Cooking and/or steam generating apparatus and equipment for preparing meals in industrial kitchens, namely, electric food cookers, electric food steamers, electric fryers, electric frying pans, and electric cooking ovens, all for commercial use and sold as a unit; gas food cookers, gas food steamers, gas fryers, gas frying pans, and gas cooking ovens, all for commercial use and sold as a unit; structural parts and fittings for the aforesaid goods