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Deficiencies in gas terminal operations led to release of odourless gas


Anton McNulty

A report into an incident where odourless gas was released from the Bellanaboy gas terminal into the gas network system has found that deficiencies in Shell E&P Ireland’s operating procedures led to the incident.
The incident occurred on September 21, 2017 when odourless gas was exported to Gas Networks Ireland’s (GNI) gas network, and as part of the response to the incident, approximately 10,000 natural gas customers in the Galway-Mayo region were instructed to turn their gas off at the meter.
The matter was investigated by the Commission for Regulation of Utilities (CRU) who found that an upgrade of the IT system at the Bellanaboy gas terminal caused the odourless gas to be pumped into the gas network.
The CRU report which was released last week found that the incident occurred during a re-start process of the terminal, following a planned maintenance shutdown, where upgrades to the IT systems were carried out.
“The IT upgrades caused the odourant injection system to default to a mode where there was no injection of odourant. The operating procedure covering the start-up process did not include a step requiring the operator to reset the odourant system to inject odourant,” the report stated.
CRU is responsible for the safety regulation of natural gas transmission and distribution, and the regulation of upstream designated petroleum activities. They found that deficiencies in Shell E&P Ireland’s (SEPIL) operating procedures led to the incident.
“There were no safety consequences as a result of this incident for personnel working at the Bellanaboy Bridge Gas Terminal or the public in the immediate vicinity. CRU directed SEPIL and partners to submit an Improvement Plan to address issues identified with operating procedures. The remedial actions set out in that Improvement Plan have been put in place and the SEPIL enforcement action is now closed,” they stated.
Gas Network Ireland are responsible for the transportation of odourised gas to customers and in relation to their role in the incident, the CRU also found some deficiencies in relation to their compliance with its accepted Safety Case.

Improvement Notice
As a result the CRU issued them with an Improvement Notice to address the risk of non-odourised gas entering the network. Under the Improvement Notice, GNI were required to complete two actions by July 1, 2018 and a third action by December 31, 2019. GNI provided submissions for the initial two actions ahead of the July deadline. The report stated that evaluation of these submissions and monitoring of the remaining action is ongoing.  The non-odourisation was identified by SEPIL as part of normal checks at the terminal, at 2.30am on the morning of September 21. GNI were immediately alerted to the issue and the Natural Gas Emergency Plan was activated at 7am.
All affected gas was directed back to the terminal and flared off, in order to remove the non-odourised gas from the system.
The report found there was no additional risk of a gas escape as a result of this incident. However, as the gas was not odourised it would not have been possible to detect an escape by smell in the event that one occurred.