Case study: gas pipeline benefits from alarm system revamp

Alarm management is a crucial part of the safety process for gas pipelines and especially so in the case of the only physically bi-directional gas pipeline between the UK and continental Europe.

Interconnector UK (IUK) runs the pipeline in question, which operates with terminals at Bacton, Norfolk in the UK and Zeebrugge in Belgium, joined by a 235km pipeline running underneath the southern part of the North Sea.

The pipeline diameter is just over one metre (1016mm or 40-inches). It has a forward capacity of 20 bcm/y and a reverse capacity of 25.5 bcm/y.

The Bacton terminal boasts four 27 MW gas turbines, which provide the power for the compressors to pump up to 58 million cubic metres of gas per day at pressures of up to 140 bar.

Alarm management is a crucial part of the safety process for gas pipelines

Zeebrugge terminal, operated remotely from Bacton (though with the ability to be run locally if circumstances require), was upgraded a decade ago to allow for the import of increased volumes of gas to the UK. It is also the conduit via an interconnector pipe to the continent that reaches as far north as Norway and as far east as Austria.

Given its strategic importance in the supply chain, the role of safe and troublefree procedures is paramount. However, despite the fact that Zeebrugge is normally unmanned and operated via Bacton, the two sites operated separate SCADA databases and reporting systems.

Without a centralised alarm historian and analytics, it was impossible to measure alarm loads on operators and difficult to merge the databases. Critical key performance indicators recommended as HSE best practice were not readily available.

IUK opted to adopt an alarm management system based on EEMUA 191, the global standard. This required continuous collection and analysis of alarm data. To enable this, it opted for ProcessVue from MAC Solutions.

Without a centralised alarm historian and analytics, it was impossible to measure alarm loads on operators and difficult to merge the databases.

The management system includes an alarm historian, alarm analytics and master alarm database, with modularised, scalable software built using modern technologies. The prime issue in the company’s choice was safety.

IUK felt that a cumbersome, difficult to use application that required days of training to get to grips with simply discouraged people from using it.

The right tools, though not used every day (in fact, they may only be employed when there is a problem or afterwards for investigation purposes), needed to be intuitive.

Special challenges had to be overcome including:

• Stitching together chronologically two databases operating on different land masses and in different timezones
• Distinguishing between normal operating mode (from Bacton) and occasional operation from Zeebrugge – and knowing which set of operators alarms must be counted against
• Differentiating forward flow (from Bacton) and reverse flow (Zeebrugge)
• Making comparative data available for the two sites.

The system was sufficiently agile to allow modifications as scenarios emerged and the use of windows of data allowed simultaneous views of all alarms across the units.

Rob Gibson, instrument and controls engineer at IUK, commented: “We’ve worked alongside MAC to produce not only a system that carries out all the necessary database analysis in the background, but also provides detailed reports that are easy to produce alongside a user-friendly interface.”