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What are the technical conditions for each type of steel pipe?

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What are the technical conditions for each type of steel pipe?

Date of release:2018-09-27 Author: Click:

Generally, according to the use of the steel pipe and its working conditions, different technical conditions should be proposed for the allowable deviation of the steel pipe size, surface quality, chemical composition, mechanical properties, process performance and other special properties.

    Generally, when seamless steel pipes are used to transport various fluid pipes such as water, gas, oil, and various structural parts, sampling tests should be conducted on their mechanical properties such as tensile strength, yield strength and elongation. The conveying pipe generally works under pressure conditions, and also requires hydraulic pressure test and process performance tests such as flaring, crushing and crimping. For large-scale long-distance crude oil, refined oil, natural gas pipeline steel pipe, it also increases carbon equivalent, welding performance, low temperature impact toughness, stress corrosion under severe corrosion conditions, corrosion fatigue and strength under corrosive environment.

    Ordinary boiler tubes are used to make superheated steam tubes and boiling water pipes for various structural boilers. High pressure boiler tubes are used for superheated steam pipes of high pressure or ultra high pressure boilers, heat exchangers and pipes for high pressure equipment. The above-mentioned steel pipes for thermal equipment are operated under different high temperature and high pressure conditions, and good surface condition, mechanical properties and process performance should be ensured. Generally, the mechanical properties should be tested, and the flattening and hydrostatic tests should be carried out. The high-pressure boiler tubes are also required to be tested for grain size and more stringent non-destructive testing.

    Mechanical seamless steel tubes must have high dimensional accuracy, good mechanical properties and surface condition depending on the application. For example, the bearing tube requires high wear resistance, uniform structure and strict inner and outer diameter tolerances. In addition to the general mechanical properties test items, low-frequency, fractured, annealed structures (spheroidized, reticular, ribbon), non-metallic inclusions (oxides, sulfides, dots, etc.) Tests on the carbon layer and its hardness index.

    High-pressure seamless steel pipes for fertilizer industry often transport chemical media (such as ammonia, methanol, urea, etc.) under the pressure of 2200 ~ 3200MPa, working temperature -40 ~ 400 °C and corrosive environment. High-pressure seamless steel pipes for fertilizer industry should have strong corrosion resistance, good surface condition and mechanical properties. In addition to mechanical properties, crushing and hydrostatic testing, the corresponding reduced corrosion test, grain size and more stringent non-destructive testing should be performed according to different steel grades.

    The steel pipe for petroleum and geological drilling works under the harsh environment of high pressure, alternating stress and corrosiveness, so it should have high strength level and can resist wear, torsion and corrosion resistance. Tests such as tensile strength, yield strength, elongation, impact toughness and hardness shall be made according to the steel grade. For the casings, oil pipes and drill pipes used in oil wells, the steel grades, categories, and additional technical conditions applicable to different environments and geological conditions are selected by the users themselves to meet different special needs.

    In addition to mechanical properties and hydrostatic tests, various non-heat-resistant and acid-resistant pipes used in chemical, petroleum cracking, aerospace and other machinery industries are also subject to corrosion tests, flattening, flare and non-destructive testing.

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