If this is cross country and is in the United States, 49 CFR part 192 regulates gas. Part 195 regulates liquids ASME B31.4 will be the code referenced and API 1104 will be the welding code. If this is out of the United States, other regulations govern. If this is in plant work, B31.4 can give some good guidelines. The elevation above the trench bottom is for installing padding fill under the pipe. This can be graded sand, clean soil, or processed backfill material using a padding machine like an Ozzy Padder.
BABRT's