+1 vote

Specifications and requirements for subsea hydraulic system cleanliness?

asked Jan 22, 2016 in Engineering by palagianomar (590 points)
Can someone please share the common specifications and requirements for subsea hydraulic system cleanliness?

2 Answers

+3 votes
answered Jan 22, 2016 by julien.cargill (1,080 points) | selected Jan 31, 2016 by odadmin
Best answer

All subsea valves associated with or controlled by the subsea control system and/or IWOCS should:

  • Be designed and manufactured to attain, as a minimum, a hydraulic cleanliness level meeting SAE AS 4059D Class 6 B-F requirements through factory acceptance testing.  Class 8 is the minimum level of cleanliness during Systems Integration Testing (SIT) and offshore work.
  • Be capable of maintaining a Class 8 level of cleanliness during subsea operations throughout the expected field life.
  • Be designed and qualified to operate properly even if the fluid cleanliness drops to Class 12 throughout the design life.  The Subsea Control Module (SCM) filter should be capable of operating at Class 8 for the design life.
  • Be assembled clean and should not rely on flushing after assembly to obtain the Class 6 cleanliness level.  Cleaning operations to be performed should include demagnetizing, vibration, cleaning in ultrasonic bath, clean room assembly and flushing.
  • Include provisions to circulate hydraulic fluid through the system for purging air/flushing and taking fluid samples.
  • Be designed to eliminate air traps and to facilitate flushing.
  • Be certified by the microscope method.
+2 votes
answered Jan 25, 2016 by Kodi.Moretz (505 points)
Fluids received in drums should be cleaned to Class 6 prior to use in any hydraulically operated permanent or running tool equipment.

Circuits for running tools and those operated exclusively by ROV hot stab should be cleaned to Class 8.

You can refer to Appendix of ISO 13628-6 Properties and Testing of Control Fluids for further information.