Abstract: An improved connecting arm for use in a Bourdon gauge is secured between one end of a Bourdon tube and an indicating needle driving mechanism of the Bourdon gauge by welding. The connecting arm is provided with a clamping end which can be firmly engaged with a Bourdon tube and the other end engaged with the driving mechanism first manually so that Bourdon gauges so assembled then can be automatically processed by an automatic welding machine in a consecutive order without further manual interference, increasing the speed and safety of welding assembly in practical production of Bourdon gauges.