Seamless steel pipe selection standard

Seamless steel pipe selection standard

Seamless steel pipe is a kind of steel pipe without weld made by hot working method such as perforation hot rolling. When necessary, the hot-worked pipe can be further cold-worked to the desired shape, size and performance.At present, seamless steel pipe (DN15-600) is the most used pipe in petrochemical production plant.

(1) Carbon steel seamless steel pipe

Material grade:

10#, 20#, 09MnV, 16Mn 4 kinds


Standard:

GB8163 Seamless Steel Pipe for Fluid Transport

GB/T9711 "Oil and Natural gas industry Conveying steel pipe delivery technical conditions"

GB6479 "High Pressure Seamless Steel Pipe for Fertilizer Equipment"

GB9948 Seamless Steel Pipe for petroleum cracking

GB3087 "Seamless Steel Tube for low and medium pressure boiler"

GB/T5310 "Seamless Steel Tube for High Pressure boiler"

GB/T8163:

Material grade: 10#, 20#, Q345, etc.
Scope of application: oil, gas and public media with design temperature less than 350℃ and pressure less than 10MPa.


GB6479:
Material grade: 10#, 20G, 16Mn, etc.
Scope of application: design temperature -40 ~ 400℃, design pressure 10.0 ~ 32.0mpa oil, oil and gas.


GB9948:
Material grade: 10#, 20#, etc.
Scope of application: not suitable for the use of GB/T8163 steel pipe.


GB3087:
Material grade: 10#, 20#, etc.
Scope of application: low and medium pressure boiler superheated steam, boiling water, etc.


GB5310:
Material grade: 20G, etc.
Scope of application: High pressure boiler superheated steam medium


Inspection:

General fluid conveying steel tubes must be subjected to chemical composition analysis, tensile test, flattening test and hydrostatic test.
GB5310, GB6479, GB9948 three kinds of standard steel pipe, in addition to the fluid transport steel pipe must be tested, but also required to carry out flaring test and impact test; The manufacturing and inspection requirements of these three kinds of steel pipes are relatively strict.

GB6479 standard also makes special requirements for low temperature impact toughness of materials.

GB3087 standard steel pipe, in addition to the general test requirements for fluid transport steel pipe, also requires cold bending test.

GB/T8163 standard steel tubes, in addition to the general test requirements for fluid transport steel tubes, are required to carry out flaring test and cold bending test according to the agreement. These two types of pipes are not as strict as the first three.


Manufacturing:

GB/T8163 and GB3087 standard steel tubes are mostly smelted by open hearth furnace or converter, which have relatively more impurities and internal defects.

GB9948 is mostly smelting by electric furnace. Most of them are added to the refining process outside the furnace, and the composition and internal defects are relatively few.

The GB6479 and GB5310 standards themselves specify the requirements for out-of-furnace refining, which has the least impurity composition and internal defects and the highest material quality.

The manufacturing quality grades of the above steel pipe standards are in order from low to high:

GB/T8163 <  GB3087 < GB9948 < GB5310 < GB6479


Choose:

In general, GB/T8163 standard steel pipe is suitable for design temperature less than 350℃, pressure less than 10.0MPa oil, oil and gas and public media conditions;

For oil, oil and gas medium, when the design temperature is more than 350℃ or pressure is greater than 10.0mpa, GB9948 or GB6479 standard steel pipe should be selected;

GB9948 or GB6479 standards should also be used for pipelines operated near hydrogen or in stress corrosion prone environments.

Generally at low temperature (less than -20℃) the use of carbon steel pipe should be adopted GB6479 standard, only it stipulates the requirements of low temperature impact toughness of the material.

GB3087 and GB5310 are standards specially set for boiler steel tubes.

"Boiler safety supervision regulations" emphasized that all connected with the boiler tubes are belongs to the scope of supervision, the application of the material and standard should comply with the rules of the boiler safety, therefore, boiler, power station, heating and petrochemical production device used in public steam pipe should be used (by the system supply) GB3087 or standard GB5310. It is worth noting that the quality of steel pipe standard, the price of steel pipe is also relatively high, such as GB9948 than GB8163 material price is nearly 1/5, therefore, in the selection of steel pipe material standard, should be considered according to the conditions of use, both reliable and economic. It should also be noted that steel tubes of GB/T20801 and TSGD0001, GB3087 and GB8163 standards shall not be used for GC1 piping (except in the case of individual sonics, quality not less than L2.5, which can be used for GC1(1) piping with design pressures not greater than 4.0Mpa).

(2) low alloy steel seamless steel pipe

In petrochemical production plant, commonly used chromium molybdenum steel and chromium molybdenum vanadium steel seamless steel pipe standards are

GB9948 Seamless Steel Pipe for petroleum cracking

GB6479 "High Pressure Seamless Steel Pipe for Fertilizer Equipment"

GB/T5310 "Seamless Steel Tube for High Pressure boiler"

GB9948 contains chromium molybdenum steel material grades: 12CrMo, 15CrMo, 1Cr2Mo, 1Cr5Mo, etc.

GB6479 contains chromium molybdenum steel material grades: 12CrMo, 15CrMo, 1Cr5Mo, etc.

GB/T5310 includes chromium molybdenum steel and chromium molybdenum-vanadium steel material grades: 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12Cr1MoVG, etc.

Among them, the more commonly used is GB9948

(3) stainless steel seamless steel pipe

Commonly used stainless steel seamless steel pipe standards are:

GB/T14976, GB13296, GB9948, GB6479, GB5310 five standards. Among them, the last three standards listed only two or three stainless steel material brand, and is not commonly used material brand.

Therefore, when the project chooses stainless steel seamless steel pipe standard, basically choose GB/T14976 and GB13296 standard.

GB/T14976 "Seamless Stainless Steel Pipe for fluid transport" :

Material grade: 304, 304L, a total of 19 kinds of suitable for the transport of general fluid.

GB13296 "Seamless Stainless Steel Pipe for Boiler and Heat exchanger" :

Material grade: 304, 304L, a total of 25 kinds.

Among them, ultra-low carbon stainless steel (304L, 316L) has excellent corrosion resistance, under certain conditions, can replace stable stainless steel (321, 347) for corrosion resistance medium; Ultra-low carbon stainless steel high temperature mechanical performance is low, generally only used for temperature below 525℃ under the condition; Stable austenitic stainless steel has good corrosion resistance, and high temperature mechanical properties, but in the 321 Ti easy oxidized and lose in the welding process, and thus reduce its corrosion resistance, its price is high, this kind of material is generally used in the important occasion, 304, 316, has the general corrosion resistance, cheap, so widely used.

Read more : How to choose the material of seamless steel pipe?