API 653 EXAM QUESTIONS AND
THEIR EXPECTED ANSWERS
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?
6"
What is the required length of RT at Tank Intersections
at:
Vertical? Horizontal?
3" on Verts weld seam and 2" on each side of verts
If there is a weld defect in a spot RT, how many RTs
are required?
2 unless there is 3" of good weld beyond the defect.
Method for RT: RT is shot to____________?
ASME Section V
What requirements are needed for Personnel to shoot
an RT on a Tank?
ASNT SNT-TC-1A
Acceptance Criteria for RT on a tank is?
ASME Section VIII
A rounded indication is one that's length is less than
or equal to ___________ times its width
3 times
100% of new vertical welds should be RT'd if the shell
thickness is greater than _______________?
1"
How many RT's are needed when a rectangular insert
plate is installed in the shell?
6 RTs
Which RT exposure technique is preferred?
Single Wall
What is the minimum # of RTs required for a
nozzle/pipe butt weld being completed using a double-
wall technique with a single view?
THEIR EXPECTED ANSWERS
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?
6"
What is the required length of RT at Tank Intersections
at:
Vertical? Horizontal?
3" on Verts weld seam and 2" on each side of verts
If there is a weld defect in a spot RT, how many RTs
are required?
2 unless there is 3" of good weld beyond the defect.
Method for RT: RT is shot to____________?
ASME Section V
What requirements are needed for Personnel to shoot
an RT on a Tank?
ASNT SNT-TC-1A
Acceptance Criteria for RT on a tank is?
ASME Section VIII
A rounded indication is one that's length is less than
or equal to ___________ times its width
3 times
100% of new vertical welds should be RT'd if the shell
thickness is greater than _______________?
1"
How many RT's are needed when a rectangular insert
plate is installed in the shell?
6 RTs
Which RT exposure technique is preferred?
Single Wall
What is the minimum # of RTs required for a
nozzle/pipe butt weld being completed using a double-
wall technique with a single view?
