API 653 Flashcards
Learn API 653
1
Q
API 653 covers tanks built to what API codes?
A
API 650 & 12C 653 - 1.1.1
2
Q
API 653 recognizes FFS API 579 assesment T/F?
A
TRUE 653 - 1.1.6
3
Q
If regulations of 653 are more strict than local AHJ regulations, which governs?
A
API 653 653 - 1.3
4
Q
What is an alteration?
A
Any work that changes physical dimensions/configuration 653 - 3.1
5
Q
Where is the critical zone?
A
annular plate within 3” of the inside of shell 653 - 3.10
6
Q
What is considered a major repair/alteration?
A
shell penetration > NPS 12; bottom penetration within 12” of shell; R&R shell plate with any dimension >12”; R&R annular plate with any dimension >12” 653 - 3.20
7
Q
What is considered a major repair/alteration?
A
removal of vert. 12” weld on shell plates or on annular ring; a whole new bottom; R&R 50% weld between shell/annular ring; jacking tank shell 653 - 3.20
8
Q
What is considered a repair?
A
work necessary to restore a tank to safe operation (includes major repair scope) 653 - 3.26
9
Q
What is considered a repair organization?
A
owner/operator who repairs/alters to 653; contractor who’s quals are acceptable to owner/user and 653; one who is not prohibited by AHJ and 653 653 - 3.27
10
Q
What is a storage tank engineer?
A
one or more persons acceptable to owner/user regarded as composite of all entities to properly assess req’s 653 - 3.30
11
Q
Roof plates corroded to what condition SHALL be replaced?
A
0.09” avg thickness in any 100 in^2 or holed through 653 - 4.2.1.2
12
Q
When evaluating alterations to a tank roof, what standard applies?
A
Current applicable standard API 650 Annex F 653 - 4.2.4.1
13
Q
Before changing service to an elevated temp of >200F, what std shall apply?
A
API 650, Annex M - 653 - 4.2.4.3
14
Q
Before changing service to a lower temp, what std shall apply?
A
Currrent applicable std 653 - 4.2.4.4
15
Q
What are options if req’s of 653 cannot be satisfied?
A
Damaged areas shall be repaired; liquid level reduced; tank retired 653 - 4.3.1.5
16
Q
Shell corrosion - critical Length L is determined by what formula, not to exceed?
A
L = 3.7sqrt(DT2) D = tank diam in FEET; T2 least thickness in INCHES; L max = 40” 653 - 4.3.2.1
17
Q
Shell corrosion - widely scattered pits may be ignored, provided that?
A
No pit is >50% of Tmin, sum of pits vert dim’s
18
Q
Shell corrosion - Tmin shall not be less than X inches for any tank course?
A
0.1” 653 - 4.3.3.1
19
Q
Shell welds - cracks in the shell to bottom weld SHALL be removed (T/F)?
A
TRUE 653 - 4.3.6
20
Q
Bottom - assesment period shall be ?
A
Less than or = to shell interval
21
Q
Bottom - Tmin for bottom plate (minimum remaining thickness)
A
Reference 653 - 4.4.5.1
22
Q
Bottom - if mim thickness will be
A
Lined, repaired, replaced or interval to next internal insp. Reduced 653 - 4.4.5.3
23
Q
Bottom - critical zone Tmin SHALL be the smaller of?
A
50% of original thickness or 50% of Tmin of bottom shell; but not less than 0.1” 653 - 4.4.5.4
24
Q
Bottom - thickness of projection of bottom plate beyond shell shall not be
A
0.1” thick and horiz. projection beyond shell shall be >= 3/8” 653 - 4.4.5.7
25
Foundation - principle causes of foundation deterioration include?
settlement, erosion, cracking, and conrete deterioration 653 - 4.5.1.1
26
Brittle Fracture - once a tank has withstood X & Y, the risk of brittle fracture is low?
Combined effects of max liquid level and lowest operating temp 653 - 5.2.2
27
Brittle Fracture - any change in service must be evaluated for brittle fracture risk (T/F)?
TRUE 653 - 5.2.3
28
Brittle Fracture - if shell is no thicker than 0.25, 0.5, 0.625 or 0.75 , brittle fracture risk is low?
0.5" 653 - 5.3.5
29
Brittle Fracture - no known brittle fracture above shell temp of 32F, 50F, 60F, or 70F?
