Electrostatic control gains importance at terminals
Aug 1, 2008 12:00 PM
Electrostatic control has gained more importance as storage tank and terminaling operations report growing incidents of fires from various ignition sources in the flammable and combustible atmospheres, according to information presented at the International Operating Conference and Trade Show June 9-11 in Houston TX.
In this environment, a structured electrical safety program is an essential element to any company's overall safety program and requires commitment from all employees, said Michael Harris of Flint Hills Resources LP. “The statistics speak for themselves,” he added. “This is not to be taken lightly.”
Harris noted the US Bureau of Labor Statistics reported that between 1992 and 2002, there were 295 fatalities per year related to electrical hazards, 2,000 people per year suffered arc-flash burns, and 4,309 employees per year lost work time.
“An electrical safety program is not an option,” said Dennis Neitzel of Avo Training, who moderated the panel on the topic at the meeting sponsored annually by the International Liquid Terminals Association (ILTA). Also participating in the discussions were Graham Tyers of Newson Gale Inc and Chip Breitweiser of HMT Inc.
Neitzel noted that the Occupational Safety and Health Administration mandates many electrical safety procedures and also supports those that have become industry standards.
While a safety program requires documentation and procedures, training, and assessment, the efforts are rewarded with increased employee safety, clearly defined rules, responsibilities and expectations, and improved training procedures, Harris said. Other benefits come from raising the awareness of contractors and encouraging equipment suppliers to consider improved designs.
Mobile equipment
Turning to static electricity and concerns about discharges from vehicles and mobile equipment, Tyers said that static electricity incidents are second only to overfilling incidents at the loading rack. He noted that static discharges can involve people as well as equipment.
“When working in or close to flammable or combustible atmospheres, it is absolutely essential to eliminate or control electrostatic discharge hazards,” he said, adding that all guidelines point to grounding.
Mobile operations that require grounding include vacuum trucks transferring liquids or loose solids, fuel service vehicles and mobile tanks, hazmat/emergency response vehicles, cleaning and maintenance vehicles, metering and calibration systems, and mobile transfer pumps, blowers, and mixing equipment.
A safety program should have an operations check list for removing flammable or combustible liquids:
Carry out pre-operation inspection and observe applicable company and regulatory permits required for the job.
Ensure workers have appropriate personal protective equipment.
Test atmosphere for airborne hydrocarbon vapors.
Locate existing grounding points, or install temporary ground.
Attach bonding line to tank ground point/structure before starting any other operations.
Directly connect conductive hose onto tank — ensure conductive parts of fill system are bonded together.
When transfer process is complete, the bonding line should remain connected until all other operations are finished.
Lightning strikes
Breitweiser pointed out that lightning-caused fires at terminals are more common than believed with about 70 occurring per year worldwide and appear to be more common in countries outside the United States.
Although lightning may strike various areas of a storage tank, he noted that nearby equipment and piping near the structure also can be vulnerable.
While lightning strikes cannot be eliminated, the risks can be ameliorated by taking certain precautions. System components must work together to provide submerged conduction paths for lightning currents. Tight-fitting primary and secondary seal systems are necessary for an effective defense against lightning-induced ignition.
Breitweiser added that risk of lightning-induced ignition is significantly reduced with a submerged protection system.
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