機器
abstract
angle
background
barrel
big
blue
bolt
business
chemical
concrete
connection
construction
energy
engineering
equipment
factory
fuel
gas
gasoline
industrial
industry
insulation
iron
line
metal
natural
oil
pipe
pipeline
piping
plant
power
pump
red
resources
row
rusty
shiny
sky
steel
supply
system
technology
transportation
tube
valves
wide
work