60F 653 - 5.3.6
30
Inspection - routine in-service visual inspections shall be made every week, month, or year?
Shall not exceed one month interval 653 -6.3.1.2
31
Inspection - Tanks shall be given a visual external by an AI at least?
Every 5 years or RCA/4N years
32
Inspection - UT of shell thickness - when shell corrosion rate is not known, UT shall be done?
At least every 5 years 653 - 6.3.3.2
33
Inspection - UT of shell thickness - when shell corrosion rate is known, UT shall be done?
15 years or RCA/2N years, whichever is smaller 653 - 6.3.3.2
34
Inspection - Initial internal interval shall not exceed 3, 5, 10 or 15 years?
10 years, unless safeguards are added per Table 6.1 653 - 6.4.2.1.1
35
Material - new materials used for repair/alt/reconstruction shall conform to?
Current applicable standard 653 - 7.2
36
Material - shell/bottom plate material shall be identified by?
Original contract drawings, API nameplates, or other suitable docs 653 - 7.3.1
37
Material - flange mat'l shall meet minimum req's of as built or current applicable std?
The "as built" standard 653 - 7.3.3.1
38
Design - shell thickness design shall be based on numbers taken within 30, 60, 90 or 180 days?
Within 180 days 653 - 8.4.1
39
Design - shell penetrations shall be design/welded to the as built or current applicable std?
Current applicable std 653 - 8.5.1
40
Tank repair - all repair work must be authorized prior to work by whom?
Authorized Inspector OR Tank Engineer 653 - 9.1.3
41
Tank Repair - Alterations must be approved by the AI, Tank Engineer or both?
Tank Engineer only 653 - 9.1.3
42
Tank Repair - Inspection hold points will be designated by AI, Tank Engineer or both?
AI only 653 - 9.1.3
43
Tank Repair - limited or routine repairs may be authorized by AI, Tank Engineer or both?
AI may authorize repairs provided no hydro or engineering evaluation is req'd. 653 - 9.1.3
44
Tank Repair - design, work execution, materials, procedures, NDE must be approved by AI, Tank Engineer or both?
AI or Tank Engineer 653 - 9.1.4
45
Tank Repair - Repair/alteration work shall be approved at HOLD points/after work completion by AI, Tank Eng or both?
AI or Tank Engineer 653 - 9.1.4
46
Shell repair - minimum dimension for a replacement shell plate is 4", 6", 12"?
12" or 12 x thickness of shell, whichever is greater 653 - 9.2.2
47
Shelll repair - replacement shell plates may be what shapes?
circular, oblong, square w/rounded corners, rectangular w/rounded corners 653 - 9.2.2.1
48
Shell repair - prior to welding new vertical joints, the horiz. Welds shall be cut 3", 6", 9" or 12" beyond the joint?
12" beyond vertical joint and vert. must be done before horiz. 653 - 9.2.2.2
49
Door sheet - if a vert cut crosses existing horiz weld, the back gouged root pass and final pass shall be PT, MT or both?
PT or MT 653 - 9.2.4.5
50
Door sheet - if a vert cut crosses existing horiz weld, the existing seam shall be MT, PT or both for how far on both sides?
MT or PT for 6" on both sides 653 - 9.2.4.5
51
Shell repairs - lap welded patch plates are acceptable on butt welded, lap welded, riveted tank or all?
All tanks when specified by owner 653 - 9.3.1
52
Shell repairs - lap welded patch plates shall not be used on shells > than 0.375", 0.5", 0.625" or 0.75"?
0.5" thick 653 - 9.3.1.2
53
Shell repairs - repair plate corners shall be rounded to a minimum radius of 0.5", 1", 1.5" or 2"?
2" minimum radius 653 - 9.3.1.4
54
Shell repair - repair plate may cross any ground butt welded seam provided it overlaps minimum 3", 6", 9" or 12"?
6" beyond weld seam 653 - 9.3.1.5
55
Shell repair - maximum dimension of a repair plate is 2'x3', 3'x4', 4'x6' or full shell course height x 8'?
4'x6' 653 - 9.3.1.7
56
Shell repair - the minimum dimension of a repair plate is 4", 6", 8", or 12"?
4" minimum dimension 653 - 9.3.1.7
57
Shell repair - repair plate shall conform to as-built std with a joint efficiency or 0.35, 0.5, 0.7, or 0.85?
