Structural Steel
This is a material used for construction and is involved in structural steel fabrication, the composition of which is standardised in most industrialised countries – including size, shape and storage, amongst other factors. There are a series of common shapes for structural steel: I-beam (including UC and UB), Z-Shape, HHS-Shape (hollow structural section), Angle (L shaped cross section), Channel, Tee, Rail Profile (asymmetrical I-beam), Bar, Rod, Plate (thicker than 6mm) and the Open Web Steel Joist.
Structural steel is constructed through various methods, including cold rolling, hot rolling, and sometimes welding flat plates together.
Grades – The European standard EN 10025 governs most steels used in Europe, although there are national British standards that also apply. Grades are designated with the letter S (which implies structural steel rather than engineering steel) and then three numbers (which specify the yield strength in Newtons per square mm of the steel). Next a letter and a number relate to the steel’s impact test values, and any further characters can specify normalised, quenched or tempered steel, or thermomechanically rolled steel.
Fireproofing – External insulation is required for adequate fireproofing and to ensure the steel doesn’t overheat and weaken or even melt during a fire. Common methods employed include endothermic, plaster coatings, intumescent and cladding.
Welding
As a welding contractor in Devon we use a range of welding methods, including the following:
MIG Welding – Metal inert gas welding involves a continuous and consumable wire electrode and gas being fed through an arc welding gun. Also referred to as gas metal arc welding, or metal active gas welding. Due to the electric arc, MIG welders use protective clothing including leather gloves and protective long sleeved jackets. Eye-protection is also employed, as with most welding, to protect the eye from the intensity of light produced.
Spot Welding – Resistance welding most commonly used to weld sheets of metal together, by pushing an electric current through a small area while clamping the two materials together – melting the material and forming a weld. The thicker the sheet metal, the harder it is to spot weld, as the electrical current dissipates into the rest of the metal sheet more easily.
MMA Welding – Manual metal arc welding is also known as shielded metal arc welding or by the informal name of stick welding. MMA welding is versatile and simple in terms of equipment and processes, so tends to domimate welding practises worldwide. As with MIG welding, an electric current forms an arc between electrodes and the metals being joined, in order to form the weld. MMA welding is used mostly to join irons and steels, although it can be used on other materials.
Cutting
Laser Cutting – Used to cut sheet materials as well as structural construction metal, this method utilises a laser guided by computer program to cut often detailed incisions and patterns which are melted or burnt away. Laser cutting has distinct advantages in being able to cut through materials that may otherwise be impossible to cut manually, asnd it also offers a high precision method that leaves a quality of edge that is hard to obtain using a physical cutting tool (which would contaminate the material being cut).
Plasma Cutting – This involves cutting steel and other metals using a plasma torch. The plasma is formed using an electrical arc through inert gas, and the heat of the plasma melts metal and blows the molten material away from the area being cut. This method is also utilised for plasma arc welding.
Powder Coating
Using a thermoplastic or thermoset polymer dry powder, a plastic skin is formed using electrostatic application and then a heated curing process to form the plastic skin. Creating a finish that is more durable than regular paint, it is also an efficient way of coating delicate structures or materials with many corners and hidden areas that would otherwise be hard to get at. There is also little difference between horizontally coated and vertically coated surfaces, although it is harder to get a thin coating so thicker coatings are normally applied.
CAD Design
CAD stands for Computer Aided Design and refers to the use of computer software to assist with designing and producing technical/engineering drawings for projects, structures or buildings. This drafting can be carried out in two or three dimensions, and software ranges from 2D vector-based systems to 3D solid and surface modelling programs. CAD offers engineering and construction workers a highly precise method of building and construction, and can be used in conjunction with computer aided methods such as laser cutting to increase the quality of workmanship.
