When is deflection testing performed?

When is deflection testing performed?

• A. 30 days after final backfill
• B. Immediately after backfill
• C. 7 days after backfill
• D. Before backfill

Answer: (A)

Deflection testing is done after the final backfill has been placed and allowed to settle, typically about 30 days later. The purpose is to verify that the pipe remains within the specified deflection limits once the surrounding soil has compacted and stabilized under normal conditions. Testing too soon can capture temporary distortions from fresh backfill, giving false indications of failure. Conducting the test before backfill doesn’t reflect the installed condition at all, and waiting about a month provides a stable, realistic measurement of how the pipe performs under load over time.

Deflection testing is done after the final backfill has been placed and allowed to settle, typically about 30 days later. The purpose is to verify that the pipe remains within the specified deflection limits once the surrounding soil has compacted and stabilized under normal conditions. Testing too soon can capture temporary distortions from fresh backfill, giving false indications of failure. Conducting the test before backfill doesn’t reflect the installed condition at all, and waiting about a month provides a stable, realistic measurement of how the pipe performs under load over time.