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ASME B16.9 Butt Welded Reducer

Views: 104     Author: Good Du     Publish Time: 2023-03-14      Origin: Site

Butt Welded Reducer is one of the pipe fittings used to connect two pipes of different diameters. ASME B16.9 Butt Welded Reducer is divided into two types: concentric reducer (that is, the central axes of the big end and the small end coincide) and eccentric reducer (that is, one outer wall of the big end and the small end is in a straight line).


Concentric Reducer is a type of steel butt welded pipe fitting. The midpoints of the nozzles at both ends of the reducers are on the same axis. Thus, there is less interference with fluid flow patterns when changing the diameter of the tube, which is beneficial for fluid flow and suitable for changing the diameter of a gas or vertical liquid tube. The reducer is shaped like a conical joint and is used to enlarge or decrease the diameter of the center line. It is easy to transport mud and abrasive fluids and is suitable for corrosive operations. It is also useful where different ratings and wear protection are required when transporting between flanges or pipes.


One end of the Eccentric Reducer is flat. When the diameter is changed , the position and direction of the tangent point will be different. Therefore, the installation and function of the eccentric reducer is also different. The specific point is: when the tangent point of the nozzle is upward, it is called the top installation. Eccentric reducer is used more, because it can ensure that the pipeline before and after the reducer has a height elevation, it can make the pipeline in the reducer part of the liquid collection phenomenon. It is usually used at the inlet of the pump to facilitate exhaust, and when the tangential point of the nozzle becomes the bottom mount, it is often used for regulator installation and drainage, and horizontal liquid pipes usually use eccentric reducers.

Manufacturing Process of Reducer

The production and processing of the reducers are produced by compression diameter pressing, expanding pressing or reducing plus expanding pressing. The reducing forming process of the reducer is to put the pipe blank with the same diameter as the large end of the reducing pipe into the forming die, and press along the axial direction of the pipe blank to make the metal move along the die cavity and shrink to form. According to the size of the reducer, it can be divided into one pressing forming or multiple pressing forming. Only the reducers with large differences in specifications and models can be formed by pressing several times. Some reducers with special specifications and models can be formed by stamping. In addition to using steel pipes as raw materials to produce reducers, some reducers can also be produced by stamping process using steel plates. The large-diameter reducer is formed by welding, and the butt welding reducer is formed by rolling steel plate and then welded.


The manufacturing process of reducer by Hot Die Pressing is currently the most widely used reducing joint manufacturing process, which is applicable to the manufacturing of all material reducer products. It uses the cylindrical tube blank rolled from steel pipe or steel plate with the same diameter and wall thickness as the large end of the product as the raw material, and is extruded and necked in the tire mold through local heating. (The shape and size of the inner cavity of the mold and the reducer are the same) The reducer manufactured by this process has a certain length of straight pipe sections at both ends, which extends the distance between the deformed part of the product and the weld bead at the pipe end, and reduces the complex stress at the pipe butt joint.

Hot Die Pressing Process

  1. Blanking: Cut steel pipe or prefabricated seam billet into pipe segments of specified length. The general length of pipe segments is equal to or slightly larger than the height of finished reducer tubes. The excess height of the outer weld bead of the seamed billet is ground to the same level as the base metal.

  2. Local heating: Place the billet in the cylindrical induction heating coil and start the medium frequency power supply to heat the deformed necking part of the billet to the specified temperature, so as to ensure that the billet is heated uniformly and without overheating.

  3. Compression forming: Place the heated hot end of the billet vertically downwards into the big end-up mould, start the press slide to press the billet down to the port level with the mould, and the heated part necks down along the inner wall of the tyre. Then the die is lifted by the press slide and turned upwards to the small end with a chain, pushed into the corresponding workstation tools under the tyre, and then the shaped reducer tube is pressed out of the tyre by the press slide with the same diameter as the small end of the reducer tube, and the reducer tube is formed.

  4. End removal shaping: Cut and remove the excess parts at both ends of the reducer pipe according to the requirements of process specifications, and retain a certain machining allowance. Then, after heating the two ends of the pipe, align the ends of the pipe on the hydraulic press to meet the requirements of machining the pipe end grooves.

  5. Weld inspection: 100% ray and ultrasonic non-destructive inspection are carried out on the longitudinal weld bead of the compacted reducer tube with seamed billet. The defective parts detected out of the standard shall be repaired according to the qualified weld repairing procedure, and the same parts shall not be repaired more than twice.

  6. Heat treatment: According to the heat treatment process specification of the material, the corresponding heat treatment is carried out to restore the crystal structure destroyed by extrusion and hot working distortion to the structure state of the raw material, so that the finished reducing tube has the same performance state as the original material. After the treatment, the surface hardness of the reducing tube is tested one by one.

  7. Surface treatment: The surface treatment of hot-moulded reducing diameter pipe and the grooving process of machined end are the same as other pipe fittings.

  8. Finished Product Inspection: After the process flow is completed, the qualified products of reducing diameter pipe are tested on the testing platform for comprehensive measurement of appearance size and position deviation data, while the qualified products are tested for comprehensive non-destructive testing.

Identification of Reducer

This is represented by the diameter of the large end multiplied by the diameter of the small end, e.g. "8" × "6" means that the diameter of the big end is 8 inches and the diameter of the small end is 6 inches.

Pressure Wall Thickness

Pressure wall thickness is Sch5s, Sch10s, Sch10, Sch20, Sch30, Sch40s, STD, Sch40, Sch60, Sch80s, XS, Sch100, Sch120, Sch140, Sch160, XXS.

Materials are Carbon Steel, Alloy Steel, Stainless Steel

Steel Type Code
Carbon Steel Q235, 20#, 35#, 45#, 20G,Q345B, 16Mn, ASTM A234 WPB/WPC
Alloy Steel ASTM A234 WP11 / WP12 / WP 5 / WP9 / WP91 / WP92,15CrMoG, 12Cr1MoVG, 12Cr5Mo, 1Cr5Mo, Cr9Mo, 10CrMo910, 12CrMo4-5
Stainless Steel ASTM A403 WP304/304L/304H, 316/316L, 310S, 317,347, 904L

ASME B16.9 Dimensional Specifications for Reducer 



We(Shanghai Zhucheng Pipe Fittings Manufacturing Co Ltd) is professional engaged in manufacture of Steel pipe(seamless/welded), pipe fittings(butt weldingsocket weldthreaded) and flanges in pipe system of all kinds of materials(carbon steel, stainless steel, alloy steel, low temp steel, pipeline steel).  In order to get to a successful cooperation with customers, normally we are willing to provide free samples to all customers if required. (The customer should be responsible for the freight and the samples should be in common size and materials)

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