Selection issue for pipe wall thickness
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For the equipment built previously, the piping was selected in accordance with the \"Chemical Pipeline Design Manual.\" The media involved included circulating water (around 50°C) and petroleum gas after high-temperature treatment (around 200°C, containing oils). Seamless stainless steel was used for the pipes, and the wall thickness was determined based on this table (1.6 Mpa). No account was taken of corrosion, so no margin for corrosion resistance was included; however, the pipes seem a bit thin – for example, those with a DN200 diameter have a wall thickness of only 3.5 mm. For safety reasons, it is planned to increase the wall thickness by 1 mm next time (since there is no mathematical basis for this, the increase is based on experience). Please discuss whether an increase in thickness is necessary and by how much it should be.
It depends on whether the medium flowing through the pipeline is corrosive; in most cases, there is no need to thicken stainless steel pipelines
According to Table 38-4 in the Chemical Process Design Handbook (5th Edition – Volume 2), wall thickness of seamless stainless steel pipes
According to Appendix D of \"GB 50316-2000 (2008 edition) Code for Design of Industrial Metal Piping\": Selection of stainless steel for severe service conditions, 4mm
The two tables are the same; the question is whether a thicker wall thickness is required for oil-containing gases
Mm-hmm, I see that the diameter of some parts has been increased by 0.5. Moreover, the values in the table represent the minimum wall thickness; I’ll assume an increase of 0.5. Thank you
The national standards for steel specify tolerances of plus or minus a certain amount; a positive tolerance means the thickness is slightly higher, while a negative tolerance means it is slightly lower. You can choose the option with a positive tolerance. It is stated in the contract
:):victory:
Learn this: for stainless steel, there’s no need to consider a corrosion allowance!
The wall thickness of pipes is calculated using the allowable stress under normal operating conditions, which is much smaller than the difference between the inner and outer dimensions