Joint efficiency not exceeding 0.7 653 - 9.3.2.3
58
Shell repair - repair plate shall conform to as-built std with a joint efficiency or 0.35, 0.5, 0.7, or 0.85?
Joint efficiency not exceeding 0.35 653 - 9.3.3.1
59
Shell penetration - reinforcing plates may be added to both outside and inside of tank provided nozzle projection (T/F)?
TRUE - must have adequate nozzle projection into tank 653 - 9.7.3
60
Shell penetration - penetrations larger than NPS 1.5, 2, 4, or 6" shall be installed with an insert plate
NPS 2" 653 - 9.8.6
61
Shell penetration - completed splice welds on bottom plate when installing a new bottom shall be PT, MT or both?
MT 653 - 9.9.4 c)
62
Tank Bottom - min dimension for a welded on patch plate that overlaps a bottom seam shall be 4", 6", or 12"
12" 653 - 9.10.1.1
63
Tank Bottom - a patch plate that does not cross a seam may be as small as 4", 6" or 9" diameter
6" diameter, must overlap any corroded area by 2" 653 - 9.10.1.1
64
Tank Bottom - max thickness for welded on patch plates in the critical zone is 1/8", 3/16" or 1/4"
1/4" 653 - 9.10.1.2
65
Tank bottom - butt welding a bottom patch plate to another is permitted in the critical zone (T/F)?
False - 653 - 9.10.1.2 d)
66
Tank bottom - welded on patch plates over existing patches are not allowed in the critical zone (T/F)?
True 653 - 9.10.1.2 e)
67
Tank bottom - new fillet welds on a tombstone patch plate shall be greater of Xin or Yt from vert weld joints
3in and 5*thickness
68
Tank bottom - use of welded on patch plates that do not meet API 653 is permitted if AI, Tank Engineer or both agree?
Tank Engineer only 653 - 9.10.1.3
69
Tank bottom - new bottom - shells made of 50ksi yield or less, existing shell penetrations need not be raised if?
min 4" between weld toes, low H electrodes, weld toes blend ground, min 3" or 2.5t between self-reinforced penetrations and bottom 653 - 9.10.2.7 b)
70
Tank bottom - weld toes shall be blend ground from 3 to 9 o'clock, 4 to 8 o'clock, or 5 to 7 o' clock
4 to 8 o'clock for circular reinforcing plates 653 - 9.10.2.7 d)
71
Tank bottom - weld toes shall be blend ground only on lower horizontal length of diamond shaped (T/F)?
True, also blend grind inside/outside of shell to bottom weld min of one penetration diam length on both sides pene. 653 -9.10.2.7 d)
72
Tank bottom - blend ground welds shall be MT, PT or both before, after or before & after hydro test?
MT only before AND after hydro 653 9.10.2.7 e)
73
Tank roof - minimum thickness of new roof plates shall be 1/8", 3/16", 1/4", or 5/16" ?
3/16" + C.A. 653 - 9.11.2.1
74
Tank roof - rim mounted seal system shall have no more than 10%, 15%, 25% or 50% removed at one time for repair
25% 653 - 9.13.1
75
Tank roof - if roof rim thickness is less than 0.1", 0.125", 3/16" or 1/4" it shall be replaced
0.1", new roof rim shall be 3/16" minimum 653 - 9.13.6.2
76
Hot Tap - min liquid level above hot tap shall be 1', 3', 5' or 10' during hot tapping?
3' 653 - 9.14.1.2
77
Hot Tap - hot taps are permitted on roof/within vapor space only with necessary permits/approval from owner/user HSE dept mgr (T/F)?
False - hot taps are not permitted on roof or in vapor space 653 - 9.14.1.3
78
Hot Tap - procedure shall be documented and carried out according to practices given in API 653, 2201, 2214 or 2271?
API 2201 653 - 9.14.2
79
Hot Tap - minimum spacing between hot tap and any nozzle shall be 6", 12", 12*shell thickness or sqrt R*T (tank shell radius INCHES x shell thickness)
Sqrt (R*T) where R is tank shell radius in inches and t is shell thickness in inches 653 - 9.14.3.1
80
Hot Tap - after reinforcing pad has been welded to the shell, pad shall be pneumatically tested to 15psi, procedure in API 650, or visual only
Pad shall be pneumatically tested per API 650 7.3.4 653 - 9.14.5.3
81
Reconstruction - reconstruction work must be authorized by the owner/user, AI, Tank engineer or repair organization, before work begins?
