I am always amazed at the number of facilities that do not understand their hazardous materials and the proper safety techniques in managing the hazards these HAZMATs present. Recently I came acorss a sitution where a contractor was left to “prepare piping for a line break”. The facility utilizes natural gas, as a fuel, within one of their covered processes so they wisely utilize their Line and Equipment Opening (LEO) Permitting process. However, the contractor who has been doing all their NG work for years, argued that compressed air is an “industry practice” (note: an IP is very different from a RAGAGEP!). Some of you may recall the 2010 Kleen Energy plant explosion that claimed the life of my friend and colleague Chris Walters, the site safety manager. Since that day, a lot changed in how we “blowdown/purge” flammable gases, specifically Natural Gas. Here are the code REQUIREMENTS and the reasons why we should NEVER use compressed air in a flammable gas process…
NOTE: NFPA 54 does provide some exceptions based on line/pipe size, length of run, and operating pressure; I do NOT subscribe to this exception as it just opens the door for people to fudge the numbers and use compressed air when they would be prohibited by the code.