Safety Spotlight: Human Fatigue

Monday, March 25, 2019 @ 05:03 PM gHale

Aftermath of the blast at BP Texas City in 2005 that left 15 workers dead and 180 injured. Human fatigue was one of the causes in addition to multiple technical, system, and organizational deficiencies that led to the disaster.
CSB photo

EDITOR’S NOTE: This is the first in a three-part series that excerpts the Chemical Safety Board’s (CSB) spotlight on the importance of safety guidelines, codes and standards to the manufacturing automation industry. The first segment talks about human fatigue as a risk factor.

In the wake of the Intercontinental Terminals Company’s plant incident in the city of Deer Park, Texas, it is even more clear industry safety guidelines, codes, and standards play a key role in protecting the safety and health of workers, the public, and the environment.

As part of its mission, the Chemical Safety Board (CSB) makes recommendations to standards developing organizations (SDOs), when industry-wide safety gaps or weaknesses are identified during an incident investigation.

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Such is the case of when on March 23, 2005, the BP Texas City refinery experienced explosions and fire in an isomerization unit (ISOM) that resulted in 15 deaths, 180 injuries, and significant monetary losses.

The accident was caused by the overfilling of a raffinate splitter tower during startup, which in turn opened pressure relief devices and dumped flammable liquid into a blowdown drum with a stack that was open to the atmosphere. The flammable liquid exceeded the capacity of the blowdown drum and erupted out of its stack into the surrounding area where it ignited, resulting in the explosions and fire.

The CSB investigation found the incident was caused by multiple technical, system, and organizational deficiencies. Among the findings, the CSB concluded the ISOM operators were likely fatigued from working long hours over consecutive days during the turnaround of the unit prior to startup. The CSB also concluded there were no industry safety guidelines or voluntary standards addressing fatigue as a risk factor.

The CSB recommended the American Petroleum Institute (API), a national trade association with more than 600 members representing the natural gas and oil industry, including large companies, exploration and production, refining, marketing, pipeline, and marine businesses, develop a fatigue standard and the United Steel Workers (USW), North America’s largest union, work with API in its development:

“Work together [API and USW] to develop two new consensus American National Standards Institute (ANSI) standards. In the second standard, develop fatigue prevention guidelines for the refining and petrochemical industries that, at a minimum, limit hours and days of work and address shift work. In the development of each standard, ensure that the committees a) are accredited and conform to ANSI principles of openness, balance, due process, and consensus; and b) include representation of diverse sectors such as industry, labor, government, public interest and environmental organizations and experts from relevant scientific organizations and disciplines.”

In April 2010, API issued Recommended Practice (RP) 755 – Fatigue Risk Management Systems for Personnel in the Refining and Petrochemical Industries. This was the first ever fatigue guidance developed for the petrochemical industry. Recognizing that additional improvements could be made, API invited CSB staff to attend and participate in the RP 755 Revision Committee meetings. The new revision improves several areas of the original standard, including:
• Revision of several ‘should’ statements to ‘shall’ statements
• Simplification of ‘hours of service limits’ with increased flexibility and clarity
• Modification of the ‘exception approval process’ to be more stringent for ‘exceptions’ with the greatest potential fatigue risk
• Guidance on managing ‘call-outs’
• Additional ‘work environment’ information
• Reference to objective and validated tools for ‘individual risk assessment and mitigation’ efforts

The 2nd Edition of API RP 755 should release in early 2019.



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