Reconstruction work must be authorized by the AI or Tank Engineer 653 - 10.1.3
82
Reconstruction - the AI, Tank Engineer or both shall approve reconstruction work at designated hold points and after construction is completed?
AI or Tank Engineer can approve 653 - 10.1.4
83
Reconstruction -no welding shall be performed when base metal temperature is below 0F, 20F, 32F, 60F?
0F 653 - 10.4.2.3
84
Reconstruction - when base metal temp is 0F to 32F or thickness is >1", base metal within 3", 6", 8" or 12" must be heated to about 140F?
3" 653 - 10.4.2.3
85
Reconstruction - maximum permissible undercut in vertical and horizontal seams is 1/16", 1/32" or 1/64"?
1/64" V and 1/32" H 653 - 10.4.2.4
86
Reconstruction - tack welds are permissible to remain in vertical tank joints with manual welding process (T/F)?
False, must be removed. 653 - 10.4.2.7
87
Reconstruction - it is permissible to leave weldable primer coatings in place provided they are on the WPQ test (T/F)?
True, all other coatings shall be removed. 653 - 10.4.2.8
88
Reconstruction - misalignment of vertical joins shall not be more than 10%, 15%, 20% or 1/8"?
10% of plate thickness with a max of 1/8" 653 - 10.4.4.1
89
Reconstruction - for shell plates >1.5", multipass welds and minimum pre-heat of 200, 250 300, 350F is required?
200F 653 - 10.4.4.3
90
Dimensional tolerances - measurements shall be taken before, after or before and after a hydrostatic test of a reconstructed tank?
Before only 653 - 10.5.1.2
91
Dimensional tolerances - max out of plumbness of top of shell to bottom shall not exceed 1/100, 1/150, 1/200 or 1/250 of total height?
1/100, not to exceed 5" 653 - 10.5.2.1
92
Dimensional tolerances - with horizontal sweep board, 36" long, peaking shall not exceed 1/8", 1/4", 3/8" or 1/2"?
1/2" 653 - 10.5.4
93
Dimensional tolerances - with vertical sweep board 36" long, banding shall not exceed 1/2", 3/4", 1" or 1.5"?
1" 653 - 10.5.5
94
Dimensional tolerance - where foundations true to a horiz. Plane are specified part 1: where concrete ringwalls are provided, should be level to?
1/8" in any 30' circumference and within +/- 1/4" in total circumference from average elev. 653 - 10.5.6.2 a)
95
Dimensional tolerance - where foundations true to a horiz. Plane are specified part 2: where concrete ringwalls are NOT provided, should be level to?
1/8" in any 30' circumference and within +/- 1/2" in total circumference from average elev. 653 - 10.5.6.2 b)
96
Welding - welding procedures for handrails, platforms, appertunances shall comply with 653, 650 or AWS D1.1, AWS D1.6 or ASME?
AWS D1.1, AWS D1.6 and ASME codes apply 653 - 11.1
97
Welding - which welds do not require welder ID? Roof plate, bottom plate, flange-to-nozzle neck, top ring to shell
roof plate and flange nozzle to neck welds do not require ID 653 - 11.2.2
98
Welding - Pre-heat and/or controlled deposition welding methods can be used in lieu of PWHT if approved by the AI, Tank Engineer, owner/operator?
Tank Engineer and owner operator both and in writing 653 - 11.3
99
Welding - preheating where impact test NOT req'd - limited to P1 mat'ls and must maintain 200, 300, 350, or 375F at 4" or 4xT both sides of groove?
300F - 653 - 11.3.1 d)
100
Welding - controlled deposition welding method is used when an impact test IS req'd - (T/F)?
True 653 - 11.3.2
101
NDE - nozzle and reinforcement plate to shell welds shall be examined by PT, MT or both?
PT or MT 653 - 12.1.2.3
102
NDE - stress relieved assemblies shall be examined by MT, PT, or both before, after or before and after hydrostatic testing?
PT or MT, after PWHT and before hydro 653 - 12.1.2.4
103
NDE - completed weld repairs of butt welds shall be examined 10%, 25%, 50% or full length by RT or UT methods?
Full length RT or UT 653 - 12.1.3.2
104
NDE - welds of permanent attachments shall be examined visually, by PT or MT?
Visually 653 - 12.1.4.1
105
NDE - completed welds of new permanent attachments shall be examined visually, PT or MT?
