Skip to Navigation

There’s an art to picture perfect results in joint integrity

An artist when surveying a landscape tends to take a step back to see the big picture. Capturing a moment in time can be done with a quick snap photograph, but for a painter further planning is crucial for an effect that often has greater impact.

The aim is to forecast how different factors will change the work and take calculated views of what the scene will look like over a period of time to get the best end result.

Hydratight joint integrity specialists are masters of their art and understand that the loads involved in the make-up of a joint are critical to its ability to remain leak-free throughout its period of operation.

While several factors are considered in determining the correct load that should remain in the bolts (the residual bolt load) to attain the leak-free status, an understanding of the method of tightening is an important task in taking a wider view of the loads exerted on the bolt (the applied load) to achieve the final aim.

For example, the loads applied during tightening using the hydraulic tensioning method are completely different to those applied during the torqueing method. Looking at the application in its entirety makes sense with critical pipeline assets.

In the torque tightening method, the residual bolt load is achieved using a turning force acting on the geometrical features of the fastener. The critical element in torqueing applications requires a good understanding of the frictional forces and the ability to control them within acceptable limits.

In the hydraulic tensioning method, the residual bolt load is achieved by exerting an axial force in the bolt (the frictional elements become almost meaningless). However, in this method it is necessary to understand the relationship when the load is transferred from the hydraulic tensioning device to the bolt.

This transfer incurs losses during the process. It is therefore necessary to account for these losses and exert a greater load in the tensioning device to achieve the target residual bolt load. The load exerted by the tensioning device is known as the applied bolt load.

While Hydratight has an extensive breadth of demonstrated experience in determining residual and applied bolt loads, having reliability proven and quality assured tightening tools (torque and tension) and having an industry leading personnel competency assurance program. there are applications that have such criticality that the residual bolt load must be verified by elongation measurement.

Hydratight uses the expertise of its people and products to provide the world’s best technological solutions for bolt load/elongation measuring and monitoring.

For example, ultrasonic monitoring equipment has allowed technicians to quickly and accurately monitor the actual elongation/load on joints at the point of application and throughout its service.

Products including Hydratight’s Boltscope ultrasonic bolt measuring equipment use industry recognized and approved pulse echo to determine load, elongation or strain.

Our customers in oil and gas, nuclear, subsea and renewables expect fast, accurate and reliable solutions to their critical assembly problems. We know our people are qualified, competent and innovative and work closely with customer teams to ensure a complete understanding of their requirements.

At the beginning of every project, we plan for changing conditions and our well-trained people ensure calculated views are taken throughout the process to ensure bolt loads are achieved and not just applied. We believe in our art as it results in leak-free joints every time – it is not painting by numbers.