If there is no letter following the date stamped on the cylinder, what does it indicate regarding requalification?

The correct indication that if there is no letter following the date stamped on the cylinder, it means that requalification is required within 12 years is based on the guidelines established by the Department of Transportation (DOT) for LP-gas cylinders. DOT regulations specify that if a cylinder does not display a letter after the date of manufacture, it defaults to a 12-year requalification period. It is essential to adhere to this timeframe to ensure the safe use of the cylinder, as this requalification process involves rigorous testing and inspection to confirm that the cylinder remains safe and suitable for continued service. The absence of a letter clearly designates the requalification timeline, and hence, understanding this detail is vital for compliance and safety in handling LP-gas cylinders.