art
background
black
bolt
circle
color
colorful
conduit
connection
construction
contour
control
element
engineering
equipment
factory
faucet
fuel
gas
gasoline
icon
illustration
industrial
industry
isolated
line
linear
lineart
metal
object
oil
outline
pipe
pipeline
piping
plumbing
power
pressure
pump
sign
steel
symbol
system
tap
technology
tube
valve
water
white