Pipe selection of gas line

It is ok to use galvanised iron instead of malable iron its dearer to buy G.I thats all.

It depends & differs from country to country.

Use of Gi pipes 1/2" thru 1" in residential houses/buildings are common since the pressures are 1/4 psi or less.

in Industrial application where the gas pressures are 8 psig thru 18 psig (in my Country) and pipe sizes vary upto 12" diameter (4"-8" common) mostly seamless Ms pipes are used for welded fabrication.

GI pipes have a seam and they tend to open when welded due to heat.Moreover, putting on fittings as elbows, tees on 4" thru 8" pipes are always at risk of leakage from threads and time factor/cost wasted hence, Ms opted.

In Industrial application I've always used Ms pipes & welded flanges/fittings. My pipe line ranges 1/2" thru 10" till date.

I too am curious now and will await somebody's technical input.

Good Question for the time being.

A small (and questionable) consideration is that natural gas can cause sulfurization of the components of galvanize that may flake off and stop up very small orfices, i.e. pilot lights in appliances, stove and heater orfices.etc. I think this would depend on the composition and wetness of the gas. Black pipe if clean will not rust INSIDE on a gas line due to the lack of O2 but may be a problem if burried or where electrolysis may occur. As always, many factors to consider in the simplest of things. Electrical Isolation of different metals at joints is a must to prevent electrolysis.

natural gas can cause sulfurization of the components of galvanize that may flake off and stop up very small orfices.

thanks 007 this may be the reason why Black clean Ms pipes are used.

thanks