Verifying Valve Position

DOE-STD-1036-93

In all cases, the instructions should minimize the interaction between the performer

and the verifier to preserve the independence of each.

Once the instructions are developed, personnel involved in performing independent

verification should be trained on the techniques. Operating experience alone may

not provide adequate knowledge for performing independent verification. Specific

training on the techniques for independent verification enhances their reliability.

The training may be performed as part of the operator qualification program

and/or the facility continuing training program.

The general guidelines that follow should be considered when developing specific

verification techniques. When possible, verification should be performed using

more than one indication or technique, e.g., performing a physical verification and

checking system parameters.

4.3.1

Verifying Valve Position

It is not always possible to determine if a valve has been completely

closed or opened by merely observing the action. The relative height of a

valve stem is not considered a reliable position indicator for independent

verification. Lines scribed on the valve stem or other positive indicators

of stem position can aid in accurately determining the valve position.

However, a mechanical indicator may not accurately reflect the position

after maintenance has been performed on the valve, or even after a period

of normal use.

The preferred method for verifying valve position is a physical

verification. A visual check of the stem position or position indicators

should be used whenever possible to confirm the physical verification.

Physical verification of a manually operated valve should be performed