During 1988 Shell Expro (‘Shell UK Exploration and Production Ltd’, operators in the UK North Sea on behalf of Shell and Esso) identified an increase in failed leak off tests in Cameron FC style valves on water injection trees.

Corrosion/erosion on a primary seal face of the upper master and flow wing valves left the trees with reduced shut off ability. Nineteen trees were involved and the implications of changing out so many trees at once prompted us to look seriously at offshore machining and repair.

To carry out this type of detailed work offshore required full manufacturers' support to arrive at a technically acceptable engineered solution that complied with Company Safety Standards and DOE requirements.

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