The B10 method uses cycle test data to predict failure rates. 

A cycle test is done on a set of products (>20) until 10% of the units under test fail. The number of cycles until failure is called the B10 point.

The B10 number of cycles is converted to a time period by knowing the cycles per hour in any particular application. 

The B10 method assumes that the constant failure rate during the useful life is due entirely to premature wear-out AND all other failure modes are insignificant.  But research shows other failure modes become significant when these products do not move frequently – some failure modes become significant if a product is static (motionless) for 100 hours. That low demand applications can generate failures that high demand applications cannot develop. 

When O-rings and other seals are part of a product, many failure modes become significant when the product remains static for a week or more.  There include stiction, cold-welding, corrosion binding, etc.  Most of these failures are dangerous.  Therefore, B10 data is NOT applicable to most applications including the process industry applications. Low demand applications can generate failures that high demand applications cannot develop.  

Cycle Testing is useful for estimating failure rates when the dominant mechanical failure rates are due to (premature) wear-out of components. This occurs in applications with frequent dynamic movement, lubrication and mechanical loading. Testing must be done until at least 10% of the population has failed. 

This method is NOT APPLICABLE to static applications such as low demand modesafety systems as it does not account for failure modes like stiction, cold welding, corrosion, etc. This is for high or continuous demand applications only.