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In Fact, the Correct Selection of Seamless Pipe Deserves Studying!
Aug 03, 2020
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In fact, the correct selection of seamless steel pipe deserves studying. So, this news is going to talk about the selection of SMLS pipe.
Seamless steel pipe is a kind of steel pipe without weld, which is manufactured by hot working method such as piercing and hot rolling. If necessary, the hot processed pipe can be further cold processed to the required shape, size and performance. At present, seamless steel pipe (DN 15 - 600) is the most widely used pipe in petrochemical plant.
(1) Material grade of carbon steel seamless steel pipe: 10, 20, 09MnV, 16Mn. Four kinds of standards: GB8163 in seamless steel pipe for fluid transportation, GB/T 9711 in technical conditions for delivery of steel pipe for oil and natural gas industry, GB6479 in high pressure seamless steel pipe for chemical fertilizer equipment, GB9948 seamless steel pipe for petroleum cracking, GB3087 in seamless steel pipe for low and medium pressure boiler, GB/T 5310 in seamless steel pipe for high pressure boiler steel pipe, GB/T 8163: material trademark: 10, 20, Q345, etc. Application scope: GB6479 in oil, gas and public medium with design temperature less than 350 ℃ and pressure less than 10MPa: material grade: 10, 20G, 16Mn, etc. Scope of application: GB9948 in oil and gas with design temperature of - 40 ~ 400 ℃ and design pressure of 10.0 ~ 32.0Mpa: material grade: 10, 20, etc. Scope of application: it is not suitable to use GB/ T 8163 steel pipe. GB3087: material grade: 10, 20, etc.
Scope of application: superheated steam and boiling water of low and medium pressure boilers. GB5310: material grade: 20G, etc. Scope of application: superheated steam medium of high pressure boiler.
Inspection:
Chemical composition analysis, tensile test, flattening test and hydrostatic test must be carried out for general steel pipes for fluid transportation.In addition to the tests that must be carried out on steel pipes for fluid transportation, flaring test and impact test are also required for the steel pipes of GB5310, GB6479 and GB9948. The manufacturing and inspection requirements of these three kinds of steel pipes are relatively strict. The standard GB6479 also has special requirements for the impact toughness at low temperature. In addition to the general test requirements of steel pipe for fluid transportation, cold bending test is also required for steel pipe in GB3087 standard. In addition to the general test requirements of steel pipes for fluid transportation, the flaring test and cold bending test shall be carried out according to the requirements of the agreement. The manufacturing requirements of these two kinds of pipes are not as strict as the first three. Manufacturing: steel pipes in GB/T 8163 and GB3087 standards are mostly made by open hearth furnace or converter, with relatively more impurities and internal defects. GB9948 is mostly smelted by electric furnace. Most of the secondary refining processes are added, and the composition and internal defects are relatively small. GB6479 and GB5310 have specified the requirements of secondary refining. The impurities and internal defects are the least and the quality of materials is the highest.
Seamless steel pipe is a kind of steel pipe without weld, which is manufactured by hot working method such as piercing and hot rolling. If necessary, the hot processed pipe can be further cold processed to the required shape, size and performance. At present, seamless steel pipe (DN 15 - 600) is the most widely used pipe in petrochemical plant.
(1) Material grade of carbon steel seamless steel pipe: 10, 20, 09MnV, 16Mn. Four kinds of standards: GB8163 in seamless steel pipe for fluid transportation, GB/T 9711 in technical conditions for delivery of steel pipe for oil and natural gas industry, GB6479 in high pressure seamless steel pipe for chemical fertilizer equipment, GB9948 seamless steel pipe for petroleum cracking, GB3087 in seamless steel pipe for low and medium pressure boiler, GB/T 5310 in seamless steel pipe for high pressure boiler steel pipe, GB/T 8163: material trademark: 10, 20, Q345, etc. Application scope: GB6479 in oil, gas and public medium with design temperature less than 350 ℃ and pressure less than 10MPa: material grade: 10, 20G, 16Mn, etc. Scope of application: GB9948 in oil and gas with design temperature of - 40 ~ 400 ℃ and design pressure of 10.0 ~ 32.0Mpa: material grade: 10, 20, etc. Scope of application: it is not suitable to use GB/ T 8163 steel pipe. GB3087: material grade: 10, 20, etc.
Scope of application: superheated steam and boiling water of low and medium pressure boilers. GB5310: material grade: 20G, etc. Scope of application: superheated steam medium of high pressure boiler.
