Because the bottle was located outside at the time of the event, and the hydrogen did not find a source of ignition while venting through the relief valve, nothing serious happened. The failed regulator was replaced and operations continued.…

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…

The following corrective actions have been taken:

• The non-return valve was dismantled, cleaned, and tested. Following positive testing, the system was restarted and pressurized without any further malfunctioning.
• The hydrogen…

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…

Hydrogen distribution lines should be designed and carefully inspected to ensure process equipment in the area is correctly and safely installed. Equipment subject to vibration should not be placed in contact with hydrogen lines or with other…

Management should ensure that a complete and thorough review of the previous work activities identified in the work package is performed at the pre-job briefing for the planned work. Work activities should be discontinued if any confusion exists…

In this case, failure to recognize a run of tubing still maintaining pressure could have been avoided if such information was provided in a safety briefing. Knowledge of any job is the utmost importance in promoting and maintaining a safe working…

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…

Safe work procedures will be prepared and followed. Hydrogen will be vented out of the system to create an inert atmosphere before working on system tubing and joints. The importance of purging hydrogen piping and equipment is discussed in the…

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…

1. Train personnel on delivery procedures and emphasize the safety aspects of hydrogen connections and disconnections, and verification of clearance for trailer movement prior to departure.
2. Provide site-specific delivery procedures…

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,…

When performing maintenance evolutions, proper work control processes must be in place to insure that process systems are adequately prepared, remain in a safe energy state during the maintenance evolution, and are properly restored afterwards.…

Although most of the hydrogen fluoride piping system was open to the atmosphere before the elbow was cut, the lines were not purged. Two plugs of residual material on either side of the elbow remained in place, thus allowing hydrogen to be…

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.

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…