RIYADH, 28 May — National Industrial Gases Co. (GAS) of Saudi Arabia announced yesterday that Germany’s Linde AG had won a $93-million contract to construct an air separation unit that will boost production by 50 percent. The unit, which is to be completed by late 2004, will be built in the eastern industrial city of Jubail, said GAS, an affiliate of industrial giant Saudi Basic Industries Corp. (SABIC). The project will expand GAS’s production capacity from 5,300 tons per day to 8,600 tpd, of which 3,000 tpd will be oxygen.