Tesoro refinery accident investigation report by CSB

Industrial Accidents

May01, 2014– The US Chemical Safety Board (CSB for short) today, under the chairmanship of Dr. Rafael Moure-Eraso approved a detailed and comprehensive investigation report with critical safety recommendations, concerning the tragic heat exchanger explosion and fire that took seven lives at the Tesoro refinery in Anacortes in April 2010. This was done in a public meeting in Anacortes,WA.

An animation of the accident has been made by the CSB and can be seen in the video below


Basically the report, available at the CSB website here, says that the immediate cause of the accident was long-term, undetected High Temperature Hydrogen Attack (HTHA) of the steel equipment, which led to the vessel rupture on the day of the accident and the massive release of highly flammable hydrogen and naphtha. It says further that it found that the industries present procedures for determining vulnerability of equipment to HTHA, are inadequate. Furthermore, the CSB also stated that it found Tesoro’s safety culture to be lacking, which led to a complacent attitude toward flammable leaks and occasional fires over the years.  The CSB made strong recommendations in these areas to both the industry group which issues guidance on HTHA, the American Petroleum Institute, as well as to Tesoro.

These findings – and similar ones in other refinery investigations  have led the CSB to recommend sweeping changes to the regulatory system. The CSB has now asked the Environmental Protection Agency to revise rules in its Chemical Accident Prevention Provisions to require the use of inherently safer systems analysis and what are called the “hierarchy of controls” to the greatest extent feasible when facilities are establishing safeguards for identified process hazards.  While this recommendation is groundbreaking for a federal agency, the application of inherent safety is broadly accepted and has been applied in industry good practice guidelines for many years.

The CSB further stated that in the current regulatory framework, companies may identify a hazard such as HTHA – which is very difficult to identify via inspection and can lead to major process safety incidents with severe consequences such as the April 2, 2010, Anacortes incident – but they are not required to install materials that are resistant to HTHA. Until the EPA can make this change in the regulations, the board recommends the agency use its authority under the Clean Air Act’s General Duty Clause without delay.

The goal is to reduce the risk of major accidents to “as low as reasonably practicable,” a concept abbreviated as ALARP.  The CSB recommends that the EPA require facilities to perform inherently safer systems analysis for all management of change, incident investigation, and process hazard analysis reviews and internal company safety recommendations, prior to the construction of a new process, process unit rebuilds, significant process repairs, and in the development of corrective actions. Workers and the public might be surprised to know that this is not currently a requirement in the chemical industry.

Currently, most federal and state regulations tend to require certain process safety activities, such as management of change and incident investigations, but in fact do not require actual risk reduction or continuous improvements as required company goals.  The CSBs thinks that it should.

The CSB recommends that Washington require refineries to develop comprehensive process hazard analyses (PHAs) which include a rigorous analysis of process hazards and their safeguards, documented rationale of safeguard effectiveness, documented damage mechanism hazard reviews conducted by a diverse team of qualified personnel, and documented use of inherently safer systems analysis and the hierarchy of controls.  This more comprehensive PHA will be subject to review by the regulator. Also the CSB recommends that the regulator be a technically qualified person and can thoroughly review the comprehensive PHAs and perform preventative audits and inspections.  In addition, workers and the public must have greater involvement in the prevention of major process safety incidents, and the CSB also recommends significant improvements in this area to the state of Washington.


The CSB is an independent federal agency charged with investigating industrial chemical accidents. The agency’s board members are appointed by the president and confirmed by the Senate. CSB investigations look into all aspects of chemical accidents, including physical causes such as equipment failure as well as inadequacies in regulations, industry standards, and safety management systems.
The Board does not issue citations or fines but does make safety recommendations to plants, industry organizations, labor groups, and regulatory agencies such as OSHA and EPA. Visit  www.csb.gov for more info.

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