Procedures, monitors essential elements for safe confined space tank truck entry

June 1, 2005
WE OPERATE from the philosophy that everything has nitrogen on everything until it's tested. That was the message from Ed Matlage of Miller Transporters

“WE OPERATE from the philosophy that everything has nitrogen on everything until it's tested.” That was the message from Ed Matlage of Miller Transporters Inc.

He and Doug Lara of Arizona Glove & Safety presented information about tank cleaning facility safety at the National Tank Truck Carriers Tank Cleaning Council Seminar March 28-29 in Phoenix, Arizona.

Matlage addressed tanks brought in for cleaning that may or may not have had nitrogen blankets applied — and the importance of proper confined space entry procedures.

Matlage pointed out that confined space entry training and practice requires various techniques based on the individual situation. He used as an example a tank trailer that had appeared safe because it had been hauling water, but nitrogen had been used for offloading.

“There's no perfect way to handle confined entry because everyone's situation is different,” he said.

He cautioned cleaning facility managers to remind workers to be wary of tanks even if they do not have nitrogen tags on them.

“Tags can come off in transit or be lost in other ways,” he said.

Lara discussed the need for detecting gas in tanks to protect workers who are required to enter tanks for cleaning.

Lara emphasized use of properly adjusted gas monitors before tank entry, pointing out that some workers may think they can rely on their senses for gas detection. Even though monitoring is required by regulation before tank entry, workers may become complacent.

He emphasized the importance of calibrating gas monitors regularly and to beware of environmental conditions, such as high levels of humidity that may result in varied readings.

Lara said sampling for gases should be conducted prior to entry — at the top, middle, and bottom of the tank — and continuously while a worker is inside the tank.

Layers of various gases are found in various parts of the tank, for example: methane will more likely be near the top, carbon monoxide in the middle, and hydrogen sulfide at the bottom.

Lara said that gas sensors being developed for the future will be the size of a fountain pen and costs for all monitors should decrease as more are produced.

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