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(1)BOP Hydraulic Control Systems.

(2) Subsea Engineer’s Handbook. Section 4. Table Of Contents Section 4 Page 1. General Description of Hydraulic Control System. 1. 2. Operation of a Surface Accumulator. 2. 3. Controlling the BOP Stack. 3. 4. Subsea BOP Control System Diagram. 4. 5. Stepping Through the Subsea Hydraulic Control System. 5. a. b. c. d. e. 6.. Hydraulic Power Unit and Surface Control Manifold Hydraulic Hose Bundle and Storage Reel Control Pods BOP Remote Control Panels Diverter Control. 5 8 10 17 20. Hydrostatic effects on Subsea Accumulator Bottles. 22. 7. API and MMS System Sizing, Response Guidelines. 23. 8. BOP Response Times. 24. 9. Hydraulic Systems Flow. 26. a. b. c. d. e.. Main Hydraulic Supply Regulator Pilot Circuits Operation of a 3 Position Function Operation of a 2 Position Function Operation of a Straight thru Function. 26 28 30 32 34. 10. Typical Hydrulic Power Unit Schematic. 36. 11. Typical Manifold Schematic. 37. 12. Typical Pod Schematic. 38. 13. Typical Stack Schematic. 39.  In-Spec Inc. 1999. BOP Hydraulic Control Systems.

(3) Subsea Engineer’s Handbook. Section 4. 14. Hydraulic Symbols. 40. 15. Fitting Information. 43. 16. Troubleshooting: Pressure Losses. 47. 17. Troubleshooting: SPM Failure. 53. 18. Troubleshooting: Leaks and Malfunctions. 56. 19. Operation of the Electrical Portion of the System. 66.  In-Spec Inc. 1999. BOP Hydraulic Control Systems.

(4) Subsea Engineer’s Handbook. Section 4. General Description of a Hydraulic Control System 1) 5 Main Components of the Surface Hydraulic Power Unit (HPU).  In-Spec Inc. 1999. 1. BOP Hydraulic Control Systems.

(5) Subsea Engineer’s Handbook. Section 4. Operation of the Surface Accumulator Bottle. Atmospheric Pressure The accumulator bottle has a bladder of tough, synthetic rubber that is shaped like a tapered cigar. It has this shape when there is no pressure on it. The tapered shape is important because it gives a pushing or squeeze action when fluid is discharging. The bladder completely separates the nitrogen precharge from the hydraulic fluid. This prevents the gas from mixing with the hydraulic fluid. Pre-Charged The bottle is precharged with nitrogen through a valve at the top of the bottle. Nitrogen is used due to its relative inertness and availability. At the bottom is the port through which hydraulic fluid is pumped. The fluid also leaves the bottle from this port. A poppet valve closes the port when the bladder pushes against it. The 1,000 psi of nitrogen precharge pushes the elastic bladder to the bottom of the bottle and closes the poppet valve preventing the bladder from being pushed out of the port. Initial Charge Next, hydraulic fluid is pumped into the bottle, and the 1,200-psi minimum pressure Is reached quickly. Fully Charged At far right, the bottle is fully charged with fluid to 3,000-psi working pressure. The additional fluid pumped into the bottle raises the pressure from the 1,200 psi initial charge to the 3,000 psi fully charged state. As fluid is used from the bottle the pressure will drop to 1,200 psi. The fluid delivered by the bottle during this process is called the usable fluid available from the bottle.  In-Spec Inc. 1999. 2. BOP Hydraulic Control Systems.

(6) Subsea Engineer’s Handbook. Section 4. Controlling the BOP Stack To be useful we must control an entire BOP stack. The system power supply must be obtained from more than 1 source – so an air powered pump is added to the system. Of course our stack will contain more than 1 ram so we have added more preventers and a control valve for them. The same regulator is used for all the ram preventers and is called the manifold regulator. Since the annular BOP may require a different pressure from the rams, a separate regulator is added to supply hydraulic fluid to it.. Bladder. Float. N2. N2. 1. Alternate Power Source 2. Operate more than one BOP 3. Operate Annular with it’s own regulator. Annular Regulator. R. R 3000 PSI. Air Pump.  In-Spec Inc. 1999. 3. BOP Hydraulic Control Systems.

(7) Subsea Engineer’s Handbook.  In-Spec Inc. 1999. Section 4. 4. BOP Hydraulic Control Systems.

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(9) Subsea Engineer’s Handbook. Section 4. Stepping Through the Subsea Hydraulic Control System 1) Hydraulic Power Unit and Surface Control Manifold The hydraulic power unit is usually mounted integrally with the surface control manifold. It supplies the hydraulic fluid, a mixture of water soluble oil and water, to the control system. The unit contains a reservoir section which includes two reservoirs and a hydraulic fluid mixing system, a pump section which includes both air and electric operated pumps, and an accumulator section. The reservoir section has two reservoirs, one for water soluble oil, and one for the mixed hydraulic fluid. The water soluble oil reservoir has typically a 100 gallon capacity. The mixed fluid reservoir contains at least enough fluid to fully charge the system accumulators from their precharge pressure to the maximum system working pressure. Both reservoirs are equipped with graduated sight glasses and lowlevel alarms. The fluid mixing system has the capability of supplying fluid at a rate greater than the combined output of all pumps. In addition, the concentrate-water mixing ratio will remain within 5 percent of its setting regardless of pressure fluctuations which might occur in the mixture supply line. The figure below shows a typical mixing system..  In-Spec Inc. 1999. 5. BOP Hydraulic Control Systems.

(10) Subsea Engineer’s Handbook. Section 4. The mix water flows through a regulator which reduces the pressure and maintains a constant flow rate. An independent air-operated pump injects the water soluble oil at a constant rate, thus maintaining the proper mixing ratio. The system is insensitive to pressure and volume fluctuations in the mix water supply as long as the rig water system is capable of supplying water faster. than the setting for the mixing system. The mix ratio can be adjusted by varying the mix water and/or water soluble oil flow rate. To protect the hydraulic fluid against freezing, the capability to mix glycol with the water soluble oil and water is provided. The glycol would be added in a manner similar to that of the water soluble oil. Glycol and water volumes are added when determining the amount of lubricant to add. The main pumps for the power unit are typically electrically driven triplex pumps. The primary consideration when selecting the capacity of the pumps is usually the amount of time it would take the pumps to charge the system accumulators from their precharge pressure to the maximum system working pressure. Charging times no longer than 15 minutes are desirable. There can be other considerations which would override charging time and require more pump capacity. These considerations usually involve saving rig time, the cost of which makes the cost of additional pump capacity negligible. When pump capacity requirements exceed 20 gpm, splitting the capacity between two pumps prevents complete dependence on one pump. To provide additional or backup pump capacity in case electric power is not available, one to three air-operated pumps are usually installed. All pumps are mounted so that any one can be isolated for repairs without interfering with the operation of the others. The pumps are equipped with pressure switches to start and stop the pumps at selected pressures and suitable relief valves. To maintain maximum accumulator fluid for a 3000 psi system, the pressure switch to stop the pumps is set at 3000 psi. The relief valve vents at 3500 psi. The fluid from the pumps is filtered by 40 micron filters. Two filters connected in parallel are used, with each filter capable of being isolated to eliminate pump shutdown for filter replacement. Fluid travels from the pumps into accumulator banks. These accumulators serve two purposes; first, they store hydraulic energy which can be used when pumping capability is lost. Second, they supply fluid at rates much higher than the pump capability and are used to achieve faster BOP actuation times. Separator-type accumulator bottles are used in all of Shaffer control systems. They have a rubber bladder than separates the gas precharge from the stored liquid. The gas precharge is injected into the accumulator through the precharge valve in the top. No fluid should be in the accumulator when it is precharged. Cameron traditionally use float type accumulator bottles in their systems. The float replaces the bladder and it is the dropping float which shuts off the bottle outlet to prevent the nitrogen from escaping from the bottle as the final fluid exits..  In-Spec Inc. 1999. 6. BOP Hydraulic Control Systems.

