Swaged Nipple

What is a Swaged Nipple?

A swaged nipple, also called a swage or reducer nipple, is a small threaded or butt-welded fitting that connects two pipes of different diameters. It has one larger end and one smaller end, with a tapered transition between them. Swaged nipples are widely used in small-bore instrumentation, tubing, and process piping where a compact size transition is needed.

Standards and Specifications

Swaged nipples are manufactured to ASME B16.11 for threaded and socket weld ends, and ASME B16.9 for butt-weld types. They conform to MSS SP-79 and BS 3799. Sizes range from NPS 1/8 by NPS 1/4 to NPS 2 by NPS 1, with either male threaded or socket weld ends. The tapered body provides a gradual flow transition.

Materials and Grades

Carbon steel A105 is standard for general high-pressure service. Stainless steel 304/304L and 316/316L provide corrosion resistance for chemical and marine applications. Alloy steel F11, F22, and F91 grades handle high-temperature refinery service. Low-temperature A350 LF2 is available for cryogenic piping. All material is forged and fully traceable.

Pressure and Temperature Ratings

Threaded and socket weld swaged nipples are rated for 3000 LB, 6000 LB, and 9000 LB pressure classes per ASME B16.11. The forged construction provides high strength in small sizes. Temperature ratings depend on material: carbon steel to 425 degrees Celsius, alloy steel to 600 degrees Celsius, stainless steel from cryogenic to 800 degrees Celsius.

Applications

Swaged nipples are used in instrument hookups, pressure gauge connections, sampling lines, hydraulic systems, small-bore process piping, and tubing transitions. They connect larger header connections to smaller instrument lines, valves, and equipment in oil and gas, chemical, power, and hydraulic systems.

Advantages

Swaged nipples are compact, forged fittings that provide a reliable size transition in small-bore piping. The tapered body minimizes turbulence and pressure drop. Threaded ends allow easy installation and removal without welding. Socket weld ends provide a stronger, leak-resistant joint for high-pressure service.

Installation Guidelines

For threaded ends, apply PTFE tape or thread sealant and tighten to the correct torque. For socket weld ends, insert the pipe fully, withdraw 1.6 mm, and fillet weld. Use matching filler metal for socket welds. Apply preheat and post-weld heat treatment for alloy grades. Pressure test the completed connection.

Quality Assurance

Each swaged nipple is marked with both sizes, material grade, pressure class, and heat number. Inspection includes dimensional checks, thread verification, visual examination, and NDE when specified. Material test certificates to EN 10204 3.1 are provided. Nipples are protected with thread caps and packaged in small boxes for export.