The purpose of this study was to determine how the effect of coolant variations on the hardness of stainless steel pipe welds by argon welding and quenching. The quenching media used in this study were salt water, oil, and coolant. The concentration of salt water used is 285.7 g / L. The oil used is the 20W 50 SG MA type, and the coolant used is the solube type with a coolant: water ratio = 1:3…