(11) Subsea Engineer’s Handbook. Section 4. The surface control manifold contains all the controls and indicators necessary to operate the valves and regulators on the subsea pods and monitor the general status of the system. The manifold contains the pod selector valve, which directs the power fluid to the active pod and vents the inactive pod to the fluid reservoir located on the power skid. The manifold can be operated remotely from any of several panels which will be discussed later. The functions on the manifold can be broken into four categories, pilot valve control, regulator control, pressure readback display, and pod selection. Each piece of equipment on the stack has a corresponding surface control valve on the manifold which pilots the pod control valve(s) that, in turn, control that piece of equipment. The control valves for the Shaffer system are 1/4-inch shear seal valves equipped with air operators to allow control of the valves from the remote panels..  In-Spec Inc. 1999. 7. BOP Hydraulic Control Systems.

(12) Subsea Engineer’s Handbook. Section 4. The hydraulic signal from each valve goes to both junction boxes on the manifold unit, through both hose bundles, and actuates SPM valves on both the active and inactive pods. Only one subsea pod, the active pod, has power fluid or main hydraulic supply (MHS) fluid supplied to it at any given time. The pod selector valve on the manifold unit directs fluid to the active pod and vents the fluid from the inactive pod. The pod selector (a 1-inch shear seal valve) operates exactly like the pilot control valves and is equipped with an air operator for remote operation. The controlled pressure side of each regulator in the subsea control pods is connected through a 3/16-inch hose to a gauge labeled pressure readback on the manifold unit. A pressure transducer transmits the readback pressure to the remote panels. A shuttle valve connects the hoses from the pods at the manifold unit and isolates the active and inactive pods. Explosion-proof housings located on the manifold unit skid contain the equipment which interfaces the remote control panels with the manifold unit. This equipment includes the pressure transducers which transmit pressures from the manifold to the control panels and pressure switches that provide status information (open, close) for the remote panels. Also included are the solenoid actuated valves which direct air to the air operators on the manifold pilot control and pod selector valves and provide regulator increase/decrease control. 2). Hydraulic Hose Bundle and Storage Reel. In hydraulic systems, the subsea power fluid supply, MHS, and all pilot signals for the control valves are transmitted through a hydraulic hose bundle which extends from the surface manifold unit, through jumper hoses to the hose reels, and from the hose reels to the subsea pods. Also hydraulic fluid from the regulated side of the subsea regulators is transmitted through the hose bundle to pressure gauges labeled pressure read-backs on the control panels. MHS fluid is supplied only to the hose bundle of the active pod while pilot pressure is supplied to both the active and inactive pods. The hose bundles used in most operations generally are composed of one 1inch ID supply hose, which supplies power fluid to the pods, and 3/16-inch ID pilot hoses for activation of the individual control valves and readbacks. The supply and pilot hoses are typically bundled with the supply hose in the center surrounded by pilot hoses. Polyurethane is the preferred outer covering material for the bundle because of its superior physical properties. The hose reel stores and supplies the hose bundle as required during drilling operations. A separate cable reel provides the means for easy running and retrieval of the pod. When the pod is run or retrieved, the junction box for the jumper hose is disconnected from the hose reel. However, to keep selected functions live during the running or retrieval operations, a few control stations are mounted on a manifold attached to the side of the reel. The live functions  In-Spec Inc. 1999. 8. BOP Hydraulic Control Systems.

(13) Subsea Engineer’s Handbook. Section 4. include at least the riser and stack connectors plus the pod latch. Contractors may select to additionally operate one or two pipe rams, fail safe valves and test valves. Below is a typical a typical diagram of reel piping through which the power fluid flows to the controlled functions during the operation of the reel.. The hose bundle leaves the reel and runs over a roller sheave down to the pod. The bundle is clamped to the wireline attached to the top of the pod at 30 to 50 foot intervals. The pressure drop in the power hose can be substantial when a function is actuated, particularly for long hose lengths. One way to compensate for this pressure loss and assure faster actuation times is to place accumulators subsea on the BOP stack. Another means is to supply fluid to the control pods through 2 or 2-1/2-inch ID conduits integral with the marine riser. These conduits are similar to small diameter choke or kill lines..  In-Spec Inc. 1999. 9. BOP Hydraulic Control Systems.

(14) Subsea Engineer’s Handbook. Section 4. 1) Control Pods Flexibility in BOP stack configuration is provided by double female controls pods. The flexibility is achieved by having discharge ports in both the upper and lower female portions and utilizing a combination of 3/4” and 1” SPM valves for preventer functions, depending on fluid requirements. These control pods also are equipped with 1-1/2” regulators to provide large flow and still maintain accurate pressure settings. The packer seals at the mated ports between sections of the pod have been tested to 12,000 psi without leakage in the transfer of high pressure fluid between sections. The subsea hose bundle terminates at the pod through a hose radius guard attached to the junction box cover. This protects the hose from kinking and prolongs its life. The pods are run and retrieved by unitized guide frames. Keyed connections provide reliable mating. The retrievable pod incorporates 1” SPM valves and 1-1/2” regulators with the SPM valves mounted in individual stainless steel pockets for ease of maintenance. Packer seals make leakproof connections between pod sections, and special coatings protect the pod against corrosion. Power fluid to operate the preventer is supplied to the pod through a one-inch hose in the hydraulic hose bundle or a rigid conduit integral with the marine riser. Power fluid is also supplied from accumulators mounted on the BOP stack. Hydraulic power fluid is normally supplied to the subsea control pod at full system working pressure; nominally 3,000 psi surface gauge. A regulator in the pod reduces the pressure to suit the requirements of the BOP equipment, normally 1500 psi surface gauge. The purpose of a regulator is two-fold. First, to reduce higher (system) pressure to a lower (working) pressure. Second, to maintain the preset pressure should external forces attempt to increase or decrease it. The regulator is controlled from the surface through a pilot hose in the hydraulic hose bundle. The shear seal type regulator employs a sliding metal seat which seals on a fixed metal surface..  In-Spec Inc. 1999. 10. BOP Hydraulic Control Systems.


(16) Subsea Engineer’s Handbook. Section 4. Centered Fluid Vented. Opened Supplying Fluid. Cameron Slide Valve. More on Cameron Control Valves  In-Spec Inc. 1999. 13. BOP Hydraulic Control Systems.

(17) Subsea Engineer’s Handbook. Section 4. Shaffer SPM Valve. Open Supplying Fluid.  In-Spec Inc. 1999. Closed Fluid Vented. 14. BOP Hydraulic Control Systems.

(18) Subsea Engineer’s Handbook. Section 4. The regulated hydraulic fluid is supplied to selected SPM valves mounted on the subsea pod. Pods may have two or three regulators depending upon drilling contractor requirements. Pods with two regulators use one to supply regulated fluid to the valves controlling the annular preventers, the other supplies regulated control fluid to the remaining functions (ram preventers and valves). In some instances the connectors will have their own regulator. The SPM valves are operated hydraulically from the drilling vessel through small pilot hoses in the hydraulic hose bundle. When operated, they supply control fluid to actuate the piston operators of preventers, valves and connectors. At the same time they vent fluid from the other side of the pistons to the sea. SPM valves are two-position, three way valves and are available in 3 nominal sizes, 3/4 inch, 1 inch and 1-1/2 inch. One-inch valves and one and a half inch valves are used to control the annular preventers. The 3/4-inch valves are used to control the other stack functions such as ram preventers, choke and kill valves, and connectors. The SPM valve is a poppet type in which a sliding piston seals on Delrin seats. In the normally closed position, a spring attached to the top of the piston shaft keeps the piston on the bottom seat, blocking hydraulic fluid from reaching the BOP. In this position, hydraulic fluid from the inactive function is vented to the sea. When pilot pressure is applied to the valve, the piston moves up against the upper seat and blocks the vent ports, allowing control hydraulic fluid to reach and function the BOP. Two SPM valves are required to operate a blowout preventer. The pilot fluid flows from the control valve at the surface, through a pilot hose to the SPM valve and lifts the valve spindle off its bottom seat. Regulated fluid flows through the SPM valve to the preventer cylinder’s CLOSE side. At the same time, the three-position, four-way, surface control valve relieves pilot pressure on the preventer’s OPEN SPM valve. The spring forces the piston to its lower seat and displaces pilot fluid to the surface. Hydraulic fluid from the OPEN side of the preventer cylinder is vented subsea through this valve. Regulated power fluid pressure acts on a small piston area on the spindle to aid the spring in holding the SPM valve closed. The surface control valve when in the centered position relieves both SPM valves of pilot pressure, thus allowing both valves to block or seal off the regulated power fluid and vent both sides of the preventer actuating cylinder to sea. When the control valve is in this position, it is said to be in the “centered”, “block”, or “vent” position. When SPM valves are operated in this manner, the two valves act as one three-position, four-way valve..  In-Spec Inc. 1999. 15. BOP Hydraulic Control Systems.