MT or PT if purchaser approves 653- 12.1.4.2
106
NDE - new welding on shell to bottom joint shall be examined full length by UT, MT, right angle vacuum box or light diesel oil?
Right angle vacuum box or light film diesel oil 653 - 12.1.6
107
NDE - repaired areas of bottom plate shall be examined by MT, PT, vacuum box or tracer gas detector?
MT or PT and vacuum box or tracer gas 653 - 12.1.7.3
108
NDE - the owner user, AI orTank Engineer shall determine the extent of further examination req'd beyond 653
Owner user w/consent of contractor 653 - 12.2.1.5
109
NDE - radiographs and radiograph records of all repaired welds shall be marked with WR, R?
Letter 'R' only 653 - 12.2.3.2
110
NDE - a hydrostatic test for 24hours shall be performed for?
Reconstructed tank, for major repair/alteration (exemptions apply), when engineering eval req's it for severe service 653 - 12.3.1
111
NDE - a hydrostatic test can be exempted if the AI, Tank Engineer or owner/user agrees in writing?
Tank Engineer and owner/user 653 - 12.3.2.2
112
NDE - Initital settlement survey, prior to tank filling, must be completed with a minimum of 4, 8, 12 or 16 points with max circum. spacing of of 32 ft?
Mimimum 8 points with max spacing 32 feet N=D/10 653 - 12.5.2
113
Marking & Records - nameplates shall be of corrosion resistant material stamped with letters not less than 5/32", 3/16", 1/4", or 5/16"?
5/32" 653 - 13.1.1.1
114
Tank Settlement - maximum spacing of bottom settlement measurement points radially outward is 10', 15' or 20'?
10' 653 - Annex B Fig B.2
115
Definiton - The owner/user, AI or manufacturer is responsible for compliance with 650?
Manufacturer 650 - 1.3.2
116
Terms - Design metal temp shall be assumed to be 0, 10, 15 or 20F above the lowest one-day mean ambient temperature of the installed location?
15F above 650 - 3.6
117
Material - shell plate underrun not more than 0.01", or 5%, 10% or 12% of thickness shall be permitted?
0.01" is max underrun regardless of shell thickness 650 - 4.2.1.2.3
118
Material - shell plates shall be limited to max thickness of 1.5", 1.75", 1.875" or 2"?
1.75" 650 - 4.2.1.4
119
Material - an impact test shall be performed on one, two or three specimens taken from a single test coupon?
Three 650 - 4.2.9.3
120
Design - shell to bottom fillet welds shall not be more than 3/8", 1/2" or 3/4" nor less than nominal thickness of thinner of two plates
1/2" 650 - 5.1.5.7
121
Design - design external pressure shall not be less than 1, 2, 5, or 10 inches of water?
1 inch of water 650 - 5.2.1
122
Design - internal floating roof uniform live load shall be 5, 7.5, 10, 12.5 psi if no auto drains and 2.5, 5, 7.5 and 10psi if auto drains are provided?
12.5 psi if no auto drains, 5 psi if auto drains 650 - 5.2.1 e)
123
Design - internal floating roof point load shall be 200, 250, 375 or 500lbf or 1sq ft?
500 lbf per sq ft 650 - 5.2.1 e)
124
Design - external roof live load projected on horizontal area shall be 10, 15, 20 or 25 lbf per sq ft?
20 lbf per sq ft 650 - 5.2.1 e)
125
Design - bottom plates shall have a corroded thickness of not less than 0.1", 0.125", 0.236" or 0.25"?
0.236" (6mm) 650 - 5.4.1
126
Design - bottom plates shall project beyond the shell a minimum 0.5", 1", 1.5" or 2"?
2" 650 - 5.4.2
127
Design - the minimum shell thickness of a 150' diam tank shall be 3/16", 1/4", 5/16" or 3/8"?
5/16" 650 - 5.6.1.1
128
Design - openings in tank shells greater than NPS 1.5", 2", 4" or 6" shall be reinforced?
NPS 2 650 - 5.7.2.1
129
Design - reinforcing plates shall be provided with a 1/8", 1/4" or 3/8" telltale hole?
1/4" 650 - 5.7.2.10
130
Design - roof plates shall have a nominal thickness of not less than 3/16", 1/4" or 3/8"?
3/16" 650 - 5.10.2.2
131
Erection - the use of oxyfuel welding process is permitted if impact testing of material is req'd (T/F)?
