2507)
Nickel Alloy	B366 N06625 (Inconel 625), N10276 (Hastelloy C-276), N08825 (Incoloy 825), Monel 400

All dimensions are in millimeters (mm).

Outlet DN	Outlet NPS	STD – Reducing	STD – Full	XS – Reducing	XS – Full	Sch 160 – Reducing	Sch 160 – Full
6	1/8	15.7	—	15.7	—	—	—
8	1/4	15.7	—	15.7	—	—	—
10	3/8	19.1	—	19.1	—	—	—
15	1/2	19.1	19.1	19.1	19.1	28.4	28.4
20	3/4	22.4	22.4	22.4	22.4	31.8	31.8
25	1	26.9	26.9	26.9	26.9	38.1	38.1
32	1 1/4	31.8	31.8	31.8	31.8	44.4	44.4
40	1 1/2	33.3	33.3	33.3	33.3	50.8	50.8
50	2	38.1	38.1	38.1	38.1	55.4	55.4
65	2 1/2	41.1	41.1	41.1	41.1	62	62
80	3	44.4	44.4	44.4	44.4	73.2	73.2
90	3 1/2	47.8	50.8	47.8	50.8	—	—
100	4	50.8	50.8	50.8	50.8	84.1	84.1
125	5	57.2	57.2	57.2	57.2	93.7	93.7
150	6	60.4	60.4	77.7	77.7	104.6	104.6
200	8	69.8	69.8	98.6	98.6	—	—
250	10	77.7	77.7	93.7	88.9	—	—
300	12	85.9	85.9	103.1	100.1	—	—
350	14	88.9	88.9	100.1	104.6	—	—
400	16	93.7	93.7	106.2	112.8	—	—
450	18	96.8	103.1	111.2	119.1	—	—
500	20	101.6	117.3	119.1	127	—	—
600	24	115.8	136.6	139.7	139.7	—	—

Tolerance: 6–20 ± 0.8 mm
25–100 ± 1.6 mm
125–300 ± 3.2 mm
350–600 ± 4.8 mm