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Stockwell Substation, London

Affixing a cantilevered GRP access platform to a fire barrier

Power upgrade works on the Northern Line began in 2018 to address poor asset condition, provide additional service resilience and enhance network power capacity for service increases on the sub-surface lines of the London Underground. The programme has included replacement of life-expired coupling transformers at Stockwell substation and upgrades to the high voltage network between Stockwell and Clapham Common substations, in a project led by contractor Balfour Beatty. Our partner Invicta was chosen to supply a fire barrier to which Dura Composites’ cantilevered GRP access platform was affixed.

Invicta was approached by Balfour Beatty to provide a solution to achieve 4-hour fire and insulation protection for existing transformer equipment at a project site in London.

The project consisted of an upgrade to the existing brick walls, which would surround transformer equipment housed in two separate bays at the Stockwell Switch House location and provide full fire compartmentation in the event of a transformer fire occurring.

Invicta designed, produced and installed a bespoke 220m² fire barrier which was carried out by four Durasteel engineers and took only six weeks. The short time frame was even more impressive given the installation works were carried out during transformer outages and a number of safety protocols had to be met.

The Durasteel barrier design, incorporating a cold rolled channel framework and other structural steel elements, needed to be substantial enough to cater for weight loads of cantilevering GRP (Glass Reinforced Polymer) structural walkways & CAT access ladders to allow for maintenance access, which is where Dura Composites came in.

As a leading designer, manufacturer and supplier of Glass Reinforced Polymer structural products for industry, Dura Composites was chosen to supply two non-conductive access platforms to enable safe access to the transformer areas for qualified maintenance personnel.

Dura Composites have extensive experience in the provision of GRP solutions for the rail and energy sectors, including Machine Access, Gantries, Stepovers and Ladders.

Our latest d² range of products deploys unique patented designs and innovative technology to deliver the safest, most cost-effective and durable solutions on the market.

In this case, Dura Composites GRP was chosen for its dielectric properties (due to the proximity to electrical equipment) as well as for its ease of workability on site.

Our extensive investment in the latest manufacturing technologies mean that all the Dura Profile sections used exceed the E23 grade, delivering superior performance. The GRP Dura Grating floor surface also provides exceptional anti-slip properties and drainage in all weathers.

Commenting on the successful project, Martin Strawford, Technical Solutions Manager at Dura Composites said:

This was a challenging and interesting project for both Invicta and Dura Composites to be involved in. The GRP structures required some ingenuity in design from our CAD team, but being able to sub-assemble the fabrication at our Dura Fabrication Centre in East Anglia meant real time and labour saving benefits for the project, as well as the ability to ensure that the resulting structures would meet the needs of these demanding electrified environments.

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Why Choose Dura Composites

Choosing a pre-fabricated GRP solution from Dura Composites significantly reduced the man-hours on site and helped to compress the project schedule. On this project, the fabricated parts were supplied sub-assembled for ease of handling and installation. As well as the non-conductivity, other benefits included a superb strength to weight ratio, lighter weight versus other materials such as steel, non-corrosiveness and a low maintenance lifecycle.

The GRP Dura Grating used as the platform floor surface is tested to over a million footfalls (to BS7976) and enables both drainage and visual inspection of the area below. All GRP profiles used in the construction of the access structure exceed the E23 grade, ensuring maximum performance.

Dura Composites are experts in the design, manufacture and supply of heavy duty, non-conductive, non-corrosive and chemically resistant access structures. We have extensive knowledge of every aspect of GRP fabrications and our first-class fabrication facilities at enable us to construct even the most complex projects safely, reliably and to the highest standards.

We have supplied access structures to a wide range of demanding environments including the defence sector, water industry, power generation industry, rail, electrical and materials handling sectors. Our services cover all aspects of the project lifecycle from feasibility studies and detailed design to cutting, fabrication, assembly and installation.

Product Guide

Product Guide | d2 GRP Access Structures

Non-corrosive, non-conductive, cost-effective, practical and safe Glass Reinforced Polymer (GRP) platforms, walkways, access structures & bespoke fabrications constructed from our market-leading d2 E23 Grade Dura Profile and Dura Grating.

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