False. Oxyfuel is not permitted if impact testing is req'd. 7.2.1.1
132
Erection - preheat shall be applied (when req'd) and maintained a minimum of 2", 3", 6" or 12" of the welding area?
3" 650 - 7.2.1.3
133
Erection - tack welds in vertical joints can remain in a manual weld process provided 100% RT or UT is performed (T/F)?
False. Tack welds shall be removed in all manual welded vert joints 650 - 7.2.1.9
134
Erection - the finished tank bottom shall be examined visually, with vacuum box, tracer gas test
Visually and vacuum box or tracer gas 650 - 7.3.3
135
Erection - internal bottom elevation measurements shall be taken prior to, after or both prior to and after the hydrostatic test?
Before and After hydro 650 - 7.3.6.8
136
Erection - completed defect repairs shall be approved by the manufacturer, Tank engineer or purchaser's inspector?
Purchaser's inspector 650 - 7.4.1
137
Erection - maximum out of plumbness of top of the shell relative to bottom of shell shall not exceed 1/100, 1/200 or 1/250 of total tank height?
1/200 650 - 7.5.2
138
NDE - each radiograph shall show a minimum of 3", 6", or 12" of weld length?
6" 650 - 8.1.2.8
139
NDE - ASME Section V req's in T-274 are used only as a guide, final acceptance is based on image and specificed hole visibility (T/F)?
True 650 8.1.3.3
140
NDE - manufacturer shall certify each visual examiner can read a Jaeger type I, II or III chart at a distance of 1 ft or more?
Jaeger Type II, annual check, also color contrast 650 - 8.5.1
141
NDE - a partial vacuum minimum of 3, 4, 5 or 10psi shall be performed witn a 6in x 30in vacuum box?
3 to 5 psi vacuum gage shall be used 650 - 8.6.3
142
NDE - bottom metal surface temp shall be between 32-100F, 32-125F, 40-100F or 40-125F for vacuum box testing
40-125F 650 - 8.6.6
143
NDE - a minimum light intensity of 1, 10, 100, 1000 Lux is req'd for vacuum box testing
1000 Lux (100 foot candle)
144
WPS and WQ - if a protective coating has been applied to weld edge prep, it shall be removed,, treated as an essential variable or non-essential?
Included as an essential variable 650 - 9.2.1.4
145
WPS and WQ - all materials to be used at a design metal temperature below 20, 32, 40 or 50F, the WPQ for vert joints shall include impact tests
50F 650 - 9.2.2.3
146
WPS and WQ - when design metal temp is below 0, 15, 20, 32F, impact test shall be made for all WPQ
20F 650 - 9.2.2.4
147
WPS and WQ - welds not requiring welder identification include- roof plate welds, flange to nozzle neck welds, bottom plate lap welds, temporary lugs
roof plate and flange to nozzle neck welds 650 - 9.4
148
Ext floating roof - deck plates shall have a minimum thickness of 1/8", 5/32", 3/16" or 1/4" ?
3/16" 650 - C.3.3.2
149
Ext floating roof - floating roofs shall have sufficient buoyancy to remain afloat on liquid with SG of 0.7, 1 or 1.1 with drains inoperative
SG of 0.7 or minimum design SG 650 - C.3.4
150
Ext floating roof - each pontoon compartment shall be provided with a manhole minimal nominal size of NPS 20, 24, 30 or 36?
NPS 20 650 - C.3.5
151
Ext floating roof - roof leg landing pads must have a minimum dimenions of 1/4" x 12" diam, 3/8" x 12" diam, 1/4" x 14" diam or 3/8" x 14" diam
3/8" x 14" diam 650 - C.3.10.5
152
Ext floating roof - roof manholes shall be a minimum of NPS 20, 24, 30 or 36 with a minimum of 1 or 2 for diam
NPS 24, minimum two manholes 650 - C.3.11
153
Internal floating roof - maximum spacing between vents shall be 10, 20, 25 or 32 ft with no fewer than four per tank
32 ft 650 - H.5.2.2.1
154
Internal floating roof - a minimum of 1 or 2 fixed roof manholes shall be provided with a nominal opening of 24" or larger
one 650 -H.5.5.1
155
UT in lieu of RT - alternative method is limited to joints where the thickness of the thinner of two memmbers joined is >= 1/4", 3/8" or 1/2"
Greater than or equal to 3/8" 650 - U.1.1
