Specifying & Ordering
In the absence of specific product standards, designers have several options when specifying purlins:
- nominate the purlins by size and specific manufacturer, to the exclusion of all others
- specify by size and manufacturer and allow equivalent manufacturers, or
- specify the major dimensions and properties, ie:
-depth
-flange width
-base metal thickness
-yield strength
-protective coating
-mass of section
and leave the choice of manufacturer to the contractor.
To make sure your product is genuine GALVASPAN® steel by BlueScope Steel, it's important to nominate the use of GALVASPAN® steel.
Selection of the correct coating weight – Z350 or Z450 – is also critical.
The choice is dependant on the environment in which the purlin is to be used.
Z350 will suit most applications that are not subject to unusually corrosive conditions. In more corrosive applications, Z450 coating class may be appropriate.
Again, be sure to consider any minor detail differences between different products from different manufacturers to ensure they meet the design requirements.
Ordering to Length
Purlins made from GALVASPAN® steel are normally produced to order for each project. They are usually:
- custom-cut to precise lengths,
- pre-punched with all necessary fixing and bracing holes, and
- delivered to site, ready to erect, with bridging, bolts and all other accessories.
Length limits for purlins are about 12m for the smaller sizes, increasing to about 20m for the larger. Most manufacturers will look at going beyond these limits on a job-to-job basis. But ultimately, maximum lengths will be determined by local transport regulations and practical handling issues.
BlueScope Steel's vast customer/distributor network helps to ensure ontime delivery to site. However, orders should still be placed early to allow for manufacture and delivery to meet the construction program.
Getting the Order List Right
Take care in preparing an order list. The order forms provided by most rollformers will help.
Remember, too, that manufacturers offer a wide range of purlins and accessories, and the same purlin reference number alone does not necessarily mean the same load capacity or durability. Again, make sure you are getting 'the genuine article'. Only BlueScope Steel makes GALVASPAN® steel, and only GALVASPAN® steel is covered by a BlueScope Steel warranty*.
*Warranty terms and conditions apply, please see our page: Warranties For Peace of Mind
