Which statement about acetylene hose nuts is true?

• A. Has a left-hand thread
• B. Has a groove cut around it
• C. May have 'ACET' stamped on it
• D. All of the above

Answer: (D)

Acetylene hose nuts are designed with safety, identification, and proper sealing in mind. They use left-handed threads so they can’t be accidentally connected to oxygen equipment, which uses right-handed threads. A groove around the nut helps with seating and sealing the connection by giving the gasket a proper seat and a definite grip for tightening. You may also see an ACET stamp on the fitting to identify that this hose is carrying acetylene. Because all of these features are commonly present, every statement about acetylene hose nuts being left-hand threaded, grooved, and stamped with ACET is true.