Sedco 704 Semi-Submersible Rig

Sedco 704 Semi-Submersible Rig

1: (BOD) Ballast Overboard Discharge Valves (ABS Approved)

Sedco 711 and 704 Semi-Submersibles

Ballast Overboard Discharge Valves

On behalf of Transocean, Monitor Systems were asked to provide ABS Approved Ballast Overboard Discharge Valves for two of their semi-submersible rigs working in the North Sea; currently operated by Maersk Oil and Talisman.

STABILITY CONTROL: Ballast control systems are a vital part of semi-submersible rigs. The ballast control system is made up of a network of pipes, valves, pumps, and tanks, which work together as a liquid control system to keep the drilling rig on an even keel.

On semi-submersible rigs, the safety of all personnel depends upon the stability of the rig. This stability is created by a special installation on-board that organises the amount of seawater in several ballast tanks; the Ballast system.

Ballast Overboard Discharge Valves Monitor Systems Aberdeen Ballast Overboard Discharge Valves

The BOD system supplied by Monitor Systems included a 12” Butterfly Valve with 4-20mA position feedback, spring return fail close Pneumatic Actuator with IP66 rated Electro Pneumatic Positioner. A separate stainless steel control enclosure was provided to house the solenoids, check valves, throttle valves etc that are required to maintain the existing control philosophy and keep proportional control over the pneumatic valve.

FAT: The four solenoid control enclosures underwent a full FAT to assure correct operation. Each enclosure was ‘leak tested’ to confirm all pneumatic fittings were secure and tight. The enclosures were then tested ‘electrically and pneumatically’ to confirm correct operation, with the three valve control functions ‘open, close and hold’ being tested.


1: Vessel Management System (VMS)

Vessel Management System, VMS

This Vessel / Marine Management System (VMS) was awarded to Monitor Systems as part of a major SPS project with the design and installation of a new Ballast Control Console and full associated Tank Gauging System to replace the old existing system.

The existing Ballast Control Console is the original panel installed when the rig was built and hence is quite basic. Monitor Systems have designed a redundant PLC based system that can monitor and control all ballast valves as well as monitor bilge levels throughout the rig.  We can also monitor the Ballast Tank, Fuel Tank, Drill Water, Pot Water and Reserve Mud Tank Levels.

VMS Ballast Console

As part of the system we are supplying, the new Ballast Control Console will blend in with their existing control room layout.  The new Ballast Control Console will be operated via seven 19” wide screen touch monitors built into the console.  Monitor Systems are also monitoring the brace leak detection and ballast flow Bilge Valves and Sensors were also supplied to monitor the Bilge Pots. New Brace Leak Detection Sensors were integrated into the system to provide automatic monitoring of the leg bracings. The seventh display shows Environmental and Heli Deck Monitoring information.

Each of the 19" HMI IPC displays connect to the system’s datanetwork. A SCADA software package especially designed for the 704 has been installed on all display IPC’s and is operable through the display’s touchscreen interface. Provision has been made for an external mouse and keyboard to be plugged into each IPC. Alarm sounders, console lamps and a beacon installed in the control room will alert personnel to situations requiring operator intervention.

Ballast Control Console

As part of the Tank Gauging System Monitor Systems are supplying 36 LevelCom liquid level computers pre installed on panels ready for connection to the tank piping.  The Ballast Control Console will be connected to remote I/O panels throughout the rig utilising a redundant fibre optic network.  Monitor Systems are also supplying new bilge valves and actuators and will be responsible for the full system installation.

Project Management of a new complete Fire & Gas System also falls under our scope of supply. Monitor Systems also supplied a UPS to power the Ballast Control System.

electronics, UPS power

A rapid & robust delivery schedule has been put forward to design and install the multi million pound contracts, all internally project managed at Monitor Systems.

Managing Director Brian Sinclair commented, ... "our engineering team and staff were all excited about this project; it comes on the back of other projects successfully completed and gives Monitor Systems the opportunity to show its strength, expertise and knowledge in this area."



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Monitor Systems Scotland Limited : Est. 1997