- Ventilation System
- Vent Stack Cap
- Pressure Relief Devices
- Burst Disk
- Ventilation System
- Venting System
The uncontrolled release of hydrogen occurred as a result of the rupture of the No. 6 hydrogen storage tube’s burst disc. This disc failed in response to being overloaded by mechanical stresses developed as water expanded and formed ice while in direct contact with the burst disc. It was the degraded condition of the vent cap (defective equipment) that enabled water to access the burst disc.
As a corrective action, eliminate burst discs from hydrogen storage assembly. Redesign venting system for the pressure relief valves to prevent or inhibit moisture build up and allow moisture drainage.
The investigation uncovered two instances where the supplier was in possession of information ("safety data") that, if successfully conveyed to plant management and subsequently acted upon, would have prevented or reduced the chance of occurrence of the subject incident. Specifically, the hydrogen supplier found ice in a vent pipe, and was aware that the vent caps were cracked (recall the cracks were painted). Had a requirement existed for this information to be communicated to the plant, then plant management would have had the opportunity to evaluate and potentially influence the supplier's maintenance and operations program.As a corrective action, contract documents for the hydrogen and nitrogen supplies will be modified to stipulate the following:
Suppliers of potentially hazardous equipment will provide plant management, for acceptance purposes, with written documentation describing the supplier’s preventive maintenance program.
The supplier shall provide the plant representative with a copy of a preventive maintenance report upon the completion of each PM check performed by the supplier. The supplier shall expeditiously rectify any identified deficiency.
Plant management will recommend to the Manager of Corporate Safety and Health that the above contract document modifications are implemented corporate wide.