API SPEC 17F:2003 pdf download

API SPEC 17F:2003 pdf download.Specification for Subsea Production Control Systems.
All control fluids introduced into the system shall meet the selected cleanliness requirements. Provisions shall be made to maintain cleanliness (e.g. filters) and to take samples.
Methods for circulation and flushing out seawater and solid particle contamination should be considered for the lifetime of the system.
The subsea hydraulic system should be designed to tolerate some contamination by seawater and solid particles. Vulnerable parts with very low fluid consumption (e.g. directional control valve pilot stages) shall be protected by filters or suitable screens.
5.1.3.3 Overpressure protection
System pressure-relief (safety) valve settings shall not exceed design pressure (rated working pressure).
The setting of the primary relieving device shall not be greater than the design pressure.
5.1.3.4 VIbration and pressure pulses
Design of the hydraulic system should consider high-pressure pulses and vibration on lines, valves and couplers.
This shall include external sources (e.g. chokes).
5.1.4 Electrical system
The electrical power for the surface control equipment of an electrohydraulic control system, its associated interfaces, and the subsea equipment should be supplied from an uninterruptible power supply (UPS) to ensure continued operation in the absence of primary power for a minimum period of 30 mm.
The UPS system should include isolation and regulation to ensure a clean constant supply of electrical power.
In order to minimize the number of conductors in the control umbilical, signal multiplexing and combining power and signal on the same pair of wires should be considered.
For subsea assemblies, electrical components of high reliability shall be used. Components shall be procured to industrial grade or better wherever possible.
Topsides equipment should be procured to industrial grade or better wherever possible. The equipment should be designed to facilitate modular replacement.
5.1.5 Redundancy
The level of redundancy will depend on the actual field development and reliability of equipment used. Generally the following guidelines are applicable.
Redundancy is most important when component replacement is difficult, or when significant production availability or operating capability is lost through single-component failure.
When redundant components are used, the reliability of the method for switching from the primary to the backup component should be evaluated.
The subsea electrical distribution system design should be redundant or include spares that can be configured to replace failed circuits.
The subsea hydraulic distribution system should be redundant or should include spares that can be configured to replace failed lines in either LP or HP service.
Redundancy of instruments should be based on criticality and retrievability of the sensors.
The level of redundancy throughout the system will influence complexity and reliability. An analysis of the expected
benefit from redundancy should be performed for all critical parts of the system.
5.1.6 Reliability
Reliability of the subsea control system should be optimized to result in maximum benefit. The use of high-reliability components should be compared against redundant components of more standard quality. Special consideration should be given to the reliability of components that are difficult to repair or replace.
Minimum reliability, mean time to repair and availability targets for subsea equipment should be stated for each project.
Critical sensor systems located on subsea trees or manifolds should have component reliability, or reliability obtained by redundancy, that is optimum relative to the need for the sensor data and the risk of subsea intervention. This is most important for sensors that trigger safety or shut down responses.
Reliability figures for all critical components and assemblies should be documented and justified by calculations. tests or an accepted industry data base.
5.2 Functional requirements
5.2.1 General performance requirements
Control system equipment built to this part of ISO 13628 should perform in a manner which is efficient, safe and protects the environment. Performance requirements for the control system as a whole should
provide for individual or multiple operation of all remotely controlled subsea valves:
provide sufficient data-readback information to operate the system safely and to react promptly to conditions requiring emergency shut-down (ESD).