bolts
building
clean
connection
curve
development
economy
energy
engineering
environment
facility
factory
gas
health
heavy
hold
hot
industrial
industry
joint
link
metal
modern
mortar
nuts
oil
pedestal
petrol
pipe
pipeline
plumbing
pollution
power
production
pump
science
standard
station
steel
strong
structure
supply
system
technology
tube
urban
valve
waste
water
white