Steel Fabrication? Huh?

Going to business meetings in Dubai and other emirates in UAE, when I mention we do steel fabrication, people get curious and ask what is steel fabrication. Here is brief description on the topic.

Steel fabrication is an interesting process. There are two ways in which steel  fabrication takes place. First is raw material approach which is also called integrated route and the other one is electric arc furnace(EAF) method of steel fabrication. In first method materials are heated up ,melted down and mixed into steels. In other method recycled steel is put into a  furnace and melted down. Once mixed with some other materials, steel is the end product.

Steel fabrication Process

Fabrication procedure

The efficiency of fabrication in steelwork dictates the success of any project involving steel-intensive construction. Steel passes through various operations during the course of its fabrication. The sequence of activities needed for fabricating steel is given below

·       Surface cleaning
·       Cutting and machining
·       Punching and drilling
·       Straightening, Bending and Rolling
·       Fitting and Reaming
·       Fastening Methods
·       Finishing
·        Surface Treatment

Surface cleaning

Structural sections from the rolling mills may require surface cleaning to remove mill scale prior to fabrication and painting. Blast cleaning is the accepted way of carrying out surface preparation in a well-run fabrication. Flame cleaning is another method of surface cleaning. The surface is cleaned using an oxy-acetylene torch which works on the principle of differential thermal expansion between steel and mill scale. In Dubai places like Horiya does great job in cleaning the steel surface at very great rates.

Cleaned Pipes

Cutting and machining

Cutting to length is always the first process to be carried out, and this is done by any of the following methods.

·       Shearing and cropping
·       Flame Cutting or Burning
·       Arc Plasma Cutting

Shearing and cropping: By  shearing and cropping sections can be cut to length by using hydraulic shears. By specialist plate shears long plates can be shaped and cut to length.

Flame cutting and burning: The steel is heated locally by a pressurised mixture of oxygen and a combustible gas such as propane, which passes through a ring of small holes in a cutting nozzle .The desired cuts are obtained quickly by this process. Flame cutting are treated specially in the design of steel .

Arc Plasma Cutting: The cutting energy is produced electrically by heating a gas in an electric arc produced between a tungsten electrode and the workpiece . The cut produced by plasma jet is very clean and its quality can be improved by using a water injection arc plasma torch.

Cut off Machine

Punching and Drilling

Steel fabrication can be done by a range of machines which can form holes for connections in steelwork. The traditional drilling machine is the radial drill, a manually operated machine, which drills individual holes in steelwork. Punching creates distortion and material strain hardening around the holes, which increase with material thickness.

Straightening, Bending and Rolling

During fabrication the material should be straightened, either rolls or gag presses are used to straighten structural shapes Gag press is generally used for straightening beams, channels, angles, and heavy bars. Long plates, which are cambered out of alignment longitudinally, are frequently straightened by rollers. When heat is applied to a small area of steel, the larger unheated portion of the surrounding material prevents expansion. Upon cooling, the subsequent shrinkage produces a shortening of the member, thus pulling it back into alignment.

Grinding Steel

Fitting and Reaming The component parts of a member are fitted-up temporarily with rivets, bolts or small amount of welds. The fitting-up operation includes attachment of previously omitted splice plates and other fittings and the correction of minor defects found by the inspector. The pieces are assembled, the holes are reamed by electric or pneumatic reamers to the correct diameter, to produce well matched holes.

Fabricated Steel case

Fastening Methods

The strength of the entire structure depends upon the proper use of fastening methods. There are three methods of fastening namely bolting, riveting and welding. Welding is the most common method of steel fabrication.

Welding

Finishing

 The term finish or mill is used on detail drawings to describe any operation that requires steel to be finished to a smooth even surface by milling, sawing or other machines.

Steel Beams

Surface Treatment

Steel is protected against corrosion by applying metal or paint coating.

Metal Coatings

The corrosion protection afforded by metallic coating largely depends upon the surface preparation, the choice of coating and its thickness. Metal coating to steel surfaces are hot-dip galvanizing, metal spraying, and electroplating. Electroplating is generally used for fittings and other small items. Galvanizing is the most common method of applying a metal coating to steel.

Paint Coatings

Painting is the principal method of protecting steelwork from corrosion. Paints are usually applied one coat on top of another, each coat having a specific function or use.

Metal Coatings

Powder Coatings