4. Specifications and appearance quality
Seamless pipe according to GB/T8162-87
4.1. Specifications: The outer diameter of the hot-rolled tube is 32-630mm. Wall thickness 2.5 ~ 75mm. Cold-rolled (cold-drawn) tube outer diameter 5 ~ 200mm. Wall thickness 2.5 ~ 12mm.
4.2. Appearance quality: There must be no cracks, folds, rolling folds, delamination, hairlines and scarring defects on the inner and outer surfaces of steel pipes. These defects should be completely removed, and the wall thickness and outer diameter must not exceed the negative deviation after removal.
4.3. Both ends of the steel pipe should be cut at right angles, and the burrs should be removed. Steel pipes with a wall thickness greater than 20mm are allowed to be cut by gas cutting and hot sawing. It is not necessary to cut the head after the agreement between the supply and demand parties.
4.4. Refer to GB3639-83 for "Surface Quality" of cold-drawn or cold-rolled precision seamless steel pipes.
5. Physical performance test
5.1. For domestic seamless pipes supplied according to mechanism performance, ordinary carbon steel is manufactured according to GB/T700-88 Class A steel (but it must be ensured that the sulfur content does not exceed 0.050% and the phosphorus content does not exceed 0.045%), and its mechanical properties should conform to the values specified in the GB8162-87 table.
5.2. The domestic seamless pipe supplied according to the hydrostatic test must ensure the hydrostatic test specified in the standard.
5.3. The physical performance inspection of imported seamless pipes shall be carried out according to the relevant standards stipulated in the contract.
6. Chemical composition test
6.1. The chemical composition of domestic seamless pipes supplied according to chemical composition and mechanical properties, such as steel No. 10, 15, 20, 25, 30, 35, 40, 45 and 50, shall comply with the provisions of GB/T699-88. Imported seamless pipes shall be inspected according to the relevant standards stipulated in the contract. The chemical composition of 09MnV, 16Mn, 15MnV steel shall comply with the provisions of GB1591-79.
6.2. Refer to the relevant parts of GB223-84 "Chemical Analysis Methods of Iron, Steel and Alloys" for specific analysis methods.
6.3. Refer to GB222-84 "Permissible Deviation of Chemical Composition of Samples and Finished Products for Chemical Analysis of Steel" for analysis deviation.
7. Main import and export situation
7.1. Generally, the import volume of seamless pipes is very large. The main importing countries are Germany and Japan. European countries such as Romania, Russia, Switzerland, France, Spain, Czech Republic, Yugoslavia, Hungary and other countries have imports. There are also a small amount imported from Argentina, Mexico and other countries in South America.
7.2. According to the different requirements of my country's consumer units, there are more than 100 specifications of imported seamless pipes, and the common specifications are 15922mm, 1595mm, and 15918mm. 114.38mm, 114.310mm, 114.313mm. The length is generally 5-8m or 4-7m. It is mainly hot-rolled carbon structure, and the steel grades are ST35, ST45 and ST65. The smallest diameter of imported specifications is 305mm, and the largest is 47813mm.
7.3. A small amount of seamless pipes with small diameter and thin wall have been imported from France and Spain, such as 183mm, 223mm, 26.93mm and so on. The general rules of the Mannesmann Tube Works in Germany apply.
7.4. The seamless pipes imported from Hungary and Japan often refer to DIN2448 and DIN1629.
7.5. In the case of import claims, the quality problems of imported seamless pipes mainly include: unqualified chemical composition, splitting in flattening test, low tensile strength, severe corrosion and pits, etc.
8. Packaging
According to the provisions of GB2102-88. There are three types of steel pipe packaging: bundling, boxing, oiled bundling or oiled boxing
