MCC-NH Gas Fitters Practice Exam

What should be done during backfilling of a trench after gas piping installation?

1. Do it all at once

2. Backfill in 6" increments

3. Leave it empty for inspection

4. Fill it with sand only

The correct answer is: Backfill in 6" increments

Backfilling a trench after gas piping installation must be done in a careful and systematic manner to ensure the integrity of the installation and safety of the system. Filling the trench in increments, specifically 6 inches at a time, allows for proper compaction of the soil around the piping. This method prevents air pockets that could lead to settling, which may cause damage to the gas pipes over time. Simultaneously, incremental backfilling allows for continuous inspection of the gas piping as the trench is being filled. Every layer can be checked for alignment and proper placement before adding more soil, mitigating the risk of future issues arising from improper installation. Using this method also promotes even distribution of load on the piping, reducing stress and potential failures. It ensures that any settling that might occur is minor and can be managed effectively during the backfilling process.