Introduction to Bolt Tensioners for Leak Proof Joints

When it comes to industrial work, the leakage problem in bolted flange joints has always been an annoying problem throughout time. However, with the advancement of technology, the bolting tools market has introduced several new and improved precision tools and torque wrenches that allow you to achieve solid joint integrity between two or more flanges. In this article, you’ll know everything about bolt/stud tensioners and how they allow you to achieve leak proof joints.

Bolt Tensioners – A Brief Introduction

A hydraulic bolt tensioner is a mechanical tool that tightens bolts of large diameter with great speed and accuracy to help you achieve high-precision preloads. It doesn’t involve torque, unlike other conventional methods of nuts and bolts tightening. Moreover, a hydraulic bolt tensioner also doesn’t require forceful turning of nuts and bolts, such as in tools like flogging spanners, torque wrenches and impact wrenches.

Apart from bolt tensioners, every other method to tighten and loosen nuts and bolts generates a great amount of friction. To overcome the frictional force between the washer and nut, more than 80-90% of the applied energy is used. Only a small amount of 10-20% energy is used to generate useful tension required in the shank of the nut or bolt.

A hydraulic bolt tensioner retains the complete load applied by the jack in the shank of the bolt. It’s simply an annular jack that fits over a nut or a bolt for tightening and loosening purposes. The bolted joint is pushed through the jack and pulls at the ending part, which requires being at least one diameter longer to easily accommodate the tensioning tool.

How Does a Bolt Tensioner Works – A Detailed Guide

The bolts and nuts are designed in a way to work together as the externally threaded fastener (Bolt) are threaded with the internally threaded fastener (Nut) to provide a leak-proof joint. With that said a stud tensioner simply stretches the bolt and generates a continuous clamping force when the nut is applied to the joint. This whole process is completely repeatable and extremely accurate.

Although you can achieve similar results by torqueing the nut to create stretches in the bolt, the process won’t be accurate because the rate of friction varies between every nut thread and surface under the unit. Talking about the bolts, they’re designed to stretch only to a small extent, that too for clamping the joints together. Every bolt attempts to return to its original un-stretched state.

This inherited spring tension in the bolt generates a clamping force that works together with the frictional force to prevent loosening in the bolt’s thread. To ensure a proper amount of clamping force, you need to provide an adequate amount of spring tension in the bolt to maintain it properly while fastening. A torque wrench creates this required spring tension by stretching the bolt.

Breaking Down a Bolt Tensioner – Types of Components

Here’s a nifty list of parts available in a typical bolt tensioner in the order they’re assembled into the bolt or nut that requires be tightening or loosening:

1. Puller

The puller is a component with an internal thread to fit the bolt. The outer part of this component is knurled to help in rotation through hand and tommy bar holes available for a final touch of tightening. The puller also consists of a nose that helps in fitting other components of a bolt tensioner such as a Cylinder with the help of a tensioning force. The puller must always engage the stud to the length of at least one diameter of the stud to avoid any slippage during operation.

2. Cylinder

The cylinder is the component that contributes to a major part of the annular hydraulic jack. It’s passed through a bolt and a puller that provides a recess in the base of the cylinder to allow it to access the Bridge. The cylinder also includes a couple of self-sealing quickly disconnecting nipples that help in connecting the hoses of the Hydraulic Bolt Tensioner properly.

The Takeaway

 Bolt Tensioners are certainly one of the most important tools in the industry. With their accuracy and precision, you can easily achieve leak proof joints without any effort. If you’ve reached this far, you surely know a lot about bolt tensioners now.

Content Sources :- ABSGroup