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HIPPS is applied to prevent over-pressurisation of a plant or pipeline by shutting off the source of the high pressure. The Mokveld HIPPS totals over 19000 operational years and are therefore proven-in-use for high reliability safety applications. 

 

A typical HIPPS safety loop
4” / ASME 2500 1oo2 mechanical HIPPS on mobile gas production unit in The Netherlands
1oo2 electronic HIPPS protecting ASME 600 installation against pressure from ASME 900 pipeline
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Product summary

Application High Integrity Pressure Protection System (HIPPS)
Final element Mokveld’s axial on-off valve with integrated actuator and solenoid or mechanical initiators
Scope Sizes: 2" - 48"
Ratings: ASME 150 - 2500 or API 3000 - 10 000
Higher pressure ratings upon request
All: DIN3381 / EN14382 certified
Full closure in 2 seconds
In preference to Flare systems
Venting or relief systems
Other designations Safety shut-down systems (SSD)
Safety Instrumented System (SIS)
Safety Instrumented Function (SIF)
Over-pressure protection systems (OPPS)
   

Main product features

Traditional systems
In traditional systems over-pressure is dealt with through relief systems. Relief systems have obvious disadvantages such as release of (flammable and toxic) process fluids in the environment and often result in a large footprint of the installation. With increasing environmental awareness relief systems are no longer an acceptable solution. A relief system aims at removing any excess inflow, where as a HIPPS aims at stopping the inflow of excess fluids and thus avoiding over-pressure.
 
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 19 000 operational years (with more than 1000 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  to deliver a full stroke in 2 seconds for applications in untreated hydrocarbons is: λ = 2,98 x 10-4 / year. The failure rate for the Mokveld mechanical initiator mounted on the final element is:
λ = 7,72 x 10-4 / year. This data enables Mokveld to supply a HIPPS to suit Safety Integrity Level (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.
 
 
 
Two types of HIPPS
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 engineering assistance
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.
 
 
For more detailed information, please contact Mokveld
 

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