Review of API-653
Replacement shell plate may be circular,oblong,square with rounded corners or rectangular
with rounded corners except when: - correct answer-an entire shell plate is replaced
Shell replacement patch plates shall be welded with butt joints with complete penetration
and complete fusion, except as: - correct answer-permitted for lapped patch shell repairs
Joints in lap-welded shell tanks: - correct answer-may be repaired according to the as-built
standard of construction
A 7/8 thick inch circular butt welded repair plate is installed in the 0.875" thick lower course
of a tank. What is the minimum weld spacing required from the vertical and horizontal plate
welds of the lower course? - correct answer-10"&10"
Lapped patch shell repairs are: - correct answer-an acceptable form or repairs for
butt-welded,lap-welded, and riveted tank shells only when specified by the owner.
Lapped patch shell repairs shall not be used on any shell course thickness (original
construction) that exceeds____ inch. - correct answer-0.500
Lapped patch shell repairs shall not be used to replace : - correct answer-door sheets or
shell plates
Lapped patch plates shall not have a thickness less than: - correct answer-0.1875 inches
If a lapped patch plate is installed on a tank,what corner(s) may be exempt from being
rounded to a minimum radius? - correct answer-The joint at the shell to bottom intersection
A lapped repair plate is installed across a butt-welded vertical seam.The seam is ground
flush and checked by ultrasonics.The inspector must specify the minimum overlap of the
patch plate.What minimum distance is selected? - correct answer-6 inches beyond the shell
seam .
Lapped repair plates positioned on the tank shell interior shall be located such that the
toe-to-toe weld clearances are a minimum of _____ to the shell-to-bottom weld. - correct
answer-6 inches
The maximum vertical and horizontal dimension of a lapped patch repair plate is: - correct
answer-48 inches and 72 inches respectively
The minimum lapped patch shell repair plate dimension is: - correct answer-4inches
An owner-user wants to put a NPS 8 shell opening (nozzle) in an AST shell. Which of the
below would not be acceptable to API 653? - correct answer-within a lapped patch shell
repair.
, Prior to application of a lapped patch shell repair, the areas to be welded shall be _____ for
plate defects and remaining thicknesses. - correct answer-UT'd
An inspector finds a 36inch by 48 inch lapped repair patch that had been installed on a shell
that has a thin area near the patch center. The owner- user asks that a lapped repair plate
be installed on the old lap patch.This installation: - correct answer-is not permitted according
to API 653.
What is the minimum hole diameter caused by the removal of an existing shell opening that
may be repaired by a lapped repair plate? - correct answer-2 inches.
What joint efficiency is used to calculate the required thickness of a lapped repair plate
installed over a shell opening caused by the removal of an existing nozzle? - correct
answer-0.7
A NPS 3 nozzle is removed from the 0.325" thick third course of an AST. The reinforcing pad
is removed from around the nozzle and welds are ground smooth. The hole left by removing
the NPS 3 nozzle is 3.75" in diameter. You are required to only have the minimum overlap
over the hole by the lapped repair plate as required by API 653. What is the minimum
diameter of the lapped repair plate? - correct answer-5.75 inches
What maximum joint efficiency may be used for a lapped patch repair plate with a full fillet
perimeter weld that is used to. repair a thin area of a tank shell? - correct answer-0.35
An AST has a thin area caused by external corrosion on the third shel course.The original
thickness of the shell course was 3/8 inch. It has thinned to 0.06 inch in a 13" by 17"
rectangular area. The lap patch is to be installed over the area to a point where the shell
thickness is at original thickness. what is the maximum thickness lap patch that you could
use to repair this thinned spot? - correct answer-1/2"
The area of metal on the tank shell that has thinned and been repaired by using a lapped
patch : - correct answer-shall not be considered as effective in carrying the calculated
service or hydrotest loads.
Lapped patch repair plates may be used to repair small. shell leaks. The repair plate must be
designed to withstand hydrostatic pressure load between the repair plate and the shell. The
joint efficiency used for this calculation is: - correct answer-0.35
If a lapped patch repair patch is used to repair a small shell leak on an AST, what are the
maximum and minimum thicknesses of the repair plate - correct answer-1/2" & 3/16"
Which of the conditions listed below would be unacceptable as an application of a lapped
patch repair plate to repair a small shell leak? - correct answer-If exposure of the fillet welds
to the product will produce crevice corrosion then this repair method shall not be used .
