Industrial maintenance businesses help factories, processing plants, warehouses and other industrial sites keep machinery, equipment and building services in working order. Their work may include planned preventative maintenance, routine inspections, fault diagnosis and repairs to production lines, pumps, motors, gearboxes, conveyors, compressors and hydraulic or pneumatic systems. Some also maintain electrical equipment, controls and instrumentation, or carry out mechanical fitting, welding and fabrication. Services can be arranged for scheduled visits, urgent breakdowns or planned shutdowns, when equipment is taken out of service for inspection, overhaul or replacement of worn parts. Contractors may test components, monitor vibration or temperature, align rotating machinery and keep maintenance records. The precise work depends on the site and its equipment; businesses may provide specialist technicians, parts and equipment, or work alongside a customer's in-house engineering team.