Because of the near invisibility of a hydrogen flame in daylight and hydrogen's extremely low ignition coefficient, if a known leak is present (e.g., an audible hissing), ignition should always be presumed. The primary cause of this incident…

1. The dilution water for making a polythionic acid aqueous solution was changed from industrial water to pure water to lower the chlorine concentration in the piping.
2. Water that accumulated in the drain was removed before heating…

1. The plant tried to increase production and decrease workload, but failed to notice the potential negative outcomes of this change.
2. It is necessary to thoroughly simulate all potential negative outcomes of a change in procedures…

• Operation and management of the hydrodesulfurization unit should be strengthened to account for abnormal phenomena such as local corrosion.
• The safety review system for remodeling existing equipment and facilities should be…

1. Inadequate Safeguards - The system was designed with low-point drains to facilitate water removal, however, these were found to be inadequate in both location and size. The fact that the mixed feed pre-heat coil was not self-draining was…

In the future, refining, petrochemical, and chemical industries need to review material verification programs to ensure that the maintenance procedures include sufficient controls and positive material identification (PMI) testing to prevent…

Installation

1. Fittings need to be visually inspected to insure ferules are in place and correctly positioned prior to swageing.
2. Research staff are responsible for communicating system specifications [gas type,…

An important lesson to be derived from this incident is the need to carefully engineer and test all repairs and modifications to high-pressure process equipment.

1. Provide additional retraining of operators. Curriculum should emphasize the proper response to high oxygen in the hydrogen gas.
2. Evaluate current knowledge of operators. Operators should know…