Main gas pipe at least 60 cm long is used to convey the gas from gas holder and is placed at top most portion of the dome.
The joint of reduction elbow with this pipe should be perfect and gas tight otherwise gas leakage from this joint can not be stopped easily. Therefore it is recommended that the reduction elbow has to be fitted in a workshop to ensure perfect air-tightness of the joint. This pipe should be made up of light quality iron and MS rod has to be welded at one end to embed it with the concrete during installation.
This pipe should be made up of high quality neoprene rubber and should not develop cracks when folded. It should have 15 mm outer and 9 mm inner diameters. The minimum wall thickness of the pipe should be 2.5 mm.