20G High Pressure Boiler Tube Performance

20G high-pressure boiler tube is a kind of seamless tube. The manufacturing method is the same as that of seamless tube, but there are strict requirements on the steel type used to manufacture steel tube. According to the use temperature, it is divided into general boiler tube and high-pressure boiler tube.

1. Overview

(1) Manufacturing method:

① The use temperature of general boiler tube is below 450℃. Domestic tubes are mainly made of 10# and 20# carbon steel hot-rolled tubes or cold-drawn tubes.

② High-pressure boiler tubes are often in high temperature and high pressure conditions during use. Under the action of high-temperature flue gas and water vapor, the tubes will oxidize and corrode. The steel tube is required to have high lasting strength, high anti-oxidation and corrosion performance, and good structural stability.

(2) Application:

① General 20G high-pressure boiler tubes are mainly used to manufacture water-cooled wall tubes, boiling water tubes, superheated steam tubes, superheated steam tubes for locomotive boilers, large and small smoke tubes and arch brick tubes, etc.

② 20G high-pressure boiler tubes are mainly used to manufacture superheater tubes, reheater tubes, gas guide tubes, main steam tubes, etc. of high-pressure and ultra-high-pressure boilers.

Uses of boiler tubes

①Generally, 20G high-pressure boiler tubes are mainly used to manufacture water-cooled wall tubes, boiling water tubes, superheated steam tubes, superheated steam tubes for locomotive boilers, large and small smoke tubes and arched brick tubes, etc.

②High-pressure boiler tubes are mainly used to manufacture superheater tubes, reheater tubes, gas guide tubes, main steam tubes, etc. for high-pressure and ultra-high-pressure boilers.

2. Types

20G high-pressure boiler tubes are divided into general boiler tubes and high-pressure boiler tubes according to the high-temperature performance they withstand. Regardless of general boiler tubes or high-pressure boiler tubes, they can be divided into various steel tubes according to their different use requirements.

3. Specifications and appearance quality

(1) GB3087-2008 "Seamless Steel Tubes for Low and Medium Pressure Boilers" stipulates. The specifications of steel tubes for various structural boilers are 43 types with an outer diameter of 10 to 426 mm. There are 29 types with a wall thickness of 1.5 to 26 mm. However, the outer diameter and wall thickness of superheated steam tubes, large smoke tubes, small smoke tubes and arched brick tubes for locomotive boilers are separately specified.

(2) GB5310-2008 "Seamless Steel Tubes for High-Pressure Boilers" The outer diameter of hot-rolled tubes is 22 to 530 mm, and the wall thickness varies from 20 to 70 mm. The outer diameter of cold-drawn (cold-rolled) tubes is 10 to 108 mm, and the wall thickness varies from 2.0 to 13.0 mm.

(3) GB3087-2008 "Seamless Steel Tubes for Low- and Medium-Pressure Boilers" and GB5310-95 "Seamless Steel Tubes for High-Pressure Boilers" stipulate. Appearance quality: Cracks, folds, folds, scars, delamination and hairline are not allowed on the inner and outer surfaces of the steel tube. These defects should be completely removed. The removal depth shall not exceed the negative deviation of the nominal wall thickness, and the actual wall thickness at the cleaning location shall not be less than the minimum value allowed by the wall thickness.

4.20G high-pressure boiler tube uses steel grades

(1) High-quality carbon structural steel grades are 20G, 20MnG, and 25MnG.

(2) Alloy structural steel grades 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, 12Cr3MoVSiTiB, etc.

(3) Rust-resistant heat-resistant steels commonly used 1Cr18Ni9, 1Cr18Ni11Nb boiler tubes, in addition to ensuring the chemical composition and mechanical properties, must be subjected to water pressure tests, expansion and flattening tests. Steel pipes are delivered in heat-treated state.

In addition, there are certain requirements for the microstructure, grain size, and decarburized layer of the finished steel pipes.