The assembly station shown is part of a multi-station manual assembly line used in the assembly of valves. Due to the weight of the final product the valve is loaded onto a common fixture for transportation through the assembly line. Within this particluar station a parts presentation system is utilised to present parts to the operator with a PC-screen used to provide operator work instructions. The work instructions are automatically selected by scanning a 2d-data matrix on the valve. A DC tightening tool is used to tighten an array of fastenings, with automatic torque selection. Full product tracibility is achieved.