Api 653 Repairs
Where to find joint types table – answer Api sec. 4, table 4.2
Where to find joint efficiency table – answer Api 653 sec. 4, table 4.2
Where to find table for type and extent of radiography performed – answer Api 653 sec.
4, table 4.2 and Api 650 sec. .8.1, fig 8-1
What is the equation for Tmin or max fill height for localized corrosion? Where is it
found? - answerApi 653 sec.4.
H=(S*E*Tmin)/(2.6*D*G)
What is the equation for Tmin or max fill height for entire shell? Where is it found? -
answerApi 653, sec.4
H=(S*E*Tmin)/(2.6*D*G)+1
Lap patch shell repairs are acceptable for what types of tank shells? - answerButt weld,
lap weld, and riveted tank shells
Lap patch repairs are considered permanent and are subject to what? - answerOngoing
inspections
Lap patch material shall comply with what requirements? - answerThe requirements of
current applicable standards of construction and API 653
Lap patch repairs shall not be used on any shell course of what thickness? Nor is it to
replace what on the shell? - answerShall not be used on shell course thicker than 1/2"
or to replace door sheets or shell plates
Except as permitted by 9.3.3.2 and 9.3.4.3, what thickness material shall a lap patch
be? - answerShall be less than 1/2" or thickness of the shell plate, but not less than
3/16"
What shape can lap patch be? - answerCircular, oblong, square, or rectangular. All
corners shall be rounded to a minimum 2" radius. Nozzle reinforcement shapes of
API650 figure 5.8 are also acceptable
Can lap patch plate cross butt welded vertical or horizontal shell seams? - answerYes.
Seam welds shall be ground flush and lap patch welds must overlap a minimum of 6"
beyond seam.
, Weld spacing requirements of figure 9-1 shall be used as a basis for what? -
answerLocating repair plates relative to butt welds, fillet welds, or riveted seams.
Can lap patch plates intersect with shell to bottom weld? - answerYes. Vertical sides of
lap patch must intersect shell to bottom weld at 90* angle and shell to bottom weld is in
compliance with figure 9.6
Can lap patches on interior of tank shell intersect with shell to bottom weld? -
answerNo. Patch shall be located a minimum 6" away from shell to bottom weld
What is the maximum vertical and horizontal dimensions of lap patch plate? -
answerMax vertical is 48". Max horizontal is 72"
What is the minimum dimensions of a lap patch plate? - answer4"
Can shell openings and their reinforcements be located within a lapped patch repair? -
answerNo
Before applying lap patch repair, what examination shall be performed? - answerArea to
be welded shall be UT'd to examine for defects and thickness
Where shall shell lap patches not be placed onto? - answerLap welded seams, riveted
seams, other lap patches, distorted areas, or unrepaired cracks/defects
Shell lap patch covering a hole shall be applied how? - answerContinuous weld on the
perimeter of the plate and perimeter of the hole. Hole must be a minimum of 2" and
corners of plate have a radius of 2"
Shell lap patch covering a removed nozzle hole must be prepared how? - answerNozzle
neck and nozzle reinforcement shall be removed before installation
How shall the shell lap patch thickness be decided? - answerShall be based on design
that conforms to the as-built standard and API 653, using a joint efficiency not
exceeding .7
For shell lap patch repairs covering a hole, what is the plate's minimum dimensions and
minimum and maximum overlap? - answerPlate shall have a minimum dimension of 4"
and Minimum overlap of 1" and Maximum overlap of 8t.
For a shell lap patch covering a hole, how much thicker may the plate be than the
adjacent shell plate to the repair? - answerIt shall not be thicker than the adjacent shell
plate.
Shell lap patch repairs may be used to reinforce what areas? - answerMay be used to
reinforce severely corroded areas that are not able to retain service loads of the tank
and also for shell plates that are below minimum thickness.
Where to find joint types table – answer Api sec. 4, table 4.2
Where to find joint efficiency table – answer Api 653 sec. 4, table 4.2
Where to find table for type and extent of radiography performed – answer Api 653 sec.
4, table 4.2 and Api 650 sec. .8.1, fig 8-1
What is the equation for Tmin or max fill height for localized corrosion? Where is it
found? - answerApi 653 sec.4.
H=(S*E*Tmin)/(2.6*D*G)
What is the equation for Tmin or max fill height for entire shell? Where is it found? -
answerApi 653, sec.4
H=(S*E*Tmin)/(2.6*D*G)+1
Lap patch shell repairs are acceptable for what types of tank shells? - answerButt weld,
lap weld, and riveted tank shells
Lap patch repairs are considered permanent and are subject to what? - answerOngoing
inspections
Lap patch material shall comply with what requirements? - answerThe requirements of
current applicable standards of construction and API 653
Lap patch repairs shall not be used on any shell course of what thickness? Nor is it to
replace what on the shell? - answerShall not be used on shell course thicker than 1/2"
or to replace door sheets or shell plates
Except as permitted by 9.3.3.2 and 9.3.4.3, what thickness material shall a lap patch
be? - answerShall be less than 1/2" or thickness of the shell plate, but not less than
3/16"
What shape can lap patch be? - answerCircular, oblong, square, or rectangular. All
corners shall be rounded to a minimum 2" radius. Nozzle reinforcement shapes of
API650 figure 5.8 are also acceptable
Can lap patch plate cross butt welded vertical or horizontal shell seams? - answerYes.
Seam welds shall be ground flush and lap patch welds must overlap a minimum of 6"
beyond seam.
, Weld spacing requirements of figure 9-1 shall be used as a basis for what? -
answerLocating repair plates relative to butt welds, fillet welds, or riveted seams.
Can lap patch plates intersect with shell to bottom weld? - answerYes. Vertical sides of
lap patch must intersect shell to bottom weld at 90* angle and shell to bottom weld is in
compliance with figure 9.6
Can lap patches on interior of tank shell intersect with shell to bottom weld? -
answerNo. Patch shall be located a minimum 6" away from shell to bottom weld
What is the maximum vertical and horizontal dimensions of lap patch plate? -
answerMax vertical is 48". Max horizontal is 72"
What is the minimum dimensions of a lap patch plate? - answer4"
Can shell openings and their reinforcements be located within a lapped patch repair? -
answerNo
Before applying lap patch repair, what examination shall be performed? - answerArea to
be welded shall be UT'd to examine for defects and thickness
Where shall shell lap patches not be placed onto? - answerLap welded seams, riveted
seams, other lap patches, distorted areas, or unrepaired cracks/defects
Shell lap patch covering a hole shall be applied how? - answerContinuous weld on the
perimeter of the plate and perimeter of the hole. Hole must be a minimum of 2" and
corners of plate have a radius of 2"
Shell lap patch covering a removed nozzle hole must be prepared how? - answerNozzle
neck and nozzle reinforcement shall be removed before installation
How shall the shell lap patch thickness be decided? - answerShall be based on design
that conforms to the as-built standard and API 653, using a joint efficiency not
exceeding .7
For shell lap patch repairs covering a hole, what is the plate's minimum dimensions and
minimum and maximum overlap? - answerPlate shall have a minimum dimension of 4"
and Minimum overlap of 1" and Maximum overlap of 8t.
For a shell lap patch covering a hole, how much thicker may the plate be than the
adjacent shell plate to the repair? - answerIt shall not be thicker than the adjacent shell
plate.
Shell lap patch repairs may be used to reinforce what areas? - answerMay be used to
reinforce severely corroded areas that are not able to retain service loads of the tank
and also for shell plates that are below minimum thickness.
