GOST 17378 – Carbon and low-alloy steel butt-welding fittings. Reducers
Concentric and Eccentric Reducers
During construction of pipelines it is inevitable that problems relating to route changes of the main line and pipe diameter will be encountered. These problems are solved with manufactured pipeline fittings (elements) tees, branches and concentric reducers.
A concentric steel reducer is a part of the pipeline structure intended for connection of pipes where pipeline diameter is changed from one to another. Using reducers it is possible to connect the end of a larger-diameter pipe with the end of a smaller-diameter pipe and vice versa, and as a result to increase or reduce media flow. Concentric reducers are used in various fields: oil and gas industry, chemical and power industries as well as the area of utility services, etc.
A concentric steel reducer is manufactured in the following ways: stamping, rolling from sheet billets and shells followed by welding and assembly, stamping of conic forged pieces followed by machining. The following materials are used for their manufacture: carbon steel grades (in low and moderately aggressive environments), namely: 10; 20; 3, alloy and high-alloy steels (highly aggressive environment), namely: 09Г2С, 15ХМ, 15Х5М, 12Х18Н10Т. Normative and technical documents for concentric reducers are determined by GOST 17378-2001. Reducers are divided into: Eccentric Concentric – Eccentric reducers are used in horizontal pipelines
Depending on the properties of the carried flow and environmental conditions, reducers may be manufactured from 20, 09Г2С, 15Х5М, 12Х18Н10Т steel grades. Reducers as per GOST 17378-01 are used under nominal pressure PN up to 16 MPa and temperature varying from 70°С below zero to 450°С above zero.
Sample conventional notation of the eccentric reducer with diameter of 89×6 mm, 57×4 mm, from 20 steel:
Reducer Э 89×6-57×4 GOST17378-01 Steel20.
Concentric reducers are used in vertical pipelines (they have the shape of a blunted cone, and are used for pipelines on suspension supports). Depending on the properties of the carried flow and environmental conditions, concentric steel reducer may be manufactured from 20, 09Г2С, 15Х5М, 12Х18Н10Т steel grades.
