MSS SP Series Standard
MSS-SP-79, 83, 95, 97 & 87 Forged Fittings
MSS-SP-83 Standard: Dimensions | Specifications | Material Grade | About MSS-SP Standard | All Product Types
Nutech Overseas manufactures and supplies high-performance forged fittings in full compliance with MSS SP Series standards, including MSS-SP-79, MSS-SP-83, MSS-SP-95, MSS-SP-97, and MSS-SP-87. These standards are issued by the Manufacturers Standardization Society (MSS) and are widely accepted across various industries for ensuring dimensional precision, pressure integrity, and material quality in piping systems. Our forged fittings under these MSS standards are suitable for high-pressure, high-temperature, and corrosive service conditions typically found in oil & gas, chemical processing, power generation, and marine engineering.
The MSS-SP-79 standard governs socket-weld fittings, including elbows, tees, and couplings. These fittings are designed for small bore piping systems and offer excellent strength and leak-proof welding connections. They are commonly manufactured in pressure classes 3000#, 6000#, and 9000#, providing flexibility across a wide range of applications.
Under MSS-SP-83, we produce forged threaded fittings such as elbows, tees, unions, and caps with NPT or BSP threading. These fittings are used for easy installation and dismantling without welding, making them ideal for utility lines and pipelines that require frequent maintenance or replacement. The threading is precision-machined to ensure tight sealing and long-term reliability.
MSS-SP-95 specifies forged plugs and bushings used for closing or reducing threaded pipe connections. Nutech supplies hex head, square head, and round head plugs along with full and half bushings. These fittings are vital for pipeline termination, test point closures, and adapting pipe sizes in confined layouts.
We also manufacture branch outlet fittings according to MSS-SP-97, including Weldolets, Sockolets, Threadolets, and more. These forged outlets are used for making 90° or angled branch connections from a run pipe and are available in Butt Weld, Socket Weld, and Threaded end types. Each outlet is designed to reduce stress concentration and reinforce the branch area, ensuring long service life and high performance.
In addition, MSS-SP-87 covers forged bull plugs and line plugs used to block off pipe ends or isolate pipeline sections. These fittings are available with plain, beveled, or threaded ends and are often used in hydrostatic testing and maintenance operations. They are machined from solid forged bars to maintain pressure integrity and withstand high mechanical loads.
At Nutech Overseas, all forged fittings are manufactured using certified raw materials, following stringent quality control procedures and testing norms to ensure dimensional accuracy, corrosion resistance, and pressure safety. Our wide material range includes Carbon Steel ASTM A105 / A105N, Low Temperature A350 LF2, Stainless Steel A182 F304 / F316 / F321 / F347, Alloy Steel A182 F5 / F9 / F11 / F22, and Duplex / Super Duplex (UNS S31803 / S32750 / S32760).
MSS-SP-79 Socket Weld Fittings, MSS-SP-83 Threaded Fittings, MSS-SP-95 Plugs & Bushings, MSS-SP-97 Branch Outlets, MSS-SP-87 Bull Plugs
For complete technical details, including dimensions, pressure ratings, weight charts, and material specifications of our MSS-SP-95 Standard Socket Weld and Threaded Fittings, please download the full Catalog PDF below.
Precision-Engineered MSS Standard Forged Fittings in Carbon Steel, Stainless Steel, Alloy Steel & Duplex for High-Pressure Applications Across Oil & Gas, Petrochemicals, Power & Marine Industries
Technical Specifications of MSS-SP-83 Standards
| Standard | Fitting Type | Connection Type | Size Range | Pressure Class | Thread Standards | Material Grades |
|---|---|---|---|---|---|---|
| MSS-SP-79 | Socket Weld Elbows, Tees, Couplings, Reducers | Socket Weld | ¼” to 4” (DN8–DN100) | 3000#, 6000#, 9000# | — | ASTM A105, A182 F304/L, F316/L, A350 LF2, Alloy Steel F5/F9 |
| MSS-SP-83 | Threaded Elbows, Tees, Couplings, Reducers | Threaded (NPT/BSP) | ¼” to 4” (DN8–DN100) | 2000#, 3000#, 6000# | ASME B1.20.1 / ISO 7-1 | Carbon Steel, SS 304/316, Alloy Steel |
| MSS-SP-95 | Plugs, Bushings (Threaded or SW) | Threaded / SW | ¼” to 4” | Up to 9000# | NPT / BSP | SS, CS, High Nickel Alloys |
| MSS-SP-97 | Weldolet, Sockolet, Threadolet, Latrolet, Nipolet, Elbolet | Welded, Threaded, SW | 1/8” to 4” Branch Size | 3000# to 9000# | As per Application | ASTM A105N, A182 F11/F22, F51, F53, Inconel, Monel, CuNi |
| MSS-SP-87 | Bull Plugs | Threaded / SW | ¼” to 4” | 2000# to 9000# | NPT / BSP | CS A105, SS F304/F316, LF2, Duplex/Super Duplex |
Complete Material Grade Chart - MSS-SP Standards
| Material | Grades / Standards / UNS Numbers |
|---|---|
| Stainless Steel | ASTM A182 F304 / F304L, F316 / F316L, F310, F321 / F321H, F347 / F347H, SS 904L, DIN 1.4301, 1.4306, 1.4401, 1.4404 |
| Carbon Steel | ASTM A105, ASTM A106 Gr B, ASTM A234 WPB, ASTM A350 LF2 CL.1, MSS-SP-75 WPHY 42, WPHY 46, WPHY 52, WPHY 60, WPHY 65, WPHY 70 |
