Name: Forged Threaded Reducing Coupling
Brand: Cunimet Alloy International

Product Overview

Forged Threaded Reducing Coupling

The Forged Threaded Reducing Coupling joins two threaded pipes of different diameters in a straight run using female NPT connections at both ends. One end accommodates the larger pipe, the other accepts the smaller pipe. Both pipes are screwed into the coupling body, creating a fully screwed, demountable joint that steps the piping bore down from a larger to a smaller size in a single compact fitting.

Cunimet Alloy International manufactures threaded reducing couplings through closed-die forging. Both ends are precision-threaded on CNC equipment to ASME B1.20.1 (NPT) tolerances. The concentricity of both thread axes is verified by dimensional inspection before dispatch to ensure consistent thread engagement and leak-free assembly. All standard ASME B16.11 size combinations are available.

ASME B16.11 ASME B1.20.1 (NPT) 2000# • 3000# • 6000# Large & Small Female NPT All Standard Size Combos

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ASMEStandardB16.11

2 NPTUnequal EndsLarge + Small Female

3/4–4"Large End RangeNPS

2000#Min. ClassAlso 3000# & 6000#

3Material GradesSS / Duplex / S.Duplex

Technical Data

Threaded Reducing Coupling — Standard Size Combinations

“L” = Overall length. Length is governed by the larger end pressure class. Thread form NPT per ASME B1.20.1. All dimensions in millimetres.

Large End NPS	Small End NPS	L — Class 2000# (mm)	L — Class 3000# (mm)	L — Class 6000# (mm)	Large End TPI	Small End TPI
3/4"	1/2"	59	64	79	14	14
1"	3/4"	73	79	98	11.5	14
1"	1/2"	73	79	98	11.5	14
1-1/4"	1"	86	94	114	11.5	11.5
1-1/4"	3/4"	86	94	114	11.5	14
1-1/4"	1/2"	86	94	114	11.5	14
1-1/2"	1-1/4"	95	102	121	11.5	11.5
1-1/2"	1"	95	102	121	11.5	11.5
1-1/2"	3/4"	95	102	121	11.5	14
2"	1-1/2"	114	117	140	11.5	11.5
2"	1-1/4"	114	117	140	11.5	11.5
2"	1"	114	117	140	11.5	11.5
2-1/2"	2"	133	140	165	8	11.5
2-1/2"	1-1/2"	133	140	165	8	11.5
3"	2-1/2"	152	162	190	8	8
3"	2"	152	162	190	8	11.5
4"	3"	190	197	235	8	8
4"	2-1/2"	190	197	235	8	8
4"	2"	190	197	235	8	11.5

Above combinations are standard per ASME B16.11. Other non-standard combinations available on request. BSP threads to BS EN 10226 available. All dimensions in millimetres.

Available Materials

Material Grades for Threaded Reducing Couplings

Grade 01

Stainless Steel 304 / 316

Austenitic stainless steel for chemical, food, pharmaceutical and water treatment threaded piping bore reductions. SS 316 provides superior chloride resistance and is the standard choice for offshore, coastal and chemical service environments.

ASTM A182 F304ASTM A182 F316ASME B16.11

Grade 02

Duplex Steel

High-strength duplex reducing couplings for offshore instrument tubing, chemical plant screwed piping and desalination utility systems where bore reduction is required in a system that also demands stress corrosion cracking resistance.

ASTM A182 F51UNS S31803UNS S32205

Grade 03

Super Duplex Steel

Premium super duplex reducing couplings with PREN greater than 40 for bore reduction connections in seawater service, offshore topsides and aggressive chloride environments where maximum corrosion resistance at every screwed joint is required.

ASTM A182 F53UNS S32750UNS S32760

Quality & Compliance

Standards, Testing & Documentation

Applicable Standards

Standard	Description
ASME B16.11	Forged Fittings, Socket-Welding & Threaded — dimensional standard
ASTM A182	Material specification for forged alloy and stainless steel fittings
ASME B1.20.1	NPT Pipe Threads — form, dimensions and tolerances
BS EN 10226	BSP pipe threads — available on request
MSS SP-25	Standard marking for forged fittings
EN 10204	3.1 MTC standard; 3.2 with TPI on request

Quality Tests Performed

Test	Method / Scope
Chemical Analysis	OES per ASTM A182 for each heat of material
Mechanical Testing	Tensile, yield, elongation and Charpy impact where specified
Hardness Testing	Brinell or Vickers per ASTM A182 requirements
Thread Gauging	100% NPT go/no-go gauge on both ends per ASME B1.20.1
PMI	100% XRF Positive Material Identification on request
Dimensional Inspection	100% per ASME B16.11 — overall length, both thread axes, concentricity

Applications

Where Threaded Reducing Couplings Are Used

01

Threaded Pipe Bore Reduction

Stepping down from a larger-bore threaded pipe run to a smaller-bore pipe or instrument connection in a single compact fitting, replacing two separate tee-and-cap arrangements in screwed piping systems.

02

Control Valve Stations

Installing a smaller-bore threaded control valve into a larger-bore screwed process line using a pair of reducing couplings at each side of the valve, maintaining compact screwed installation throughout.

03

Instrument Line Connections

Connecting large-bore process line tapping points to small-bore instrument impulse tubing or sample lines using reducing couplings in Stainless Steel or Duplex Steel for the required corrosion resistance.

04

Chemical Dosing Systems

Reducing from chemical injection pump outlet nozzle bore to smaller-bore injection quill tubing connections in dosing skid pipework using corrosion-resistant alloy threaded reducing couplings throughout.

Threaded Fittings Range

Forged Threaded Reducing Coupling

Forged Threaded Reducing Coupling

Threaded Reducing Coupling — Standard Size Combinations

Material Grades for Threaded Reducing Couplings

Stainless Steel 304 / 316

Duplex Steel

Super Duplex Steel

Standards, Testing & Documentation

Applicable Standards

Quality Tests Performed

Where Threaded Reducing Couplings Are Used

Threaded Pipe Bore Reduction

Control Valve Stations

Instrument Line Connections

Chemical Dosing Systems

Other Forged Threaded Fittings

Threaded Full Coupling

Threaded Half Coupling

Threaded Union

Threaded 90° Elbow

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