MCC-NH Gas Fitters Practice Exam

What is a requirement for trench construction in gas piping installations?

1. Trenches must be at least 8" deep

2. Trenches must be self-draining

3. Trenches should be at least 12" down

4. Trenches should be lined with concrete

The correct answer is: Trenches should be at least 12" down

In gas piping installations, it is crucial to maintain a minimum depth for trench construction to ensure the safety and integrity of the system. The requirement for trenches to be at least 12 inches deep typically serves two main purposes: it helps to protect the gas piping from physical damage and also minimizes the risk of accidental contacts with other utilities that may be buried in the vicinity. When trenched to the correct depth, the likelihood of the pipe being disturbed or damaged from surface activities is significantly reduced. Additionally, deeper trenches help ensure proper burying of the piping, which contributes to the overall safety of the installation. Other options may not conform to established industry practices or safety codes. For instance, a depth of 8 inches would not provide adequate protection in many situations. The idea of trenches being self-draining is relevant in preventing water accumulation but is secondary to the requirements of depth. Finally, lining trenches with concrete is not a standard requirement in most gas piping installations, as it could inhibit the necessary flexibility and adaptability in the installation process.