API 653 Risk-Based Inspection (RBI) & Aboveground Storage Tank Integrity
Master Exam Guide: API 580 RBI Methodology, Likelihood and
Consequence of Failure Analysis, Owner/Operator RBI Responsibility,
Corrosion Risk Assessment, Inspection Interval Optimization, Storage Tank
Bottom Plate Thickness Requirements, New and Existing Tank Floor
Minimum Thickness Criteria, Coated and Uncoated Bottom Plate
Evaluation, Leak Detection and Containment Systems, Annular Plate
Design and Butt Weld Requirements, Lap-Welded Bottom Plate
Configurations, Shell-to-Bottom Joint Integrity, Critical Zone Corrosion
Limits, Magnetic Flux Leakage (MFL) Inspection Techniques, Ultrasonic
Testing (UT) Verification, Radiographic Testing (RT) Requirements for Shell
Welds, Welding Procedure Specification (WPS), Procedure Qualification
Record (PQR), Welder Performance Qualification (WPQ), Three-Plate Lap
Joint Restrictions, Fillet Weld Sizing Requirements, Tank Bottom
Settlement and Distortion Assessment Exam Questions Verified and
Provided with Complete A+ Graded Answers Latest Updated 2026
Who Determines to use RBI methodologies?
Owner/Operator
RBI Document - API Code?
API 580
What are the two factors of Risk?
,Consequence of failure and Likelihood of Failure
RBI Assessments must be thoroughly___________?
Documented
Who conducts an RBI Assessment?
Team of Knowledgeable of RBI Principles
RBI Assessments shall be repeated at least every ______ Years?
10 years
Two Primary Factors of Consequence of Failure are?
Product Type and Volume
Minimum thickness of a NEW tank bottom plate?
0.250"
Minimum thickness of an existing tank bottom plate without coating or detection/contain leak?
0.100"
,Minimum thickness of an existing tank bottom plate with a thick reinforced coating (>50 mils)
0.050"
Minimum thickness of an existing tank bottom plate with detection and contain a leak?
0.050"
Typical Shell Floor plates are welded how?
Lap Welded
Annular Shell floor plates are welded how?
Butt Welded
Minimum size of a new bottom fillet weld?
Full fillet
Three-plate Laps must be ______ inches from everything else?
12"
What is the minimum radial width of an annular plate? (Shell to nearest Lap Weld)
, 24"
What is the minimum width of a bottom plate extension on outside of shell? (Answer for both
New & Existing)
New - 2", Existing - 3/8"
What is the minimum thickness allowed of an existing bottom plate extension at the shell-
bottom weld?
0.100"
Most existing tank bottoms are inspected with _________. Areas of concern found are normally
checked with ____________.
MFL, UT
What is the width of the Critical Zone on existing tank bottoms?
3"
What is the minimum thickness of an existing tank bottom in a Critical Zone?
Less of 1/2 of original floor or. 1/2 T-min of 1st Shell Course, Typically it is 0.125"
What is the required length of RT on a Vert or Horizontal Tank Weld?
Master Exam Guide: API 580 RBI Methodology, Likelihood and
Consequence of Failure Analysis, Owner/Operator RBI Responsibility,
Corrosion Risk Assessment, Inspection Interval Optimization, Storage Tank
Bottom Plate Thickness Requirements, New and Existing Tank Floor
Minimum Thickness Criteria, Coated and Uncoated Bottom Plate
Evaluation, Leak Detection and Containment Systems, Annular Plate
Design and Butt Weld Requirements, Lap-Welded Bottom Plate
Configurations, Shell-to-Bottom Joint Integrity, Critical Zone Corrosion
Limits, Magnetic Flux Leakage (MFL) Inspection Techniques, Ultrasonic
Testing (UT) Verification, Radiographic Testing (RT) Requirements for Shell
Welds, Welding Procedure Specification (WPS), Procedure Qualification
Record (PQR), Welder Performance Qualification (WPQ), Three-Plate Lap
Joint Restrictions, Fillet Weld Sizing Requirements, Tank Bottom
Settlement and Distortion Assessment Exam Questions Verified and
Provided with Complete A+ Graded Answers Latest Updated 2026
Who Determines to use RBI methodologies?
Owner/Operator
RBI Document - API Code?
API 580
What are the two factors of Risk?
,Consequence of failure and Likelihood of Failure
RBI Assessments must be thoroughly___________?
Documented
Who conducts an RBI Assessment?
Team of Knowledgeable of RBI Principles
RBI Assessments shall be repeated at least every ______ Years?
10 years
Two Primary Factors of Consequence of Failure are?
Product Type and Volume
Minimum thickness of a NEW tank bottom plate?
0.250"
Minimum thickness of an existing tank bottom plate without coating or detection/contain leak?
0.100"
,Minimum thickness of an existing tank bottom plate with a thick reinforced coating (>50 mils)
0.050"
Minimum thickness of an existing tank bottom plate with detection and contain a leak?
0.050"
Typical Shell Floor plates are welded how?
Lap Welded
Annular Shell floor plates are welded how?
Butt Welded
Minimum size of a new bottom fillet weld?
Full fillet
Three-plate Laps must be ______ inches from everything else?
12"
What is the minimum radial width of an annular plate? (Shell to nearest Lap Weld)
, 24"
What is the minimum width of a bottom plate extension on outside of shell? (Answer for both
New & Existing)
New - 2", Existing - 3/8"
What is the minimum thickness allowed of an existing bottom plate extension at the shell-
bottom weld?
0.100"
Most existing tank bottoms are inspected with _________. Areas of concern found are normally
checked with ____________.
MFL, UT
What is the width of the Critical Zone on existing tank bottoms?
3"
What is the minimum thickness of an existing tank bottom in a Critical Zone?
Less of 1/2 of original floor or. 1/2 T-min of 1st Shell Course, Typically it is 0.125"
What is the required length of RT on a Vert or Horizontal Tank Weld?
