Tilbury Docks Pintle Replacement and Shotbolt Installation

The project involved the replacement of three pairs of lock gates at the entrance lock to the port, with each gate being approximately 15 metres tall, 19 metres wide, and weighing 270tonnes; the equivalent of approximately 3 double-decker buses high and the length of a cricket pitch wide!

As part of the works package, Kaymac were contracted by the Principal Contractor, Balfour Beatty, to design, fabricate and install two bespoke 18.5m long steel Limpet Dams, which would provide a dry temporary working area to replace the existing gate pintles.

Kaymac undertook detailed underwater diving surveys at each pintle location to determine the optimal position and size of the limpet dams.  Kaymacs dive team gathered this information during a detailed survey of the dock invert in near-zero visibility.  With this information and coupled with our extensive experience, Kaymac’s engineers developed an outline, bespoke limpet dam design.  An external designer then undertook a detailed structural analysis of the concept design to confirm its suitability.

Once the design had been confirmed, Kaymac produced detailed fabrication drawings to enable both limpet dams to commence fabrication.  Kaymac’s engineers undertook weekly visits to the fabrication facility to carry out the checks that would allow a fully documented and evidenced Inspection and testing Plan to be developed and submitted to the client ahead of the limpet dam installations.

Once fabricated, both 25t limpet dams were delivered to the site, with a tandem lift undertaken to safely lift the limpet dams from a horizontal to a vertical position, and our dive team expertly installed the limpet dams to the quay wall.

Once installed, the dams were de-watered and the pintles replaced by our confined space teams, ahead of each new set of gates being installed.  Each pintle was replaced during a time-critical lock possession.

Alongside the pintle replacement works, Kaymac was also involved in the installation works of the new shot bolt cans for the new outer flood gates.

The installation of the shot bolt cans involved multiple stages, each requiring precision engineering and detailed dive surveys to ensure the cans were installed to millimetre accuracy.

The first stage of the installation involved excavating two holes on the dock invert for the Shotbolt cans. An underwater excavator was used work along the dock invert approximately 16m below water. The excavation work was supported by Kaymac’s in-house dive team who surveyed the position and size of the excavations to ensure the cans could be installed safely and as per design.

The information from the dive surveys were transferred into a 3D model produced by Kaymacs Project Engineers, enabling a live visualisation of the excavation progress in the near-zero visibility water.

On completion of the excavation works, Kaymac commenced the design and fabrication of multiple guide frames to ensure the cans were installed as per the design and to within +/- 5mm tolerance. The guide frames replicated the underside of the new floodgates and were based on a known point at the dock invert i.e., the newly replaced outer pintle.

Further extensive dive surveys were undertaken to obtain as much detail on the excavations as possible, and to enable bespoke lifting and levelling frames to be designed and fabricated for the 12tonne cans.

These frames ensured the cans were correctly positioned in the XYZ plane and, therefore, in the correct position to withstand the hydraulic forces applied to the floodgates. After the installation of the shotbolt cans, a concrete surround was poured with over 40 cubic meters poured in each excavation.

The project required significant collaboration between Kaymac and TEAM2100 to ensure that the works were completed on time and to the highest standard. Kaymac’s engineers, divers, and operatives worked tirelessly to ensure the successful replacement of the gate pintles and the installation of the shotbolt cans. Their attention to detail and precision engineering ensured that the pintles and shotbolt cans were installed to millimetre accuracy and in the safest manner. The successful completion of the project has enhanced the flood defences at Tilbury Docks, enabling the docks to better withstand the impacts of climate change.