HIPPS Development Project

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Kelly May
5 years ago
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1 Hydraulic HIPPS

2 HIPPS Development Project This presentation describes the Energy Equipment Corporation Hydraulic HIPPS control development project, and gives: Brief background information about Energy Equipment Corporation and the Hydraulic HIPPS concept. How it works. Reliability. The advantages of the system. Project status & objectives.

3 Background to the HIPPS Project. Energy Equipment Corporation are US based manufacturers of valves, actuators and chokes, used mainly within the oil industry. Founded in 1986 the company has grown steadily and turnover during 2006 is expected to exceed $40Million. The EEC hydraulic Subsea HIPPS is one of several development projects currently in progress. EEC took the decision to develop a hydraulic subsea HIPPS for several reasons.

4 Background to the HIPPS Project. EEC were confident that a simple, more cost effective and potentially more reliable system of HIPPS control could be developed, based on the same mechnical principles as their Line Pressure Operated Valve. In addition, the situation in the GoM, with the MMS slow to approve HIPPS using programmable electronic controls, it seems there may be good reasons for developing an alternative control arrangement. In essence, our objective was to design a control arrangement similar to that used with the EEC Line Pressure Operated Valve, but for a safety critical subsea application. Our concept resulted from bringing together this technology and placing it into the context of existing subsea systems.

5 General Project Objectives Improve/enhance current HIPPS technology. Reduce the need for project specific HIPPS design. Reduce the reliance upon E/E/PE features within the system design. Why? A different approach to provide diverse control means within a layered system, i.e. one system controlled using programmable electronics, and one with no safety critical E/E/PE controls. To create a simple solution..iec states These systems are usually complex, making it impossible in practice to fully determine every failure mode or test all possible behaviour

6 The EEC HIPPS Control Concept The key to this concept is a differential pilot pressure dump valve operated using the PCS LP or HP system supply pressure as a reference. There need be no specific relationship between the system supply pressure used and the required HIPPS trip pressure. Reference pressure direct Vent from the HPU. (HP or LP) The key to this design is the differential pilot pressure dump valve. Pressure transfer barrier HIPPS Valve SCM

7 Differential Pilot Pressure Dump Valve Pressure A Pilot 1. Pressure B Vent Line Pilot 2. Pressure C HIPPS Valve Fig. 1. The Differential Pilot Pressure Dump Valve is configured for specific applications, i.e. the relationship between the opposing pilot piston areas, and the ability to change this relationship during the system design stage is used to determine the way in which the valve operates. In the example above, Pressure C can be lower than Pressure A but because Pilot 1 piston has a smaller area than Pilot 2, Pressure C will apply sufficient force to the main stage piston, to move the valve to the vent position. This means that Pressure A need have no specific relationship to Pressure C,

8 Example (HP) For this example, the PCS HP system supply pressure is 690 bar. The design pressure of the pipeline to be protected is 207 bar. With a safety margin, the HIPPS trip pressure is specified at 200 bar. The close pilot piston is 20mm in diameter and therefore has an area of mm² = Therefore X = required open pilot piston area of mm² (37.15 mm dia), to make the dump valve open when the open pilot is exposed to more than 200 bar.

9 HPU HV 1 Energy Equipment C O R P O R A T I O N HV 2 O C O C O C O C O C O C I B I I B I E 1 E 2 TFL CHEM MFL SCM The HIPPS unit takes a hydraulic reference pressure, directly from the controls distribution system

10 Configuration. The pressure reference source can be either HP or LP. Local demand for fluid within the system will result in system pressure reduction for periods of time. A pressure stabilisation means will be included in the system, to prevent the changes in pressure from triggering a HIPPS valve shut down. The HP system can be used as a source and the need for any pressure stabilisation will be unlikely. A pressure transfer barrier (sealed metal diaphragm design) is required. Consideration must be given to the additional force required to drive the PTB when calculating piston areas.

