Galvanized pipes for instrument air
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The specifications state that galvanized steel pipes should be used for instrument air pipelines; is galvanizing required on both the inside and outside? Is the use of stainless steel pipes common?
For specific references, see: GB 50029-2014 Code for Design of Compressed Air Stations, 9.0.4; HG/T 20510-2014 Code for Design of Instrumentation Air Supply, 8.1; SH/T 3020-2013 Code for Design of Instrumentation Air Supply in Petrochemical Industries, 6.1. When high requirements are placed on compressed air quality, stainless steel or copper pipes should be used.
The specifications state that galvanized steel pipes used for instrument air pipelines generally refer to those that are galvanized on both the inside and outside. Stainless steel pipes are also a commonly used material, as they offer better corrosion resistance and a longer service life. However, when making a choice, cost and the actual usage environment need to be taken into consideration. .
Thin-walled stainless steel pipes are also at atmospheric pressure. Galvanized pipes are galvanized on both the inside and outside.
The relevant standards for SH HG mention that galvanized steel pipes can be used, but stainless steel pipes and copper pipes with plastic coatings are preferred. In particular, gas supply pipes of small size (with a diameter of about 18 mm or less) are all made of thin-walled stainless steel pipes.
According to GB 8163, galvanizing of steel pipes requires the use of dip plating, so both the inner and outer surfaces are galvanized.
Are there galvanized pipes with a coated outer or inner wall? :L