API Spec 16D:2004 (2013) pdf download

API Spec 16D:2004 (2013) pdf download.Specification for Control Systems for Drilling Well Control Equipment and Control Systems for Diverter Equipment.
a. Two (2)coniplete sets of pilot-operated control valves with each set mounted in one of two control pods located on the LMRP.
h. Two (2) control hose bundles, each stored on and deployed from an umbilical reel, to connect the two subsea pods to the surface control equipment.
c. Two (2) or more means of surfacelsubsea power fluid supply (e.g.. hydraulic conduits, hydraulic umbilical hoselsi). At least one of these means shall satisfy the response time requirements specified in this section. and two (or more) supplies shall be selectable from at least two primary control stations.
5.3.3 Accumulators and Manifolds
Accumulators and manifolds for hydraulic control systems for subsea HOP stacks shall meet the requirements of 5.2.
5.4 ELECTRO-HYDRAULIC AND MULTIPLEX (MUX) CONTROL SYSTEMS FOR SUBSEA BOP STACKS
5.4.1 General
Electro-hydraulicimultiplcx (MUX) control systems employ multi-conductor armored subsea umbilical cables deployed from storage reels aboard the vessel. The cables transmit coded commands that activate solenoid operated pilot valves in the subsea pods. Within the pod. each solenoid valve activates a pilot-operated control valve to direct power fluid to a particular function.
5.4.2 Redundancy
Because the subsea BOP stack is not easily accessible for maintenance and repair, redundant backup) system elements shall he deployed. Specifically these include:
a. Two (2) complete sets of solenoid valves and pilot-operated control valves with each set mounted in each control pod located on the LMRR
h. Two (2) control cables, each stored on and deployed from an umbilical reel, to connect the two subsea pods to the surface control equipment.
c. Two (2) or more means of surface/subsea power fluid supply. (examples: hydraulic conduitis]. hydraulic umbilical hoselsi). At least one of these means shall satisfy the response time requirements specified in this section, and two (or more) supplies shall be selectable from at least two primary control stations.
5.4.3 Electrical Power
lilectrical power (excluding the PLJI1W systems) shall be supplied from one or more uninterruptable power supplies with backup battery capacities to operate the controls for at least 2 hours.
5.4.4 Command Signals
Electrical command signals transmitted over lengthy subsea umbilical cables have shorter response times than hydraulic pilot signals transmitted over hose bundles of equal length. Electrical command signals operate subsea solenoid valves which, in turn, provide hydraulic pilot signals directly to operate the pod valves that direct power fluid to the subsea functions
A MUX control system processes multiple signals on each signal conductor in the umbilical. Multiplex systems serialize and code the command signals which are then sent subsea via shared conductors in the umbilical cable. Multiplex control system logic can incorporate additional security by requiring transmission of a coded message to the subsea pod. return of the message to the surface by the pod electronics package for verification, and re-transmitting the verified command before execution of the function.
An electro-hydraulic system has a pair of conductor wires in the subsea umbilical cable dedicated to each function.
5.4.5 Central Control Unit (CCU)
In systems employing a CCU. the CCU is the central control point (corresponding to the hydraulic control manifold of a discrete hydraulic control system). When used to satisfy the requirements of 5.2.4 and 5.2.5. the CCIJ shall provide full functional and pressure regulation capability.
Upon restoration of power. following an electrical power interruption, the CCU shall bor* up all functions in the non-energiied position. The status of the system at the time of loss of power shall be displayed aridor recorded in some form, The last position of block function shall not be displayed when an electrical power loss in the surtice paneks) could result in an incorrect position indication.
5.4.6 Electrical Power and Signal Distribution Cables
5.4.6.1 Two complete independent subsea umbilical cables shall be used. Each electrical umbilical cable shall contain all communications and/or power conductors required to control all the subsca functions through one pod. The severing. opening, or shorting of one cable assembly should not disable the surface equipment and the pod connected to the other cable should remain fully functional
5.4.6.2 Shipboard cabling from the electrical control units to the cable reels should be muted along separate paths, where practical, to reduce the possibility of both cables being simultaneously damaged.
5.4.6.3 All armored cable shall be designed to avoid kinking and twisting. The cable shall be designed to be capable of supporting at least. two times the anticipated load which is typically the load applied by the unsupported length of deployed cable. The electrical conductors and electrical insulation shall not be used as load bearing components in the cable assembly.
5.4.6.4 All underwater electrical umbilical cable terminations shall prevent water migration up the cable in the event of connector failure or leakage and prevent waler migration from the cablc into the subsca connector termination in the event of water intruskm into the cable. Conductor terminations shall ensure that seawater intrusion does not cause electrical shorting. A pressure compensated junction box or pressure balanced fIeld installable. testable cable tennination containing dielectric fluid may be used to accomplish this.
5.4.6.5 Underwater connectors shall be provided with pressure tes ports to verify the seal integrity of mated plug-receptacles. These ports shall be plugged and scaled when not in use for testing.