(19) Subsea Engineer’s Handbook. Section 4. After passing through the SPM valve, the power fluid exits the pod and flows to the appropriate function first through a hydraulic hose and then through a shuttle valve mounted adjacent to the function. The shuttle valves, which isolate the inactive pod from the operated functions, are an integral part of the redundant two-pod design. Shuttle valves are used to direct power fluid from the active pod to the function while at the same time isolating the inactive pod from the control pod in use. A cut away drawing of the shuttle valve is located on page 40 where you can see the internal operation. When the pods are switched, fluid from the active pod shifts the shuttle in the valve to isolate the inactive pod from the function. Also, note that the corresponding SPM valve in the inactive pod is piloted open concurrently with valve in the active pod; however, no power fluid flows from inactive pod’s valve because the hydraulic fluid line has been vented on the surface. Not all functions on the BOP stack are controlled through valves on the pod. Function that require less volume, e.g., ball joint pressure, are controlled directly from the surface through small hoses in the hydraulic hose bundle. The fluid flows through a hole drilled directly through the pod. These functions are called straight through as opposed to functions requiring SPM valves. Thus far, only the operation of a single function through the subsea pod has been discussed. The pod must have additional capabilities or requirements to meet today’s drilling needs; some of them are: • Capable of being run and retrieved with the riser package, • Capable of being run and retrieved independently, • To be fully redundant, • To have all hydraulic seals on the retrievable portion of the pod, • To have all functions go to the exhaust position if communications are cut with the surface and, • To allow any leaks occurring downstream of the pod to be isolated either at the pod or upstream of the pod. To meet the preceding criteria, the pods must be mounted on the upper stack section (LMRP) which is retrieved with the riser..  In-Spec Inc. 1999. 16. BOP Hydraulic Control Systems.

(20) Subsea Engineer’s Handbook. Section 4. 2) BOP Remote Control Panels The Driller's Control Panel is the primary operating centre for the BOP Control System: the electrically operated Mini Remote Control Panel and the manual operated hydraulic Control Manifold are secondary centres. Operating voltage for The Driller’s Control Panel is typically 12 VDC or 120 VDC. The control panel is designed with a graphic overlay of the BOP stack and choke and kill lines. The graphic overlay helps the driller locate quickly the functions to be operated. The driller’s control panel also enables remote operation of the diverter control functions. The controls for the diverter functions are also arranged in a graphic overlay for ease of identification. The entire control panel is protected from physical and environmental damage by two Lexan doors.. a) Function Pushbutton/Indicator Lights The main section of the Driller's Control Panel contains the push button/indicating lights for control of the BOP Stack and Lower Marine Riser Package (LMRP) functions..  In-Spec Inc. 1999. 17. BOP Hydraulic Control Systems.

(21) Subsea Engineer’s Handbook. Section 4. These functions duplicate the functions on the Hydraulic Control Manifold. A typical list of functions is listed below: Stack & Riser Functions Pod Selector Accumulator Isolator Blue Pod Latch Yellow Pod Latch Upper AnnularOpen Block Close Riser Connector Riser Connector Secondary Shear Rams Upper Pipe Rams Middle Pipe Rams Lower Pipe Rams Outer Kill Inner Kill Upper Outer Choke Upper, Inner Choke Lower Outer Choke Lower Inner Choke Stack ConnectorUnlock. Block. Lock Stack Connector Secondary Upper Wedgelocks Lower Wedgelocks. Function Positions Blue. Block. Yellow Open. Close Vent. Latch Vent. Latch Unlock. Block. Lock, Unlock Vent Open. Block. Close Open. Block. Close Open. Block. Close Open. Block. Close Open. Vent Open. Vent Open. Vent Open. Vent Open. Vent Open. Vent Unlock. Vent Unlock. Block. Lock Unlock. Block. Lock. b) Lamp Test Pushbutton To the left of the stack overlay, is the Lamp Test pushbutton. When this button is pushed, all the panel lights should illuminate c) Warning Panel To the immediate right of the function pushbuttons is the warning panel. This small panel typically contains five red alarm indicator lights for the following: • • • • •. Glycol Level Soluble oil Level Accumulator Pressure Fluid Level Rig Air Pressure. If the pressures or levels of the above listed items drop to a predetermined low level, the red indicating lights illuminates to warn the driller. The driller should check the low pressures and low liquid levels and restore them to acceptable levels before proceeding with control system operations.  In-Spec Inc. 1999. 18. BOP Hydraulic Control Systems.

(22) Subsea Engineer’s Handbook. Section 4. When any of the red warning lights come on, an audible horn also sounds at the Driller's Control Panel. To turn the horn off, the rig- hand presses the Horn Cancel button at the bottom of the warning panel. d) System Pressure Meters To the right of the Driller's Control Panel are two electrically operated Pressure meters. The Accumulator Pressure meter indicates Line Pressure or the main hydraulic supply from the main accumulator bottles to the stack functions. The PILOT PRESSURE meter indicates the pressure in the pilot system. The RIG AIR PRESSURE meter indicates the rig air pressure to the Hydraulic Power Unit. The correct meter readings are as follows: • • •. Pilot Pressure Accumulator Pressure Rig Air Pressure. 3000 3000 100- 125 psi. e) Flow Meter A flow meter is located on the Driller's Control Panel immediately below the two pressure meters. The flow meter on the panel indicates the amount of fluid that has been used at the completion of a function operation. The electric flow meter on the Driller's Control Panel is linked to the hydraulic flow meter on the Hydraulic Control Manifold. The flow meter registers the volume in tenths of a gallon. Careful observation of the flow meter can signal the driller that a leak is present in the control system. After a function has been operated, the flow meter at the Driller's Control Panel can be reset to zero by pressing the Flowmeter Reset pushbutton to the left of the flow meter. f) Pressure Regulation Stations On the left side of the Driller's Control Panel are five additional electrically operated pressure meters. These meters are: • • • • •. Annular Regulator Pilot Pressure Annular Regulator Readback Pressure Manifold Regulator Pilot Pressure Manifold Regulator Readback Pressure Pilot Pressure. The readings on these meters correspond to the readings on the pressure gauges on the Hydraulic Control Manifold. To the right of the meters are two increase, decrease pushbutton stations. One station is for the annular pressure regulator, the second is for the manifold pressure regulator. Note that the three-way Unit/Remote Panel Selector switch on the Hydraulic Control Manifold must be in the Remote Panel position before  In-Spec Inc. 1999. 19. BOP Hydraulic Control Systems.

(23) Subsea Engineer’s Handbook. Section 4. the regulator pressures can be controlled from the Driller's Control Panel. When the driller operates either the annular pressure regulator or the manifold pressure regulator, the pressure is indicated on the Annular Regulator Pilot Pressure and Manifold Regulator Pilot Pressure meters respectively. When the regulated pressure pilot signal is retrieved subsea, the subsea HKR regulating valves send signals back to the Driller’s Control Panel. These return signals are indicated on the two readback pressure meters. When all system equipment is operating correctly, the Pilot Pressure and Readback Pressure meters for the two regulated functions read the same. 3) Diverter Control Section a) Function Pushbutton Indicator Lights The right side of the typical Driller’s control panel contains the controls for the diverter control system. These controls enable remote operation of the diverter equipment from the Driller’s control panel. The diverter control section of the Driller’s control panel contains the pushbutton/ indicator lights and regulators for control of the diverter functions. The panel is designed with a graphic overlay of the diverter functions, which helps the driller locate quickly the functions, which are to be operated. The seven functions reflect the functions of the diverter substructure panel. The functions and positions are listed below : Positions Open, Close Unlock. Lock Unlock. Lock Unlock. Lock Vent. Pressure Open. Close Port / Starboard Open. Function Diverter Element Insert Packer Lockdown Dogs Diverter Lockdown Dogs Diverter Support Lockdown Dogs Flowline Seals Shale Shaker Valve Overboard Valves. Unlike the panel functions or the BOP Control System, the panel functions for the Diverter Control System do not contain Block positions. Diverter functions can be put into the Block position only at the Diverter Substructure Panel. b) Pressure Regulation Stations Three sets or pressure regulation pushbuttons are located in the center of the diverter control section. The three pressure regulators are for the Diverter Element Regulator. Diverter Manifold Regulator. and Slip Joint Regulator. Each regulator is provided with an Increase and Decrease pushbutton. Note that the three way remote panel selector switches at the diverter substructure panel must be in the remote panel position before the regulator control pressures can be controlled from the driller’s panel.  In-Spec Inc. 1999. 20. BOP Hydraulic Control Systems.

