- Smaller Root opening
- Lower Heat Input
- Larger Root face
- Irrelevant Electrode Size
In order to reduce the level of lack of penetration, a welder must use suitable welding supplies according to concerning joint configuration. One bigger reason for weld lack of penetration is lower heat applied. The welding associates must use pre-heated welding rods and ensure the good heat settings by giving adequate current and voltage. Also see How to minimize lack of fusion in weldment?
Below video is about pipe welding build up, to repair lack of penetration. The welder made a repair weld using Shield Metal Arc process.
As we know Shield Metal Arc (SMAW) process is type of arc welding which melts and joins the work piece by the creation of high temperature arc. The groove between the work pieces is filled by addition of flux coated welding electrodes. Flux helps to maintain arc and provides a protective covering of shield gases on weld. The core of a flux coated electrode, is the metal of similar type and composition of work piece to be joined. The core metal is melted in the heat of arc and is transferred to molten weld pool, passing through an ionized arc pathway. During solidification of molten weld metal, a protective coating of fused slag (from flux), is produced that assists the solidification mode and also prevents any contamination that may lead to catastrophic porosity and cavities.
Heat Settings in Stick Welding
The provision of constant current by electric power supply, assists to build an arc between filler electrode and work piece. Both direct and alternating current modes can be executed according to electrode and procedure type, but normally quality welding results are achieved by DC current modes. Welding current is a primary concern in arc process and normally refer to as amperages. Amperages required in stick welding, is a function of electrode size, material thickness and even the position of welding. So the upper and lower ends of current are selected, primarily according to the above mentioned parameters.
- Selection of suitable heat parameters
- Use of clamps to the joint
- Tack welds before welding
- Some post welding techniques
- Distortion minimization techniques using pressure jacks etc.