ACL^® Clamp Life

Introduction

All common sanitary clamp unions utilise similar parts. The majority of the component parts do not experience the usual types of degradation that other engineered systems experience. The majority of the degradation is experienced by the threaded fasteners and their contact points.

The removal and thus retightening of threaded fasteners results in a detrimental effect on the achievable bolt pre-load. As the bolt pre-load is the determining factor in the sealing integrity of the sanitary union, it should be considered as the critical component in the assembly. The bolt pre-load is the force that clamps the union together and prevents gasket blow out and movement of the constituent parts.

In the sanitary union, there exists a balance between the gasket sealing, maintaining the gasket intrusion limit, avoiding galling and clamp longevity. Elastomeric gaskets are the most commonly used gasket in the sanitary union; they are also the most susceptible to degradation due to their molecular structure. As a result of this, it is a requirement that they are frequently changed. This means that the clamp has to be removed and re-assembled.

It is a well known fact that the achievable clamping force (pre-load) for a threaded component is reduced after the first tensioning (utilising the same torque value).