black
bolt
building
conduit
connection
construction
crane
cross
drain
element
engineering
faucet
fitting
flange
flow
fuel
gas
gasoline
icon
illustration
industrial
manometer
metal
metallic
oil
part
pipe
pipeline
piping
plumbing
pressure
set
sewerage
shape
sign
silhouette
steam
steel
stream
symbol
system
tap
technical
technology
tube
valve
water
welding
wheel