Views: 3 Author: Site Editor Publish Time: 2025-09-09 Origin: Site
Stainless steel forged coupling, as the core connecting components of industrial pipelines, must comply with strict international standards to ensure quality and compatibility. Mainstream standards include:
ASME B16.11: The most commonly used standard for stainless steel forged coupling, specifies the material requirements, dimensional tolerances, manufacturing processes, and inspection specifications for forged pipe clamps, and is applicable to connection forms such as threads and sockets. It is a universal standard for forged pipe fittings.
EN 10241: The European standard for forged threaded fittings specifies in detail the dimensions, tolerances, marking, and testing requirements. Its main purpose is to ensure the interchangeability and reliability of threaded fittings.
ISO 4144: For forged pipe threaded fittings, it specifies the thread accuracy, structural dimensions, and performance indicators of coupling, and is widely applicable in the European and international markets.
According to the connection method, stainless steel forged couplings are mainly divided into two categories:
Threaded Coupling: It is connected by interlocking the internal thread with the external thread of the pipeline, without welding, and is easy to install. Common types include straight threaded coupling and reducing threaded coupling (variable diameter connection).
Socket weld coupling: using socket welding structure, the pipeline is fixed by welding after being inserted into the socket of the coupling, with strong sealing performance and high pressure bearing capacity, suitable for high pressure, high temperature and vibration conditions, including straight socket weld coupling, reducing socket weld coupling, etc.
Nominal diameter (NPS): ranging from 1/8 inch to 4 inches, such as NPS 1/2 (corresponding to DN15), NPS 2 (corresponding to DN50).
Thread specifications: NPT, BSPP, BSPT, etc. Thread accuracy meets ANSI/ASME B1.20.1 to ensure sealing performance.
Dimension of Threaded Coupling
| Nominal Size | End-to-End | Outside Diameter | Length of Thread | |||
| DN | NPS | W | D | L 5 min | L 2 min | |
| 3000 & 6000 | 3000 | 6000 | ||||
| 6 | 1/8 | 32 | 16 | 22 | 6.4 | 6.7 |
| 8 | 1/4 | 35 | 19 | 25 | 8.1 | 10.2 |
| 10 | 3/8 | 38 | 22 | 32 | 9.1 | 10.4 |
| 15 | 1/2 | 48 | 28 | 38 | 10.9 | 13.6 |
| 20 | 3/4 | 51 | 35 | 44 | 12.7 | 13.9 |
| 25 | 1 | 60 | 44 | 57 | 14.7 | 17.3 |
| 32 | 11/4 | 67 | 57 | 64 | 17.0 | 18.0 |
| 40 | 11/2 | 79 | 64 | 76 | 17.8 | 18.4 |
| 50 | 2 | 86 | 76 | 92 | 19.0 | 19.2 |
| 65 | 21/2 | 92 | 92 | 108 | 23.6 | 28.9 |
| 80 | 3 | 108 | 108 | 127 | 25.9 | 30.5 |
| 100 | 4 | 121 | 140 | 159 | 27.7 | 33.0 |
Weight List(KG)
| NOMINAL SIZE | THREADED COUPLING WEIGHT | ||
| DN | NPS | 3000# | 6000# |
| 6 | 1/8 | 0.06 | 0.09 |
| 8 | 1/4 | 0.08 | 0.13 |
| 10 | 3/8 | 0.11 | 0.24 |
| 15 | 1/2 | 0.22 | 0.40 |
| 20 | 3/4 | 0.30 | 0.52 |
| 25 | 1 | 0.55 | 1.06 |
| 32 | 1-1/4 | 0.86 | 1.32 |
| 40 | 1-1/2 | 1.26 | 2.20 |
| 50 | 2 | 1.65 | 3.37 |
| 65 | 2-1/2 | 3 | 4.81 |
| 80 | 3 | 4.25 | 7.25 |
| 100 | 4 | 7.80 | 12.0 |
Tolerance of Threaded Fittings
| TOLERANCES FOR THRD FITTINGS | |||||||||||||||||||
| Nominal Size | Elbows,Tees & Crosses | Couplings | Half- couplings | ||||||||||||||||
| Center-to-End | End-to-End | End-to-End | |||||||||||||||||
| DN | NPS |  A J | W | W/ 2 | |||||||||||||||
| 6~8 | 1/8~1/4 | ± 1.0 | ± 1.0 | ± 1.0 | |||||||||||||||
| 10~20 | 3/8~3/4 | ± 1.5 | ± 1.5 | ± 1.5 | |||||||||||||||
| 25~50 | 1~2 | ± 2.0 | ± 2.0 | ± 2.0 | |||||||||||||||
| 65~100 | 21/2~4 | ± 2.5 | ± 2.5 | ± 2.5 | |||||||||||||||
Diameter (NPS): 1/8 inch to 4 inches, consistent with threaded coupling.