(24) Subsea Engineer’s Handbook. Section 4. Pressure Meter Diverter Element Pressure Slip Joint Pressure Diverter Manifold Pressure. Operating Pressure (psi) 750 300 Driller’s choice (usually 1000 to 1250 psi). A fourth pressure meter for the Diverter Accumulator Pressure - Is located on the diverter section on the Driller's Control Panel. This meter displays the accumulator pressure or, the Diverter Substructure Panel and should, read 3000 psi..  In-Spec Inc. 1999. 21. BOP Hydraulic Control Systems.

(25) Subsea Engineer’s Handbook. Section 4. Hydrostatic Effects on Subsea Accumulator Bottle Precharge. 3000 psi Working Pressure System Water Depth. 1. Precharge, psi (1,000 psi + Water depth x .445psi/ft). Available Fluid from 10 Gallon Subsea 1 Bottle. 0 ft.. 1,000 psi.. 5.0 gal.. 500 ft.. 1,223 psi.. 4.8 gal.. 1,000 ft.. 1,446 psi.. 4.6 gal.. 1.500 ft.. 1,669 psi.. 4.4 gal.. 2,000 ft.. 1,890 psi.. 4.2 gal.. Calculated on a 3,000 psi WP system using 1,200 psi as the minimum usable fluid pressure. The % of usable fluid delivered from the bottle is equal to: (precharge + hydrostatic head) (-)minus (precharge + hydrostatic head) (Min. pressure + hydrostatic head) (System WP + hydrostatic head).  In-Spec Inc. 1999. 22. BOP Hydraulic Control Systems.

(26) Subsea Engineer’s Handbook. Section 4. API and MMS System Sizing and Response Guidelines Reference. API RP-53, 3rd Ed. Response - Sec. 13.3.5 Volume - Sec. 13.3.2. API Spec 16D Response - Sec. 2.2.2.1 Volume - Sec. 2.2.2.5. Response Time Requirements. Accumulator Sizing Criteria. • • • •. Rams close in less than 45 sec. Valves not to exceed rams Annulars close in less than 60 sec. LMRP Connector unlatch in less than 45 sec.. Close & Open all rams plus one annular with remaining pressure to be 200 psi above precharge pressure. • • • •. Rams close in less than 45 sec. Valves not to exceed rams Annulars close in less than 60 sec. LMRP Connector unlatch in less than 45 sec.. Open & close all rams plus one annular plus 50% reserve with remaining pressure to be above precharge pressure then Open & close all rams plus one annular with remaining pressure above calculated minimum ram or valve operating pressure. 1.5x the volume to close all preventers with remaining pressure to be 200 psi above precharge pressure. MMS CFR 250 Chapter II Subpart D Sec. 250.406-d-1.  In-Spec Inc. 1999. 23. BOP Hydraulic Control Systems.

(27) Subsea Engineer’s Handbook. Section 4. BOP Response Times The closing time of a subsea BOP control system consist of two parts: signal time and fill-up time. The signal time is the elapsed time from when a function on a panel is operated until all valves in the sub-sea pod have operated. The fill-up time is the elapsed time from when the valves in the pod operate until the stack function if fully operated (open or close) 1) Signal Time In an all hydraulic system there are five factors which affect signal time. a) Hose length - this is a customer requirement and cannot be changed. For each type hose the greater the length the slower the reaction time. b) Hose Volumetric expansion - a stiffer hose, i.e., a lower volumetric expansion will produce a faster signal transmission. c) Hose diameter - for a constant length and stiffness, increasing the diameter of the hose within limits will decrease the signal response time. d) Temperature - tests or calculations at room temperature are inadequate. Corrections must be made to account for the colder water (approximately 350F) since most of the hose will be underwater. Colder temperatures will cause a longer response time. Response time calculations typically are at 350F. e) Amount of ethylene glycol - for adequate antifreeze protection, a 40% solution of ethylene glycol should be used in the pilot lines while operating in sub zero temperatures. Increasing the concentration of ethylene glycol will significantly slow the response time of a given hose. 2) Fill Up Time Fill up time of a preventer is affected by the supply of fluid and the hydraulic circuitry on the stack. a) Fluid supply to preventers is accomplished in two ways. Fluid is delivered from the surface via hose or rigid conduit. Fluid can also be supplied from stack mounted accumulators. If lines from the surface to the annular are not able to deliver fluid at a minimum of 180 gpm for an 18 3/4” 10,000 psi annular then stack accumulators are necessary. The accumulators should contain enough usable fluid to close one annular..  In-Spec Inc. 1999. 24. BOP Hydraulic Control Systems.

(28) Subsea Engineer’s Handbook. Section 4. b) Hydraulic circuitry between the pod and preventer restrict the flow of fluid to that preventer. Connections to an annular may include two one inch SPM valves supplied by a 1½ inch regulator and sufficient usable fluid in stack mounted accumulators to close the annular. In tests on fill up time conducted on Shaffer pods in the ship yard, to close an 18-3/4 inch 5,000 psi Spherical required 18 to 21 seconds. The 18 3/4 inch 10,000 psi Spherical with the same circuit will close in 28-30 seconds. Connections to the annular included four one inch SPM valves supplied by a 1 1/2 inch regulator and sufficient usable fluid in stack mounted accumulators to close the annular..  In-Spec Inc. 1999. 25. BOP Hydraulic Control Systems.

(29) Subsea Engineer’s Handbook. Section 4. HYDRAULIC SYSTEM FLOW 1) Main Hydraulic Supply Hydraulic fluid, made up by automatically mixing potable water and water soluble oil concentrate, is stored in a reservoir. It is picked up by electric pumps and/or air pumps and flows through two 40 micron filters in parallel. The fluid then enters a bank of accumulators where it is stored at a maximum pressure of 3,000 psi (with a 1,000 psi nitrogen precharge in accumulators). The hydraulic fluid also continues through a flow meter (FM). An accumulator pressure gauge is located on the front of the hydraulic control manifold and a pressure transducer (PT) transmits pressure readings to the remote panels. A low accumulator alarm switch activates whenever the accumulator pressure falls below 1,500 psi. Hydraulic fluid flows from the accumulator bottles through a 1” check valve on its way to a 1” manipulator type 4-way valve which selects the pod which receives the Main Hydraulic Supply (MHS) The pod which receives MHS is called the active pod. The pod selector valve is on the front of the accumulator unit and operates either manually or remotely for a remote panel. When MHS flows from the valve to either of the pods, the pressure activates either one of the pressure switches in the output lines to operate the appropriate pod indicator light on the remote panels to indicate the active pod. Main hydraulic supply leaves the pod selector valve and flows to the BOP control pod located subsea. This line is a 1” hydraulic hose located in the hose bundle. The MHS line enters the pod through the large connection in the center of the kidney plate. The flow then continues to the two subsea regulators (1 l/2” HKR’s). Some systems send the fluid subsea down a rigid conduit line. This is permanently attached to the riser in a manner similar to a choke and kill line..  In-Spec Inc. 1999. 26. BOP Hydraulic Control Systems.


