Selection of Galvanised finish when considering the longevity of cable containment and support bracketry.

In the modern Rail industrial market, it has never been more important for projects to be designed with “total design life criteria” including the need for cable containment and pipe work support bracketry installations to meet much longer system design life periods and as such the longevity of the product finish on these installations is critical when specifying products to meet these expectations.

Galvanising is the most widely used form of corrosion resistance and is chosen because it offers a proven and cost effective solution for longevity of resistance to atmospheric corrosion.  In general it will give a predictable rate of corrosion in differing environments.  The process allows the surface of the material to oxidise to form a protective layer which acts as a barrier for the base material.  The zinc is sacrificial and corrodes over time rather than the steel, so design life can be worked out from initial coating thickness.

Unistrut provide both pre-galvanised materials for internal applications which are manufactured after the galvanising has been applied and post-galvanised (known as hot dipping) which gives a galvanised finish to a greater depth after the product is manufactured.

When specifying a post manufacture hot dip galvanised product, there are many considerations to take into account.  Hot dip galvanizing provides steel products with protection through a continuous, tough, bonded coating with a much greater galvanised thickness than standard pre-galvanised finishes.  As previously stated, the rate of corrosion is fairly predictable so as the length of design life period increases so too must the thickness of galvanising.  The galvanising limitation is determined by the thickness and makeup of the base material. With our years of experience in providing solutions for harsh environments combined with long design life, especially in tunnel applications, standard mild steels have a limited capacity for deeper galvanising.  If standard steel is coated with galvanising that is too deep then flaking off will occur, but with our knowledge of selecting and manufacturing from special steels with higher silicone content, much greater depths of galvanising can be achieved.

To help you understand the best finish for your application and environment, an early consultation with Unistrut’s project team can help to advise you of the ideal finish specification and best practice installation guidelines, and supporting this, Unistrut gives an industry leading 10 year warranty on a complete metal framing pre-galvanised system made entirely from Unistrut branded products.

We work closely with our specialist suppliers of steel and galvanising and are happy to visit you to provide information on expected corrosion rates for the specific environmental conditions.  Our team will work with you to provide a solution for your application and then help engineer the system to your needs, including the design of bespoke support brackets that need to be galvanised to allow for the free flow of zinc to all surfaces even in our curved channel tunnel support bracketry.

One point often overlooked is that to maintain the life expectations of the overall solution, it is critical to ensure the integrity of the galvanised finish of the products. Care must be taken where alterations or cuts to materials are carried out on site so that the altered areas are treated to ensure the integrity of the corrosion finish.

To overcome this problem, Unistrut can provide a modular prefabrication service, utilising both standard and bespoke products, designed and engineered to your specifications and delivered to site schedule, giving you overall cost and on-site installation time savings as well as maintaining the galvanising integrity of the solution.

Unistrut engineer products from various materials and in a variety of finishes which, apart from the standard galvanised products include stainless steel, GRP and aluminium. These variations help to meet the exacting needs in the Rail industry today and provide us with support channel and cable containment products that are approved to the LUL (London Underground) specifications.

Unistrut, part of Atkore International, is a global business with facilities in the UK, USA, Australia, France, New Zealand and China.  It is best known for the metal framing systems pioneered by the company in the 1930’s.  These are used extensively in building and construction for the support of mechanical and electrical services. 

More recently the inclusion of a comprehensive range of cable management products including Steel cable ladder, tray, basket and trunking make Unistrut a world leading supplier of Cable containment and support solutions.

If you would like more information, please Click Here or contact our Unistrut technical team for free support on unistrut@dpbuildingsystems.co.uk or 0121 706 7777