API 653 Aboveground Storage Tank Inspector Practice Questions — 10 Free (2026)

When making cuts parallel to existing weld seams during dismantling, what is the minimum required distance from the weld?

• A. 50 mm
• B. 75 mm
• C. 100 mm
• D. 150 mm ✓
• E. 200 mm

To keep weld integrity intact, any cut through the shell shall stand off from existing welds by 150 mm (6 in.) at the least. API 653, 10.3.2.1 / Fig 10.1

An aboveground storage tank is being assessed for microbiologically influenced corrosion. Which location does API RP 571 identify as characteristically affected?

• A. The upper shell courses, where thermal cycling is greatest
• B. The vapour space immediately beneath the fixed roof
• C. The roof-to-shell junction, where condensate runs back into the product
• D. The external shell surface above the wind girder
• E. The bottom water layer of the tank ✓

Typical MIC locations include water-cooled heat exchangers, piping that runs stagnant or at low flow, piping buried in certain soils, and the layer of water sitting at the bottom of storage tanks. Standing water plus little or no movement is the shared condition, and a tank bottom supplies both. API RP 571, Par. 3.45, Affected Units or Equipment

Per T-720, the magnetic particle examination method is applied to detect discontinuities in what type of materials?

• A. Nonporous materials
• B. All metals
• C. Ferromagnetic materials ✓
• D. Austenitic stainless steel
• E. Aluminum alloys

Detection of discontinuities at the surface, or just under it, in ferromagnetic materials is specifically what MT is used for. ASME Section V T-720

For the tmin calculation in SI units, what are the units for Diameter (D) and Height (H)?

• A. Meters ✓
• B. Millimeters
• C. Centimeters
• D. Inches
• E. Feet

In the SI version of the formula, both the tank diameter and liquid height must be entered in meters. API 653, 4.3.3.1

What is the consequence of applying an inorganic zinc lining below its normal dry film thickness range?

• A. The coating mud cracks and disbonds immediately after application
• B. The steel is inadequately protected and flash rusting can occur ✓
• C. The coating cures faster than intended but performs normally in service
• D. There is no consequence, since the zinc protects galvanically at any thickness
• E. The coating becomes electrically insulating and interferes with cathodic protection

Go under the usual 3 to 5 mil range and the steel lacks adequate protection, so flash rusting sets in. Go over it and the coating mud cracks, disbonding as soon as it is applied. A range rather than a minimum is specified because both limits matter. API RP 652, inorganic zinc linings

What is the termination point for one or more test leads used for structure-to-electrolyte potential measurements?

• A. Rectifier
• B. Anode bed
• C. Test station ✓
• D. Secondary containment
• E. RPB

Test stations provide accessible points for technicians to monitor the health of the CP system without excavation. API 651, 3.53

A tank shell has 410 ft of completed vertical butt joint of one type and thickness, welded by a single welder. The thinner plate at the joint is 3/8 in. How many spot radiographs are required for that vertical joint? Given: Vertical butt joint length = 410 ft; one type and thickness; one welder.

• A. 5 ✓
• B. 4
• C. 6
• D. 7
• E. 10

One spot radiograph is taken in the first 10 ft of completed vertical joint, then one in each 100 ft thereafter. The first 10 ft gives one and the remaining 400 ft gives 4 more, so 5 in total. Counting straight through at one per 100 ft, or forgetting the radiograph owed on the first 10 ft, are the common errors. API 650, 8.1.2.2

For which materials must certification of contaminant content be obtained for all liquid penetrant materials used?

• A. Only cast materials, where surface porosity may retain penetrant residues after post-cleaning
• B. Any material examined at a surface temperature above 125 deg F
• C. Carbon steel and low alloy steel only, where the component is to be postweld heat treated
• D. Nickel base alloys, austenitic and duplex stainless steels, and titanium ✓
• E. All materials without exception, whenever a solvent removable penetrant technique is used

Titanium, duplex and austenitic stainless steels, and nickel base alloys all demand contaminant certification for the penetrant materials applied to them. Nickel alloys suffer from residual sulfur; austenitic stainless and titanium suffer from residual halogens. The trigger is therefore what the material is susceptible to, not the technique or the temperature used. Batch numbers from the manufacturer and the test results both belong in that certification. ASME BPVC Sec. V, Art. 6, Mandatory Appendix II

A corrosion rate has been reported in mils per year. What is the remaining life at this location? Given: t_actual = 0.388 in., t_minimum = 0.261 in., corrosion rate = 6.5 mpy.

• A. 2.0 years
• B. 59.7 years
• C. 19.5 years ✓
• D. 195.4 years
• E. 40.2 years

One mil is one thousandth of an inch, so 6.5 mpy is 0.00650 in./yr and the remaining life is 19.5 years. Two of the wrong options misplace the decimal by one place. API 653, Sec. 4 and API 575, 7.1

Refer to Exhibit WPS-PQR-WPQ-07. The welder performance qualification records that the welder last used the shielded metal arc welding process 10 months before the date of this review, and has used no other process since. Is the welder qualified to make the production weld?

• A. No, the coupon thickness qualified does not cover the production base metal thickness
• B. Yes, the welder performance qualification was signed and dated by the testing laboratory
• C. Yes, the qualification remains valid because the welder was tested to a qualified procedure
• D. No, the welder qualified in the 3G position and the production weld is in the flat position
• E. No; the welder has not used the process within the past 6 months ✓

A welder stays qualified in a process only while the gap since he last ran it is 6 months or less. Here the SMAW qualification has run out at 10 months and needs renewal before production welding. Signing, dating and welding to a qualified procedure all matter and are all in order here, yet none of them keeps the qualification alive. ASME BPVC Sec. IX, QW-322.1