From the following, which list contains unacceptable fittings?

From the following, which list contains unacceptable fittings?

• A. Close nipples, street elbows, street tees
• B. Unions, couplings, elbows
• C. Street elbows, street tees, unions
• D. Close nipples, couplings, street tees

Answer: (A)

In gas piping, joints must provide a reliable seal and be easy to inspect and service. Close nipples are not allowed because their very short length means limited thread engagement and a higher chance of leaks or damaged threads during installation or future disassembly. Street fittings, like street elbows and street tees, have a male-threaded end. The exposed male end can be damaged more easily, seals are harder to verify, and leak testing is more difficult compared with standard fittings that have female ends on both sides. Because all three of these types are considered unacceptable in gas installations, the list containing close nipples along with street elbows and street tees is the one that fits the question. The other options mix in fittings that are generally acceptable when installed correctly, such as unions, couplings, and standard elbows.

In gas piping, joints must provide a reliable seal and be easy to inspect and service. Close nipples are not allowed because their very short length means limited thread engagement and a higher chance of leaks or damaged threads during installation or future disassembly. Street fittings, like street elbows and street tees, have a male-threaded end. The exposed male end can be damaged more easily, seals are harder to verify, and leak testing is more difficult compared with standard fittings that have female ends on both sides. Because all three of these types are considered unacceptable in gas installations, the list containing close nipples along with street elbows and street tees is the one that fits the question. The other options mix in fittings that are generally acceptable when installed correctly, such as unions, couplings, and standard elbows.