Belleville Spring Washers

Spring washers are installed between the nut and the bolt on reflex and transparent glass gages. Their contoured shape assists in adding tension to the bolt when installed. The added tension maintains the proper torque for a longer period of time.
Spring Washers are highly recommended when the gage is hard to get to. This can be due to insulation of the gage, difficulty seeing the gage if it is on a platform, or maybe it is hard to access the gage regularly. In these cases, spring washers will increase the reliability and extend the time between duty cycles.
 
Proper torque on the gage keeps all pieces tight together to prevent the gage from leaking. Proper torque will increase the life cycle of the gage.  The best practice upon receiving a gage is to re-torque before installation, as the vibration from movement during shipping can loosen the bolts. In high temperatures, the best practice is to hot torque the gage. With the addition of spring washers, the hot torque between duty cycle changes can be extended.