Representation of 20 pipes
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In GB150, the material GB 6479 includes a 20G grade, whereas this grade is not present in GB6479-2000. Sw6 also has 20G. What material is specified on the drawing now? It is specified as 20G, but the equipment manufacturer doesn’t have it; a material substitution form is required. If it’s written as 20, then how should it be calculated in the calculation sheet? It needs to be calculated based on an allowable pressure of 20G. The problem of headaches
*It is customary to classify them based on standards: GB8163 20, GB3087 20G, GB5310 20G, GB6479 20 (normalized state)
I’ve encountered this issue these past two days as well: the design pressure for one of the coils is 12 MPa. I chose steel pipes in accordance with the GB6479 standard, although the standard specifies only a value of 20. For the strength calculations, I used the allowable stress value specified in GB150 for 20G grade steel. However, the allowable stress obtained by dividing the tensile strength of pipe No. 20 according to GB6479 standards by the safety factor of 3.0 is the same as that specified in GB150.
After comparing the 20-type pipes specified in GB6479 and GB5310, their chemical compositions and mechanical properties are essentially the same; the only difference is that GB6479 has a higher impact value. Therefore, we generally choose GB6479.
It should be noted that pipes do not have a 20g designation; 20g refers to steel plates used for boilers
20G should refer to GB5310, which pertains to high-pressure seamless steel tubes for boilers; then there’s 20/GB3087, and that 20G is probably GB713
It’s better to check the standard texts directly: GB8163-1999 – Standard for seamless steel tubes used for transporting fluids; GB3087-2008 – Seamless steel tubes for low and medium pressure boilers; GB5310-2008 – Seamless steel tubes for high pressure boilers; GB6479-2000 – Seamless steel tubes for high pressure fertilizer processing equipment. These can all be found on websites. Hehe
The 20G grade is no longer available
20R can be used as a substitute; 20G is simply not available on the market.