CRE Equipment and Tools Knowledge 4

Question 1

A CMMS (Computerized Maintenance Management System) work order history is being used for reliability analysis. Which metric is DIRECTLY calculated from work order timestamps?

Accepted Answer

Mean Time To Repair (MTTR)

Answer

MTTR is calculated directly from work order start and completion timestamps, representing the average time to restore a failed asset to service.

Question 2

In a vibration velocity spectrum, a peak at 2× gear mesh frequency with sidebands spaced at shaft speed is MOST likely caused by:

Accepted Answer

Gear tooth wear or load distribution problem

Answer

Harmonics of gear mesh frequency with shaft speed sidebands indicate gear tooth wear, eccentricity, or uneven load distribution across the gear face.

Question 3

Which insulation resistance test parameter best indicates the rate of moisture or contamination build-up on motor windings over time?

Accepted Answer

Insulation resistance trend over multiple test dates

Answer

Trending insulation resistance measurements over time reveals gradual degradation from moisture, contamination, or aging better than any single-point test.

Question 4

When using a dial indicator to measure shaft runout, a total indicator reading (TIR) of 0.006 inches is recorded. The actual eccentricity of the shaft is:

Accepted Answer

0.003 inches

Answer

TIR represents the total diametric variation, so the actual eccentricity (radial offset from true center) is TIR ÷ 2 = 0.003 inches.

Question 5

A reliability engineer uses a proof test to validate the safety function of a pressure relief valve. The primary purpose of proof testing in this context is to:

Accepted Answer

Reveal dangerous undetected failures that accumulate between tests

Answer

Proof tests for safety instrumented systems reveal hidden (unrevealed) failures that cannot be detected during normal operation, reducing the probability of failure on demand.

(CRE) Certified Reliability Engineer Practice Test

(CRE) Certified Reliability Engineer Practice Test

CRE Equipment and Tools Knowledge 4