RotaBolt® tension control fasteners have been chosen for the new Open Water Lubricator Valves (OWLV) being used on offshore drilling rigs as safety testing devices in open water riser systems. The new valves have been manufactured by the leading international oilfield service company Expro, and are being used in a deep water oil and gas field application off Port Harcourt, Nigeria.
The OWLV is a relatively recent development and is used as an integral part of an open water riser system during the installation and work-over of subsea Xmas trees. It typically sits 50-200 meters below the rig floor and allows the introduction and external pressure testing of the down-hole tooling string, ensuring that all the elements function correctly and can withstand well-bore pressure prior to installation.
“This is the first time we have used RotaBolt technology,” commented design engineer Chris Cusack from Expro. “We have been very pleased with it and found that the installation and tooling times were considerably reduced. The tension control assurance delivered by RotaBolt gave us an added comfort factor – we knew we could be confident about the pre-load on the joints. We had tried traditional torque techniques before, but found them unpredictable. The client also liked the fact that in-service maintenance and bolt pre-load checking was made easy.”
The RotaBolt 2 system was selected because it provides an even greater range of tension control on installation, tightening and in-service checking. It offers two tension settings in a single sensor and features a dual load indicator cap – the outer cap for the high tension setting and the inner cap for low tension – giving the choice of an operational tension range for overload or maintenance control.
The OWLV also allows testing of the riser string and surface well control equipment above it, and provides an additional safety barrier between the sub-sea wellhead and the drilling rig. Each OWLV is approximately 132 in. (3,353 mm) long, has an external diameter of 24.20 in. (950 mm) and a through bore of up to 7.375 in. (187 mm). Ten RotaBolt 2 fasteners are fitted to the flanges at each end of the OWLV.
