This work aimed to evaluate the welding quality and the sustainability of an automatic metal active gas with mixing gases (MAG-M) process for welding the valve boss on liquefied petroleum gas (LPG) upper cylinder half, in comparison to the presently used automatic submerged arc welding (SAW) process. The weld quality of MAG-M welding samples met the ASME standards, comparably to the SAW welding samples. In addition, the MAG-M welding process for welding LPG valve bosses is preferable over the SAW welding process on the condition that >73,339 pieces are processed. However, the welding fumes and noises from this process have stronger environmental and social effects than those from SAW welding. Besides, the SAW process is preferable in LPG valve boss production up to 73,339 pieces. The solid waste or slag generated in this welding process should be managed.