Ship Lift Preparation and Painting

Encapsulation to a mechanical lift which is designed to raise and lower submarines and ships, into and out of the dock waters. We are Grit blasting the internal steel infrastructure of the lift, working inches above sea level, while being mindful of the delicate wooden beams on the surface.

The lift can be seen in the photographs as the wooden slatted flooring in front of the doors of the Devonshire Dock Hall. A team of Blasters, Painters and Cleaners are working below this flooring on 27 separate bays which make up the area of the lift that we are currently working on.

Once the steel has been blasted clean we apply a water proofing coat. This ensure the steel is protected for many years to come from the extremities of the natural environment it is exposed to during the course of it’s continued use.

The contract, completed final quarter of 2005 is worth over £1,000,000

 T.I. Protective Coatings have recently begun the 3rd & final phase of an abrasive-blasting and painting project on the Ship Lift at BAE Systems Submarines in Barrow-in-Furness. The structure consists of 54 sub-sections running horizontally across the lift, with a total area in excess of 38,000 metres². Each beam is controlled by 2 independent winches; which when running in unison are able to lower the entire lift 19 metres below the surface of Devonshire Dock

This way BAE are able to launch or retrieve vessels ranging in size and weight.
Due to the environmental conditions involved with the location of the lift, often 30cm above dock water level, corrosion of the steel substrate and the weakening of the lift is of grave concern to the operators. The programme consists of steam cleaning the structure to remove years of built up grease, abrasive-blast cleaning using inert Silica-free Australian Garnet & applying a 3 coat paint protection system.

The site is located directly above the dock water and the obvious environmental issues of working adjacent to a Special Area of Conservation (SAC) & SSSI sites within Walney Channel which is adjacent the Dock complex that makes up the Barrow site.
As part of the process a tent is erected over the working area at the start of each of the 3 stages of the project, this ensures that dust generated in the blasting process does not escape into the surrounding environment nor enter sections of the lift which have been previously treated. In addition the enclosure provides weather protection thus reducing
downtime due to inclement conditions. The tent is erected using a scaffold and monoflex sheeting, this creates a greenhouse effect on the surface of the lift; where temperatures often reach over 30°C, to improve the working conditions for the comfort of the operatives the air flow through the encapsulation is increased, T.I. Protective Coatings utilizes Dust Extraction Units to remove the particles dust in the atmosphere and a Bifurcated fan is installed with sufficient ducting to provide a constant flow of air while removing any fumes potentially hazardous to health.

These factors alone make for a difficult challenge, however when combined with the Health & Safety and Environmental issues the logistics of a team of Blasters& Painters working on a subterranean 2 tier scaffold 30cm over the dock gaining access through a single meter hatch, then retrieving 1400 tonnes of spent abrasive out of the hatches prior to painting, has the makings of a goliath effort in co-operation with your team members, client and Sub-contractors.
Fortunately T.I. Protective Coatings has an excellent relationship with Site Engineering Services Dpt, BAE Systems and together over the previous 3 years they have overcome numerous difficulties involved with the structure. The most unusual of  which is the constant changing level of the  dock water, which results in the lower platform level of scaffolding being submerged periodically, these are secured in place to prevent the boarding from being washed away.

The varying dock water level also results in a project programme issue due to the bottom flanges of the 54 beams also being submerged when levels rise, these must be blast cleaned and have a 3-coat paint system applied in the window of opportunity that the tides present.
Approximately 60,000 litres of the 3-coat Amerlock 400 glassflake epoxy paint system developed by Ameron Paints is applied to the steel once it has been blast cleaned to SA2½. This system was selected due to its beneficial properties of being able to withstand submersion in salt waters. The coats are applied using a combination of spray techniques and brushwork to ensure total overcoating reaches those areas where access proves difficult.
The minimum Dry Film Thickness achieved after all coats have been applied is 475 microns. T.I. Protective Coatings deploy one of their in-house Institute of Corrosion Accredited Paint Inspectors to the site to ensure that the application is carried out to ISO 9001:2000 standard which the company operates. In order to carry out testing the inspector utilizes calibrated inspection equipment, including a Salt Meter to ensure that the surface is not contaminated before application, an Elcometer 456 DFT Gauge to ensure the coatings thicknesses have been achieved throughout the substrate, a Dewpoint Meter to assess the atmospheric conditions prior to application, a Steel Temperature Gauge and a Steel Profile Gauge are also used to assist in the pre-paint inspections.
Once T.I. Protective Coatings has completed the final phase of the restoration, which is due to finish in August 2006, BAE Systems Submarines Plant Services maintenance team can begin the complex process of replacing the sheaves and winches which were removed for protection prior to the start of the project.

When the components of the lift are replaced testing is carried out on the lift to ensure that it is fully operational for the launch of the Astute class submarine which is currently nearing completion in the Devonshire Dock Hall adjacent to the lift.

All pictures are courtesy of BAE Systems Submarines, our thanks go to them for their co-operation during the writing of this study.