機器
boiler
cave
channel
check
chemical
circular
confined
construction
corrosion crude
danger
dark
dirty
economy
energy
engineering
environment
equipment
flange
flow
fuel
gas
gate
heat
hole
industrial
line
metal
mine
mud
oil
open
petrol
pipes
power
pressure
pump
repair
rusty
safety
sand
steel
storage
storage tank
technology
texture
tool
tunnel
work