10 free, exam-style NBBI (NBBI) practice questions with answers and explanations. No signup required. Work through them below, then take the full free NBBI practice test to study every exam domain.
These 10 free NBBI questions are organized by exam domain, so you can see how each part of the NBBI blueprint is tested. Reveal the answer and explanation under each question.
An in-service vessel has a current thickness of 0.380 in., a minimum required thickness of 0.300 in., and a corrosion rate of 0.020 in./year. Using the standard NBIC approach, what is the maximum recommended interval to the next inspection?
Correct answer: C - 2 years
Before entering a boiler to perform an internal inspection, which action must the inspector ensure is completed FIRST?
Correct answer: B - Isolate and lock out the steam, water, and fuel lines
A pressure vessel shell measured 0.500 in. thick when new. After 8 years in service it measures 0.420 in. What is the average corrosion rate?
Correct answer: B - 0.010 in./year
An austenitic (300-series) stainless steel vessel in chloride-bearing service develops branching cracks under tensile stress, with no measurable general wall thinning. This damage is BEST classified as:
Correct answer: C - Stress corrosion cracking
A safety valve discharge pipe on a power boiler must be sized and arranged so that:
Correct answer: D - Back pressure cannot impair the valve's relieving capacity
A cylindrical pressure vessel shell has an inside radius of 24 in., a maximum allowable stress of 17,500 psi, a joint efficiency of 1.0, and a wall thickness of 0.500 in. (no corrosion allowance remaining). Using the ASME Section VIII, Division 1 formula, what is the MAWP?
Correct answer: D - 360 psi
A vertical pressure vessel is filled with water and stands 30 ft tall. The MAWP marked at the top connection is 150 psi. What total pressure acts on the bottom head?
Correct answer: B - 163 psi
An inspector must examine a 300-series (austenitic) stainless steel component for surface-breaking cracks. Which examination method is LEAST suitable because of the component's material?
Correct answer: D - Magnetic particle testing
A power boiler has a MAWP of 200 psi and is protected by two safety valves. Under ASME Section I, what is the highest permissible set pressure for the additional (higher-set) valve?
Correct answer: A - 206 psi
On an automatically fired steam boiler, what is the primary purpose of the low-water fuel cutoff?
Correct answer: C - Cut off the fuel when the water drops below a safe level
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