MSS SP-79 Socket Weld Reducer Inserts

MSS SP-79 Reducer Inserts Manufacturer & Exporter in India

Socket weld reducer inserts to MSS SP-79 are forged inserts that fit into the socket of a standard socket weld fitting and provide a smaller socket for a smaller pipe. They let a buyer make a reducing connection, for example a 1" tee with a ½" branch, from a stocked equal fitting and an insert, instead of ordering a special reducing fitting.

Raaj Fittings manufactures MSS SP-79 reducer inserts at our two plants in India in Class 3000 and 6000, in carbon, low-temperature, alloy and stainless steel, duplex and nickel alloys, matched to our ASME B16.11 socket weld fittings.

How a Reducer Insert Works

The outside of the insert is welded into the socket of the larger fitting with a fillet weld, and the smaller pipe is then socket welded into the insert. MSS SP-79 defines several insert configurations, depending on how large the size reduction is and how the insert sits in the socket, so that the wall of the insert and both welds are adequate for the pressure class.

Classes and Sizes

Class 3000 and 6000, matching the socket weld class of the fitting they are inserted into.
Size combinations from small reductions (for example 1" × ¾") to large reductions (for example 2" × ½").
Give the large socket size, the small socket size and the class when ordering.

When to Use Inserts — and When Not To

Inserts are convenient for maintenance and small quantities, and they reduce the range of fittings a site must stock. They add a second weld and a second crevice to the joint, so many piping specifications prefer one-piece reducing fittings or swage nipples in critical, cyclic or crevice-corrosive service. Follow your piping specification.

Testing and Documentation

Every reducer insert is made from PMI-verified material, dimensionally inspected against the ordered standard and marked with material, size, rating and heat number. Orders are supplied with EN 10204 3.1 certificates; EN 10204 3.2 certification and inspection by the buyer's nominated third-party agency are available on request.

Frequently Asked Questions

MSS SP-79 Reducer Inserts — FAQs

What is a socket weld reducer insert?

A forged insert that is welded into the socket of a socket weld fitting to provide a smaller socket, so a smaller pipe can be connected without a special reducing fitting.

Which standard covers reducer inserts?

MSS SP-79 covers socket welding reducer inserts, used with ASME B16.11 socket weld fittings.

What classes are reducer inserts made in?

Class 3000 and 6000, matching the class of the socket weld fitting.

Are reducer inserts allowed in all services?

Not always. They add an extra weld and crevice, so some specifications prefer one-piece reducing fittings or swage nipples in critical service.