What is High Integrity Pressure Protection Systems (HIPPS)?


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High Integrity Pipeline Protection Systems Principle

They are so reliable that the need for other safety related devices such as Safety Relief Valves can be minimised. They have the following advantages:

  • Negating the need for flare systems to be sized for the case of a well failing to close.
  • Production piping downrating, giving potential cost benefits of more than 25%
  • Fast inventory isolation within two seconds
  • Huge capital cost savings

HIPPS Systems reduce the need for traditional mechanical relief devices and the level of flaring in oil and gas applications. New installations can use the benefits to minimise the requirement for pressure relief valve manifolds and flare systems.

On existing processing plants HIPPS Systems may eliminate the need to upsize the flare and the relief valve manifold as a result of increased throughput and in some cases actually provide the technology to remove an existing system.

Installing a HIPPS system at the wellhead or pressure source allows the downstream piping to be down rated and as a result reduce capital expenditure. On offshore installations flaring can be significantly reduced and on new installations, significant weight savings may be attained with the use of HIPPS.

The HIPPS design must be in accordance with IEC 61508 /61511. These standards define the configuration of the Certified (Typically TUV) Safety Instrumented System (SIS) to provide the necessary risk reduction and meet the required Safety Integrity Level (SIL).

The principal of operation is that the 2003 voted redundant pressure instrumentation trips on high pressure and isolates the pipeline very rapidly (typically within two seconds) by rapidly closing the valve. Dependant on the level of reliability required sometimes two HIPPS systems are installed in series.

The need for this is determined by reliability analysis against a required facility reliability figure. These figures are determined by factors such as safety, environmental, public perception of a prescribed event and cost of an event.

TYPICAL APPLICATIONS

  • Onshore Gas Pipelines
  • Offshore and Onshore Gas Well Pipelines
  • Offshore Subsea Applications

Integral Mechanical HIPPs systems - 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. The main features of Mokveld’s integral mechanical HIPPS are;

• 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 system

Full Electronic HIPPS - with Electronic Pressure Transmitters

Full Electronic HIPPS - with Electronic Pressure Transmitters - When designing a HIPPS it is best to treat 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. The main features of a full electronic HIPPS are;

• Integrated safety loop to IEC 61508 / EN 12186

• No limit on distance between transmitters and final element

• Communication with Plant Safety System

• Possibility of integrated monitoring

• Hard-wired solid-state logic solver

• System to SIL 3 or 4

• High integrity manifold block for safer operation

Full Electronic HIPPS - with Electronic Pressure Transmitters