TWI Industrial Member Report Summary 547/1996
G J Carter
Electrode formulations were examined to obtain sound root runs of good profile in single-sided welds.
Fabrication of large structures, such as platform jackets, often requires closure welds, made without backing, and with access only from the outside. The size of the members renders it difficult to obtain good joint fit-up, and, even with the highest welding skill, the root run cannot be guaranteed free from flaws which may substantially reduce fatigue life of the joint.
Basic low hydrogen manual metal arc (MMA) electrodes are most commonly used for offshore structures. However, consumables to AWS 5.1-1991 E7018 for example would be expected to be prone to root pass porosity because of their limited gas shielding, while E7016 electrodes provide more shielding but have been maximised for toughness and tend not to deposit the smooth root bead profiles desirable for maximum fatigue life.
- The project aimed at deriving manual metal arc electrode formulations to facilitate deposition of sound root runs of good profile in single-sided welds for heavy section steel fabrications.