background
bolt
chemical
conduit
connection
construction
control
drain
element
energy
engineering
equipment
factory
faucet
flange
fuel
gas
gasoline
grey
icon
illustration
industrial
industry
isolated
metal
natural
object
oil
petroleum
pipe
pipeline
piping
plumbing
power
pressure
pump
sign
steel
symbol
system
tap
technology
tube
valve
water
white