CRE Equipment and Tools Knowledge 5

Question 1

A reliability engineer receives a vibration report showing sub-synchronous vibration at approximately 0.43× running speed in a journal bearing machine. This pattern is MOST consistent with:

Accepted Answer

Oil whirl instability

Answer

Oil whirl in journal bearings typically occurs at approximately 40–48% of running speed (0.43–0.48×) due to the average oil film velocity in the bearing clearance.

Question 2

Which tool is used to determine the natural frequency of a piping system to assess risk of acoustic resonance with pump pulsations?

Accepted Answer

Finite element analysis (FEA) software or modal testing

Answer

FEA software or experimental modal testing (impact hammer + accelerometer) identifies the mechanical natural frequencies of piping to compare with excitation frequencies.

Question 3

A thermographic camera with a temperature sensitivity (NETD) of 0.05°C is MOST valuable for:

Accepted Answer

Detecting small, early-stage thermal anomalies in electrical equipment

Answer

High thermal sensitivity (low NETD) allows detection of subtle temperature differences indicative of early-stage electrical faults before they become severe.

Question 4

An X-ray fluorescence (XRF) analyzer is used in oil analysis to detect which type of contamination?

Accepted Answer

Wear metal elemental composition (iron, copper, lead, etc.)

Answer

XRF and ICP spectrometry identify and quantify wear metal elements in oil, helping diagnose which components are degrading based on their elemental signature.

Question 5

During a pump reliability improvement project, a team installs real-time flow and pressure transmitters. The PRIMARY reliability benefit is:

Accepted Answer

Enabling detection of off-BEP (best efficiency point) operation that causes cavitation and wear

Answer

Operating a pump away from its best efficiency point increases internal recirculation, radial loads, and cavitation risk, all of which reduce bearing and seal life.

(CRE) Certified Reliability Engineer Practice Test

(CRE) Certified Reliability Engineer Practice Test

CRE Equipment and Tools Knowledge 5