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. 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…

1. The plant tried to increase production and decrease workload, but failed to notice the potential negative outcomes of this change.
2. It is necessary to thoroughly simulate all potential negative outcomes of a change in procedures…

• 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…

For the use of mechanical fittings in hydrogen service, administrative controls should be in place, as in this case, to ensure that leak testing is conducted on a regular basis. It should never be assumed that every fitting is tight. Additional…

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…

• 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…

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…

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…

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,…

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 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…

The lessons of this event fall into five categories: (1) proper in-plant communications during events, (2) proper valve application for use with hydrogen, (3) excess flow check valve set point, (4) heating and ventilation and air conditioning (…

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…

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…

Based on the results of the company investigation and analysis of an amateur video, the company determined that the incident could have been caused by the failure of one of the following plant components:
· pipes leading to the reactor…

In addition to the probable causes listed above, the lack of a standard operating procedure for hydrogen leak detection was one of the probable causes of this incident. Additional contributing factors included the following:
- Severe pipe…

The following actions were proposed as a result of this incident:

•  The company in charge of valve calibration and maintenance will be subject to approval of the plant service inspection team.
•  Plant operating…

1. Carbon steel Nelson curve methodology cannot be depended on to prevent HTHA equipment failures and cannot be reliably used to predict the occurrence of HTHA equipment damage. Revisions to recommended practices should be considered…