Sunday, February 7, 2010
At least five workers are dead at the Middletown, Connecticut “Kleen Energy Systems” Power Plant that was still under construction. At least a dozen workers were being treated for multiple injuries after being thrown 30-40 feet. They are still searching for the remaining workers. It was reported that around 50 workers were in the plant when gas lines were being “purged”.
This is the second industrial explosion in less than a year related to purging of gas lines. On June 9, 2009 an explosion at the ConAgra Foods, Inc., Garner, North Carolina plant, which makes Slim Jim beef jerky products, killed four people and injured dozens of others. It also caused an ammonia leak that caused some injuries and led to a fish kill in nearby streams.
A settlement last month between ConAgra and the state Department of Labor said a contractor released a mixture of pressurized gas and air into an enclosed room while installing a natural gas-fired water heater. ConAgra agreed to pay $106,000 for workplace safety violations. That is a paltry sum considering the dead and wounded workers, injured residents, and the accompanying contamination of the environment.
As a result of this tragedy, state officials have called for the adoption of safety codes used by the National Fire Protection Association and the American Gas Association, which require that natural gas be vented outdoors when gas lines are purged. In cases where that would be unfeasible, companies would be required to seek a variance from local officials before purging gas indoors, including approval of a risk evaluation and hazard control plan. That plan would require the use of combustible gas detectors to continuously monitor gas concentrations. Current national safety codes say gas purges "shall not be discharged into confined spaces or areas where there are sources of ignition unless precautions are taken."
What is the difference between an accident and a tragedy? A tragedy suggests that a fatal flaw was present at the time of the accident. More often than not, an underlying human flaw causes it. For example, “The Battle of the Little Bighorn” was no accident. The pride and ambition of Gen. George Armstrong Custer directly contributed to the tragedy, which will forever be known as “Custer’s Last Stand”.
For all of the pipefitters reading this, do not pressure test or purge piping systems with compressed air. And most certainly, do not vent a combustionable gas indoors where it can accumulate and then explode with nothing more than a spark.
If you must test gas lines, do so with an inert gas at pressures expected in the line, such as 10 psig in main gas lines. Test with for leaks with an approved gas meter. Yes, they do work. Some can, as a former foreman once said, “pick up a flea fart at fifty paces”. Beware, you may get false positive results. The meter that I used this past month reacted to uncured pipe dope and even to the “non-freezing” soap bubbles that we used to confirm leaks.
Follow up on any suspected leak with soap bubbles. Keep at it until you know that the system is safe. Then, before opening any of the gas lines make a serious risk assessment of the site. Are there any sources for combustion that can be eliminated? Are sections of the system isolated so that you can work step by step? Are sections vented safely outdoors away from any possible intakes? There are many more steps that you could and should incorporate into your specific work site.
I know that the foreman may be impatient and the general contractor will cry and squeal like his “teat is caught in the wringer”, but what is the alternative? And further, what is the consequence of poor planning and execution? The answer to this is simple…injury, death, and possible manslaughter charges.