FTSE 250 engineering group Rotork has beefed up its valve kits offering through the acquisition of privately-owned Prokits.Prokits is a designer and manufacturer of valve adaptor kits and accessories for the valve industry. It has gross assets of £0.6m. The sole owner of Prokits, Craig Mellins, has been appointed as general manager of Rotork Valvekits into which the Prokits business will be merged. In a weak engineering sector on Thursday morning, Rotork was trading down 9p at 1,799p.NR