Replacement shell plate may be circular,oblong,square with rounded corners or rectangular
with rounded corners except when: - correct answer-an entire shell plate is replaced
Shell replacement patch plates shall be welded with butt joints with complete penetration
and complete fusion, except as: - correct answer-permitted for lapped patch shell repairs
Joints in lap-welded shell tanks: - correct answer-may be repaired according to the as-built
standard of construction
A 7/8 thick inch circular butt welded repair plate is installed in the 0.875" thick lower course
of a tank. What is the minimum weld spacing required from the vertical and horizontal plate
welds of the lower course? - correct answer-10"&10"
Lapped patch shell repairs are: - correct answer-an acceptable form or repairs for
butt-welded,lap-welded, and riveted tank shells only when specified by the owner.
Lapped patch shell repairs shall not be used on any shell course thickness (original
construction) that exceeds____ inch. - correct answer-0.500
Lapped patch shell repairs shall not be used to replace : - correct answer-door sheets or
shell plates
Lapped patch plates shall not have a thickness less than: - correct answer-0.1875 inches
If a lapped patch plate is installed on a tank,what corner(s) may be exempt from being
rounded to a minimum radius? - correct answer-The joint at the shell to bottom intersection
A lapped repair plate is installed across a butt-welded vertical seam.The seam is ground
flush and checked by ultrasonics.The inspector must specify the minimum overlap of the
patch plate.What minimum distance is selected? - correct answer-6 inches beyond the shell
seam .
Lapped repair plates positioned on the tank shell interior shall be located such that the
toe-to-toe weld clearances are a minimum of _____ to the shell-to-bottom weld. - correct
answer-6 inches
The maximum vertical and horizontal dimension of a lapped patch repair plate is: - correct
answer-48 inches and 72 inches respectively
The minimum lapped patch shell repair plate dimension is: - correct answer-4inches
An owner-user wants to put a NPS 8 shell opening (nozzle) in an AST shell. Which of the
below would not be acceptable to API 653? - correct answer-within a lapped patch shell
repair.
, Prior to application of a lapped patch shell repair, the areas to be welded shall be _____ for
plate defects and remaining thicknesses. - correct answer-UT'd
An inspector finds a 36inch by 48 inch lapped repair patch that had been installed on a shell
that has a thin area near the patch center. The owner- user asks that a lapped repair plate
be installed on the old lap patch.This installation: - correct answer-is not permitted according
to API 653.
What is the minimum hole diameter caused by the removal of an existing shell opening that
may be repaired by a lapped repair plate? - correct answer-2 inches.
What joint efficiency is used to calculate the required thickness of a lapped repair plate
installed over a shell opening caused by the removal of an existing nozzle? - correct
answer-0.7
A NPS 3 nozzle is removed from the 0.325" thick third course of an AST. The reinforcing pad
is removed from around the nozzle and welds are ground smooth. The hole left by removing
the NPS 3 nozzle is 3.75" in diameter. You are required to only have the minimum overlap
over the hole by the lapped repair plate as required by API 653. What is the minimum
diameter of the lapped repair plate? - correct answer-5.75 inches
What maximum joint efficiency may be used for a lapped patch repair plate with a full fillet
perimeter weld that is used to. repair a thin area of a tank shell? - correct answer-0.35
An AST has a thin area caused by external corrosion on the third shel course.The original
thickness of the shell course was 3/8 inch. It has thinned to 0.06 inch in a 13" by 17"
rectangular area. The lap patch is to be installed over the area to a point where the shell
thickness is at original thickness. what is the maximum thickness lap patch that you could
use to repair this thinned spot? - correct answer-1/2"
The area of metal on the tank shell that has thinned and been repaired by using a lapped
patch : - correct answer-shall not be considered as effective in carrying the calculated
service or hydrotest loads.
Lapped patch repair plates may be used to repair small. shell leaks. The repair plate must be
designed to withstand hydrostatic pressure load between the repair plate and the shell. The
joint efficiency used for this calculation is: - correct answer-0.35
If a lapped patch repair patch is used to repair a small shell leak on an AST, what are the
maximum and minimum thicknesses of the repair plate - correct answer-1/2" & 3/16"
Which of the conditions listed below would be unacceptable as an application of a lapped
patch repair plate to repair a small shell leak? - correct answer-If exposure of the fillet welds
to the product will produce crevice corrosion then this repair method shall not be used .
