Review of API-653
Replacement shell plate may be circular,oblong,square with rounded corners or
rectangular with rounded corners except when: - answeran entire shell plate is replaced
Shell replacement patch plates shall be welded with butt joints with complete
penetration and complete fusion, except as: - answerpermitted for lapped patch shell
repairs
Joints in lap-welded shell tanks: - answermay 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? - answer10"&10"
Lapped patch shell repairs are: - answeran 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. - answer0.500
Lapped patch shell repairs shall not be used to replace : - answerdoor sheets or shell
plates
Lapped patch plates shall not have a thickness less than: - answer0.1875 inches
If a lapped patch plate is installed on a tank,what corner(s) may be exempt from being
rounded to a minimum radius? - answerThe 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? - answer6 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. -
answer6 inches
The maximum vertical and horizontal dimension of a lapped patch repair plate is: -
answer48 inches and 72 inches respectively
The minimum lapped patch shell repair plate dimension is: - answer4inches
, 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? - answerwithin 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. - answerUT'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: - answeris 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? - answer2 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? - answer0.7
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? - answer5.75 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? - answer0.35
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? - answer1/2"
The area of metal on the tank shell that has thinned and been repaired by using a
lapped patch : - answershall 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: - answer0.35
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 - answer1/2" & 3/16"
Replacement shell plate may be circular,oblong,square with rounded corners or
rectangular with rounded corners except when: - answeran entire shell plate is replaced
Shell replacement patch plates shall be welded with butt joints with complete
penetration and complete fusion, except as: - answerpermitted for lapped patch shell
repairs
Joints in lap-welded shell tanks: - answermay 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? - answer10"&10"
Lapped patch shell repairs are: - answeran 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. - answer0.500
Lapped patch shell repairs shall not be used to replace : - answerdoor sheets or shell
plates
Lapped patch plates shall not have a thickness less than: - answer0.1875 inches
If a lapped patch plate is installed on a tank,what corner(s) may be exempt from being
rounded to a minimum radius? - answerThe 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? - answer6 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. -
answer6 inches
The maximum vertical and horizontal dimension of a lapped patch repair plate is: -
answer48 inches and 72 inches respectively
The minimum lapped patch shell repair plate dimension is: - answer4inches
, 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? - answerwithin 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. - answerUT'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: - answeris 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? - answer2 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? - answer0.7
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? - answer5.75 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? - answer0.35
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? - answer1/2"
The area of metal on the tank shell that has thinned and been repaired by using a
lapped patch : - answershall 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: - answer0.35
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 - answer1/2" & 3/16"
