OEM manufacturer MSS SP-79 · ASME B16.11
Socket Weld Reducer Inserts — MSS SP-79
A socket weld reducer insert fits into the socket of a standard socket weld fitting so that a smaller pipe can be connected. Teshi Group manufactures reducer inserts to MSS SP-79 in Class 3000 and 6000, in carbon, low-temperature, alloy and stainless steels.
Also called: reducing insert, SW reducer insert, socket weld reducing insert, MSS SP-79 insert
What is a Socket Weld Reducer Insert?
A reducer insert is a forged piece with a male spigot that goes into the socket of a tee, elbow or coupling, and a smaller socket that receives the reduced pipe. It turns a standard equal fitting into a reducing one, so a plant can stock fewer reducing fittings. MSS SP-79 covers socket welding reducer inserts, with socket dimensions consistent with ASME B16.11 fittings. Both the spigot and the smaller pipe are fillet welded.
Key features
- Dimensions per MSS SP-79
- Class 3000 and 6000
- Converts equal SW tees, elbows and couplings into reducing fittings
- Cuts inventory of reducing socket weld fittings
Specification
| Supply | OEM manufacturer — Teshi Group, India |
|---|---|
| Standard | MSS SP-79 |
| Pressure class | Class 3000 and 6000 |
| Size range | Large-end and small-end combinations as tabulated in MSS SP-79 |
| Pipe compatibility | Class 3000 → Sch 80, Class 6000 → Sch 160 pipe |
| Materials — carbon steel | ASTM A105 / A105N; ASTM A181 Cl 60, Cl 70; ASTM A266 Gr 2, Gr 4 (large forgings) |
| Materials — high-yield carbon steel | ASTM A694 F42, F46, F48, F50, F52, F56, F60, F65, F70 (MSS SP-44 grades F52–F70) |
| Materials — low-temperature carbon steel | ASTM A350 LF1, LF2 Cl 1, LF2 Cl 2, LF3, LF6, LF9 |
| Materials — alloy steel (Cr-Mo) | ASTM A182 F1, F2, F5, F5a, F9, F11 Cl 1 / 2 / 3, F12 Cl 1 / 2, F21, F22 Cl 1 / 3, F22V, F91, F92, F911; ASTM A336 F11, F22 (large forgings) |
| Materials — stainless steel | ASTM A182 F304, F304L, F304H, F304LN, F309H, F310, F316, F316L, F316H, F316LN, F316Ti, F317, F317L, F321, F321H, F347, F347H, F348 |
| Materials — 904L and 6Mo | 904L (ASTM A182 F904L, UNS N08904); 254 SMO / 6Mo (ASTM A182 F44, UNS S31254); AL-6XN (ASTM A182 F62, UNS N08367) |
| Materials — duplex stainless steel | ASTM A182 F51 (UNS S31803), F60 (UNS S32205, 2205) |
| Materials — super duplex stainless steel | ASTM A182 F53 (UNS S32750, 2507), F55 (UNS S32760), F61 (UNS S32550) |
| Materials — nickel alloys | ASTM B564 / B160 / B462: Nickel 200 / 201 (N02200 / N02201), Monel 400 (N04400), Monel K-500 (N05500), Inconel 600 (N06600), Inconel 625 (N06625), Inconel 718 (N07718), Incoloy 800 / 800H / 800HT (N08800 / N08810 / N08811), Incoloy 825 (N08825), Hastelloy C276 (N10276), Hastelloy C22 (N06022), Hastelloy B2 / B3 (N10665 / N10675), Alloy 20 (N08020) |
| Materials — titanium | ASTM B381 Grade F1, F2, F5 (Ti-6Al-4V), F7, F12 |
| Materials — copper-nickel | Cu-Ni 90/10 (UNS C70600) and 70/30 (UNS C71500), ASTM B151 bar; flanges to ASME B16.5 or EEMUA 145 |
| Grade availability | Every grade listed is made or supplied against order, with EN 10204 3.1 certificates (3.2 / third-party inspection when specified) and PMI on alloy, stainless, duplex and nickel grades. |
| Testing | Visual, dimensional and thread/socket gauge inspection; PMI on alloy and stainless grades; hardness check; MPI/DPT when specified |
| Documents | EN 10204 3.1 mill test certificate; 3.2 / third-party inspection when the order specifies; dimensional inspection report; IBR certification for boiler/steam service when specified |
Applications
- Reduced branches from standard SW tees
- Instrument and sampling connections
- Drain and vent takeoffs
- Small-bore utility piping
FAQ
Socket Weld Reducer Insert: common questions
Which MSS standard covers reducer inserts?
MSS SP-79, Socket Welding Reducer Inserts. The inserts fit into the sockets of standard ASME B16.11 socket weld fittings such as tees, elbows and couplings of the same class.
How is a reducer insert installed?
The spigot end is inserted into the socket of the fitting and fillet welded, then the smaller pipe is inserted into the insert's socket and fillet welded. Leave the usual expansion gap at each socket bottom.
Why use an insert instead of a reducing tee?
Inserts let you use standard equal tees and elbows with a smaller pipe, so you stock fewer special reducing fittings and can make up reductions on site.
Is the class of the insert tied to the fitting?
Yes. Use an insert of the same class as the fitting it goes into — Class 3000 with Class 3000 fittings, Class 6000 with Class 6000.
Need a size or grade not listed here?
Our engineering team manufactures against your drawing or datasheet, with dimensional sign-off before dispatch.
Send us your specificationTraceability
From mill heat to your site
- 01
Approved mill material
Received against the mill certificate; heat number registered.
- 02
Forging & machining
Heat number carried through every stage in our Indian works.
- 03
PMI, dimensional & NDT
Every lot inspected to the governing standard; TPI witness on request.
- 04
Stamped & certified dispatch
Hard-stamped pieces with EN 10204 3.1 / 3.2 certificates.
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