機器
environmental
blue
building
chemical
chemistry
color
complex
duct
energy
engine
engineering
environment
equipment
facility
factory
fuel
gas
green
heavy
high
industrial
industry
iron
landscape
machinery
metal
oil
oilnature
outdoor
petrochemical
petroleum
petrolium
pipe
pipeline
piping
plant
power
production
refinery
silhouette
sky
station
steel
structure
tanks
technology
tower
tree
tube