“Integra Technologies presents a new episode of Principles of Joint Integrity, where we will discuss: ‘Cross-Load Loss Factor’

Second only to Hydraulic Nuts, Bolt Tensioning is the next fastest, safest, most accurate and reliable method of controlled bolting.

Ideally, you preform 100% Tensioning, where there is a bolt tensioner installed on every stud, and all are tensioned simultaneously.

However, some joint configurations won’t allow for 100% tensioning. In these cases, INTEGRA’s Engineering Group suggests 50% tensioning as the minimum.

But with all tensioning procedures less than 100%, it is necessary to use multiple tightening pressures to compensate for load loss.

All forms of bolting experience load-loss, but unlike inferior methods such as torqueing, where compensating for load-loss will always be uncontrolled and inaccurate, there is a predictable and known load-loss associated with tensioning

Tensioned bolts lose some load but it is lost predictably and uniformly across the flange.

When accounting for this load loss in 50% tensioning, INTEGRA’s Engineering Group will recommend 2 tightening pressures.

Referred to as Pressure A and Pressure B.

These two pressures are necessary to compensate for the bolt load loss that occurs when a bolt is tensioned next to an already tensioned bolt.

The already tensioned bolt loses load as load is applied to its adjacent bolt.

To compensate for this predictable load-loss, extra load is applied in the form of Pump Pressure A to the first bolts, so that they relax down to the required load when Pump Pressure B is applied to the next bolts.

Contact our engineering group today for help developing your bolt tensioning procedures”

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