background
caution
chemical
city
connection
construction
danger
do
energy
environment
equipment
forbid
forbidden
fuel
gas
hand
handle
icon
industrial
industry
label
many
metal
metallic
natural
no
oil
outside
palm
people
petroleum
pipeline
power
prohibited
prohibition
red
restriction
safety
sign
silver
steel
stop
structure
symbol
system
technology
touch
warning
white