Partial Stroke Testing A.F.M. Prins
Partial Stroke Testing PST in a safety related system. As a supplier we have a responsibility to our clients. What do they want, and what do they really need? I like to explain the concept based on a simple example: HIPPS
HIPPS What is a HIPPS? HIPPS stands for High Integrity Pressure Protection System A HIPPS is a protection device. It acts like a fuse; if the current is too high, the fuse blows. L O G IC S O L V E R If the pressure is too high; M A N IF O L D & TRANSM ITTERS the valves close. SH U T O F F V A L V E S The system behind is safe!
A HIPPS is that something NEW? HIPPS are used for more than 30 years. And HIPPS are still used, all around the world. In all kind of applications.
Why a HIPPS? A HIPPS is, or can be a protection against Human casualties Environmental damage Damage to your Investments Penalties due to emissions (no flaring policy) Too high investments.?
When Availability & Integrity Really Count
SAFETY A.F.M. Prins
process risk Residual risk level Tolerable risk level Risk inherent in process SIS Risk reduction Other External Process Risk
risk graph Extent of damage (S) S 1 : Minor injury/damage S 2 : Serious injury, death of one person S 3 : Death to several persons S 4 : Catastrophic consequences S 1 A 1 G 1 w 1 1 1 w 2-1 w 3 - - Frequency of exposure (A) S 2 G 2 2 1 1 A1: Seldom A2: Quite often to permanent Avoiding of hazard (G) G1: Possible G2: Almost impossible S 3 A 2 A 1 A 2 G 1 G 2 2 3 3 4 2 2 3 3 1 2 2 3 Probability of event (W) S 4 4 4 3 W1: High W2: Low W3: Very low
requirements safety instrumented system From the risk graph a Target SIL for the SIS will result The target SIL indicates the maximum average Probability of failure on demand (PFD) the safety system may have Safety Integrity Level Average Probability of failure on demand Safety Availability Risk Reduction Factor 4 10-5 to < 10-4 > 99.99% > 10 000 3 10-4 to < 10-3 99.9-99.99% 1 000-10 000 2 10-3 to < 10-2 99-99.9% 100-1 000 1 10-2 to < 10-1 90-99% 10-100 0 (Control NA)
Industrial standards for safety IEC 61508 Functional safety of electrical/electronic/programmable electronic safety-related systems (E/E/PE) IEC 61511 Can be applied to all electro-mechanical systems across a wide range of industries. Functional safety / Safety Instrumented Systems for the process industry Targeted at end users implementing SIS for the process industry, it has with more emphases towards PROVEN IN USE
Fault tolerance
three most significant aspects of IEC 61508 The Safety Lifecycle The Pipe-to-Pipe approach The quantitative safety assessment
Periodic proof test interval PFD 10-5 SIL 10-4 3 10-3 10-2 Required SIL 2 1 10-1 T0 T1 T2 T3 T4 Time
Safety Instrumented System Pipe to pipe Process pipe Process pipe Logic solver Input A A D D Protection logic Output O O Air Vent. Transmitter Safety valve Sensors Final elements
Quantitative Assessment Total Loop The safety requirements concern (as a minimum) a complete safety loop and are expressed in Safety Integrity Levels (SIL). PFD The SIL levels correspond to the average Probability of failure on demand (PFD target) of a complete safety loop. Quantification Calculations need to be performed to show that a specific safety loop meets its required SIL level.
Probabilities / Safety Integrity Level Pfd loop = SIL = Pfd target Pfd sensors + Pfd logic solver + Pfd final elements TR TR Air Vent TR TR Safety Safety Interlocks Interlocks TR TR Safety valve
HIPPS Functionality A.F.M. Prins
Process parameter range Boom? Mechanical safety level Safety Unsafe Condition ESD action Trip level Alarm Condition Operator takes action High alarm level Control Normal Condition High level Process value Low level Time
What is a HIPPS HIPPS, the last line of defense ProSafe COM / Sequent of event / Alarm handling Status information / Analogue values Modbus RS-232, RS-485 MC-562 AI repeat Communication to PLC/DCS/SCADA Local SOE recorder Modbus HIPPS ESD PSD 4-20 ma 4-20 ma Prog. Tripamp AI-917 Prog. Tripamp AI-917 4-20 ma Prog. Tripamp AI-917 2oo3 HIPPS Logic Solenoid Driver Output FO-529 DO-523 Lamp driver 4 * 5 W Solenoid driver DCS P T P T P T 2oo3 manifold Inputs for: Reset, valve test Proximity switches, other Input DI-511 8-channel Prog. Tripamp AI-917 Analog value discrepancy Alarm Logic HIPPS solenoid local reset HIPPS solenoid local reset HIPPS solenoid local reset HIPPS solenoid local reset Flow direction HIPPS valve HIPPS valve
Pressure Transmitter A.F.M. Prins
TÜV SIL 2 Approved
Measuring Transmitters; certified for use in a SIL 2 loop 3 transmitters meeting SIL 3 SIL 4 voting 2oo3 or 1oo2. What is the influence of a common fault...
MANIFOLD A.F.M. Prins
Triple Manifold
Locking Manifolds Key controlled procedures in single manifolds. Double block and bleed Mechanical interlock Detection SIL approval
LOGIC SOLVER A.F.M. Prins
Innovation and Continuity 1997 1990 ProSafe-SLS 1970 MagLog 24 1960 MagLog 14 MagLog 3 A PROVEN CONCEPT COMFORTABLE IN SAFETY
Magnetic Core B B H H Rectangular Hysteresis loop Flat Hysteresis loop Magnetic particle orientation Anticlockwise magnetisation Clockwise magnetisation
AND Function Write output Read X Y & Z
AND function X Y A A B-pulse (Clock) 0 +20V B A 0 +20V B A-pulse (Clock) 0 +20V A Z Logical 0 X & Z Logical 1 Y
HIPPS Valves A.F.M. Prins
Control of the Valves Solenoids Actuator Valve
HIPPS Valves Testing of a Valve Partial stroke testing What are we testing? What do we claim? Is that safe? Please note that Partial Stroke test can never replace a full stroke test!!! Full stroke test
HIPPS Philosophy Isolate the source of the problem rather than releasing to the atmosphere. To do so; High reliable equipment is required! A failure in your HIPPS will result in damage of equipment or endanger the safety of personnel.
CERTIFICATION A.F.M. Prins
safety consultancy Wherever you need safety expertise, whether in bid phase, early project involvement, or in project execution contact a Safety Assurance & Consultancy
Conclusion A.F.M. Prins
Conclusion on PST
Conclusion In general you can say: A well designed HIPPS, not only saves money but makes the world a little safer after all.
Thank you for your attention. Commitment means building the future to last.