Does a left hand thread offer any advantages over a right hand thread?
Left pedals on most bicycles have left-hand threads to keep the pedal from unscrewing. Some cars (MGs, e.g.) used to have left-hand lug nuts on the left side, but that's not so common anymore. Some circular saw blades are secured with left-hand nuts for a similar reason.
Turnbuckles obviously have opposite handed threads on either end.
Fuel gas bottles have left hand threads & oxidizer gas bottles have right hand threads as a safety measure for welders. That's why the propane tank on your gas grill is left-handed.
When I was a teenager I nearly stripped the lug nut studs on my Mom's '65 Dodge when changing a flat. The nut seem to be getting tighter and a friend watching suggested it might have a left hand thread, which it did.
They prevent unscrewing in applications where the screw fixes a rotating object, and also help to differentiate gas from hydraulic/liquid/etc lines in cars, burners, etc.
Are u saying that gas lines are always fitted with left hand theads???
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