What is a HIPPS?
This application provides an interactive guide to High-Integrity Pressure Protection Systems (HIPPS). A HIPPS is an automated Safety Instrumented System (SIS) designed to prevent the over-pressurization of a plant, pipeline, or process. Unlike conventional pressure relief valves (PSVs) that release excess pressure (and process fluids) to the environment, a HIPPS proactively isolates the source of the high pressure *before* the design limits of the system are exceeded.
Primary Goal
Containment. It stops the problem at the source, preventing loss of containment and environmental release.
Safety Integrity Level (SIL)
Typically designed to SIL 3 or SIL 4 standards, representing a very high level of reliability and risk reduction.
Response Time
Extremely fast-acting, often required to close final valves in under 2-3 seconds from detection.
System Architecture
A HIPPS consists of three main parts that work together to provide automated, high-reliability protection. The system relies on redundancy (e.g., multiple sensors and valves) to ensure it functions when needed and avoids "spurious trips" (false shutdowns). Click on the buttons below to explore each component and see it highlighted in the diagram.
HIPPS Process Flow
Sensors / Initiators
These are the "eyes" of the system. A HIPPS uses multiple independent pressure transmitters (e.g., 3 sensors) installed on the line. To ensure reliability and avoid false alarms, it uses "voting logic." For example, in a 2-out-of-3 (2oo3) configuration, at least two of the three sensors must detect an overpressure condition before a shutdown signal is sent. This provides high safety (it will work if one sensor fails) and high availability (it won't trip if one sensor gives a false reading).
Operational Scenarios
A HIPPS has two primary states: normal operation, where it is "on guard," and an upset condition, where it takes action. The system is designed to be "fail-safe," meaning it will move to the safe (closed) state if it loses power or detects a critical fault. Select a tab to see how the system behaves.
Normal Operation: System Monitoring
During normal operation, the process pressure is below the HIPPS setpoint. The sensors continuously report a "safe" status to the logic solver. The logic solver sees that no shutdown condition is met and commands the final element valves to remain open. Product flows freely to the downstream protected system.
HIPPS vs. Conventional PSV
This section compares HIPPS with traditional Pressure Safety Valves (PSVs). While both protect against overpressure, they operate on fundamentally different principles. A PSV is a reactive, mechanical device that *releases* pressure, while a HIPPS is a proactive, instrumented system that *prevents* it. The chart below visualizes the vast difference in reliability.
Risk Reduction Factor (RRF) Comparison
Note: Chart uses a logarithmic scale to visualize the vast difference in RRF.
| Feature | HIPPS (High-Integrity Pressure Protection System) | PSV (Pressure Safety Valve) |
|---|---|---|
| Principle | Preventive. Isolates the source of high pressure. | Reactive. Relieves excess pressure by opening to atmosphere/flare. |
| Process Fluid | Contained within the system. | Released from the system. |
| Environmental Impact | None. No emissions during an event. | High. Releases process fluids (gases/liquids) to the environment or flare system. |
| Reliability (RRF) | Very High (SIL 3-4). RRF of 10,000 to 100,000. | Moderate. RRF typically 10 to 100. |
| Complexity | High. An instrumented system with sensors, logic, and valves. | Low. A simple, self-contained mechanical device. |
| Testing | Can be tested online via Partial Stroke Testing (PST) without stopping flow. | Requires removal and bench testing, or in-situ testing which may require shutdown. |
Applications & Standards
HIPPS are specified in high-risk applications where conventional relief systems are undesirable or insufficient. Their design and implementation are governed by strict international safety standards, which are listed here for reference.
Common Applications
- Upstream Oil & Gas: Protecting pipelines from high-pressure wellheads.
- Subsea Operations: Preventing overpressure in subsea flowlines and manifolds.
- Refineries & Petrochemical: Protecting reactor vessels and other critical equipment.
- LNG Plants: Safeguarding cryogenic processes and storage.
- Flowlines: Allowing the use of lower-rated (and more economical) downstream piping.
- Toxic/Flammable Service: Anywhere releasing the process fluid is environmentally unacceptable or extremely hazardous.
Governing Standards
- IEC 61508: Functional Safety of Electrical/Electronic/Programmable Electronic Safety-Related Systems. (The foundational standard).
- IEC 61511: Functional Safety - Safety Instrumented Systems for the Process Industry Sector. (The specific standard for HIPPS).
- API 14C: Recommended Practice for Analysis, Design, Installation, and Testing of Basic Surface Safety Systems for Offshore Production Platforms.
- ASME B31.8: Gas Transmission and Distribution Piping Systems.