HERA Report R8-41: HERA Guide to Shielding Gases for Seismic Welds

Description

This technical guide is for shielding gas used in the welding processors such as gas metal arc welding (GMAW), flux cored arc welding (FCAW), gas tungsten arc welding (GTAW). The primary purpose of shielding gas is to protect the molten weld metal from oxygen, nitrogen and hydrogen contained in the air. The reaction of these elements with the weld pool can lead to porosity, cold cracking and excessive spatter. The shielding gas also plays an important role in determining weld penetration profiles, arc stability and mechanical properties of the weld metal. There is a variety of shielding gas options available to suit welding processes and filler materials. The cost of the gas, finished weld properties, preparation and post-weld clean up, productivity aspects all need to be taken into account when selecting a shielding gas. The choice of the shielding gas is also subject to manufacturer’ recommendations, limitations of the welding procedures and additional requirements imposed by Ships’ Classification Societies approval as discussed in this guide.