Design for Galvanizing

Design Service Information Sheets 

At Highland we offer a free design service and have developed a range of Design Service Information sheets to compliment this. The objective of these documents is to provide specific guidance, targeted at areas within the fabrication process, that will lead to improvements in the finished product. It is our aim to educate and provide awareness to all our customers that will save money and time by correcting these potential design flaws.

To achieve a high quality galvanized finish it is important to take the galvanizing process into consideration when designing steelwork. Will it fit in the zinc bath? Are the venting and draining holes the right size? Where do I locate the holes? These are all important design considerations that require some thought before an item is fabricated.

To understand what needs to be considered in the design stages prior to galvanizing it may be beneficial to watch our short educational video on Design for Galvanizing by clicking here.

To further assist in the design process we have also developed a handy information booklet called the Fabricators Guide to Galvanizing which is filled with useful advice. A downloadable version is available by clicking here.

If you are at all unsure about any aspect of a design, one of our technical experts would be more  than happy to discuss this with you – after all it is much easier and less expensive to change a drawing than to alter material after fabrication.

As members of the UK and Republic of Ireland Galvanizers Association we also have access to their comprehensive guidance on design for galvanizing plus many technical aspects and these can be can be found by clicking on these links

The Engineers and Architects Guide:
https://www.galvanizing.org.uk/publication/engineers-and-architects-guide/

Design for galvanizing:
https://www.galvanizing.org.uk/publication/design-galvanizing-wall-chart/
https://www.galvanizing.org.uk/design-for-galvanizing/

The Technical Data Sheets:
https://www.galvanizing.org.uk/publication/datasheets/

Request your free Design For Galvanizing Wall Chart

Watch our videos about Galvanizing.

Coating Characteristics

powder coating scotland

Design Life

The functional life of a fabrication will be determined by the quality of the initial coating, the maintenance regime and the particular environment that it sits in. Galvanizing offers considerable advantages over its competitors due to its long, maintenance free life. The expected life of galvanizing in a specific location can be calculated relatively easily due to the unique way in which the coating reacts when exposed to the environment. Unlike paint, which will peel exposing the steel below, galvanizing slowly depletes a small amount each year. The rate of depletion can range from 0.5 microns in rural locations to 4 microns per year in exposed coastal locations. The link below opens a map showing the depletion rates for galvanized coatings in all parts of the UK which will allow an approximate design life to be determined.

Zinc Corrosion Map

The thickness of the steel will also affect the thickness of the galvanized coating. The thicker the steel is the thicker the zinc coating will be. The galvanizing standard ISO 1461 states that a 6mm section of steel should have a minimum average thickness of 85 microns. The average is taken from measuring 6 random locations on the surface.

For extremely harsh environments, such as offshore, it may be necessary to apply a thicker zinc coating. This can be achieved by specifying Marine galvanizing. The surface of the steel is reprofiled by shot blasting before galvanizing; this will ensure that a minimum average zinc thickness of 140 microns is achieved.

Design life

The powder topcoat of Colourgalv acts to protect the galvanized layer by creating a barrier between the zinc and the elements. Thus the coating will retain its full protection whilst the topcoat is present. Colourgalv is a robust coating capable of performing under a wide range of conditions, and on request we are able to offer a guarantee for the performance of the coating.”

Watch our videos about Powder Coating.

Metal Preparation

Shot blasting

On some occasions it may be necessary to shot blast steel prior to the galvanizing process. The following are examples of when shot blasting may be required.

  • Heavily rusted steel has been used in a fabrication
  • The material is being refurbished and old paint layers need to be removed
  • Red oxide paint or shellac coated steel has been used in fabrication

Shot blasting is available at both Cumbernauld and Elgin sites at a competitive hourly rate. Blasting is carried out to SA 2.5, this ensures that all rust, mill scale and foreign particles are removed.  If material needs to be blasted we will ensure that the customer is informed before the job is started.

We do not advise galvanizing cast iron as the heat can lead to cracking and certain cast irons are soluble at this temperature. We can however blast the items and offer a 2 coat powder system which combines a zinc rich base coat and a polyester top coat.

Shot blasting can be carried out in Glasgow, Edinburgh, Aberdeen, Dundee, throughout Scotland and beyond. Please contact us for further information regarding this process.

Zinc Stripping

Occasionally, due to modifications or simply to refresh the zinc coating, items it may need to be re-galvanized. In order to do this it is necessary to strip the zinc prior to re-galvanizing. This service is available at both sites at a premium based on tonnage.Please contact us for information regarding pricing.

Powder Coating

Highland Galvanizers are able to provide fully comprehensive powder coating services in Aberdeen, Glasgow, Dundee, Edinburgh and all across the North Of Scotland. Sectors we are able to provide powder coating for include engineering, agriculture, street furniture and many more.

