Online valve repair maintains Total gas flow

Edited by the Engineeringtalk editorial team Dec 6, 2004

Big savings were achieved at the Total St Fergus gas terminal recently, when a leaking valve on the main gas import line was safely sealed by Furmanite without interrupting operation.

Big savings were achieved at the Total St Fergus gas terminal recently, when a leaking valve on the main gas import line was safely sealed by Furmanite without interrupting operation.

The import line handles some 10% of the gas supply for the UK, so when a leak was discovered at the stem of the 32in Class 900lb ball valve, caused by excessive wear of the O-rings, it was important that shutdown to repair the leak was avoided.

Furmanite, renowned for its services geared to maximising asset uptime, was called in to help.

Furmanite was able to inject the valve under pressure, while it remained online and operating at 70bar(g) and temperatures from -29 to +50C.

The O-ring seal bottom groove was first located, and an adapter valve fitted externally.

With this in place, an isolation valve could be assembled with a glanded arrangement to enable live drilling into the O-ring groove.

A compound was then injected under pressure and cured to form a seal, stopping the leak and keeping the valve in service until the next planned shutdown some seven months later.

Furmanite technicians were mobilised to seal the leak within 24 hours of receiving the call from Total, and the whole procedure (including hazardous operation and safety risk assessments) was completed the following day.

Commenting on the work Total St Fergus plant manager Pierre Alexandre Rives said: "Given the significance of the import line and critical function of the valve it was vital to be able to respond quickly, and to minimise disruption as this would be extremely costly".

"Thanks to Furmanite's online pressure leak sealing expertise the valve was repaired with no disruption to operation - ensuring production continued without jeopardising the safety of the personnel".

Furmanite Offshore Business Manager Graham McKay commented: "This is typical of what we do - apply our range of engineering services and technologies to help customers avoid unscheduled downtime, save time and lost production, and keep their assets earning".

Furmanite is renowned for its pioneering pressure leak sealing technology and seals some 40-50 leaks daily for industry, from steam, gas and hydrocarbons to a range of chemical systems, at pressures up to 350bar(g) and temperatures to 600C, using the latest materials and compounds, and specialist techniques.

The company's latest techniques for valve gland packing under full line pressure can be modified to suit all duties, and can now provide longer gland packing life at high temperatures, as well as acid and hot gas/oil-resistant packings.

The Total St Fergus terminal, situated 60km north of Aberdeen, receives and processes gas from over 20 North Sea fields handling an average daily throughput of some 60 million cubic metres of natural gas and 2500 tonnes of natural gas liquids.