Inspection:
Chemical composition analysis, tensile test, flattening test and hydrostatic test must be carried out for general steel pipes for fluid transportation.In addition to the tests that must be carried out on steel pipes for fluid transportation, flaring test and impact test are also required for the steel pipes of GB5310, GB6479 and GB9948. The manufacturing and inspection requirements of these three kinds of steel pipes are relatively strict. The standard GB6479 also has special requirements for the impact toughness at low temperature. In addition to the general test requirements of steel pipe for fluid transportation, cold bending test is also required for steel pipe in GB3087 standard. In addition to the general test requirements of steel pipes for fluid transportation, the flaring test and cold bending test shall be carried out according to the requirements of the agreement. The manufacturing requirements of these two kinds of pipes are not as strict as the first three. Manufacturing: steel pipes in GB/T 8163 and GB3087 standards are mostly made by open hearth furnace or converter, with relatively more impurities and internal defects. GB9948 is mostly smelted by electric furnace. Most of the secondary refining processes are added, and the composition and internal defects are relatively small. GB6479 and GB5310 have specified the requirements of secondary refining. The impurities and internal defects are the least and the quality of materials is the highest.
The order of manufacturing quality grade of the above steel pipe standards from low to high: GB/T 8163 < GB3087 < GB9948 < GB5310 < GB6479 selection: in general, the steel pipe of GB/T 8163 standard is applicable to the oil, oil and gas and public medium with design temperature less than 350 ℃ and pressure lower than 10.0Mpa. For oil and oil gas medium, when the design temperature is higher than 350 ℃ or the pressure is greater than 10.0MPa,steel pipes of GB9948 or GB6479 standards shall be used and selected. For pipelines operating in the presence of hydrogen or working in the environment with stress corrosion tendency, GB9948 or GB6479 standards should also be used. The standard GB6479 shall be adopted for all carbon steel pipes used at low temperature (less than - 20 ℃), only because it specifies the requirements for low temperature impact toughness of materials. GB3087 and GB5310 standards are specially set for boiler steel pipe. "Boiler safety supervision regulations" emphasizes that all pipes connected with boilers are within the scope of supervision, and the application of materials and standards should comply with the provisions of "boiler safety supervision regulations". Therefore, the common steam pipes (supplied by the system) used in boilers, power stations, heating and petrochemical production units should adopt GB3087 or GB5310 standards. It should be noted that the price of steel pipe with good quality is also relatively high. For example, the price of GB9948 is nearly 1 / 5 higher than that of GB8163 material. Therefore, when selecting steel pipe material standard, comprehensive consideration should be made according to the service conditions, which should be reliable and economical. It should also be noted that steel pipes in accordance with GB/T20801 and TSGD0001. GB3087 and GB8163 standards shall not be used in GC1 pipes (except for ultrasonic waves one by one, the quality shall not be lower than grade L2.5, and it can be used for GC1 (1) pipes with design pressure no more than 4.0Mpa).
(2) In the petrochemical production unit of low alloy steel seamless steel pipe, the commonly used standards of chromium molybdenum steel and chromium molybdenum vanadium steel seamless steel pipe are GB9948 in seamless steel pipe for petroleum cracking, GB6479 in high pressure seamless steel pipe for chemical fertilizer equipment, GB/T5310 in seamless steel pipe for high pressure boiler. GB9948 contains the material grades of chromium molybdenum steel: 12CrMo, 15CrMo, 1Cr2Mo, 1Cr5Mo, etc. The grades of chromium molybdenum steel of GB6479 contains 12CrMo, 15CrMo, 1Cr5Mo, etc. The grades of chromium molybdenum steel and chromium molybdenum vanadium steel of GB/T5310 contains 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12Cr1MoVG, etc. Among them, the more commonly used is GB9948, and the selection conditions are shown as above.
(3) Stainless steel seamless steel pipe
The commonly used stainless steel seamless steel pipe standards are: GB/T 14976, GB 13296, GB9948, GB6479 and GB5310. Among them, only two or three stainless steel grades are listed in the latter three standards, which are not commonly used. Therefore, when the standard of stainless steel seamless steel pipe is selected in engineering, the standards of GB/T 14976 and GB13296 are basically selected. GB/T14976 in stainless steel seamless steel tubes for fluid transportation: there are 19 kinds of material grades: 304, 304L, etc., which are suitable for general fluid transportation. GB 13296 in stainless steel seamless steel tubes for boilers and heat exchangers: there are 25 kinds of material grades: 304, 304L, etc. Among them, ultra-low carbon stainless steel (304L, 316L) has excellent corrosion resistance, which can replace stable stainless steel (321, 347) for medium corrosion resistance under certain conditions. Ultra-low carbon stainless steel has low high-temperature mechanical properties, which is generally only used at the temperature below 525 ℃. Stable austenitic stainless steel has good corrosion resistance and high-temperature mechanical properties, However, the Ti in 321 is easy to be oxidized and lost in the welding process, which reduces its corrosion resistance. Its price is high. This kind of material is generally used in more important occasions. 304 and 316 have general corrosion resistance and they are cheap, so they are widely used.
