image of a hydrogen fuel cell

H2Incidents: Hydrogen Incident Reporting and Lessons Learned

About H2Incidents | Advanced Search

H2Incidents Help!

Definitions

Incident
An incident is an event that results in:
  • a lost-time accident and/or injury to personnel
  • damage to project equipment, facilities or property
  • impact to the public or environment
  • an emergency response or should have resulted in an emergency response.
Near-Miss
A near-miss is an event that, under slightly different circumstances, could have become an incident. Examples include:
  • any unintentional hydrogen release that ignites, or is sufficient to sustain a flame if ignited, and does not fit the definition for an incident
  • any hydrogen release which accumulates above 25% of the lower flammability limits within an enclosed space and does not fit the definition of an incident
Non-Event
A non-event is a situation, occurrence, or other outcome relevant to safety that does not involve a particular incident or near miss. For example, a non-event might consist of a failed safety inspection.
Close

H2Incidents Help!

Navigation

The left navigation on the H2Incidents website is two-fold.

  1. Links
    By clicking on the links in the left navigation, you can view all incident reports matching that lone selection. For example, clicking on "Minor Injury" within the "Damages and Injuries" category will return a list of all incident reports that included "Minor Injury."
  2. Checkboxes
    Selecting checkboxes next to navigation items—then clicking the "Update Criteria" button—will provide a restrictive search on the criteria selected. Each selected checkbox will restrict the results to only incident reports that include that criteria. For example, selecting the checkbox next to "Minor Injury" in the "Damages and Injuries" category and selecting the checkbox next to "Decision Making" in the "Factors" category will return a list of all incident reports that included both "Minor Injury" and "Decision Making."
Close

Incident Report

Hydrogen Explosion Damages Chemical Plant

Incident Date: 2007

 

Severity:
Incident

Was Hydrogen released?
Yes

Was there Ignition?
Yes

No Ignition Source Defined.

Description

An explosion occurred within the hydrogen processing system of a chemical plant that produces sodium chlorate for bleaching pulp and paper. The chemical process utilizes electrolytic cells and is pH-dependent. Hydrogen is produced as a byproduct and is utilized as a fuel.

At the time of the incident, the plant was at an abnormal operating level of 25% capacity. A non-routine maintenance operation to repair high-pH liquid piping was in progress. To assist, operations personnel rerouted the high-pH liquid stream to the plant sump. However, in doing this, the liquid eventually made its way back into the electrolytic process by design. Ultimately this created the root cause of the explosive condition in that the pH of the electrolytic process increased faster than the computer-controlled acid-injection system could compensate for in this abnormal setup. (The acid system is designed to maintain proper process pH by lowering pH in the electrolytic process.) As the amount of high-pH electrolyte circulating through the system continued to increase, so did the amount of oxygen generated by the electrolytic process until the hydrogen concentration fell below the upper flammability limit (UFL). In spite of existing standard operating procedures (SOPs) and training, operations personnel on duty failed to realize and act according to the seriousness of the condition, and also questioned instrument readings.

After operating with the increased oxygen level and the hydrogen concentration below the UFL for several hours, the hydrogen ignited and an explosion occurred in the system. The explosion caused extensive damage to piping, process vessels and the containment building, but did not start a fire or cause any injuries. This event shut down the manufacturing process for over a week for emergency repairs.

Setting

Equipment

Piping/Fittings/Valves

Process Equipment

Damage and Injuries

Probable Cause(s)

Contributing Factors

No Characteristics Defined.

The incident was discovered During Maintenance.

Lessons Learned/Suggestions for Avoidance/Mitigation Steps Taken

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 proper response, such as contacting engineering or management support as needed, to evaluate any potentially dangerous process conditions they might observe.

3. Revise interlock strategy. The plant control system was reviewed and enhanced with additional interlocks that automatically shut down the process and safely secure the hydrogen systems on certain pH levels and certain oxygen levels.

Date Added to H2Incidents: 5/26/2009