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 and possibly include a checklist as a reminder of key safety items prior to departure.

1. Defects in equipment, such as welds, may not be evident during initial proof testing and operation.
2. When an equipment defect is found, check equipment for possible similar defects in other areas of the equipment.

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, Maximum Allowable Working Pressure(MAWP)] and testing requirements to service provider.
3. Lines that run through ceilings and chases should be pressure-tested at the MAWP of the materials of that line.

Commissioning

1. System owners/users should specify QA requirements such as leak testing and service providers/installers must provide appropriate documentation.
2. System owners/users should document that they have accepted work.
3. The system owner is responsible for tracking, through safety documentation such as IOPS or SOPs, system modifications and procedural changes. Use of safety documentation prevents off normal events that could arise through staff turnover.

Best practices related to fittings and joints in compressed hydrogen gas piping systems are discussed in the Hydrogen Safety Best Practices Manual.

The practice of making gas mixtures in the laboratory should be eliminated, and gas mixtures with a known low hydrogen concentration should be purchased for use. The concentration of hydrogen used should be such that it is not possible to form an explosive mixture on dilution with air (i.e., hydrogen concentration less than 4% after mixing with air from a leak, damage to the chamber, or inadvertent admission of air to the chamber). A gas monitor with a built-in alarm should be purchased and installed to continuously monitor both hydrogen and oxygen concentrations in the chamber, and to provide visible and audible indication of any problems. The manufacturer’s instructions and manuals should be closely followed. All users should be fully trained in the use of the equipment, and should be fully conversant with the potential hazards and how to manage the associated risks. Hydrogen use in anaerobic chambers is discussed in the Lessons Learned Corner on this website.

After this accident, a safety inspection team was organized. An investigation of this incident and an inspection of all other experimental equipment was conducted by the team. As a result of this inspection, the heaters are now hard-wired to the temperature controllers. Follow-ups on the remainder of the team's findings for all other experimental equipment have not yet been completed.

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.

This occurrence points to the importance of gathering and organizing all applicable administrative controls and other commitments prior to commencing work. It also re-emphasizes the importance of attention to detail, not only by the person responsible, but also by anyone confirming compliance.

The primary lesson learned was that the active hydrogen facility and existing operating procedure, at the time of the accident, were sound. While this now has been determined, the previous form(s) of this system, associated documentation, and accident history did not provide sufficient basis to assume continued safe operation. The review of furnace operation subsequent to this accident now provides a basis to evaluate the safe operation of furnace #4 as well as other similar facilities.

The failure to apply the appropriate procedure suggests the need for either additional administrative controls and/or periodic refresher training.

Some hydride materials (e.g., sodium alanates) may be rapidly exothermic, even pyrophoric, if exposed to water or humid air or slowly exothermic, even pyrophoric, if exposed to oxygen. Reactive materials, including fine metal powders, should be handled (as in this incident) in an inert atmosphere such as a glove box. The protocol for handling these materials should be incorporated into a standard operating procedure and appropriate safety training conducted for laboratory personnel, including guest staff.

Additional discussion about working with reactive metal-hydride materials in the laboratory can be found in the Lessons Learned Corner on this website and in the Hydrogen Safety Best Practices Manual.

The manager in charge acknowledged that, while he made relatively recent modifications to the high-pressure gas storage side of the system and had directed a major rebuilding of various units, the moderate-pressure interconnecting system (the source of the problem) remained essentially in its original condition. He acknowledged waiting for safety definitions in the Safety Manual and thereby letting improvements be delayed. He supported the decision to have an independent engineering review after the second incident, pointing out that this essential step assisted in defining the actual root cause and led to more constructive and long-range corrective actions.

This incident occurred due to moisture in the sample line monitoring system. Removing moisture from the sample line increases the reliability of the equipment. Further evaluations are being considered for improving system reliability.

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 trapped in the elbow. In the future, piping systems containing hydrogen fluoride or other chemicals should be purged to ensure that they are free from hazards prior to starting D&D activities.

Follow-up investigation of this occurrence confirms that it was inadvertent. Attention to detail while performing any task is a must for all personnel. This is to insure the safety of both the individual performing the task and others that may become involved.

Work pre-planning is essential whenever maintenance or work activities may have an adverse impact on everyday operations. When there are changes to the operational status of any critical system, especially a safety critical system, those changes must be communicated to affected personnel. Standard operating procedures (SOPs) must be fully implemented, and the implementation should be verified during facility and organizational assessments.

Additional information on planning for maintenance and start-up and inspection of equipment is available in the Hydrogen Safety Best Practices Manual.

The simplicity of this situation has made us aware that increased consideration must be given to all aspects of the workplace when preparing preliminary hazard assessments. Some hazardous situations appear so trivial that they can be easily overlooked and serious consequences not understood. Also, some hazardous situations are not readily recognized by the layman and we should consider inviting professionals from other organizations to assist us with assessments and reviews on a periodic basis.

Adequate ventilation of battery charging facilities is addressed in the Lessons Learned Corner on this website.

Hazard assessment is critical during the design, fabrication, and installation of system modifications to ensure hazards and potential hazards are addressed prior to system start-up and operation.

Personnel should be aware that items requiring special receiving inspections should still be verified/examined by the end user prior to use.

Given that the anaerobic chamber and associated nearby electrical equipment were not designed or expected to handle a potentially explosive atmosphere, nearly all conditions necessary to have a much more serious event were present if the problem had not been discovered and the bag was not successfully purged of the hydrogen mixture.

Hydrogen use in anaerobic chambers is discussed in the Lessons Learned Corner on this website.

All chemicals, including gases, should be clearly labeled and expiration dates (if applicable) identified. Incidents are more common when incompatible chemicals are mixed or when chemicals are stored/transferred using incompatible equipment. Personnel should ensure that labels are read and understood prior to mixing, dispensing, or transferring chemicals.

The manufacturer will be notified of the failed parts identified as a result of the follow-up testing plan. These results may be useful to them for their information and forwarding to others with the same equipment.

Designs for high-tech systems/components evolve based on operating experience. The design changes should resolve identified deficiencies and are part of a continuous improvement process to increase reliability and productivity.