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What are the technical conditions for different steel pipes?
Jul 20, 2017

In general, according to the use of steel pipe and the different working conditions, the allowable deviation, surface quality, chemical composition, mechanical property, process performance and other special properties of steel pipe are proposed.
General seamless steel tube used for conveying water, gas, oil and other fluid pipelines and manufacturing various structural parts, the mechanical properties such as tensile strength, yield strength and elongation rate of the sample test. In general, the conveying pipe works under the condition of pressure, and it also requires the test of hydraulic pressure test and expansion, flattening and crimping. For large-scale long-distance crude oil, refined oil, natural gas pipeline steel pipe is to increase the carbon equivalent, welding performance, low-temperature impact toughness, harsh corrosion under the conditions of stress corrosion, corrosion fatigue and corrosive environment, such as the strength of the requirements.
Ordinary boiler tubes are used to manufacture superheated steam pipes and boiling water pipes of various structural boilers. High-pressure boiler tubes are used for superheated steam pipes, heat exchangers and piping for high-pressure equipment in high-pressure or ultra-high pressure boilers. The above-mentioned thermal equipment used in different high-temperature and high-pressure conditions, should ensure good surface conditions, mechanical properties and process performance. In general, it is required to test its mechanical properties, do flattening and hydrostatic tests, and the high-pressure boiler tubes also require the inspection of grain size and more rigorous nondestructive testing.
The mechanical seamless steel tube According to the use request must have the high dimensional accuracy, the good mechanical performance and the surface condition. such as bearing pipe requirements of high wear resistance, organization uniformity and strict internal and external diameter tolerances. In addition to the general mechanical properties of the test items, but also do low, fracture, annealing microstructure (spherical tissue, mesh light, ribbon), non-metallic inclusions (oxides, sulphides, dots, etc.), decarbonization layer and its hardness index test.
High-pressure seamless steel tubes used in the chemical fertilizer industry often carry chemical media (such as ammonia, methanol, urea, etc.) in the environment of 2200~3200MPA, working temperature-40~400℃ and corrosive. High-pressure seamless steel pipe for chemical fertilizer industry should have strong corrosion resistance, good surface state and mechanical properties. In addition to mechanical properties, flattening and hydrostatic tests, the corresponding simplified corrosion test, grain size and more rigorous nondestructive testing should be done according to different steel grades.
Oil and geological drilling steel pipe in the high-pressure, alternating stress, corrosive environment of the work, it should have a high strength level, and can resist wear, torsion and corrosion resistance performance. According to the different steel grade should do tensile strength, yield strength, elongation, impact toughness and hardness test. For oil well casing, tubing and drill pipe, it is a detailed classification of steel grades, categories, and applicable to different environments, geological conditions by the user's own choice of higher requirements of additional technical conditions to meet different special needs.
Chemical, petroleum cracking, aviation and other machinery industry used a variety of stainless steel heat-resistant acid pipe In addition to do mechanical properties and hydrostatic test, but also specialized works between corrosion testing, flattening, expanding and nondestructive testing.

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