(31) Subsea Engineer’s Handbook. Section 4. 2) Regulator Pilot Circuits We now need pilot lines to control the two subsea regulators (HKR’s). Pressure is supplied from the main accumulator bank through a 1” check valve to the manifold pilot pressure regulator and the annular pilot pressure regulator. These two regulators (1/2” AKR’s) in the hydraulic control manifold apply pilot pressure through the pilot lines (MR and AR) to the subsea manifold and annular HKR’s, respectively. Regulator pilot pressure is also fed to panel mounted gauges & pressure transducers. The subsea HKR’s supply output pressure at a 1 to 1 ratio. A 1,500 psi pilot pressure produces 1,500 psi output pressure from the subsea HKR for the blowout preventers. The output of the manifold subsea HKR goes to all of the ram preventer, valve, and connector functions while the output of the annular subsea HKR supplies power only to the annular preventers. A pilot line leaves each of the subsea HKR’s and returns back to the surface through the hose bundle. These two, 3/16” lines supply manifold and annular readback pressures to gauges and pressure transducers located on the hydraulic control manifold. A shuttle valve is located on the input to each gauge between readback lines from both the blue and yellow pods (“This Pod” and “That Pod”). Since there is no MHS to the inactive pod, only the active pod supplies readback pressure through the shuttle valve to the gauge and pressure transducer..  In-Spec Inc. 1999. 28. BOP Hydraulic Control Systems.


(33) Subsea Engineer’s Handbook. Section 4. 3) Operation of a 3 Position Function The pilot pressure required to control a function begins at the main accumulators where 3,000 psi hydraulic fluid supplies two, ten gallon pilot pressure accumulator bottles (with 1,500 psi precharge) through a 1/2” check valve. The pressure in the pilot pressure accumulators is monitored by a gauge and pressure transducer. These pilot pressure accumulators supply pressure to the ¼” manipulator valves on the front of the hydraulic control manifold. Here we see a valve to control a Hydril BOP. Pilot lines (number 29 and 36) leave the manipulator valve, connect to pressure switches, then leave the manifold and go to both pods (both “This Pod” and “That Pod”). Once in the pod, both lines connect to SPM valves. Both SPM valves attempt to supply hydraulic pressure to either open or close the annular preventer. Remember, only the active pod receives MHS and actually operates the preventer. When the handle of the function’s valve is operated, pilot pressure leaves the ¼” manipulator valve through one pilot line and activates the associated pressure switch to turn on an indicator light on the remote panel. The pilot pressure then enters both hose bundles and continues subsea to the kidney plates. The pilot lines then lead to the proper SPM valve in each control pod. Pressure forces the SPM (Sub Plate Mounted) valve into the open position. This then allows hydraulic fluid to flow from the subsea annular HKR and through the open SPM valve to operate the annular preventer. The opposite pilot line is simultaneously vented by the manipulator valve, releasing pressure in that pilot line. When pilot pressure is released from the opposite SPM valve, the SPM returns to the closed position by spring action and vents operating pressure from the BOP into the sea. Note that both pods receive pilot pressure but only one pod will actually be supplying fluid to operate the preventer. This is the pod which is receiving Main Hydraulic Supply (MHS) pressure from the pod selector valve. In the center, or block position, the manipulator valve vents both pilot lines to the Annular BOP. This allows both SPM’s to close and vent all control pressure off the preventer. The “Block” position indicates that the Control System blocks pressure from going to the function and vents all control pressure off that function..  In-Spec Inc. 1999. 30. BOP Hydraulic Control Systems.


(35) Subsea Engineer’s Handbook. Section 4. 4) Operation of a 2 Position Function A two position function differs from a three position function due to the presence of only 1 pilot line from the pilot valve. The two position function reefers to the ability of the circuit to only supply pressure and vent hydraulic pressure. These functions are used for such items as subsea failsafe valves which must be pumped into the open position or vented to allow them to close under their own spring power. Other applications are “Connector Secondary Unlock, where pressure is applied or vented. Power for either pilot pressures originate in the pilot accumulator bottles. Only one pilot line leaves the ¼” manipulator valve of a 2 position function. Leaving the valve, the pilot line leads to a pressure switch and to both pods by way of the RBQ’s, hose bundles, and kidney plates. The single pilot line then leads to the proper SPM in the subsea control pod. When it is desired to open a subsea failsafe valve, it must be pumped into the open position against spring force. To initiate this, the ¼” manipulator valve is put into the “open” position . This supplies pressure to the pressure switch in the pilot line which turns on the indicator light on the control panel. The pilot pressure also enters both pods through the pilot lines and activates the proper SPM valve. The SPM valve is forced into the open position which allows hydraulic pressure to flow from the subsea manifold HKR in the active pod, through the open SPM, and into the opening chamber of the subsea failsafe (fail-safe) valve. When it is desired to close the failsafe valve, the ¼” manipulator valve is placed in the center, or “close” position, which vents off all pilot pressure to the subsea SPM valves and the pressure switch. The pressure switch turns on the proper indicator light on the remote panel. With pilot pressure removed from the SPM valves, they return by spring force to the closed position and also vents pressure from the opening chamber of the subsea failsafe valve. With no hydraulic pressure to hold it in the open position, the failsafe valve closes due to spring force..  In-Spec Inc. 1999. 32. BOP Hydraulic Control Systems.


(37) Subsea Engineer’s Handbook. Section 4. 5) Operation of a Straight Through Function Functions which use small volumes of fluid use 3000 psi pilot pressure directly at the function and avoid the requirement of an SPM valve. These are often items such as the pod latch (shown here as the manipulator valve on the far right-hand side), stack mounted SPM valves for stack mounted accumulators, and ball joint pressure. With these functions, pilot pressures are sent down to the pod through the hose bundle from manipulator valves located on the hydraulic control manifold. Pilot pressures flow through the pod directly to the pod latch piston or through the pod to stack mounted SPM valves Ball joint pressure originates at the ball joint pressure regulator located on the hydraulic control manifold. The pressure is carried down a pilot line through the upper female and to the ball joint..  In-Spec Inc. 1999. 34. BOP Hydraulic Control Systems.


(39) Subsea Engineer’s Handbook. Section 4. Typical Hydraulic Power Unit Schematic.  In-Spec Inc. 1999. 36. BOP Hydraulic Control Systems.

(40) Subsea Engineer’s Handbook. Section 4. Typical Manifold Schematic.  In-Spec Inc. 1999. 37. BOP Hydraulic Control Systems.

(41) Subsea Engineer’s Handbook. Section 4. Typical Pod Schematic.  In-Spec Inc. 1999. 38. BOP Hydraulic Control Systems.

(42) Subsea Engineer’s Handbook. Section 4. Typical Stack Schematic.  In-Spec Inc. 1999. 39. BOP Hydraulic Control Systems.

(43) Subsea Engineer’s Handbook. Section 4. Shuttle valves for redundancy 1. Shuttle valve - the point where the redundant systems, blue and yellow, come together. 2. Shuttle makes a decision "Who is going to operate this function, blue or yellow pod" 3. Shuttle is passive. It is shifted by the active pod when pods are shifted. 4. Mounts directly onto the preventer since redundancy stops at this point2 5. Stops flow out through shuttle into the inactive hose and pod if there should be a leaking hose on the inactive pod.. 2. Systems which are “hard piped” from the shuttle valve to the equipment port may deviate from this general rule.  In-Spec Inc. 1999. 40. BOP Hydraulic Control Systems.

(44) Subsea Engineer’s Handbook. Section 4. Hydraulic Symbols 1) Hydraulic and Air Lines. Preferred. Acceptable. Hydraulic. ANSI. Air. 2) Check Valves. Simple. Pilot Operated Check Valve (POCV). 3) Shuttle Valve. 4) Relief Valves, Adjustable.  In-Spec Inc. 1999. 41. BOP Hydraulic Control Systems.

(45) Subsea Engineer’s Handbook. Section 4. 5) Regulators. Manually Adjusted. Hydraulically Piloted. 6) Miscellaneous Items. Flow Meter. Gauge. Pressure Switch. Pressure Transducer. 7) Pumps. Air Driven. Electrically Driven. 8) Accumulator Bottles.  In-Spec Inc. 1999. 42. BOP Hydraulic Control Systems.