11 The dump valve is bolted to this surface Push rod end Pressure Converter The pressure transfer barrier is better described as a pressure converter. It uses the pressure from the pipeline to create a force. The force acts upon the dump valve main stage piston, via a pushrod. Metal-to-metal sealing coupling

12 Pressure Converter In this view, pipeline pressure is below HIPPS trip pressure. The piston / diaphragm / pushrod, are therefore in the retracted position Pressure from pipeline

13 Pressure Converter In this view, pipeline pressure has increased to above the HIPPS trip pressure. The piston and diaphragm have moved, and the pushrod is extended. To prevent damage to the diaphragm from over pressure, the top surface of the diaphragm matches the top surface inside the diaphragm chamber.

14 HPU Controls Umbilical Containing HP and LP Supplies SCM DSV Flow from tree

15 HPU Controls Umbilical Containing HP and LP Supplies SCM The EEC HIPPS uses a hydraulic control system. DSV Flow from tree

16 HPU Controls Umbilical Containing HP and LP Supplies SCM The Differential Pilot Pressure Dump Valve forms the basis of this system DSV Flow from tree

17 HPU Controls Umbilical Containing HP and LP Supplies SCM The dump valve is configured to use any available control system supply pressure DSV Flow from tree

18 HPU Controls Umbilical Containing HP and LP Supplies SCM Pressure from the HP supply applies a force to the closing pilot DSV Flow from tree

19 HPU Controls Umbilical Containing HP and LP Supplies SCM Flow from tree Pressure from the pipeline applies an opposing force to the opening pilot DSV

20 HPU Controls Umbilical Containing HP and LP Supplies SCM The required pilot piston diameters are each calculated at the design stage, to achieve the required HIPPS trip pressure. DSV Flow from tree

21 HPU Controls Umbilical Containing HP and LP Supplies SCM In this example: The HIPPS will use 10,000 PSI, from the control system HP hydraulic supply DSV Flow from tree

22 HPU Controls Umbilical Containing HP and LP Supplies SCM DSV To provide a pipeline HIPPS Trip Pressure of 2,750 PSI Flow from tree

23 HPU Controls Umbilical Containing HP and LP Supplies SCM 10,000 PSI is supplied to a 20mm diameter closing pilot piston DSV Flow from tree

24 HPU Controls Umbilical Containing HP and LP Supplies SCM When the pipeline pressure increases, and the 38.14mm diameter opening pilot piston is exposed to 2,750 PSI DSV Flow from tree

25 HPU Controls Umbilical Containing HP and LP Supplies SCM The opposing forces, to close or open the dump valve become equal. DSV Flow from tree

26 HPU Controls Umbilical Containing HP and LP Supplies SCM So, when the pressure in the pipeline exceeds 2,750 PSI DSV Flow from tree

27 HPU Controls Umbilical Containing HP and LP Supplies SCM DSV Flow from tree The force applied to the opening pilot increases

28 HPU Controls Umbilical Containing HP and LP Supplies SCM This exceeds the closing force and pushes the dump valve to the open position. DSV Flow from tree

29 HPU Controls Umbilical Containing HP and LP Supplies SCM The HIPPS valve actuator starts to vent DSV Flow from tree

30 HPU Controls Umbilical Containing HP and LP Supplies SCM In the closed position, the HIPPS valve now provides protection for the pipeline section downstream of the HIPPS DSV Flow from tree

31 Significant Issues Subsea test and calibration. Susceptibility to supply pressure fluctuation triggering ESD.

32 Supply Pressure Fluctuation The supply (reference) pressure, now passes through a device we call a supply pressure stabiliser (SPS) prior to reaching the dump valve closing pilot. The SPS provides pressure damping, preventing short term pressure fluctuations from reaching the HIPPS Controls.

33 Subsea Test and Calibration During a meeting in December 2005 with the MMS in Houston, their concerns relating to how the system would be tested were discussed. A proposed method of system testing was presented to the MMS in March The proposal was reviewed against a list of requirements originally set out by the MMS in December 2005, and judged to be satisfactory.

