This paper describes the need for and subsequent development of a firesafe device which locks open wellhead surface safety valves while conducting through-wellhead operations, and which is manually releasable to allow closure of the valve in an emergency.

The device incorporates a eutectic material which will provide for closure of the valve in a fire and meets the requirements of API Specification 14D for fusible lockopen devices. Existing fusible lockopen equipment used by offshore operators is not manually releasable once the hold-open pressure applied to the actuator is released (by activation of the platform emergency shutdown system) due to the large forces involved.

This new assembly is a significant improvement over existing equipment because: (1) it is manually releasable, (2) it can be released remotely by utilizing a cable/pulley system (3) all component parts are retained upon release, (4) it is adaptable to most valves and actuators currently in use, and (5) it greatly enhances well shut-in capabilities while conducting through-wellhead operations.

You can access this article if you purchase or spend a download.