Seamless steel pipe is a steel pipe without welds manufactured by hot processing methods such as perforation hot rolling. If necessary, the hot-processed pipe can be further cold-processed to the required shape, size and performance.
Seamless steel pipe is a steel pipe without welds manufactured by hot processing methods such as perforation 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 (DN15-600) is the most widely used pipe in petrochemical production equipment.
(I) Carbon steel seamless steel pipe
Main material grades:
10#, 20#, 09MnV, 16Mn, 4 types in total
Main standards:
GB8163 "Seamless steel pipe for fluid transportation"
GB/T9711 "Technical conditions for delivery of steel pipes for petroleum and natural gas industry"
GB6479 "High-pressure seamless steel pipe for fertilizer equipment"
GB9948 "Seamless steel pipe for petroleum cracking"
GB3087 "Seamless steel pipe for low and medium pressure boilers"
GB/T5310 "Seamless steel pipe for high-pressure boilers"
GB/T8163:
Material grades: 10#, 20#, Q345, etc.
Scope of application: oil products, oil and gas and public media with a design temperature of less than 350℃ and a pressure of less than 10MPa.
GB6479:
Material grades: 10#, 20G, 16Mn, etc.
Scope of application: oil products and oil and gas with design temperature of -40 to 400℃ and design pressure of 10.0 to 32.0MPa.
GB9948:
Material grades: 10#, 20#, etc.
Scope of application: occasions where GB/T8163 steel pipes are not suitable.
GB3087:
Material grades: 10#, 20#, etc.
Scope of application: superheated steam and boiling water of low and medium pressure boilers, etc.
GB5310:
Material grades: 20G, etc.
Scope of application: superheated steam medium of high pressure boilers
Inspection:
Generally, steel pipes for fluid transportation must undergo chemical composition analysis, tensile test, flattening test and water pressure test.
In addition to the tests that must be carried out on steel pipes for fluid transportation, the three standards of GB5310, GB6479 and GB9948 also require expansion test and impact test; the manufacturing inspection requirements of these three steel pipes are relatively strict.
GB6479 standard also makes special requirements for the low-temperature impact toughness of materials.
In addition to the general test requirements for steel pipes for fluid transportation, steel pipes of GB3087 standard also require cold bending tests.
In addition to the general test requirements for steel pipes for fluid transportation, steel pipes of GB/T8163 standard require expansion test and cold bending test according to the agreement. The manufacturing requirements of these two pipes are not as strict as the first three.
Manufacturing:
Steel pipes of GB/T8163 and GB3087 standards are mostly smelted by open furnace or converter, and their impurity components and internal defects are relatively more.
GB9948 is mostly smelted by electric furnace. Most of them have added the refining process outside the furnace, and the composition and internal defects are relatively less.
GB6479 and GB5310 standards themselves stipulate the requirements for refining outside the furnace, with the least impurity components and internal defects and the highest material quality.
The manufacturing quality levels of the above steel pipe standards are in order from low to high:
GB/T8163 < GB3087 < GB9948 < GB5310 < GB6479
Selection principles:
Generally speaking, steel pipes of GB/T8163 standard are suitable for oil, oil and gas and public medium with design temperature less than 350℃ and pressure less than 10.0MPa;
For oil, oil and gas medium, when the design temperature exceeds 350℃ or the pressure is greater than 10.0MPa, steel pipes of GB9948 or GB6479 standard should be selected;
For pipelines operating in the presence of hydrogen or working in an environment prone to stress corrosion, GB9948 or GB6479 standard should also be used.
For carbon steel pipes used at low temperatures (less than -20℃), GB6479 standard should be adopted, as it is the only standard that specifies the requirements for low-temperature impact toughness of materials.
GB3087 and GB5310 standards are standards set specifically for boiler steel pipes.
The Boiler Safety Supervision Regulations emphasize that all pipes connected to the boiler are subject to supervision, and the application of their materials and standards should comply with the provisions of the Boiler Safety Supervision Regulations. Therefore, the public steam pipes (supplied by the system) used in boilers, power stations, heating and petrochemical production equipment should adopt GB3087 or GB5310 standards.
It is worth noting that the price of steel pipes with good quality standards is also relatively high. For example, the price of GB9948 is nearly 1/5 higher than that of GB8163 materials. Therefore, when selecting steel pipe material standards, comprehensive considerations should be made based on the use conditions, and both reliability and economy should be considered. It should also be noted that according to GB/T20801 and TSGD0001, steel pipes of GB3087 and GB8163 standards shall not be used for GC1 pipelines (unless they are ultrasonically tested one by one and the quality is not less than L2.5 level, they can be used for GC1(1) pipelines with a design pressure of no more than 4.0Mpa).
(II) Low alloy steel seamless pipes
In petrochemical production equipment, the commonly used chromium-molybdenum steel and chromium-molybdenum-vanadium steel seamless pipe standards are
GB9948 "Seamless steel pipe for petroleum cracking"
GB6479 "High-pressure seamless steel pipe for fertilizer equipment"
GB/T5310 "Seamless steel pipe for high-pressure boiler"
The chromium-molybdenum steel material grades included in GB9948: 12CrMo, 15CrMo, 1Cr2Mo, 1Cr5Mo, etc.
The chromium-molybdenum steel material grades included in GB6479: 12CrMo, 15CrMo, 1Cr5Mo, etc.
The chromium-molybdenum steel and chromium-molybdenum-vanadium steel material grades included in GB/T5310: 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12Cr1MoVG, etc.
