HIPPS

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 (or HIPS)?

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 Instrumented Functions (SIF) and Safety Instrumented Systems (SIS) when discussing a solution to protect equipment, personnel and environment. A system that closes the source of over-pressure, with at least the same reliability as a safety relief valve, is usually identified as a HIPPS. Systems using other sensors may be called HIPS, High Integrity Protection System. Generally both HIPS and HIPPS require a Safety Integrity Level SIL3 and a Systematic Capability SC3.
The systems can also be designed to EN12186, the final elements are in compliance with EN14382.

A HIPPS or HIPS is a complete functional loop consisting of:

• Electronic or mechanical initiators, the sensors. For HIPPS these detect the pressure
• 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 field data and derived reliability data for the valve actuator combination.
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 50 000 operational years (with more than 3.700 final elements). The Mokveld final elements are therefore proven-in-use for high reliability safety applications in upstream and downstream Oil and (hydrogen) Gas service.

The third party certified failure data enables Mokveld to supply safety systems to suit SIL3 or even SIL4 with proof test intervals that may exceed 1 year.

The Systematic Capability (SC3 / 4) is confirmed by the Functional Safety Management System (FSM) in accordance with IEC 61508 and IEC 61511. The safety systems will be designed and integrated by Functional Safety Engineers (FSE’s) present in all departments across the company.

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.

Based on our vast experience and expertise Mokveld offers two types of HIPPS

1. Integral mechanical HIPPS, since 1974
2. Full electronic HIPPS, since 2000

1. Integral mechanical HIPPS - using mechanical initiators

In 1974 the German DVGW certified the Mokveld final element including mechanical initiators in accordance with EN 14382 (former DIN 3381). Since that date Mokveld has field experience with safety shut-off valves (with actuator and initiator) closing within 2 seconds. 

Main features of Mokveld’s integral mechanical HIPPS:

• Integrated safety loop to IEC 61508 / EN 12186
• Safe and simple
• Option not requiring external energy (stand-alone HIPPS)
• No wiring required
• Set point accuracy < 1%
• System to SIL 3 or 4
• Third party validated failure data

Integral mechanical HIPPS 1oo2, pneumatic version

Unique and stand-alone

A safety system with Mokveld’s mechanical initiators is a unique system. The fully mechanical initiators are our own design and development from Mokveld and they are available for hydraulic or pneumatic actuated final elements. Mokveld’s integral mechanical HIPPS is easily identifiable in the plant, easy to operate and simple. This makes it an inherently safe system. As an option a full stand-alone system requiring no external energy is available for applications in remote areas.

Third party validated

Because Mokveld gained field data on their HIPPS (both final element and mechanical initiator) since 1974 a vast amount of reliable operational data is available. Third parties have validated this data. Mokveld can therefore supply a fully integrated (mechanical) HIPPS for your SIL 3 or SIL 4 applications.

2. Full electronic HIPPS - with electronic pressure transmitters

When designing a HIPPS Mokveld always treats a HIPPS (and other SIS) as a complete certified functional loop and not on separate component level. Safety wise the HIPPS loop is designed in accordance with IEC 61508 and 61511. On the specification side of the final element the design is in accordance with EN 14382 (DIN 3381). The misunderstanding that ‘system’ stands for controller and that a SIS can be designed on component level, is the cause of the biggest problem in the implementation of HIPPS. The under specification of mechanical components and the acceptance of component Safety Integrity Level (SIL) certification, instead of verification of the complete loop SIL is still a pitfall.

Main features of Mokveld’s full electronic HIPPS:

• Integrated safety loop to IEC 61508 and 61511
• No limit on distance between transmitters and final element
• Communication with Plant Safety System
• Possibility of integrated monitoring
• Hard-wired solid-state logic solver
• High integrity manifold block for safer operation
• System to SIL 3 or 4 

Full electronic HIPPS 2oo3, pneumatic version

Mokveld engineers can provide support in an early phase of the project. We can assist in defining suitable HIPPS architecture, fault tree analysis, determining the pressure rise in the protected volume and the required stroking times and set points of the entire system.

HIPPS are critical elements in a process loop. Malfunction or failure of a HIPPS can seriously affect plant operation, the environment and personnel. The design of a HIPPS should be based on sound technical and economical arguments and long-term perspectives. Selecting a Mokveld HIPPS with proven reliable performance will ensure a safe and reliable operation of your plant.