The test was carried out as part of ABB's EPC contract for Enterprise Energy Ireland and its offshore Corrib Field development. "The choke will be the primary method of controlling the onshore flow of gas in an unusual requirement which means the valve could operate an unprecedented 600,000 times during field life," said ABB Control Valves development engineer, Mr Andrew Green.

The test was originally commissioned for a million actuator cycles, which were completed without any problems being revealed by routine checks every 100,000 cycles.

"When Enterprise suggested putting the two Directional Control Valves (DCVs) through one million cycles each, it was agreed to double the test length to give even greater confidence," Mr Green said. "The second million cycles were completed as uneventfully as the first, and the whole programme finished within the original time window."

Mr Green added the choke actuator and DCVs showed minimal indication of wear and both units passed post-endurance acceptance tests with flying colours. In addition, all torque measurements and fluid leakage rates remained within factory acceptance levels for brand new equipment. There are about 500 Hydrostep actuators already installed on subsea chokes around the world, according to Mr Green.