Failure rates for process industry applications

SIL Safe Data is a web site listing a number of product categories used in process control
and the expected range of failure rates for process industry applications.

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About SILSafe Data

The use of realistic and application appropriate failure rate data has a significant impact on the validity of SIL verification calculations. Unfortunately there is often conflicting or incomplete information readily available to perform this task.

The impact of poor information can be dangerous under design or expensive overdesign.

Low Bound
3/12
High Bound
11/12

Determining if data is suitable for use is a critical first step. The SILSafeData.com website is a listing of upper and lower bounds for various devices commonly used in safety instrumented functions. These bounds were derived from statistical analysis of FMEDA results which represent design variations and application variations in combination with extensive comparisons with realistic field failure data. exida calls this technique “Predictive Analytics.”

SILSafe Data

The upper bound and lower bound dangerous failure rate data in SILSafeData is presented to perform quick comparisons with any piece of data. If the dangerous failure rate provided is not within the limits, further analysis and justification is warranted before using the provided data.

Data Check

Dangerous Undetected Failure Rates for Generic Sensors

Category Type Other DU Low Bound DU High Bound
Pressure Switch Mechanical 50 1000
Pressure Transmitter Analog/Smart 80 500
Pressure Transmitter Safety Certified 20 150
Temperature Switch Mechanical 50 1000
Temperature Pyrometer Smart 200 460
Temperature Transmitter Analog/Smart 600 1600
Temperature Transmitter Safety Certified 25 90
Thermocouple Close Coupled (<1 meter) excludes open circuit* 5 100
Thermocouple Extension excludes open circuit* 100 1000
Two/Three Wire RTD Close Coupled (<1 meter) excludes open circuit* 10 200
Two/Three Wire RTD Extension excludes open circuit* 110 2000
Four Wire RTD Close Coupled (<1 meter) excludes open circuit* 10 150
Four Wire RTD Extension excludes open circuit* 80 1800
* detected by input device
Level Switch Mechanical 50 1000
Level Transmitter Analog/Smart Radar 160 750
Level Transmitter Safety Certified Radar 70 750
Level Transmitter Analog/Smart Buoyancy 80 330
Level Transmitter Safety Certified Buoyancy 50 150
Level Transmitter Analog/Smart Capacitance 70 300
Level Transmitter Safety Certified Capacitance 50 150
Level Transmitter Analog/Smart Vibration 60 300
Level Transmitter Safety Certified Vibration 15 150
Level Transmitter Analog/Smart Ultrasonic 60 250
Level Transmitter Safety Certified Ultrasonic 40 150
Flow Transmitter Analog/Smart Magnetic 200 650
Flow Transmitter Safety Certified Magnetic 100 400
Flow Transmitter Analog/Smart Ultrasonic 400 850
Flow Transmitter Safety Certified Ultrasonic 200 700
Flow Transmitter Analog/Smart Coriolis 200 650
Flow Transmitter Safety Certified Coriolis 100 450
Flow Transmitter Analog/Smart Vortex 200 600
Flow Transmitter Safety Certified Vortex 100 400
Flow Transmitter Analog/Smart Thermal 200 1500
Flow Transmitter Safety Certified Thermal 100 800
Current Transmitter Analog/Smart 80 400
Current Transmitter Safety Certified 40 250

Dangerous Undetected Failure Rates for Generic Logic Solver Subsystems

Category Type Other DU Low Bound DU High Bound
Main Processor PLC/DCS General Purpose 500 2000
Power Supply PLC/DCS General Purpose 10 200
Analog Input Module PLC/DCS General Purpose 100 250
Analog Input Channel PLC/DCS General Purpose 5 40
Digital Input Module PLC/DCS General Purpose 50 150
Digital Input Channel PLC/DCS General Purpose 25 100
Digital Output Module PLC/DCS General Purpose 50 150
Digital Output Channel PLC/DCS General Purpose 25 250

Category Type Other DU Low Bound DU High Bound
Main Processor Safety PLC General Purpose 0 300
Power Supply Safety PLC General Purpose 0 50
Analog Input Module Safety PLC General Purpose 50 150
Analog Input Channel Safety PLC General Purpose 2 15
Digital Input Module Safety PLC General Purpose 10 30
Digital Input Channel Safety PLC General Purpose 3 10
Digital Output Module Safety PLC General Purpose 10 30
Digital Output Channel Safety PLC General Purpose 2 10

Dangerous Undetected Failure Rates for Generic Final Element Devices

Category Type Other DU Low Bound DU High Bound
Actuator Pneumatic Piston spring return 120 1000
Actuator Hydraulic Piston spring return 130 2000
Actuator Pneumatic Diaphragm spring return 110 910
Actuator Pneumatic Rack & Pinion double acting 400 2200
Actuator Pneumatic Rack & Pinion spring return 300 900
Actuator Hydraulic Scotch Yoke double acting 500 1600
Actuator Hydraulic Scotch Yoke spring return 400 1200
Actuator Pneumatic Scotch Yoke double acting 500 1650
Actuator Pneumatic Scotch Yoke spring return 400 1250
Actuator Motor Driven 500 2400
Valve Triple Offset Butterfly Close on Trip 450 750
Valve Triple Offset Butterfly Tight Shutoff 800 1800
Valve Triple Offset Butterfly Open on Trip 350 850
Valve Single/Double Butterfly Close on Trip 525 800
Valve Single/Double Butterfly Tight Shutoff 1200 2000
Valve Single/Double Butterfly Open on Trip 425 700
Valve Globe Close on Trip 350 2100
Valve Globe Tight Shutoff 900 2400
Valve Globe Open on Trip 250 2100
Valve Floating Ball Close on Trip 300 900
Valve Floating Ball Tight Shutoff 800 3000
Valve Floating Ball Open on Trip 200 800
Valve Trunnion Ball Close on Trip 400 900
Valve Trunnion Ball Tight Shutoff 900 3000
Valve Trunnion Ball Open on Trip 300 800
Valve Gate Close on Trip 300 2000
Valve Gate Tight Shutoff 800 3000
Valve Gate Open on Trip 200 1800
Quick Exhaust Valve Diaphram Type 5 80
Quick Exhaust Valve Pilot Operated 50 200
Volume Booster Valve DTT - Exhaust on trip 20 350
Poppet Solenoid Valve Direct Acting 3/2 DTT - Exhaust on trip 40 240
Poppet Solenoid Valve Pilot Operated 3/2 DTT - Exhaust on trip 60 420
Solenoid Valve Spool Direct Acting 3/2 DTT - Exhaust on trip 100 650
Solenoid Valve Spool Pilot Operated 3/2 DTT - Exhaust on trip 150 720
Solenoid Valve Spool Direct Acting 5/2 DTT - Exhaust on trip 200 900
Solenoid Valve Spool Pilot Operated 5/2 DTT - Exhaust on trip 250 950
Motor Contactor 0 - 600V DTT  100 500
Motor Contactor 600V - 15000V DTT 150 600
Motor Overload Relay Mechanical 100 400
Motor Overload Relay  Smart 600 2000
VFD Drive DTT  - Electrical Active 400 1000
VFD Safe Torque Off   DTT - Electrical Active 100 400

SERH - The Safety Equipment Reliability Handbook

The SERH provides a collection of failure rate data that is applicable for use in Safety Instrumented System (SIS) conceptual design verification in the process industry. The Safety Equipment Reliability Handbook remains the ultimate reference source for any safety engineer involved in Conceptual Design and Safety Integrity Level verification.

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SERH

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