File Name: bolt torquing and tensioning procedure .zip
- Torque Tightening
- 002-BOLT TIGHTENING (Structural).pdf
- Flange Bolt Torque Sequence and Torque Table – A Complete Bolt Tightening Procedure
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Proper alignment of any bolted joint can be achieved by the use of either torque or tension methods of bolting. While both methods of securing the joint produce the same end result, the debate continues about which method delivers the most accurate and consistent bolt load value. If the proper bolt loads are not achieved during installation the integrity of the joint will be compromised, leading to misalignment and, if not checked, ultimate failure of the joint. These two methods of bolting are used in wind turbine installation and maintenance through the use of hydraulic torque wrenches and hydraulic bolt tensioners.
Flange joints require proper tightening to avoid the leak of the fluid from the joint. Bolt tightening sequence or torque sequence is defined in the torque tightening procedure. Most company has their Flange bolt torque tightening procedure that used during construction and operation of the plant. Flange joints are torque tight with the help of a torque wrench Manual or hydronic wrench. To achieve the benefits of the pre-loading, the clamping force in the screw must be higher than the joint separation load.
002-BOLT TIGHTENING (Structural).pdf
To obtain a leak-free flange connection, a proper gasket installation is needed, the bolts must be assign on the correct bolt tension, and the total bolt strength must be evenly divided over the whole flange face. With Torque Tightening the application of preload to a fastener by the turning of the fastener's nut the correct bolt tension can be realized. Correct tightening of a bolt means making the best use of the bolt's elastic properties. To work well, a bolt must behave just like a spring. In operation, the tightening process exerts an axial pre-load tension on the bolt. This tension load is of course equal and opposite to the compression force applied on the assembled components. It can be referred to as the "tightening load" or "tension load".
Obtaining a leak-free flange connection can be a difficult task on-site without a plethora of equipment to fall back on. A proper gasket installation, bolts with correct tension, and an evenly divided bolt strength must be adhered to to create a good flange connection. However with torque tightening the correct tensions can be realised for the ultimate connection for your flange. Correct tightening of a bolt means making the best use of the bolt's elastic properties. To work well, a bolt must behave just like a spring and create equal and opposite compression force applied on the assembled components, also known as the 'tightening load'. With tips from Wermac , here's our 5 step guide to create the ultimate torque tightening for your flange:.
The correct placement of gasket and proper tightening of bolts in a flanged joint will ensure a leak-free joint. Proper bolt tightening will ensure uniform load distribution in all bolts without damaging the gaskets. The following procedure describes how to tighten flange bolts. Leakage through a flanged joint is prevented as gasket material flows inside the flange surface imperfections and seal them. But there are limitations that a gasket can successfully seal.
Always use a torque wrench or other controlled-tensioning device for tightening. The sequence in which bolts or studs are tightened has a substantial bearing.
Flange Bolt Torque Sequence and Torque Table – A Complete Bolt Tightening Procedure
Risk Assessment will have been prepared by the Risk Assessment Team RAT ranking the hazards associated with project works and control measures to be taken to mitigate the hazards to an acceptable level. Each work scope or task will have a completed and approved Job Safety Analysis JSA identifying the potential hazards and control measures that will be implemented to protect people and environment. In addition to the above, employees conducting bolts tightening works will wear required PPE and highly visible vest where traffic or other hazards may exist. For additional safety requirements for a particular or specific task please refer to the JSA prepared for that task. The construction manager is responsible for the overall management of the project construction team to ensure that safe and effective operations are conducted and properly documented.
Note: As with every bolt pretensioning method, Turn-Of-Nut may only be performed after all steel plies in a connection have been drawn into firm contact, i. Failure to do so will result in inadequate bolt pretension and loose connections. Turn-Of-Nut is performed by rotating the nut or bolt of a fastener assembly a specific turn angle based on the fastener's length, and diameter while restraining the unturned element from rotating.
This technique has created an accepted formula for relating torque to tension.