HIPPS is an abbreviation of “High Integrity Pressure Protection System”. It’s reliable in very rapid isolation of pipelines. HIPPS systems are applied to prevent over-pressurisation of a plant by shutting-off the source of the high pressure.
Idea of HIPPS is to be used instead of traditional safety systems such as relief devices with four main advantages:
- Environment protection: relief systems release the service fluid to the atmosphere which while HIPPS avoid flui released out of the system keeping the environment free of emissions.
- HIPPS have to be a safety level equal or higher than the traditional relief methods; calculated safety levels show to be ten times more reliable than traditional methods.
- Creating a frontier between two parts of the installation allows the downstream part of the valves of the HIPP lower pressure and therefore, to reduce the cost of pipes and related pressure equipments
installed on that part.
They are so reliable that the need for other safety related devices such as Safety Relief Valves can be minimised.
A HIPPS is designed and built in accordance with IEC 61508 and IEC 61511 standards. These international standards refer to safety functions and safety instrumented systems when Dependable pressure protection for downstream systems discussing a solution to protect equipment, personnel, and environment. A system that closes the source of overpressure within the required timeframe and incorporates redundancy within the initiators (pressure sensors), logic solver, and final elements (shutdown valves) with at least the same reliability as a safety relief valve is usually identified as a HIPPS.
A High Integrity Pressure Protection System is a complete functional loop consisting of:
- The sensors, (or initiators) that detect the high pressure
- The logic solver, which processes the input from the sensors to an output to the final element
- The final elements, that actually perform the corrective actions in the field by bringing the process to a safe state. The final element consists of a valve, actuator and possibly solenoids.
Hydraulic (mechanical) HIPPS safety loop
The hydraulic (mechanical) HIPPS provides a self-contained, independent protection system operated on demand with one-out-of-two (1oo2) or two-out-of-three (2oo3) (voting) pressure sensor inputs, a hydraulic logic solver, and two spring-return hydraulically actuated safety valves. The unit is typically self powered and can be provided with additional real-time controls via a hydraulic power unit (HPU). This pressurizes the system and opens the safety shutdown valves. The system remains open (armed) until an abnormal condition is detected. If an abnormal condition is detected, then the system closes the two actuated final element valves, protecting the downstream production or facility.
Electronic HIPPS safety loop.
The electronic HIPPS is a self-contained, independent system operated on demand with 1oo2 or 2oo3 (voting) pressure transmitter inputs, an electronic logic solver, and two spring-return hydraulically actuated safety valves. The unit can be self powered with a manual hand pump or HPU and can also be configured to operate using facility power sources. This pressurizes the system and opens the safety shutdown valves. The system remains open until an abnormal condition is detected. If such an event is detected, the system closes the two actuated final element valves, protecting the downstream production or facility.
Typical safety loop.
The primary function of HIPPS is to detect high-pressure conditions and close isolation valves to protect lower-rated downstream infrastructure. The system operates autonomously and is independent of the facilities’ process shutdown (PSD), emergency shutdown (ESD), or control systems. HIPPS are fail-close by design based on the signal of an overpressure event and can be configured to operate on other events, such as a loss of motive power of instrument signal. It is typically fail-close for any loss of instrument air, hydraulic power, electric power, or instrument signals. Each HIPPS loop is independent. A HIPPS is designed with redundant safety functions to reduce the risk of failure on demand and to maximize availability.
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
Main features of 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
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
Applications
Wellhead flowline
Pipeline and compressor stations
Flaring systems
Separation and processing facilities
Gas plants
Gas storage
Floating production storage and offloading (FPSO) vessels
Offshore platforms
Onshore operations
Benefits
Protects downstream equipment
Minimizes flare system requirements
Reduces weight of downstream systems
Maximizes system availability
Reduces high-pressure pipelines or vessel overpressure risk
Improves economic viability of a development
Reduces risk to a facility, plant, or flowline
Reduces the total load of relief in a relief or flare system
Features
High-integrity, flexible mechanical and electronic design
Pneumatic and hydraulic actuator options (conventional or compact)
Self-contained hydraulic system
Partial- or full-stroke testing (automated or mechanical)
SIL 3 certified design
System diagnostics and status feedback
Conformance to safety regulations and environmental policies