Dokka Product Range

Hex bolts (M12-M100)

Stud bolts (M20-M100)

Threaded rods (M20-M100)

Tower flange bolts (M12-M72)

Foundation bolts (M20-M100)

Hub and nacelle fasteners

Blade connection kits

State of the art productions processes

In 2010 we invested in new manufacturing equipment which enables us to handle the production of our bolts completely automatic. This results in high quality bolts with great consistency in the quality. We continuously invest heavily in improving our productivity quality and innovation, in order to meet our customers’ demands.

Lately we have invested in a new production cell, which enables us to support our customer’s range of high tensile bolting up to M100. The production cell contains full automation on hot forging, CNC machining, thread rolling and full non-destructive testing, such as ultrasonic inspection, hardness and magnetic particle inspection. The bolts will for example be fastening monopiles and transistion pieces, instead of a grouted solution.

Quality based on tests and certification

Dokka Fasteners is ISO9001 certified and qualified to do the intensive testing required for our wind power customers. Further, we provide 3.1 certificates on all items.

The test includes:

• Tensile and compression testing (600kN and 2000kN)

• Hardness test (Brinell & Vickers and HV0,3-HV30)

• Charpy impact test (300J with cooling equipment down to -100ºC)

• Torque test

• Spectrometer for chemical analysis

• Elcometers for coating thickness measurements

• Measuring tools and gauges for dimensional inspection

• Stereo, optical, and inverted axial microscopes for metallurgical analysis

• Magnetic particle test

It is possible to get 3rd party inspection performed by TÜV and DNV.

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