Release and fire from a hydrogen pipeline

At 17:30 on 5 may 2019, the pipeline operator was notified by a third party that there was a possible leak on its hydrogen pipeline, as identified by sound.
Operator personnel arrived on the site at 18:30 and confirmed that hydrogen was present in the area. The location was in an isolated area. Manual isolation valves were shut to close in the segment and it was manually blown down.
At 08:52 on of the day after the operator determined that the incident met reportable criteria and called the national response centre at 09:22.
Blowdown of the isolated segment was completed at 12:30 on 6 may 2019.
There was no immediately recognizable cause of the incident. No excavators were operating in the area, and cathodic protection (CP) testing showed no abnormalities. The suspected area of the leak was excavated, but the pipe was shown to be in excellent condition. Upon further investigation, it was determined that the leak was most likely located underneath a small non-navigable drainage canal. Unable to excavate under the water, a new segment of pipe was installed, rerouting around the leak.
The pipeline was put back into service on 6 days later.

The INITIATING cause of the damage which caused the leak was probably a lightning discharged through a rod passing in the vicinity of the pipeline.

The inactive segment of pipe where the leak was found was further investigated with a tethered inline inspection (ILI) tool in order to further investigate the cause of the leak. Results showed an anomaly near a grounding rod for a nearby electrical transmission tower.
An additional direct current voltage gradient (DCVG) inspection showed a similar anomaly, correlating the results of the ILI. It is therefore suspected that lightning struck the tower during a storm, creating a surge of energy that released into the ground through the grounding rod. This electrical energy created the anomaly on the pipe which eventually led to the small leak.

underground pipepine

DESCRIPTION OF THE FACILITY
The pipeline had been produced and installed in 1992, diameter = 10 inch (0.24 m), wall thickness = 0.228 in (5.8 mm)
It was at 2 metre depth.

No consequence to environment or persons. Only costs related to materials damage and emergency intervention.

Manual isolation valves were shut to close in the segment and it was manually blown down.
Blowdown of the isolated segment was completed in one day.
64 thousand standard cubic feet went lost during the leak (unintentional release), 759 because of the depressurisation action (intentional release)

The new segment of pipe was installed away from the grounding rod.
An external inspection company was hired to review pipeline locations with similar environments throughout the pipeline system. No other anomalies were discovered and a similar incident is not suspected to occur again.