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What is the maximum pipe size for which threaded joints can be used without the approval of the AHJ?

  1. 2 inches

  2. 6 inches

  3. 4 inches

  4. 8 inches

The correct answer is: 2 inches

The maximum pipe size for which threaded joints can be used without the approval of the Authority Having Jurisdiction (AHJ) is indeed 2 inches. This limitation is set to ensure safety and integrity in gas piping systems. Threaded joints are generally considered less reliable than welded or flanged joints, especially as pipe sizes increase. For pipes larger than 2 inches, the risk of leaks and structural failure becomes a greater concern, thus requiring oversight by the AHJ to ensure that proper installation practices and standards are followed. This regulation is in place to promote best practices in safety and to minimize potential hazards associated with gas handling systems. Using this threshold allows for a standardized approach, where smaller pipes can be assembled with less specialized oversight, while larger pipes necessitate more stringent measures to ensure the public's safety and compliance with building codes.