The correct selection of seamless steel pipes is actually very knowledgeable!

What are the requirements for selecting seamless steel pipes for fluid transportation commonly used in our process industry? Look at the summary of our pressure pipeline staff:

Seamless steel pipes are steel pipes without welds manufactured by hot treatment methods such as piercing and hot rolling.

If necessary, the hot treatment pipe can be further cold-drawn to the required shape, size and performance. At present, seamless steel pipes (DN15-600) are the most widely used pipes in petrochemical production equipment.

（一）Seamless Carbon steel Pipe

Material Steel Grade :10#、20#、09MnV、16Mn  in 4 kinds

Standard:

GB8163 Seamless Steel Pipe for Fluid Service

GB/T9711  Petroleum and natural gas industries—Steel pipe for pipeline transportation systems

GB6479 High-pressure seamless steel pipe for fertilizer equipment”

GB9948 Seamless steel tubes for petroleum cracking

GB3087 Seamless steel pipe for low and medium pressure boiler

GB/T5310 Seamless steel tubes and pipes for high pressure boiler

GB/T8163:Material Steel Grade: 10#, 20#, Q345, etc.

Scope of application: oil, oil and gas and public media whose design temperature is less than 350℃ and pressure is less than 10MPa.

GB6479:Material steel Grade: 10#, 20G, 16Mn, etc.

Scope of application: oil and gas with design temperature -40～400℃ and design pressure 10.0～32.0MPa.

GB9948:

Material steel Grade: 10#, 20#, etc.

Scope of application: occasions where GB/T8163 steel pipe is not suitable.

GB3087:

Material steel Grade: 10#, 20#, etc.

Scope of application: superheated steam and boiling water for low and medium pressure boilers.

GB5310:

Material steel Grade: 20G etc.

Scope of application: superheated steam medium of high pressure boiler

Inspection: Generally steel pipes for fluid transportation must undergo chemical composition analysis, tensile test, flattening test and hydraulic test. GB5310, GB6479, and GB9948 standard steel pipes, in addition to the tests that must be carried out on steel pipes for fluid transport, flaring tests and impact tests are also required; the manufacturing inspection requirements for these three steel pipes are relatively strict. The GB6479 standard also makes special requirements for the low-temperature impact toughness of the material. In addition to the general test requirements of steel pipes for fluid transportation, the steel pipes of the GB3087 standard also require cold bending tests. GB/T8163 standard steel pipes, in addition to the general test requirements for fluid transport steel pipes, according to the agreement requires the expansion test and cold bending test. The manufacturing requirements of these two types of tubes are not as strict as the first three types.

Manufacturing: GB/T8163 and GB3087 standard steel pipes are mostly smelted in open hearth or converter, and their impurities and internal defects are relatively large. GB9948 mostly uses electric furnace smelting. Most of them have joined the refining process outside the furnace, and the composition and internal defects are relatively small. The GB6479 and GB5310 standards themselves stipulate the requirements for refining outside the furnace, with the least impurity composition and internal defects, and the highest material quality

Selection: In general, GB/T8163 standard steel pipe is suitable for oil, oil and gas and public media with a design temperature of less than 350°C and a pressure of less than 10.0MPa; for oil, oil and gas media, when the design temperature exceeds 350°C Or when the pressure is greater than 10.0MPa, GB9948 or GB6479 standard steel pipes should be used; for pipelines operated in hydrogen, or pipelines working in stress corrosion prone environments, GB9948 or GB6479 standards should also be used. All carbon steel pipes used at low temperatures (less than -20°C) should adopt the GB6479 standard, and only it specifies the requirements for the low-temperature impact toughness of the material. The GB3087 and GB5310 standards are standards set specifically for boiler steel pipes. The “Boiler Safety Supervision Regulations” emphasizes that all pipes connected to the boiler belong to the scope of supervision, and the application of materials and standards should comply with the requirements of the “Boiler Safety Supervision Regulations”. Therefore, they are used in boilers, power stations, heating and petrochemical production facilities. All public steam pipes (supplied by the system) should adopt GB3087 or GB5310 standards. It is worth noting that the price of steel pipes with good quality steel pipe standards is relatively high. For example, the price of GB9948 is nearly 1/5 higher than the price of GB8163 materials. Therefore, when selecting steel pipe material standards, comprehensive consideration should be given to the conditions of use, which must be reliable and Be economical. It should also be noted that steel pipes in accordance with GB/T20801 and TSGD0001, GB3087 and GB8163 standards shall not be used for GC1 pipelines (unless one by one is ultrasonic, the quality is not lower than L2.5, and it can be used for GC1 with a design pressure not greater than 4.0Mpa pipeline).

（二）Low alloy pipe seamless steel pipe

In petrochemical production equipment, the 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 pipe for high-pressure boiler 》GB9948 contains chromium-molybdenum steel material grades: 12CrMo, 15CrMo, 1Cr2Mo, 1Cr5Mo, etc. The chromium-molybdenum steel material grades included in GB6479: 12CrMo, 15CrMo, 1Cr5Mo, etc. GB/T5310 contains chromium molybdenum steel and chromium molybdenum vanadium steel material grades: 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12Cr1MoVG, etc. Among them, the more commonly used one is GB9948, see above for selection conditions

（三）Seamless stainless steel pipe

Commonly used stainless steel seamless steel pipe standards are:

There are five standards: GB/T14976, GB13296, GB9948, GB6479, and GB5310. Among them, only two or three stainless steel material grades are listed in the last three standards, and they are not commonly used material grades.

Therefore, when stainless steel seamless steel pipe standards are used in engineering, GB/T14976 and GB13296 standards are basically used.

GB/T14976 “Stainless steel seamless steel pipe for fluid transportation”:

Material grades: 304, 304L and other 19 kinds are suitable for general fluid transportation.

GB13296 “Stainless steel seamless steel tubes for boilers and heat exchangers”:

Material grades: 304, 304L and other 25 kinds.

Among them, ultra-low-carbon stainless steel (304L, 316L) has excellent corrosion resistance. Under certain conditions, it can replace stable stainless steel (321, 347) for corrosion resistance to media; ultra-low-carbon stainless steel has low high-temperature mechanical properties, generally Only used at temperatures below 525℃; stable austenitic stainless steel has both good corrosion resistance and high temperature mechanical properties, but Ti in 321 is easily oxidized and lost during welding , Thus reducing its anti-corrosion performance, its price is relatively high, this kind of material is generally used in more important occasions, 304, 316 has general anti-corrosion performance, the price is cheap, so it is widely used.