Factory Mutual issues warning
Factory Mutual (FM) warns against using torches, welding, or other electrical resistance heating methods for thawing ice plugs in sprinkler piping. Explaining that these methods are “potentially catastrophic practices for removing ice plugs and piping,” FM`s Mark Blank, a loss prevention specialist, recommends using safer alternatives such as hammering and steam or hot water to thaw the ice. If the automatic sprinkler piping for crossmains/feedmains is threaded, FM explains, a manual pipe cutter can be used to remove the existing pipe and the cut pipe can be replaced with rolled grooved pipe.
FM also has developed an ultrasonic testing procedure for detecting ice plugs. It uses high-frequency sound pulses to detect solid ice or liquid. Once the plug is detected, it can be dissolved with an antifreeze, such as glycol. n