Hydraulic Flange Bolting

The tightening of flange connections using a hydraulic power unit is a proven method in practice, typically applied to bolt sizes from M20 to M48.

With the correct assumptions for friction coefficients and a predefined tightening sequence carried out in multiple steps, the tolerance of the applied preload is approximately ±3% of the calculated installation bolt force.

As an alternative, or as a supplement, bolting in the M20 to M30 range can now also be carried out using electric torque wrenches, achieving the same tolerance range.

Bolt Stretching Method

The bolt stretching method is the most accurate tightening procedure for flange connections, as it works without friction. Using hydraulic cylinders, the bolts are tensioned with their calculated preload force. Afterwards, the nut is manually tightened against the flange, and the bolts are then released. The applied “stretched” load remains in the joint.

This method is particularly suitable for thread sizes from M52 to M110 / UN1" to UN4", for high-pressure applications, or when tightening RTJ flange connections.

Flange Service

For us, flange service means:

• Tightening of all types of flange connections as a service, including, where required, determination of tightening torques (pre-verifiable by notified bodies) and preparation of assembly documentation.
• Provision of a supervisor for the assembly of critical flange connections – independent of whether the materials are supplied by our company or not.
• Inspection of flange connections in accordance with EN 1591-4 and our internal standards 357 and 362.

In all these cases, we assume full responsibility and guarantee the functionality of the flange connection for all controlled components and monitored assembly operations.