Advantages of HIPPS
HIPPS provides a technically sound and economically attractive solutions to protect equipment in cases where:
- High pressures and / or flow rates are processed
- The environment is to be protected
- The economic viability of a development needs improvement
- The risk profile of the plant must be reduced
What is HIPPS?
HIPPS is an instrumented safety system that is designed and built in accordance with the IEC 61508 and IEC 61511 standards. These international standards refer to safety functions (SF) and Safety Instrumented Systems (SIS) when discussing a solution to protect equipment, personnel and environment. A system that closes the source of over-pressure within 2 seconds, with at least the same reliability as a safety relief valve, is usually identified as a HIPPS.
A HIPPS is a complete functional loop consisting of:
- The initiators that detect the high pressure. These initiators may be electronic or mechanical.
- For electronic HIPPS, a logic solver, which processes the input from the initiators to an output to the final element.
- The final elements, that actually perform the corrective action in the field by bringing the process to a safe state. The final element consists of a valve and actuator and possibly solenoids or mechanical initiators.
Mokveld reliability
Third parties, like the German TÜV and Atomic Energy Agency, have validated the Mokveld database of installations and the derived reliability data. Failure rates for both clean and unclean fluids are available for 2 seconds stroking time applications. Mokveld’s vast experience in fast stroking final elements totals over of 35 000 operational years (with more than 2500 valves). The Mokveld final elements are therefore proven-in-use for high reliability safety applications in natural gas and multiphase hydrocarbons.
The certified Mokveld failure rate for the final element (being the valve + actuator) for a failure to deliver a full stroke in 2 seconds for applications in untreated hydrocarbons is: λd = 1,0 x 10-4 / year. The failure rate for a single Mokveld hydraulic mechanical initiator is: λd = 9,7 x 10-4 / year. This data enables Mokveld to supply a HIPPS to suit SIL 3 or even SIL 4 with a proof test interval of 1 year or a system fully in accordance with EN 12186 or EN 14382.
The Mokveld final elements do not require additional electronic systems, like partial stroke testing devices, to meet SIL 3 with a 1 year test interval. A separate technical datasheet on this subject is available.
