Design, research, development, production, processing, repair, and sales of specialized petroleum equipment; design, research, development, production, processing, repair, and sales of engineering vehicles; production, processing, and sales of specialized chemical equipment; production, processing, and sales of pressure vessels (with certificate) and atmospheric pressure vessels; production and sales of metal welding and cutting parts; research, development, production, installation, and sales of steel structure buildings; sales of electromechanical products, metal materials (excluding hazardous items), and office equipment; leasing of buildings and mechanical equipment; anti-corrosion engineering; petroleum engineering technical services; import and export trade (excluding commodities and technologies restricted or prohibited by the state for company operation or import/export). (Items involving licensed operations shall be conducted only after obtaining relevant department permits.)