US urged new safety standards days before Middletown explosion

Only three days before the massive explosion that killed at least five workers at a newly constructed natural gas plant in Middletown, Conn., the US Chemical Safety Board (CSB) issued urgent new recommendations on how to prevent explosions when handling or purging natural gas pipelines.

It is too soon to know what happened at Kleen Energy Systems. But workers at the site were reportedly purging a natural gas pipeline prior to the explosion.

In its documentation detailing why it was recommending new safety standards, the CSB cited incidents that show striking similarities to the Connecticut disaster. In at least seven incidents since 1997, workers have died and large-scale damage has been done to buildings as a result of pipelines being purged in an enclosed area.

"We have far more incidents in the database than the half dozen that we have listed," says Sandy Gilmour, a CSB spokesman. "The incidents listed were just the ones that jumped out to our investigators, because they were severe cases or because they could be documented."

According to the CSB, purging of natural gas pipelines is a common occurrence as utilities and other businesses either prepare to begin using natural gas or decommission a pipeline. There are 84 gas-fired turbines in 35 different plants that are either being tested or are still under construction, according to the Edison Electric Institute. A study by the Interstate Gas Association of America Foundation (INGAA) estimates that as many as 62,000 miles of new pipelines could be built in the next 20 years.

Almost all of those new pipelines, as well as the hookups to utilities and industrial companies, will have to go through the process of eliminating air that could mix with the natural gas to become a highly explosive mix. Normally, this process is accomplished by pushing a pressurized inert gas, such as nitrogen or carbon dioxide, through the pipeline before the natural gas is run.

However, according to the CSB documents, this is not always done safely by venting gases outside or having adequate ventilation. One of the major problems appears to be that workers rely on their sense of smell to detect natural gas leaks.

But the human nose very quickly becomes desensitized, resulting in something called “odor fatigue” or “odor fade.” The CSB recommended that purged fuel gases should be directly vented outside, away from people and ignition sources. If it is not possible to vent outside, the CSB recommends that venting inside a building only be done with the proper authorities, such as fire officials, present.

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