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.

Learn More     Check The Data

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
High Bound

Determining if data is suitable for use is a critical first step. The 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

Failures per 109 hours (FITs)
Category Type Other Low Bound High Bound
Actuator Pneumatic Piston spring return 190 1000
Actuator Hydraulic Piston spring return 200 2000
Actuator Pneumatic Diaphragm spring return 160 910
Actuator Pneumatic Rack & Pinion double acting 600 2200
Actuator Pneumatic Rack & Pinion spring return 500 900
Actuator Hydraulic Scotch Yoke double acting 600 2000
Actuator Hydraulic Scotch Yoke spring return 500 1600
Actuator Pneumatic Scotch Yoke double acting 600 2200
Actuator Pneumatic Scotch Yoke spring return 500 1800
Actuator Motor Driven   900 1200
Valve Triple Offset Butterfly Close on Trip 450 750
Valve Triple Offset Butterfly Tight Shutoff 1000 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   542 2100
Valve Floating Ball Close on Trip 300 900
Valve Floating Ball Tight Shutoff 800 3000
Valve Floating Ball Open on Trip 250 800
Valve Trunnion Ball Close on Trip 400 900
Valve Trunnion Ball Tight Shutoff 1000 3000
Valve Trunnion Ball Open on Trip 300 800
Valve Gate Close on Trip 400 2000
Valve Gate Tight Shutoff 800 3000
Valve Gate Open on Trip 300 1800
Solenoid Valve Poppet 3 way   60 400
Solenoid Valve Spool 5/3   450 1200
Failure Rates are for dangerous failures assuming no automatic testing.  Failure rates are in units of failures per billion hours (FITs). Valve failure rates cover both clean and severe service.

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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