bolt
chemical
chemistry
closed
connection
connector
construction
control
crane
distribution
energy
engineering
equipment
factory
flow
flowing
fossil
fuel
gas
gasoline
industrial
industry
iron
line
metal
methane
natural
oil
physical
pipe
pipeline
power
pressure
production
pump
reservoir
rig
screw
steel
supply
system
tap
technology
transmission
transport
transportation
tube
tubing
valve
yellow