In Class I Division 1 locations, Group C equipment, threaded joints shall be made up with at least how many threads fully engaged?

In Class I Division 1 locations, Group C equipment, threaded joints shall be made up with at least how many threads fully engaged?

• A. 7
• B. 4
• C. 5
• D. 3

Answer: (C)

In Class I Division 1 locations with Group C equipment, threaded joints must be made up with five full threads engaged. This minimum provides enough metal-to-metal contact to resist loosening from vibration and to maintain a proper seal, which is crucial for preventing gas leaks in hazardous environments. Engaging fewer than five threads would weaken the joint and increase the risk of leakage or a compromised flame path, while five meets the established safety requirement without needing extra length or components.

In Class I Division 1 locations with Group C equipment, threaded joints must be made up with five full threads engaged. This minimum provides enough metal-to-metal contact to resist loosening from vibration and to maintain a proper seal, which is crucial for preventing gas leaks in hazardous environments. Engaging fewer than five threads would weaken the joint and increase the risk of leakage or a compromised flame path, while five meets the established safety requirement without needing extra length or components.