Dimension of ASME B16.11 Socket Weld Coupling
DN | NPS | B | D | C | |||||||
| 3000 | 6000 | 9000 | 3000 | 6000 | 9000 | ||||||
| 6 | 1/8 | 10.9 | 6.1 | 3.2 | - | 3.18 | 3.18 | 3.96 | 3.43 | - | - |
| 8 | 1/4 | 14.3 | 8.5 | 5.6 | - | 3.78 | 3.30 | 4.60 | 4.01 | - | - |
| 10 | 3/8 | 17.7 | 11.8 | 8.4 | - | 4.01 | 3.50 | 5.03 | 4.37 | - | - |
| 15 | 1/2 | 21.9 | 15.0 | 11.0 | 5.6 | 4.67 | 4.09 | 5.97 | 5.18 | 9.53 | 8.18 |
| 20 | 3/4 | 27.3 | 20.2 | 14.8 | 10.3 | 4.90 | 4.27 | 6.96 | 6.04 | 9.78 | 8.56 |
| 25 | 1 | 34.0 | 25.9 | 19.9 | 14.4 | 5.69 | 4.98 | 7.92 | 6.93 | 11.38 | 9.96 |
| 32 | 11/4 | 42.8 | 34.3 | 28.7 | 22.0 | 6.07 | 5.28 | 7.92 | 6.93 | 12.14 | 10.62 |
| 40 | 11/2 | 48.9 | 40.1 | 33.2 | 27.2 | 6.35 | 5.54 | 8.92 | 7.80 | 12.7 | 11.12 |
| 50 | 2 | 61.2 | 51.7 | 42.1 | 37.4 | 6.93 | 6.04 | 10.92 | 9.50 | 13.84 | 12.12 |
| 65 | 21/2 | 73.9 | 61.2 | - | - | 8.76 | 7.62 | - | - | - | - |
| 80 | 3 | 89.9 | 76.4 | - | - | 9.52 | 8.30 | - | - | - | - |
| 100 | 4 | 115.5 | 100.7 | - | - | 10.69 | 9.35 | - | - | - | - |
Weight List(KG)
| DN | NPS | 3000 | 6000 | 9000 |
| 6 | 1/8 | 0.05 | 0.06 | - |
| 8 | 1/4 | 0.06 | 0.07 | - |
| 10 | 3/8 | 0.08 | 0.10 | - |
| 15 | 1/2 | 0.13 | 0.16 | 0.29 |
| 20 | 3/4 | 0.20 | 0.28 | 0.47 |
| 25 | 1 | 0.28 | 0.48 | 0.68 |
| 32 | 1-1/4 | 0.48 | 0.65 | 1.08 |
| 40 | 1-1/2 | 0.52 | 0.94 | 1.12 |
| 50 | 2 | 0.95 | 1.65 | 1.95 |
| 65 | 2-1/2 | 1.52 | - | - |
| 80 | 3 | 1.75 | - | - |
| 100 | 4 | 2.8 | - | - |
Tolerance of Socket Weld Fittings
| Nominal Size | All Fittings | Elbows, Tees & Crosses | Couplings | Half- Couplings | Reducer Inserts | Unions | |||||||||||||
| Socket Bore Dia. | Bore Dia. of Fittings | Center to Bottom of Socket | Laying Lengths | Laying Lengths | Laying Length | Shank Dia. | Length | Laying Length | |||||||||||
| DN | NPS | B | D | A H | E | F | A | SD | SL | E | |||||||||
| 6~8 | 1/8~1/4 | +0.4 0 | +1.5 0 | ± 1.0 | ± 1.5 | ± 1.0 | +1.5 0 | ± 0.25 | 0 -1.5 | ± 1.5 | |||||||||
| 10~20 | 3/8~3/4 | +0.4 0 | +1.5 0 | ± 1.5 | ± 3.0 | ± 1.5 | +1.5 0 | ± 0.25 | 0 -1.5 | ± 3.0 | |||||||||
| 25~40 | 1~11/2 | +0.4 0 | +1.5 0 | ± 2.0 | ± 4.0 | ± 2.0 | +2.0 0 | ± 0.25 | 0 -2.0 | ± 4.0 | |||||||||
| 50 | 2 | +0.5 0 | +1.5 0 | ± 2.0 | ± 4.0 | ± 2.0 | +2.0 0 | ± 0.5 | 0 -2.0 | ± 4.0 | |||||||||
| 65~80 | 21/2~3 | +0.5 0 | +3.0 0 | ± 2.5 | ± 5.0 | ± 2.5 | +2.5 0 | ± 0.5 | 0 -2.5 | ± 5.0 | |||||||||
| 100 | 4 | +0.5 0 | +3.0 0 | ± 2.5 | ± 5.0 | ± 2.5 | +2.5 0 | ± 0.7 | 0 -2.5 | - | |||||||||
Representative material: ASTM A182 F304/F316
Chemical composition: F304 contains 18% -20% Cr and 8% -11% Ni; F316 additionally adds 2% -3% Mo to enhance corrosion resistance.
