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the ultimate fixing for major constructions

Excalibur Screwbolts

Our ability to innovate bespoke solutions for any fixing application sets us apart from many of our competitors. Over the years we've worked with market-leading clients designing and producing Screwbolts for unique applications and specific projects. Whatever the engineering challenge, we have proven experience of delivering the optimum fixing solution.

Below are some case studies of recent innovations; do please get in touch to discuss your individual requirements.

Client Brief

A non-corrosive, 120 year life, extra long screwbolt for use in Crossrail’s tunnels, to secure platform edge screens.

Our Solution

Excalibur further developed their PLUS Bolt, a long-lasting bolt highly resistant to corrosion, and had it independently tested.

Crossrail installs the PlusBolt

Excalibur's PLUS bolt was tested in over 11,000 hours' worth of salt spray and revealed no significant signs of corrosion. In addition, a UKAS accredited test house tested the bolt for 6,200 hours, sufficient for their evaluation purposes. The Ford Motor Company also evaluated the bolt through their nine week accelerated cyclic corrosion test. Results showed no signs of corrosion. An unofficial comment was made that "they had seen nothing better."

The Excalibur PLUS Hexagonal Head Screwbolt was launched at a tunnelling exhibition in London. Following the success of Excalibur's installations in the Channel Tunnel Rail Link project, Crossrail consultants expressed an interest in using Excalibur's screwbolts.

Tunnels being subjected to C5 environmental conditions meant any anchors fixing into the tunnel lining needed to have a life of 120 years: the new Excalibur PLUS Screwbolt was ideal.

Particularly long bolts however were required to fix the platform edge steelwork to the tunnel lining. Excalibur manufactured a small quantity of longer bolts for testing that combined the anti-corrosion specification of the PLUS bolt with a 120-year design life. Vinci Technology provided mock up sections of the tunnel lining into which the Excalibur samples were installed and rigorously tested at Imperial College London.

In July 2015 Excalibur PLUS Screwbolts were first used in the installation of the platform edge screens at Tottenham Court Road station. Four further Crossrail stations have since been commissioned; Bond St., Farringdon, Liverpool St. and Whitechapel.

Excalibur has now produced a range of M12, 16 and 20 Hexagonal Head PLUS Screwbolts for the tunnelling and marine industries. Not only are the concrete screw anchors highly resistant to corrosion, they have all the advantages of the standard anchor for ease of use and speed of application.

Client Brief

A fast, easy to use and time saving method of fitting 3rd & 4th rail insulator pots.

Our Solution

We met with the client (London Underground) and sleeper manufacturer (Tarmac) to trial suitable fixings. After detailed consultation we designed a special Excalibur Screwbolt for this unique application.

Above images show London Underground Limited Insulator Pot Part No. 915P3

3rd & 4th Rail Insulator Pot Screwbolt

Working for London Underground and Network Rail, Excalibur developed a special Screwbolt which can be secured quickly and easily into pre-formed holes in the sleeper, or cast in plastic inserts to secure rail insulator pots.

Now widely used across the London Underground network this has been a great success in both functionality and time savings, leading to reduced costs and increased productivity.

Client Brief

Alstom needed a bespoke fixing for their new generation of actuator points for Network Rail.

Our Solution

We met with the client (Alstom) and their customer (Network Rail) and submitted bespoke designs for testing. After rigorous evaluation, our 20mm Actuator Studbolt was accepted as the most suitable fixing for their requirements.


After considering various options for securing their new generation of point actuators - or backdrives - to concrete bearers, Alstom selected the Excalibur Screwbolt thread which was then submitted for Network Rail approval. A large number of turnouts have already been successfully installed throughout the UK and work will continue as part of an on-going replacement programme over the next 25 years.

Client Brief

The new Channel Tunnel Rail Link project needed a high performance and cost effective fixing solution for both permanent and temporary applications.

Our Solution

Excalibur attended on site demonstrations to test Screwbolts’ suitability for a broad range of different fixing requirements.

New Channel Tunnel Rail Link

At the start of the new Channel Tunnel Rail Link project, fixings manufacturers and distributors were invited to submit samples for evaluation for this prestigious project. Having submitted our products we were proud to be shortlisted to attend an on site demonstration, where our anchors were rigorously tested before then being selected for utilisation.

Excalibur Screwbolts’ products were rigorously tested for use in attaching cable tray brackets inside the tunnel. Testing involved inserting them into fibre reinforced tunnel lining segments. The tests - using Excalibur Screwbolt HSB12 x 100 - involved timed drilling and installation methods which utilised both hand and impact wrenches. These tests showed that for a project of this scale, the impact wrench was the most viable method.

The tensile (pullout) capacity of the bolt was then tested which gave a result of 78 kN. Further successful tests were then conducted with HSB16 x 100 bolts to determine their suitability for fixing the fire mains brackets with HSB16 x 200 for attaching services brackets to the approach diaphragm walls. The tensile tests for this latter application were stopped when the results indicated 100 kN as this figure was well above any live load to which the bolts would be subjected.

Of particular interest was the decision to use diamond drills when it was necessary to insert Screwbolts for brackets at ‘specific centres'.

In testing, diamond drills performed better than the Special Direct System (SDS) drill bit. The SDS bit was inclined to ‘bend’ when rebar was encountered thus preventing full embedment of the Excalibur Screwbolt. The diamond drill produced a straight hole through any rebar, allowing full embedment.

Following Excalibur Screwbolt’s successful test performance, our products (Screwbolt sizes M6, M8, M10, M16 and M20) were rolled out for use throughout the project including: supports for extractor fans within the tunnel; securing cable clips to the concrete sleepers; and supporting the temporary lighting cable by hook and eye headed Screwbolts.

Client Brief

A quick, simple and economic precast switchrooms and sprinker control rooms.

Our Solution

The resulting design was to provide insulated composite wall panels complete with floors and roof which were “bolted” together using HSB 20 x 300 Excalibur Screwbolts. This reduced the construction time of each unit from several weeks to 1 day and allowed follow-on trades immediate access. The units are an outstanding success and are now specified for all the future developments on this project.

ACP (Concrete) Ltd Quick Erection Precast Rooms

ACP (Concrete) Ltd was asked to provide a precast solution to form robust switchrooms and sprinkler control rooms for a major project in Scotland. The essential requirement was that they had to be robust and quick to erect so that they were no longer on the critical path of the site construction. ACP (Concrete) Ltd worked with Excalibur Screwbolts Ltd to provide a quick, simple and economic solution.