Concentric Pipe Reducer for Uniform Flow – ASME B16.9

A concentric pipe reducer connects pipelines of different diameters, with the center points of both ends on the same central axis.

This design enables fluids to maintain a uniform flow profile at the reducing section, greatly reducing eddy current and pressure loss. It is highly suitable for horizontal pipelines and working conditions requiring stable flow patterns.

Unlike the eccentric reducer, the concentric structure prevents liquid accumulation at the bottom and air blockage at the top, making it the preferred option for the transmission of most liquids, gases and steam media.

The concentric weld reducer supplied by AIFN is available in a wide range of materials to meet diverse requirements for corrosion resistance, temperature and pressure resistance. Typical parameters are listed in the table below:

All AIFN products undergo dimensional inspection, radiographic testing or hydrostatic testing to meet the sealing requirements of API 598. For ss concentric reducer, we also provide pickling and passivation treatment to strengthen resistance to chloride ion corrosion.

With over 15 years of professional experience in flange and pipe fitting manufacturing, AIFN provides full-size traceability reports and third-party inspection services (SGS, BV, etc.). All concentric pipe fittings are marked by laser with clear specifications and heat numbers. For non-standard reducing products such as 6″ x 3″ concentric reducer, customized production based on drawings is supported, with the shortest delivery time of 7 days.

Q1: Can a concentric pipe reducer be used in horizontal pipelines carrying liquids?

A: Yes, but caution is needed. Concentric reducers maintain centerline alignment and work well in horizontal lines with clean, low-viscosity fluids. However, for slurries or liquids that may contain gas pockets, an eccentric reducer (flat side down) is recommended to avoid air accumulation. Always refer to piping design standards (e.g., ASME B31.3) for fluid-specific guidance.

Q2: What is the difference between a concentric weld reducer and a seamless one?

A: “Weld reducer” typically refers to a fabricated reducer formed from welded plate (often used for larger diameters >24″), while seamless reducers are forged from a solid billet (available up to 24″). Seamless types offer uniform grain structure and higher pressure integrity; welded reducers are more cost-effective for large sizes. Both comply with ASME B16.9 when properly manufactured.