Name: Socket Weld Reducing Coupling
Brand: Cunimet Alloy International

Socket Weld Reducing Coupling – Forged SS 304 316 Duplex Super Duplex

Product Overview

Forged SW Reducing Coupling

The Socket Weld Reducing Coupling is a two-socket forged fitting used to permanently join two pipes of different diameters in a straight run. One end carries a larger socket bore to accept the larger pipe, while the opposite end carries a smaller socket bore for the smaller pipe. Both pipe ends are welded with fillet welds after insertion, forming a compact, leak-proof reducing connection in one fitting.

The reducing coupling is the most compact method of stepping down pipe bore in socket weld piping systems, requiring only one forged fitting and two weld joints, compared to the two-fitting, two-weld alternative using two full couplings and a spool piece. Cunimet Alloy International supplies all standard ASME B16.11 reducing combinations in the stated material grades.

Both socket bores are precision-machined to ASME B16.11 tolerances on CNC equipment, and the fitting body is dimensionally inspected to confirm concentricity of the two socket axes before dispatch.

ASME B16.11 MSS SP-79 3/4"×1/2" to 4"×3" 3000# • 6000# All Standard Reducing Combos

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ASME Standard B16.11

2 Unequal Sockets Large + Small End

3/4–4" Large End Range NPS

3000# Pressure Class Also 6000#

3 Material Grades SS / Duplex / S.Duplex

Technical Data

Standard Reducing Combinations — ASME B16.11

All standard ASME B16.11 reducing combinations are available. The table below lists the standard combinations. The overall coupling length “L” is governed by the larger end pressure class. All dimensions in millimetres.

Large End NPS	Small End NPS	Large Socket Bore (mm)	Small Socket Bore (mm)	Overall Length 3000# (mm)	Overall Length 6000# (mm)
3/4"	1/2"	26.9	21.6	59	73
1"	3/4"	33.6	26.9	70	92
1"	1/2"	33.6	21.6	70	92
1-1/4"	1"	42.4	33.6	83	105
1-1/4"	3/4"	42.4	26.9	83	105
1-1/4"	1/2"	42.4	21.6	83	105
1-1/2"	1-1/4"	48.5	42.4	92	114
1-1/2"	1"	48.5	33.6	92	114
1-1/2"	3/4"	48.5	26.9	92	114
2"	1-1/2"	60.5	48.5	108	130
2"	1-1/4"	60.5	42.4	108	130
2"	1"	60.5	33.6	108	130
2-1/2"	2"	73.2	60.5	127	159
2-1/2"	1-1/2"	73.2	48.5	127	159
3"	2-1/2"	89.1	73.2	146	178
3"	2"	89.1	60.5	146	178
3"	1-1/2"	89.1	48.5	146	178
4"	3"	114.5	89.1	178	222
4"	2-1/2"	114.5	73.2	178	222
4"	2"	114.5	60.5	178	222

Above combinations are standard per ASME B16.11. Other non-standard reducing combinations available on request. All dimensions in millimetres, nominal per ASME B16.11 latest edition.

Available Materials

Material Grades for SW Reducing Couplings

Grade 01

Stainless Steel 304 / 316

Austenitic stainless steel for general-purpose reducing connections in chemical, food, pharmaceutical and water treatment piping. SS 316 recommended for chloride-bearing or marine environments.

ASTM A182 F304 ASTM A182 F316 ASME B16.11

Grade 02

Duplex Steel

High-strength duplex alloy for reducing connections in offshore, chemical plant and desalination environments. Higher yield strength allows thinner wall at equivalent pressure rating compared to austenitic grades.

ASTM A182 F51 UNS S31803 UNS S32205

Grade 03

Super Duplex Steel

Premium super duplex alloy with PREN greater than 40 for the most demanding reducing connections in seawater service, subsea production systems and aggressive chemical environments.

ASTM A182 F53 UNS S32750 UNS S32760

Quality & Compliance

Standards, Testing & Documentation

Applicable Standards

Standard	Description
ASME B16.11	Forged Fittings, Socket-Welding & Threaded — dimensional standard
MSS SP-79	Socket Welding Reducer Inserts — complementary standard
ASTM A182	Material specification for forged alloy and stainless steel fittings
ASME B31.3	Process piping code — socket weld gap and weld procedures
MSS SP-25	Standard marking for valves, fittings and flanges
EN 10204	3.1 MTC standard; 3.2 on request

Quality Tests Performed

Test	Method / Scope
Chemical Analysis	OES per ASTM A182 for each heat of material
Mechanical Testing	Tensile, yield, elongation, Charpy impact where specified
Hardness Testing	Brinell or Vickers per ASTM A182 requirements
PMI	100% XRF on request
Dimensional Inspection	100% per ASME B16.11 — both socket bores, depths, overall length and concentricity
Visual Inspection	100% per MSS SP-55 acceptance criteria

Applications

Where SW Reducing Couplings Are Used

01

Pipe Bore Reduction

Stepping down from a larger bore header or main line to a smaller bore branch or sub-header in process plant piping, where a single compact fitting replaces a fabricated reducer assembly.

02

Pump & Compressor Connections

Connecting larger process line bore to smaller pump suction or compressor inlet nozzles, or reducing from a compressor outlet nozzle to a smaller discharge pipe size.

03

Control Valve Stations

Installing a smaller bore control valve into a larger bore process line using a pair of reducing couplings on each side of the valve, maintaining a compact, weld-only installation.

04

Chemical Injection Systems

Reducing from a chemical injection pump outlet nozzle to small-bore injection quill tubing in offshore and onshore chemical dosing systems where corrosion-resistant alloys are mandatory.

Socket Weld Fittings Range

Socket Weld Reducing Coupling