We can know the level of hardness of SMAW weld joints (shielding Metal Arc Welding) can be influenced by several factors, including the size of the welding amperage, the type of electrode and the treatment after welding. The object of this research test was carried out on a welded connection of a 3kg LPG gas cylinder which is the construction of a transition energy conversion gas cylinder from kerosene used by the community. The 3kg LPG cylinder is a pressure vessel that is a storage place for LPG (Liquidfied Petroleum Gas) with medium carbon steel plate material type JIS 295 with a plate thickness of 2.5 mm. in addition, the 3kg LPG gas cylinder has 3 general parts consisting of a tube handguard, tube body and footring tube with tube height ±80 mm and tube diameter 25 mm