Compressed air line explosions

Compressed air lines are very susceptible to a combustion gciienition e.xplosion, fueled by oil or cliar on tlie pipe walls. E.xplosions in pipelines c ui cause considerable damage. Pipelines witliin wliich gas, vapor, or dust explosions can occur must be designed to have sufficient mechanical streiigtli to withstand pressure or stress beyond tliat required by the application. 

Compressed air lines with traps and accumulators will minimize buildup of flammable oils in lines. Compressed air lines require routine cleaning or purging to minimize fire and explosions within the pipes. ... 

The second hazard is the tank s location close to ultra-high compressed air lines and equipment. A high pressure pipeline explosion could result Ifom a malfunctioning safety valve, a human error in operating the equipment, damage to a pipeline, or from other causes. Blast or flying debris could conceivably strike the propane tank, rupture it and cause it to explode with the same consequences as for a run-away vehicle. 

Many operators find it hard to grasp the power of compressed air. Section 2.2 (a) describes how the end was blown off a pressure vessel, killing two men, because the vent was choked. Compressed air was being blown into the vessel, to prove that the inlet line was clear. It was estimated that the gauge pressure reached 20 psi (1.3 bar) when the burst occurred. The operators found it hard to believe that a pressure of only twenty pounds could do so much damage. Explosion experts had to be brought in to convince them that a chemical explosion had not occurred. 

If Premix burners of any type are used, then, whether required by local law or not, a non-return valve of approved type should be fitted to the fuel gas line. Should compressed air or oxygen accidentally leak into the gas pipes, an explosive mixture may be formed, and the consequences can be serious indeed. A gas meter has been known to explode violently as a result of such a leak. Fortunately, no one was injured, but the risks are obvious. 

Only a very thin film of oil is needed to produce an explosion in the pipework of compressed-air systems, even if the oil is not dispersed into the air prior to ignition. Many industrial fires and explosions have occurred in systems utilizing oil-lubricated air compressors. Therefore, adding air to an empty hydrocarbon line, or to purge a hydrocarbon line, is potentially hazardous because trace amounts of flammable materials may be clinging to the pipe walls. On one occasion, an explosion occurred in a cmde-oil pipeline to which air had been added, even though the line had been first emptied by displacement with water between two scraper plugs. 

---