Standard Operating Procedures for the Manual Arc Welding of Structural Steel
1. Introduction
Arc welding is a process that involves joining two pieces of metal by using an electric arc to melt base materials together. Structural steel is commonly used in the construction of building and other structures and is specifically designed for this purpose. As such, accurate and reliable welding of structural steel is extremely important to ensure that the finished structure is safe and fit for purpose. This document outlines standard operating procedures for manual arc welding of structural steel in order to ensure that the welds produced are of the highest quality, and meet the appropriate standards.
2. Equipment Requirements
In order to carry out manual arc welding of structural steel, a range of specialized equipment is required, including personal protective equipment, welding machines and welding supplies.
2.1 Personal Protective Equipment
Helmet: A welding helmet should be used to protect the eyes and face from harmful UV radiation and also to protect the welder from sparks, spatter and debris.
Gloves: Arc welding gloves should be used to protect the hands from burns and cuts. Additionally, separate work gloves should be used to protect from sharp edges, extreme temperatures and splinters.
Apron / overalls: Aprons and overalls provide protection from sparks and will help to reduce the risk of burns.
Shoes: Closed-toe, steel-toed shoes should always be worn to protect the feet from injury.
2.2 Welding Machines
Welding machines used for arc welding must be capable of providing a constant and reliable power output. The type of machine chosen should depend on the materials being welded and the thickness of the metal being joined.
2.3 Welding Supplies
A selection of welding supplies must be used to ensure a successful weld. This may include welding rod, flux, backing tape and welding wire.
3. Preparation
Prior to commencing work, all work surfaces should be prepared to ensure an even and strong weld. Preparation steps may include grinding, brushing or sanding the area to be welded. Furthermore, if the weld is being carried out on an already existing joint, then this should be checked for gaps, corrosion or other defects. Any rough edges should be removed and the area cleaned of any rust, dirt or paint prior to welding.
4. Welding Procedure
4.1 Setting the machine
The welding machine should be adjusted according to the electrode type, size and power level recommended by the manufacturer. Before beginning to weld the electrode should be checked to ensure it is the correct size and is in good condition.
4.2 Starting the Weld
The electrode should be fired up and the pulsed current slowly adjusted depending on the electrodes and material being welded. To ensure that the arc strikes, the electrode should be held slightly above the surface of the metal at an angle of approximately 10 degrees. As the electrode touches the surface, the polarity should be reversed and the arc started. This should be done in a smooth and steady motion to produce a neat bead.
4.3 Making the Passes
In order to produce the desired weld, a series of passes should be carefully made across the area to be welded. Different techniques may be used depending on the size of the weld and the thickness of the metal. Generally, the first pass should be made along the length of the weld, followed by subsequent passes at a right angle. Small beads should be made with a push technique, with the electrode pointing in the direction of the weld. Conversely, long single beads should be made with a drag technique, where the electrode is pointed in the direction opposite the weld.
4.4 Finishing
Once the passes have been made, the weld should be left to cool naturally. The weld should then be inspected to ensure it meets with the appropriate standards and that the welding machine has been correctly calibrated.
5. Conclusion
This document outlines the standard operating procedures for manual arc welding of structural steel. It is important that these procedures are followed carefully in order to ensure the quality and safety of the finished welded structure, and that the appropriate safety equipment is used. With the correct equipment, preparation and technique, it is possible to produce a weld of the highest quality and strength.
