Monday, September 10, 2012

Tubular Fabrications & Hollow Structurals Cleaning

Tubular Fabrications & Hollow Structurals Cleaning

Tubular assemblies (handrails, pipe columns, pipe girders, street light poles, transmission poles, pipe trusses, sign bridges) are commonly galvanized because corrosion protection is afforded to the interior and exterior of the product. To provide an optimal galvanized coating, hollow products require proper cleaning, venting, and draining.

As with all steel, pipe and other hollow materials must be thoroughly cleaned before the molten zinc will metallurgically bond with the steel. Pipe can present two special cleaning challenges. First, the mill coating (varnish, lacquer, and similar materials) applied by pipe manufacturers requires extra time and effort to remove at the galvanizing plant. Some galvanizers do not have the capability to remove this coating. Some organic mill coating formulations, both foreign and domestic, are

extremely difficult to remove with common cleaning solutions, so blasting may be required. Ordering uncoated pipe avoids costly attempts to remove these mill coatings. In some cases, it may be more cost effective to substitute tube for pipe.

Second, welding around mill coatings burns and carbonizes the varnish in the surrounding areas and cannot be removed
by the normal cleaning process at a galvanizer. This soot must be removed by blasting or other mechanical cleaning methods prior to delivering steel to the galvanizing facility.