blue

business

chemical

conduit

construction

control

energy

engineering

environment

equipment

factory

fuel

gas

gasoline

gauge

heavy

helmet

industrial

industry

line

manufacturing

metal

natural

oil

petrochemical

petroleum

pipe

pipeline

piping

plant

power

pressure

processing

production

pump

red

refinery

service

sky

station

steel

storage

supply

system

tank

technology

tube

valve

white

work