This incident illustrates how difficult it is to completely purge hydrogen out of a large, complex piece of equipment. Uniform mixing and dilution is unlikely in all the partially enclosed spaces, crevices, etc. If a hazardous operation such as…

This incident illustrates the danger of hydrogen being inadvertently released through blown water seals. Similar incidents have occurred in non-nuclear industrial facilities, but offgas systems present a special hazard because of the…

These events show the importance of preventing combustible gas mixtures from accumulating in piping. In both of the above described events, hydrogen and oxygen gases apparently accumulated to a combustible level which then catastrophically failed…

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. It is important to understand the requirements and standards associated with safe equipment design (especially electrical equipment containing an internal ignition source with flammable gas) in potentially explosive atmosphere environments.…

1. Management must ensure that operating decisions are not based primarily on cost and production. Performance goals and operating risks must be effectively communicated to all employees. Facility management must set safe, achievable operating…

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…

• Replace the existing copper and carbon steel hydrogen pipeline with ¾-inch schedule 40 stainless steel.
• Reroute the new hydrogen line in the preferred location.
• Locate new hydrogen shut-off valves in a more convenient…

Recommendation 1 - Overhaul and replace the diaphragms on all cells showing low-purity results. Check on a routine basis the individual cell purity levels to monitor the deterioration of performance of individual cells. Certain…

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…

Personnel should be properly supervised, and supervisors should be aware of the activities of their personnel. Personnel must be motivated to adhere to established policies and procedures. All personnel associated with potentially hazardous work…

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…

The tube was 403 stainless steel, which is subject to hydrogen embrittlement. It is requested that all gauges that have bourdon tubes be replaced with 303 stainless steel.

A web-based resource developed by Sandia National Laboratories to…

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…

• 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. 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…

The SS 24-inch pipe that failed was replaced with 1-1/4 Cr 1/2 Mo alloy pipe that is corrosion-resistant to SCC. A revised HTS bypass piping layout was installed to prevent the hazardous conditions that lead to the failure. A detailed hazard…

To prevent a similar flashback, the following measures have been taken:

1. The valve is opened slowly to avoid a major leading shock into the venting line.
2. A special nozzle (Laval or similar) is mounted directly after the…

Recommendations:

1. The using organization should define necessary activities in order to place hydrogen systems in long-term periods of inactivity. The defined activities should address requirements for rendering inert, isolation (i.…

• Active GH2 sensors should be installed and continuously monitored in all enclosed buildings near GH2 sources. All buildings near areas where hydrogen is used should be designed to preclude GH2 entrapment (e.g., sloping roof with…