Performance: High toughness, good weldability, resistant to organic acid and saltwater corrosion at room temperature, F316 has better resistance to seawater and chemical media, suitable for food, medicine, and marine engineering.
Chemical Composition
| CHEMICAL | LIMITS | C | Mn | P | S | Si | Ni | Cr | Mo |
| ASTM A182 F304 | MIN | 8.00 | 18.00 | ||||||
| MAX | 0.080 | 2.00 | 0.045 | 0.030 | 1.00 | 11.00 | 20.00 | 0.10 | |
| ASTM A312 TP316 | MIN | 10.00 | 16.00 | 2.00 | |||||
| MAX | 0.080 | 2.00 | 0.045 | 0.030 | 1.00 | 14.00 | 18.00 | 3.00 |
Mechanical Properties
| MATERIAL | ASTM A182 F304 | ASTM A182 F316 |
| T.S (MPA) | 515 min | 515 min |
| Y.S (MPA) | 205 min | 205 min |
| EL % | 30 min | 30 min |
| R/A % | 50 min | 50 min |
Representative material: ASTM A182 F51/F53.
Chemical composition: Contains Cr 22% -25%, Ni 5% -7%, Mo 3% -4%, and N element is added.
Performance: It combines austenite toughness and ferrite strength, with a tensile strength of ≥ 620MPa, strong resistance to pitting corrosion and stress corrosion, and is suitable for strong corrosion conditions such as chemical and petroleum extraction.
Chemical Composition
| CHEMICAL | LIMITS | C | Mn | P | S | Si | Ni | Cr | Mo | N | Cu |
| ASTM A182 F51 | MIN | 4.50 | 21.00 | 2.50 | 0.08 | ||||||
| MAX | 0.03 | 2.00 | 0.030 | 0.020 | 1.00 | 6.50 | 23.00 | 3.50 | 0.20 | ||
| ASTM A182 F53 | MIN | 6.00 | 24.00 | 3.00 | 0.24 | ||||||
| MAX | 0.03 | 1.20 | 0.035 | 0.020 | 0.80 | 8.00 | 26.00 | 5.00 | 0.32 | 0.50 |
Mechanical Properties
| MATERIAL | ASTM A182 F51 | ASTM A182 F53 |
| T.S (MPA) | 620 min | 800 min |
| Y.S (MPA) | 450 min | 550 min |
| EL % | 25 min | 25 min |
| R/A % | 45 min | 15 min |
| HARDNESS | 310 max |
Strong Corrosion Resistance
High Strength
Flexible Installation
Good Universality
Dimension inspection: Use calipers and micrometers to measure the outer diameter, inner diameter, wall thickness, length, and other parameters of stainless steel forged pipe clamps, with deviations in accordance with ASME B16.11 standard; The threaded coupling needs to be checked for thread accuracy with a thread gauge.
Surface inspection: visual or penetrant testing (PT), the surface must be free of cracks, dents, burrs, roughness ≤ Ra 6.3 μ m, and ensure no impurities remain.
Spectral inspection: Use a direct reading spectrometer to detect the chemical composition of the material. For example, for 304, ensure that Cr ≥ 18% and Ni ≥ 8% to avoid material mixing.
Mechanical performance testing: Sampling for tensile strength and hardness testing (such as 304 hardness ≤ HB 201) to ensure strength during use.
Dimension Inspection of Socket Weld Coupling
Dimension Inspection of Threaded Coupling
