37 Machinery installation, maintenance and repair services; maintenance and repair services of machinery for industrial plants; installation, maintenance and repair of industrial apparatus and instruments, namely, heat exchange and transfer apparatus employing catalytic chemical reactions; installation, maintenance and repair of electrical systems; installation, maintenance and repair of heating apparatus; installation, maintenance and repair of steam generating apparatus; installation, maintenance and repair of water apparatus, namely, water supply and water desalination apparatus; installation, maintenance and repair of gas installations and equipment, namely, gas turbine engines; installation, maintenance and repair of apparatus for use in measuring energy, energy generation and the supply of energy; installation, maintenance and repair of computer hardware and computer peripherals; installation, maintenance and repair of apparatus used for cooking, refrigerating, drying, ventilating and sanitary purposes; repair of heat exchange and transfer apparatus; maintenance and servicing of data processing installations and apparatus; maintenance of electronic monitoring devices; diagnostic maintenance of apparatus for heating and steam generation; provision of advice, information and consultancy services in relation to the aforesaid