(46) Subsea Engineer’s Handbook. Section 4. 9) Valves, 2-way. Needle or Ball Valve. 10) Spool and Shear Seal Valves, 3 and 4-way. Manual 4-way 3-position Selector. Manual 4-way 3-position Manipulator. Return to Reservoir. Plugged. Unconnectable. Air Pilot and Manual Operation. Hydraulic Pilot Operation with Spring Return. Solenoid Operation with Spring Return. Manual 2-way.  In-Spec Inc. 1999. 43. BOP Hydraulic Control Systems.

(47) Subsea Engineer’s Handbook. Section 4. Survey of Fittings Found on the BOP Stack 1) Threaded Fittings a) Tapered Pipe Threads The tapered pipe thread, either U.S. or British, has always had a sealing problem. The U.S. thread is NPT (National Pipe Taper) and the British thread is BSP.. The wedging action of the pipe taper will always be a problem. Any poorly trained mechanic can take a large wrench to a pipe fitting and by putting too much torque on the wrench he can split the casting of an expensive component because of the wedging action of the taper. At sizes above 1" the NPT fitting is not rated for pressures above 3,000 psi. b) Straight Thread Fittings To solve the problems of a tapered thread a straight thread has been developed which seals with an O-ring. The thread machined into the housing is an SAE fine thread, but at the top, a chamfer is machined which will accommodate the O-ring. When the fitting is screwed into a port it can be tightened until the fitting makes a metal-to-metal seat on the housing and the O-ring provides the fluid seal. Since there is no taper on the threads, there is no wedging action to split the housing..  In-Spec Inc. 1999. 44. BOP Hydraulic Control Systems.

(48) Subsea Engineer’s Handbook. Section 4. 2) Flare Fittings a) 45o SAE Flare Fittings The concept of flaring tube to provide a seal and holding power to the connection is very old. Its origin goes back to the early days of the automobile. Different types of flared connections including 45o single and double flares, inverted flare, 30o flare, etc., were developed for coolant, fuel, brake and lube systems of the automobile. The SAE (Society of Automotive Engineers), formed in 1910, made itself responsible for the manufacturing standards of all items used in automobile manufacture, and tubing was one item to be so controlled. A set of dash numbers was introduced so that the manufacture's part number followed by a dash and a number would identify it as being made to SAE standards. Dash numbers such as -5 for 5/16" O.D., were assigned with similar dash numbers for other sizes. A hand flaring tool was developed so mechanics could make an outward flare on the end of a piece of copper tubing, and the inside flare surface always finished off with an exact 45o angle. This became the standard angle for all SAE flare fittings. The thread, identifying dash numbers, and fitting to be used with each size tube was regulated by SAE. This was the beginning of all the dash sizes we now have in use in fluid power connectors. The American made hose ends and adapter fittings did not match with those made in other countries, especially in Europe and Asia. The confusion was especially felt in the oil well drilling business as the drilling rigs were moved from one location to another. b) 37o JIC Flare Fittings The 37o flared fitting is the most widely used fitting throughout the world. Because the fitting can be used to connect to inch tubing, metric tubing and also a hose assembly, this versatility offers the user a greater international acceptance as compared to other fitting styles..  In-Spec Inc. 1999. 45. BOP Hydraulic Control Systems.

(49) Subsea Engineer’s Handbook. Section 4. With American support, arrangements were made with manufacturers in many other countries for an all-world seminar to arrange common standards. This seminar was called the Joint Industry Conference and the standards which came out of it were called JIC standards. The first thing to be done was to make an easily noticed difference between an SAE and a JIC fitting. The face chamfer angle on the female hose ends was changed to 37o, enough difference to be noticed by the eye. Also, many thread sizes were made to different diameters so JIC fittings would not mate with SAE fittings. In some cases the number of threads per inch was made different. Each mechanic could tell that a JIC fitting could not be used with an SAE adapter. However, a variation of the dash numbering system was agreed upon for the hose manufacturing trade, so that the I.D. sizes were in sixteenths of an inch. Thus, 1/2" I.D. hose became 8/16 " or -8 size. The JIC hose ends for the ½" hose have female JIC swivel end fittings are identified with the same dash number, -8, for example. 3) Bite Type Fittings The bite type fitting is a flareless fitting that consists of a body, a one-piece ferrule, and a nut. On assembly, the ferrule "bites" into the outer surface of the tube with sufficient strength to hold the tube against pressure, without significant distortion of the inside tube diameter. The basic bite type fitting was first developed in Europe in the early 1930s.. The bite type fittings provide a fairly secure and easily made-up method of employing tubing on the control system. The bite type fittings are generally not considered as "bullet-proof" as the 37o JIC fitting system. The ferrule also forms a pressure seal against the fitting body. Bite type fittings allow the fitting assembler to visually inspect the bite quality, thus significantly minimizing the risk of improper assembly and related service problems.  In-Spec Inc. 1999. 46. BOP Hydraulic Control Systems.

(50) Subsea Engineer’s Handbook. Section 4. 4) Flange Fittings a) SAE Flange The SAE flange hose end fitting has come into wide usage in the last several years since system operating pressures have risen above 3,000 psi (the limit for large diameter NPT threaded fittings). It is primarily intended for high pressure connection of a hose to a component port pad. It is only for hose and is not normally used on rigid plumbing. The flange end fitting is crimped on to the end of a hose or the end of the hose is threaded into a flange block. These fittings come either as a straight-through connection or with various angles from 22 ½ o to 90 o. The flange is clamped to a machined port pad on the component, usually a valve, pump, valve manifold, or BOP, by two half flanges using hex head cap screws. An O-ring fits into a circular groove in the hose flange and makes a seal against the port pad on the component.. These flange fittings are made in several pressure ratings, for pressures from 2500 to 6000 psi. They are available in sizes as small as 1/2" and up to 3 inches. Although they were originally built for mobile hydraulic systems, they are being used on industrial systems as well. Size identification is with dash numbers similar to those used on other fittings, expressed in sixteenths of an inch. Several variations of the basic design have been developed. The Code 62 is the most common type used in BOP control systems. b) SAE Flange with Integral Seal Sub A modification of the SAE flange is to replace the face mounted O-ring seal with a radial seal in both halves of the connection. A seal sub is an additional item which is added to the assembly to form the radial seal in both halves of the connection..  In-Spec Inc. 1999. 47. BOP Hydraulic Control Systems.

(51) Subsea Engineer’s Handbook. Section 4. Troubleshooting: Pressure Losses While the B.O.P. is down, pressure losses do occur. Isolating them as best as possible and repairing the components where possible can keep downtime as a result of pulling the BOP or Pods at a minimum. The areas that losses are sorted into 5 categories. 1) The “Koomey Unit” – the Hydraulic Power Unit (HPU) Components, which are the most common sources of pressure losses at surface, are: • • • • • • • •. Pod selector valve. Relief valve. Check valves on the air and electric pumps discharges. Hydro-air pressure switch. Increase/decrease solenoids. Manual regulator. Tubing and piped connections. Four way valves.. Most components above can be easily repaired (at an opportune time such as bit trips, etc.) by securing pressure to the components and securing the air and electric pumps. Four way valves for instance one or another may not be possible to change out as circumstances dictate and would have to be prolonged until the B0P/LMRP is pulled. Operations will always dictate how and when repairs can be conducted safely. 2) The Pilot System The pilot pressure system begins at the two pilot pressure accumulators at the Koomey Unit and ends at each pod block. A pressure drop on the HPU pilot pressure gauge while the unit is idle will indicate a loss of pressure in the system. Components in the system are: • • • • • • • • •. Tubing/pipework from the accumulators to the 4 way valves. The 4 way valves, and regulators. RBQ junction plates for each jumper hose. The RBQ junction boxes at each pod reel. The hose reel hot line system. Any splices or damaged areas in each hose. The termination of the pilot hoses to the kidney plate. The stainless steel tubing and connections from the pod top plate assembly to the pod valve block. The pilot signal passage way in the pod valve block and the SPM..  In-Spec Inc. 1999. 48. BOP Hydraulic Control Systems.

