Situation

Hot work behind 36” single riser valve.

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During a short maintenance stop on the L10-A complex, which is the central hub for the main subsea gas transport pipeline NGT, there were hot work activities planned on the riser platform. As there was just a single riser valve isolating the location of the hot work from the NGT sea pipeline this was not considered safe following the Process Isolation Procedure of Neptune Energy. However, with the DBB-SAVER a tight shut-off isolation could be guaranteed and after thorough review for this first DBB-SAVER deployment for Neptune Energy, the working principles were explained. Due to the added safety and ease of deployment, decision was made to go ahead.

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The DBB-SAVER was connected to the body cavity of the 36” ESD valve, connecting the L10-AR with the NGT pipeline, as well as the 10” kicker/bypass valve of the pig trap in parallel, making 100% sure there was no possibility of any gas passing from the NGT line towards the safe work area and create hermetically sealed valves. The vent outlet of the DBB-SAVER was connected to the common vent header to be released to safe area, with an additional local vent stack on the DBB-SAVER unit for start-up, which remained closed during the deployment of the DBB-SAVER.

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Result

Guaranteeing safe work environment with double block & vacuum.