Issues regarding the use of 20GB3087 material for steel pipes
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Regarding the use of the 20GB3087 material for steel pipes: There is a container with DN273*12, where the design pressure is 9.8 Mpa and the design temperature is 50℃. The length of the cylinder is 1700 mm. The material specified for manufacturing this cylinder is 20GB6749 steel pipe with dimensions φ273*12. Now, since there is available 20GB3087 steel pipe of the same dimensions φ273*12, can it be used instead? In other words, is it possible to use 20GB3087 steel pipe φ273*12 as a substitute for 20GB6749 steel pipe? At 50°C, the allowable stress σ]t for steel pipe 20GB6749 is 137 Mpa, while for steel pipe 20GB3087 it is 142 Mpa. Since this value of 142 Mpa for σ]t cannot be found in GB150, it was determined using interpolation methods in GB9222-2008. I’m not sure if this is correct. Please let me know, those with experience – under the specified design conditions, can steel pipe 20GB3087 be used as a substitute for steel pipe 20GB6749? Why? Thank you.
Steel pipe grade 20 according to GB3087, which is used in low- and medium-pressure boilers, can replace steel pipe grade 20 specified in GB8163; however, since your wall thickness is greater than 10 mm, GB3087 steel pipes cannot be used. Steel pipes grade 20 specified in GB5310, which are used in high-pressure boilers, can be used as a substitute for steel pipes grade 20 specified in GB6479.
The statement on the second floor is very accurate; see GB150 Appendices A3.2 and A3.3.
Firstly, your stress levels are too high; 3087 is not suitable in this case – 5310 is what’s needed. Additionally, when considering steel pipe standards, it’s not enough to focus only on the allowable stress; factors such as the operating environment and the properties of the medium also play an important role. For example, 8162 is generally not suitable for use in pipelines.
The allowable values for steel pipes shall comply with the relevant provisions of GB150-2011. My opinion: Only steel pipes specified in GB9948 or GB6479 can be used.