(52) Subsea Engineer’s Handbook. Section 4. a) Any leaks found in the tubing/piping can be visually found and stopped by securing the pressure to that function. b) On the 4 way valves most leaks can be detected by listening to the valve and listening for a washed valve body. Also the regulators and the 4 way valves can be checked for pressure loss by removing the vent return lines and watching for a leak. c) A visual check on the RBQ's both at the Koomey Unit and the hose reel and the pilot line connections should reveal any leaks. A way of decreasing the chances of having a leak at a junction box, is by first visually inspecting the male/female check valves for debris, broken “O-ring”, and secondly by placing all the functions, where possible, into the block position at the 4 way valves when the junction box is removed or installed. If there is no pressure on the check valves when mating them together there is less of a chance of washing out or cutting the “O-rings” before the junction plates are fully mated. d) The pod reel hot line system gets its power from the 1" -3000 psi supply line and it is still possible to lose pressure in the pilot system. Since the hot line system 4 way valves and regulators tie into the main pilot line/hose inside the reel, any pressure applied to the pilot lines once the hose reel junction boxes are mated can back flow through the components and be lost through the vents. By securing the supply valves and keeping the check valves in good order, the chance of this happening can be greatly reduced. e) Although pressure losses can occur from damaged areas in the pod hose, this will most likely be the last place that you'll look. Leaks here will be hard to detect. That's why it is essential when the pod or BOP is on deck and being tested any pressure losses should be scrutinised so that you can be absolutely sure that you can eliminate this area as a possible source pilot line pressure losses. f) As above, the termination of the pilot hoses to the pod top plate assembly and the stainless steel tubing and the connections to the valve body are not areas of high probability where you are going to have leaks. However if these areas are corroded particularly at the kidney plate, they can become high suspect areas. Also consideration should be given to this area if you know that an object (T.V. frame, guideline tools may have hit or jarred the pod guide arms). g) The SPM, besides the check valves at the pad hose reel, is going to be the most likely place for a leak in the pilot line system..  In-Spec Inc. 1999. 49. BOP Hydraulic Control Systems.

(53) Subsea Engineer’s Handbook. Section 4. SUMMARY If you have a leak in the pilot line system and you can rule out the loss of pressure is occurring top side then the way to find this leak is by systematically placing each four way valve into the block position and observing the leak until you find the pilot signal that is losing the pressure. Once the leak is found and depending upon it's severity and the rigs situation any action or no action may be taken. 3) The Accumulator/Pod Manifolds System and BOP Functions: The accumulator/pod manifolds system provides the way for fluid to get to the SPM at the right pressure to be sent on it's way by the SPM to the designated function on the BOP. The components that must handle this fluid are: • • • • • • • •. Accumulator bottles at the Koomey unit. Pod selector valve. Pod hose, reel swivel connection, pod hose. The 3000 psi pipe work from the pod top plate to the regulators and the discharge piping to the valve block. BOP accumulator isolator valves The internal pod valve block manifolds. Hoses from the pod receptacles to the shuttle valves. Hoses from the shuttle valve to the functions on the B.O.P.. Most probable leak points are: a) The accumulator bottles; unless there is a visual leak here in the pipe work to the pod selector valve you won't have any problem. b) Any leak associated with this entire system will show up on the flowmeter and on the accumulator pressure gauge. c) The Pod selector: the selector valve (which is of the manipulator type) can be easily checked for leaks. Listen to the valve for leak noise with a mechanic’s stethoscope. By breaking the pipe work on the return side of the 1″ pod valve any leak can be checked visually. d) The Pod hose reel swivel connection, and pod hose; unless you can visually see a leak in the top side of this system the only way to isolate the 1″ hose down to the pod is to do the following: e) Bleed down both the pilot signals to the pad manifold and annular regulators and put the riser connection 4 way valve into the block position, this will isolate the.  In-Spec Inc. 1999. 50. BOP Hydraulic Control Systems.

(54) Subsea Engineer’s Handbook. Section 4. 3000 psi –1″ hose, the 3000 psi pipe work in the pod and the 3000 psi system downstream of the subsea accumulator SPM. A loss of pressure will be indicated on the accumulator pressure gauge. To continue and to find the leak, send a pilot signal to the Subsea accumulator SPM establishing communication to the subsea bottles. Observe for leaks. If no loss of pressure is found, continue on by placing each 4 way valve into block (thus closing all SPMs). f) By putting a pilot signal to each regulator you will find if you have any leaking SPMs while they are closed. Next, by placing each 4 way valve into the drilling mode (rams open, annular open, failsafes closed) this will detect if the leak is taking place from the open SPM to the designated function. If a leak is found here, to determine if it's from the open SPM to the shuttle valve or from the shuttle valve to and including the function just switch pods. Then place all 4 way valves into block and individually open the suspected leaking function. If the leak is not found here then this will tell you the leak is not from the shuttle to the function. The problem must be the SPM or the hose going to the shuttle valve. If the leak is still found on the other pod then the leak is from the shuttle valve to the function. SUMMARY Once it is determined where the pressure loss is occurring, a number of actions can take place. They are: 1. Put pressure on the leaking SPM/function line then place 4 way valve into block position and leave it like that. 2. Switch pods. 3. Pull pod. 4. If leak is below (downstream) SPM/pod, the BOP stack or LMRP will have to be pulled. In conclusion, if the leak is to the main 3000-psi hose or pipe work or if a regulator is leaking the pod will most likely have to be pulled and repaired. If the SPM is working and you are losing pressure through it, and it holds pressure when it is closed (the SPM) you can most likely leave it in the block position until the BOP is pulled. And finally if the leak is from the shuttle valve to the function depending upon the situation the B.O.P. will have to be pulled to repair the leak. 4) Hose Reel Manifold The hose reel manifold is designed to give control to the pods so that a few primary functions can be operated while the BOP is being run or pulled. The system should be used during these times and not during normal operations..  In-Spec Inc. 1999. 51. BOP Hydraulic Control Systems.

(55) Subsea Engineer’s Handbook. Section 4. The hose reel manifold receives its primary fluid pressure from the 1″-3000 psi feed into the reel via the swivel connection. A 3/16” I.D. jumper hose tee off from the 1" line feeds the main shut off valve for the hot line system (manifold supply shut off). The manifold supply shut off feeds a common manifold from which the following 4 way valves are fed fluid pressure: • • • • • •. Riser Connector - primary latch and unlatch SPM's. Riser Connector - secondary unlatch SPM. Wellhead Connector primary latch and unlatch SPM's. A Shear or Pipe Ram open and closed SPM's (pending hook up). A regulator for ball joint pressure. (This is no longer required but some older rig systems may still have the regulator not hooked up). A regulator for the manifold pressure command pilot signal to the live pod.. Selecting one of the above pod hose 4 way valves; Riser Connector Secondary Wellhead Connector, Shear or Rams, and placing it in the desired mode of operation sends a pilot signal to the pod to lift that particular SPM. With the manifold regulator adjusted to 1500 psi and with the manifold regulator shut off valve open a pilot signal is sent to the manifold regulator at the pad. With this signal the regulator will then regulate the 3000-psi feed to the desired pressure (1500-psi). Now with the SPM lifted off of its seat, manifold pressure can now flow to the desired function and operate the function. With the 4 way valve kept in the desired mode (say riser connect lock) and with the pod reel regulator adjusted to 1500 psi, the regulator will reduce the 3000 psi feed to 1500 psi, and keep 1500 psi on the riser connector lock while the BOP is being run or pulled. Obviously this is of primary concern whilst running or retrieving a BOP stack - maintaining hydraulic closing pressure on the L.M.R.P. connector. An important consideration to keep in mind while working and the way valve is that they are of the “selector type” . If a “manipulator type” body is installed once the reel hot line system is shut down and the junction box is mated together any pilot signal using the above 4 way valves can be bled off because a manipulator valve bleeds of pressure from its functions while in block, where as the selector valve will hold pressure in the block position. Therefore Pod hose valves should always be selector type which will not bleed off pressure when thrown into a block position. a) The procedure for activating the reel hot line system for running or pulling the BOP is as follows: • Place the pod selector to either blue or yellow pod (use the same pod that was previously used). • Go to the hose reel and check to see if all 4 way valves are in block, if not put them in the block position..  In-Spec Inc. 1999. 52. BOP Hydraulic Control Systems.

