Answer: (1) Compressed air pipelines should meet the user's requirements for compressed air flow, pressure and quality. The choice of its laying method should be determined based on the local terrain, geology, hydrology and meteorology conditions after technical and economic comparison. Compressed air pipelines in factories (mines) in hot and warm areas should be laid overhead. Compressed air pipelines in factories (mines) in extremely cold areas should be laid in the same trench as thermal pipelines or buried underground. Anti-freeze measures should be taken when overhead laying compressed air pipelines in cold and extremely cold areas.
(2) Pipelines that transport saturated compressed air should be equipped with devices that can discharge oil and water accumulated in the pipeline system. The slope of pipelines with slopes should not be less than 0.002.
(3) Carbon steel pipes should be used as compressed air pipeline materials. Stainless steel pipes can be used for dry and purified compressed air pipelines with water vapor content less than 7.98mg and dust particles less than 0.5μm.
(4) For the cut-off valves of dry and purified compressed air pipelines with water vapor content less than 7.98mg and dust particles less than 0.5μm, stainless steel ball valves or stainless steel bellows valves should be used. Thermal compensation should be considered for overhead compressed air pipelines in factories (mines).
(5) For the connection of compressed air pipelines, except for flanges or threaded connections at equipment and valves, welding should be used for other parts. The connection of pipelines for conveying dry and purified compressed air should comply with the relevant provisions of GB 50073-2001 "Design Specifications for Cleanrooms".
(6) Compressed air pipelines should be equipped with cut-off valves, pressure gauges and flow meters at the entrance of gas-using buildings. For pipelines conveying saturated compressed air, oil-water separators should be installed. For users with large fluctuations in compressed air load or requiring stable gas supply pressure, gas storage tanks or other pressure stabilizing devices should be installed nearby.
(7) Overhead compressed air pipelines in workshops should be laid along walls and pillars. Their height should not hinder transportation and should be easy to repair. When compressed air pipelines need to be grounded for lightning protection, they should be grounded in accordance with GB 50057-1994 "Building Lightning Protection Design Code".
(8) Compressed air pipelines buried in the ground should be treated with corresponding anti-corrosion treatment according to the corrosiveness of the soil. Buried pipelines for transporting saturated compressed air in factory (mine) areas should be laid below the freezing line. When the buried compressed air pipelines in the factory (mine) area cross the railway or road; the crossing angle should not be less than 45°, the top of the pipe should not be less than 1.2m from the railway track surface; and should not be less than 0.7m from the road surface. When the compressed air pipelines buried in the factory (mine) area cross the railway or the road that is inconvenient to dig, a casing should be installed. The two ends of the casing shall not extend less than 1m from the railway roadbed or the roadside. If there is a drainage ditch beside the railway or road, it should extend 1m from the ditch.
(9) The clearance between compressed air pipelines and buildings, structures, traffic routes and other pipelines in the factory (mine) area shall comply with the provisions of GB 50187-1993 "General Layout Design Code for Industrial Enterprises".