| Low Temperature Carbon Steel | ASTM A420 WPL3, ASTM A420 WPL6 |
| Alloy Steel | ASTM A182 F1, F5, F9, F11, F12, F22, F91, ASTM A234 WP1, WP5, WP9, WP11, WP22, WP91 |
| Duplex Steel | ASTM A815 UNS S31803, S32205, Werkstoff No. 1.4462 |
| Super Duplex Steel | ASTM A815 UNS S32750, S32760, S32950 |
| Nickel Alloys | Nickel 200 (UNS N02200), Nickel 201 (UNS N02201), Inconel 600 (UNS N06600), 601 (UNS N06601), 625 (UNS N06625), 800 (UNS N08800), 825 (UNS N08825), Monel 400 (UNS N04400), Monel K500 (UNS N05500), Hastelloy C276 (UNS N10276), Hastelloy C22 (UNS N06022), Alloy 20 (UNS N08020), Nimonic 75 / 90 |
| Copper Nickel | Cu-Ni 90/10 (C70600), Cu-Ni 70/30 (C71500), CuNi10Fe1Mn, CuNi30Mn1Fe |
| Titanium | Grade 1, Grade 2, ASTM B381 |
| Aluminium | ASTM B361, Aluminium 6061, 6082, 7075 |
| Brass | ASTM B62, C23000, C26000 |
| Bronze | Tin Bronze, Aluminium Bronze (C95400), Leaded Bronze (C93200), ASTM B148 |
| 254 SMO | UNS S31254, ASTM A182 F44 |
The MSS SP Series refers to a set of technical standards developed by the Manufacturers Standardization Society (MSS) of the Valve and Fittings Industry. These standards define the design, material requirements, pressure ratings, testing methods, and dimensional tolerances for various types of forged steel fittings, specifically:
- MSS-SP-79: Covers socket weld fittings.
- MSS-SP-83: Specifies threaded fittings.
- MSS-SP-95: Deals with plugs and bushings.
- MSS-SP-97: Defines branch outlet fittings like Weldolet, Sockolet, etc.
- MSS-SP-87: Standard for bull plugs.
These standards ensure compatibility, safety, and durability in high-pressure piping systems across petrochemical, power generation, oil & gas, and marine industries. They are globally recognized and often used in conjunction with ASME B16.11 and BS 3799 for comprehensive forged fitting specifications.
Each MSS SP standard serves a unique purpose in defining forged fittings:
- MSS-SP-79: Governs Socket Weld Forged Fittings including elbows, tees, couplings, and crosses. It emphasizes dimensional consistency and pressure ratings.
- MSS-SP-83: Covers Threaded Forged Fittings, such as threaded elbows, tees, couplings, and unions. It focuses on NPT/BSP threading tolerances and mechanical strength.
- MSS-SP-95: Specifies requirements for Plugs and Bushings, which are pressure-bearing accessories used to block or reduce pipe ends.
- MSS-SP-97: Standard for Integrally Reinforced Branch Outlet Fittings such as Weldolet, Sockolet, Threadolet, Latrolet, etc. This standard includes design criteria, marking, testing, and tolerances.
Each standard ensures fittings are engineered for high-pressure and high-temperature service, compliant with industry practices, and are interchangeable across systems when manufactured correctly.
MSS-SP-97 ensures that branch outlet fittings such as Weldolet, Sockolet, and Threadolet are manufactured with precise reinforcement calculations, pressure ratings, and welding guidelines. This standard promotes:
- Leak-free integration into run pipes
- Consistent wall thickness for structural integrity
- Compatibility with ASME B31.3 and other pressure piping codes
- Uniformity in dimensions, ensuring smooth fabrication on-site
Using MSS-SP-97-compliant fittings guarantees enhanced mechanical performance and safety in critical systems such as oil & gas, power, and chemical plants.
MSS-SP-83 sets the benchmark for threaded forged fittings like elbows, tees, unions, and couplings in 3000# and 6000# pressure classes. Manufacturers adhere to this standard to ensure:
- Precise thread engagement (typically NPT or BSPT) for secure sealing
- Pressure integrity under extreme operating conditions
- Dimensional uniformity for interchangeability
- Material traceability and marking for inspection and compliance
This makes MSS-SP-83 fittings ideal for refineries, chemical plants, marine systems, and other industries demanding threaded connections with long-term durability.
MSS-SP-95 plays a vital role in defining the technical parameters for NPT and BSP threaded fittings such as plugs, bushings, and couplings. It covers:
- Thread design and accuracy to ensure leak-tight performance
- Pressure ratings up to 9000 PSI depending on class
- Marking and inspection criteria for full traceability
- Guidance for heat treatment and surface finishes
This standard supports manufacturers in producing fittings that are compatible across international piping systems, particularly in high-pressure oil, gas, and steam applications.
MSS-SP-79 outlines the manufacturing, dimensioning, and inspection requirements for Socket Weld forged fittings like elbows, tees, caps, and reducers. Its implementation ensures:
- Precise socket depth and bore alignment for optimal weld penetration
- Wall thickness uniformity to match pressure class requirements
- Smooth internal surfaces to reduce turbulence and erosion
- Strict tolerance control for pipe-end fitment and flow efficiency
This makes MSS-SP-79-compliant fittings highly reliable for high-pressure, high-temperature service lines in oil & gas, petrochemical, and power generation industries.
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