34 Subsea Test and Calibration In the example presented to the MMS, the section of pipeline between the PWV upstream of the HIPPS, and a pipeline test isolation valve downstream of two HIPPS valves, could be pressurised via a chemical line. With the PWV closed and the pipeline test isolation valve closed, pressure is gradually increased until a HIPPS valve ESD is triggered. The pressure required to trigger the ESD is monitored using pressure transducers positioned alongside the HIPPS valves, on the pipeline. In addition to the pipeline pressure and the control system hydraulic supply pressure, six events are monitored/recorded during the test. They are the two HIPPS valve closures and four dump valve closures. (four because they are dual redundant, two on each HIPPS valve actuator) Position indicators are used to monitor HIPPS and dump valve positions during the tests.

35 Subsea Test and Calibration The additional up stream and downstream system valve tests can be carried out by pressurising the pipeline, again via the chemical line, and isolating pressure within the required section for a specific valve test. These tests will also use pressure transducers positioned at the HIPPS to monitor pressure. In a layered system where the hydraulic HIPPS control is working along side a programmable electronic HIPPS control, the pressure transducers used during testing will be the same as those used to supply the data on which the 2oo3 voting is based. However, although this instrumentation is used during testing, no data from instrumentation forms any part of the ESD decision making process within the hydraulic HIPPS.

36 Reliability An evaluation of the HIPPS design has been carried out by Risktec, risk analysts specialising in SIL assessment. They provided a preliminary reliability statement, concluding that the EEC HIPPS will be capable of meeting the requirements for a SIL 3 protection system. A copy of the report can be made available on request.

37 Advantages Fully compatible with existing production control systems. Will provide a strong contrast to E/E/PE based controls when used within a layered system. Significantly reduced project specific design and qualification..hence lower costs and reduced timescales

38 Design Focus The new part of this system, and therefore the focus of qualification testing, will be the pressure converter and the dump valve. As many field proven parts as possible will be used in the system. The pressure converter/diaphragm is a new design. An interface block, linking the pressure converter to an existing small bore valve is a new design. The small bore valve/actuator will have minor modifications made, to allow the actuator to link up with the adaptor, and also to minimise travel from the open to the closed position.

39 This slide shows a sectional view of the 1 bore LB Bentley valve selected for use as the basis for the dump valve and briefly describes the required modifications Significant Issues The stem is extended/modified to allow a pulling (opening) force to be applied The gate is reversed and the through bore within the gate and seats is machined as a slot, to reduce travel (currently to 0.37 ) from the closed to the open

40 The pulling force applied to stem moves the gate to the open position The Diaphragm to Dump Valve Adaptor Top of the LB Bentley valve actuator Push rod from pipeline diaphragm applies pulling force to stem

C O R P O R A T I O N HV 1 Energy Equipment HV 2 Configuration O C O C O C I B I O C O C O C I B I E 1 E 2 TFL CHEM MFL Dump valve 90 push rod to stem arrangement Closing

41 C O R P O R A T I O N HV 1 Energy Equipment HV 2 Configuration O C O C O C I B I O C O C O C I B I E 1 E 2 TFL CHEM MFL Dump valve 90 push rod to stem arrangement Closing hydraulic Supply Dump valve Dump valve position indicator Dump valve actuator 2 1/16 flanged diaphragm housing T to two parallel HIPPS controls HIPPS Dump Vent HIPPS valve/ actuator

42 Design Decisions The width of the slot through the seat/gate assembly within the dump valve may be changed, to provide the required speed of HIPPS pipeline valve closure. Currently the flow area is around 5 X that of a controls DCV. Whether to include a facility for a bolt-on arrangement (shown in the next slide) to accommodate SCMMB and SCM on EEC HIPPS skid. A provision for installation of the instrumentation necessary for a PES control will be made.

43 HIPPS Layered System HIPPS control module and mounting base HV 1 Energy Equipment C O R P O R A T I O N HV 2 O C O C O C O C O C O C I B I I B I. E 1 SPS E 2 TFL CHEM MFL

44 Hydraulic HIPPS

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