Sustainability

powder coating scotland

Galvanized steel is one of the most sustainable materials available today. It’s widely used in construction, manufacturing, renewable energy equipment, and any other setting where weather and corrosion resistance is essential.

Effective corrosion protection is a vital means of reducing the energy demands of any built environment. The longevity, high corrosion resistance and subsequent maintenance free nature of hot dip galvanizing will lead to reduced energy consumption over the life of any steel fabrication.

It does this by extending the useful life of the object reducing the necessity to remake and replace, and by eliminating ongoing maintenance it reduces its carbon footprint demands.

The galvanizing process can also be viewed as environmentally sustainable. By products from the Zinc Bath, such as dross and ash, are recovered and used in other industries, such as agriculture and cosmetics. Heat from the Zinc bath is captured and reused in other parts of the process improving overall efficiency. Even wires used for suspension are recycled to be used again in other industries.

With advanced recyclability, galvanized steel fits in well with any project with strong sustainability goals.

Further information on sustainability can be found at the Galvanizers Association website by clicking on this link

Sustainabilityhttps://www.galvanizing.org.uk/rail-corrosion-protection/galvanizing-and-sustainability/

shot blasting scotland

The addition of a powder layer on top of galvanizing, not only adds style, but it also aids corrosion protection by creating a barrier that stops the galvanizing from depleting. The coating itself is made of an organic material and has a zero VOC content. The durability of the coating requires little maintenance and can with suitable preservation last over 15 years, which also adds to Colourgalv’s sustainability credentials.

Surface Finish

Galvanizing

The primary use of galvanizing is to prevent corrosion in steelwork. Due to the process and factors outwith the galvanizer’s control,  such as steel composition and design, there are number of appearance features that are acceptable under ISO 1461 as they will not affect the protection performance of the zinc coating. A list of common appearance features and their acceptability appears below.

Colourgalv 

Powder coating provides a level of  corrosion protection but it’s main purpose is for aesthetics.

Repair Procedures

Due to transport damage or onsite cutting it may be that a coating is damaged or removed . It is important that the coating is repaired to ensure that the design life and appearance of the product is not compromised.

Galvanizing

The galvanizing standard ISO 1461 provides several methods of repairing the Zinc coating up to a maximum area of 10cm2, which is around the size of a 50 pence piece. The easiest method is to apply several coats of  Zinc in  paste or paint form to the affected area. It is important that the area is dry and has been rubbed down with a wire brush before the coating is applied. Each layer should be allowed to dry before the next layer is applied. If the area is larger than 10cm the standard recommends that the steel is stripped and re-galvanized.

Powder Coating

Powder coating can also be repaired using a similar method. The area should be cleaned with a panel wipe degreaser and allowed to dry. The area should then be lightly sanded in preparation for painting. The grade of sand paper should be 320-400 grit or finer. Paint can either be applied with a brush or aerosol, with the latter providing the best finish. The coats should be applied in thin layers to ensure that the paint does not run.

Highland is able to supply touch up paints for both galvanizing and powder coating from our facilities in Elgin or Cumbernauld. The aerosol paints for powder coating are colour matched by the powder supplier ensuring consistency in colour and gloss level. Highland Galvanizers are able to fully carry out powder coating in Glasgow, Dundee, Aberdeen, Edinburgh, throughout Scotland and Beyond.

Transport

Elgin Transport 

From our Elgin depot we currently have weekly scheduled transport runs in Peterhead, Fraserburgh, Inverurie and Aberdeen areas. For areas outside these catchments we run transport on an adhoc basis so please contact the Elgin office on 01343 548855 to establish if we can organise transport to collect and deliver material in your area. To service our Northern based customers who require material to be galvanized and powder coated (Colourgalv) we also run a weekly service to our Cumbernauld powder coating facility. This currently departs on a Wednesday and returns your material to Elgin the following Friday.

Cumbernauld Transport 

From our Cumbernauld depot we currently have weekly scheduled transport runs in Edinburgh, Carlisle, Fife, Newcastle and the Scottish Borders. For areas outside these catchments please contact the Cumbernauld office on 01236 731444 to establish if we are can organise transport to collect and deliver material in your area.

To allow us to serve the north of England more efficiently we have developed partnerships that enable local collections and deliveries in the Newcastle and Carlisle areas. Both sites are conveniently located for easy access to the road network.

For the North East contact Franklin Steel Stockholders on 0191 499 0222

Franklin Steel Stockholders,
Franklin Industrial Estate,
Patterson Street
Blaydon
Newcastle upon Tyne
NE21 5TL

For the North West contact Thomas Graham Ltd on 01228 525 364

Thomas Graham Ltd,
Kingmoor Park East,
Carlisle
CA6 4SQ

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