(56) Subsea Engineer’s Handbook. • • • •. • • • •. Section 4. Open the manifold supply shut off valve. Open the manifold regulator shut off valve. Adjust both regulators to the desired operating pressures (manifold 1500 psi). If BOP is to be run, place riser connector to lock position wellhead connector to open (unlatch) position. REMOVE THE HANDLE TO THE RISER CONNECTOR VALVE WHILE RUNNING OR PULLING THE B.O.P. AS A SAFETY PRECAUTION. If BOP is to be retrieved put the riser connector to lock, and wellhead connector to the latch position. Then put manifold pressure at pod reel to minimum 1500 psi. Go to Koomey Unit, place all four way valves into the block position, bleed off regulators, place regulator selectors to block position. Remove junction boxes from hose reels and activate hose reel functions. You are ready to go about with your BOP stack operation.. b) To deactivate the hot line system if the BOP is down: • Mate on junction box, make sure air to motor and lock pin on reel is engaged. • Go to unit, place all 4 way valves into the drilling mode (rams open, annular open, failsafes closed and (Connectors locked). • Select mode of operation for the regulators (electric or manual). Set regulators to drilling pressures. • Go to the reel and secure the manifold regulator shut off valves. • Bleed down regulators. • Place 4 way valves into the block position. • Secure manifold supply shut off valve. c) To secure the reel hot line system if BOP is on deck: • Secure ball joint and manifold regulator shut off valves. • Bleed down regulators. • Place 4 way valves into block position. • Secure manifold supply shut off valve. d) A few comments about the Pod Reel hot line system: • To avoid any confusion at the pods, always use the reel hot line system on the pod that is on line. • The hot line system is not to be used when the reels junction boxes are mated. • The 4 way valves are of the selector type..  In-Spec Inc. 1999. 53. BOP Hydraulic Control Systems.

(57) Subsea Engineer’s Handbook. Section 4. Troubleshooting: SPM Failure 1) 42 Line Pod Scenario: B.O.P. on beams ready to be run or at the wellhead and a function fails to operate. What should be done? a) If no fluid flow is indicated by the flowmeter check the following: • The Pod selector valve is selected to proper pod. • The Regulator pressures: manifold and annular regulator selectors are in proper mode and both regulators have the right amount of pressure on them Check read back gauges to verify. • Pod reel junction box is on and secured. • Pod reel hot line system is secured. To do this check: a) 4 Way valves are in block position. b) The Pod reel shut off valves (manifold supply, manifold regulator and the prehistoric ball joint regulator if still in use) are closed. c) The Regulators are bled off. b) Switch pods, try same function again (same panel): • If function works this tells you that your problem is between the RBQ’s (for that pad that did not work) at Koomey Unit to the shuttle value going to that function. • If function still does not work check out: a) Air pressure at Koomey Unit. b) Electricity to unit (proper current, voltage). c) Obstructions that may stop the 4 way valves from working. c) Try function again from another source and if the function works then check out: • Panel which would not operate: The easy way to check out the solenoid is to disconnect the air fitting to air piston. `Try functioning again and you should get a shot of air. If you don't check out the electrics for that function and solenoids. (Electrical box right hand side of main control panel). • If function still doesn't work review steps 1 a • If the function did work on the other pod, switch back to the pod which is malfunctioning. d) Try functioning it again, if it still doesn't work: • Go to pod reel, find proper pilot line and disconnect it on the inside of the reel so that you can see if the signal is getting through the junction box check valves. Be sure pod hose reels are locked out and can not be rotated. • If you are getting a good pilot signal through, then the signal you are getting should be a good one at the pod. Obviously a leaking pilot line in the hose bundle can prevent the signal lifting the SPM.  In-Spec Inc. 1999. 54. BOP Hydraulic Control Systems.

(58) Subsea Engineer’s Handbook. •. •. Section 4. If you don't get a signal here, reconnect pilot line and disconnect it on the outside of the pod reel before the check valves, if you get a signal here then either the male or female check valve is damaged -change out the check valve. If you don't get a signal, go to Koomey unit and inspect the check valves on the RBQ and also check to see if the correct pilot line is hooked up between the unit and pod reel.. e) If you are getting a good pilot signal to the pod: • Try another function that will use the same regulator on the pod to determine if the regulator is shot. • If the other function works you can be fairly sure that: a) The SPM is not working. b) The shuttle valve is jammed and not allowing the fluid flow to the function. c) Or the component functioned is inoperable. f) If at anytime that you operate the function and the fluid flow doesn't stop and the function works on the other pod then you have a broken hose or connection on the pod side to that particular function. Once you have the problem isolated to an SPM, then the only operation to pull the pod (see section on PULLING A POD). • After pulling the pod, repairing the SPM, function testing it on surface, rerun the pod. Use a T.V. camera, don't stab it blind. • Function test pod. • If the function still doesn’t work from any source, the shuttle valve must be jammed. Depending on the particular function, wellhead connector, shear or pipe rams, failsafes, or lower annular then both halves of the BOP will have to be pulled. If the riser connector, upper annular, or choke and kill connector SPM1S fail then your only need to pull the L.M.R.P. section to surface. g) Basically a function needs only 4 requirements to be fulfilled and they are: • The regulators need a continuous feed of high pressure fluid (3000 psi). • A Pilot signal to the regulator telling it what pressure to reduce the 3000 psi to. • A pilot signal (3000 psi) to the SPM, to lift it off its seat. • An uninterrupted means of letting regulated fluid to the function (hose, shuttle, valve). • If you can be sure these requirements are met then it can only be 2 things: the SPM or the function (ram operator, annular assembly, failsafe or connector pistons)..  In-Spec Inc. 1999. 55. BOP Hydraulic Control Systems.

(59) Subsea Engineer’s Handbook. Section 4. Final Note: Remember that the manner and way you troubleshoot your control system problem is vital to the rigs safety. How you derive the problem will determine whether you require to make a surface repair, pull a pod, pull the L.M.R.P. or pull the complete BOP stack. Therefore know your system well..  In-Spec Inc. 1999. 56. BOP Hydraulic Control Systems.

(60) Subsea Engineer’s Handbook. Section 4. Troubleshooting: Leaks and Malfunctions 1) Leaks and Malfunctions Normally, a fluid leak in the system is detected by watching the flow meter on the driller's panel. If the flow meter indicates a fluid flow when no functions are being performed, or if it continues to run and does not stop after a function is performed, this generally indicates that there is a leak in the system. Once you have determined that there is a leak, you should begin a check of the system to determine the location of the leak. 'Me first thing to do is to make a thorough visual inspection of the surface equipment. You do this by carefully examining the hydraulic control manifold and accumulators to see if you can find a broken line in the system or a fluid leak at any of the fittings. If no leak is found, next check the jumper hoses and hose reels to see that all connections are tight and that no hoses are damaged. Sometimes a bad connection at a hose reel R13C junction box will result in a leak. Examine the connections carefully to be certain that they have a firm seat. While at the hose reel, check the hose reel manifold to make certain that all of the valves are in the centre position. Also, make certain that the needle valve to the manifold pressure supply shutoff is tightly closed. If this valve is left open when the RBQ junction box is connected to the reel, it will allow fluid pressure to be forced back through one of the surface regulators and vent into the tank, thus indicating a leak in the system. If you find this valve in the open position, then close it and check the flow meter to see if the fluid flow has stopped. If this procedure does not prove successful in locating and stopping the leak, you should then return to the driller's panel to begin an item by item check of the system. Upon returning to the driller's panel, change the pod selector valve to operate the system on the other pod. For example, if you are operating on the blue pod, switch over to the yellow pod. This will tell you whether the leak is in one side, or both sides, of the system and will let you begin to isolate the leak. If the leak stops when you change from the blue to yellow pod, then you know that the leak is located in the blue side of the system. If the leak doesn't stop when you change control pods, then you know that the leak is either below the control pods or somewhere in the hydraulic control manifold. Let's take a hypothetical example and say that the flow meter stopped when you changed from the blue to the yellow pod. Ibis tells you that the leak is somewhere in  In-Spec Inc. 1999. 57. BOP Hydraulic Control Systems.

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