Wall thickness selection
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I have a question. For steam pipes, a corrosion allowance of 1.5 mm is adopted, and pipes made of GB/T 8163 grade 20 steel are used. The design temperature is 250 degrees Celsius (at which the allowable stress is 110 Mpa), and the design pressure is 2.2 MPa. Will using the SCH20 pipe wall thickness series be sufficient to meet the design requirements? According to the formula T=sch*D/1.75/1000+2.54, a wall thickness of 3.5 for a Φ76 pipe is sufficient? Please correct me.
Pressure pipelines should be used; GB/T 8163 seamless steel pipes for fluid transport are not suitable, and it is recommended to use seamless steel pipes for low and medium pressure boilers (GB 3087-1999).
Yes, 3. The wall thickness of 5 fully meets the usage requirements.
Thank you for the reply. But is there any basis for the claim that “GB/T 8163 is not applicable to seamless steel pipes for fluid transportation”? These are steam transmission pipes within the factory area, not those inside the boiler; can pipes in accordance with GB/T 8163 be used?
For safety reasons, it is better to choose GB9948-2006
2.2 MPa; using a wall thickness of 3.5 results in an excessively low safety factor
The temperature and pressure are very high; it is recommended to increase the wall thickness by one grade.
Seamless steel pipes in accordance with GB/T 8163 can be used; we are in the chemical industry, and over 95% of our applications involve such pipes.
I indeed didn’t pay attention to the pressure limits for the use of carbon steel pipes specified in GB8163-1999 before. I checked HG20553-93 and GB8163-1999, but they don’t specify any pressure limits for their use. However, on page 71 of “Pressure Pipeline Design and Engineering Examples,” it states that “the scope of application for GB/T8163-1999 is oils, gas oils, and utility media with a design temperature below 350°C and a pressure less than 10 MPa.” ”I think this can be used as a basis; GB8163-1999 seamless carbon steel is widely used in ordinary steam and chemical media.
According to GBT20801, seamless pipes of GB8163 can be used for pressures up to 4.0 MPa.
"It is incorrect to say that GB/T 8163 applies only to seamless steel pipes for fluid transport. 3.5mm is no problem!
Should a corrosion margin of 1.5mm be added as well?