API 653 Flashcards
Flange material used for tank repair and alteration shall meet the minimum requirements for the material specifications in which:
The as built standard
If at any time settlement is deemed excessive, the tank should be ______.
Emptied and Re-leveled
Perimeter welds on welded on patch plates in the critical zone to be _______.
Two-pass and examined visually and by MT or PT
Any work on a tank that changes its physical dimensions or configuration.
Alteration
The coating shall be included as an essential variable, if a protective coating ______.
Has been applied to weld edge preparations.
The maximum interpass temperature permitted, in API 653, when using the preheat alternative to PWHT welding method.
600°F
Prior to each liquid penetrant examination, the surface to be examined and all adjacent areas within ______ shall be dry and free of all dirt, grease, lint, scale, ….
1 inch
Shell Settlement Types (components)
Uniform Settlement
Rigid Body Tilting of the tank (Planar Tilt)
Out-of-Plane Settlement
Lead Letter “B”
1/2” height 1/16” thick
Backscatter
Maximum Weld Reinforcement Thickness
Table 10.1
Maximum or Minimum Radius
Table 10.2
Tank Diameter feet
Radius inches
When using the preheat alternative weld method, the temperature shall be checked ______ to assure the minimum temperature is maintained during welding.
Four inches (100mm) or four times the material thickness whichever is greater on each side of the groove.
Two factors have a significant influence on toughness and resistance to brittle fracture.
Steel Cleanliness
&
Grain Size
The reinforcing plates may be added to the ______ of the tank provided that sufficient nozzle projection exists.
Inside
The portion of the tank bottom or annular plate within 3 inches of the inside edge of the shell, measure radially inward.
Critical Zone
For tanks constructed of material having a yield strength equal to or less than ______, existing shell penetrations need not be raised if certain conditions are met.
50,000 psi.
The minimum thickness of new roof plates shall be _______, plus any corrosion allowance as specified in the repair specifications.
3/16”
When performing qualification tests for tank bottom examination procedures and personnel on a sample tank bottom, the sample should be a minimum of _____.
70ft² (21m)
Two main considerations when welding austenitic stainless steels are
Solidification cracking
&
Hot cracking
Dimensions for Nozzles
Dimensions for Nozzles/Pipe/Plate
Table 5.6
Table 5.7
Maximum permitted transmitted density between the iqi & the area of interest.
4.0 ± .05
MT examination
Shall be done by the continuous method
Either wet or dry particles
The requirements of which standard shall be considered in the evaluation and subsequent alteration to the tank roof and roof to shell junction.
Current Applicable Standard
The minimum preheat temperature is
300°F
Densitometers shall be calibrated at least every ______ & a _______ step tablet or a step wedge with densities from at least 1.0 through 4.0, shall be used.
90 days
National Standard
Austenitic stainless steel are alloys that typically contain ______.
Low carbon, chromium between 15% to 32% and, nickel between 8% to 37%
Tramp Elements
Sulfur, phosphorus, tin, antimony, and arsenic
Hardness Test
Brinell
Rockwell
Knoop
Vickers
The maximum speed of UT scanning should be ______.
Stated in the procedure
Light image of the letter “B” on a dark background shall be considered _______.
Unacceptable
Density of material is best defined as
Mass per unit volume
Soil corrosion appears as external thinning with ______.
Localized loss due to pitting
The minimum height of tank liquid above the hot tap location shall be at least _____ during the hot tapping operation.
3 Feet
The sample tank bottom should be a minimum of _______ to provide space for the designed flaws.
70ft²
What is the minimum external projection outside the shell for bottom plates in a new tank?
2 inches
The maximum vertical and horizontal dimension of the repair plate is _______ inches and _______ inches respectively.
48
72
The minimum repair plate dimension is _____ inches. The repair plate shall be formed to the shell radius.
4
When does API 653 require two tension specimens to be taken at right angles to each other from a corner of each plate?
When the direction of rolling is not definitely known
The maximum acceptable undercut for vertical butt joints of reconstructed tanks.
1/64”
HAZ (Heat Affected Zone)
Regions heated to greater than 1350°F
Geometric Unsharpness Limitations
ASME SEC.V Article 2
T-274.2
For existing shell plates over 1/2 inch thick, the outer edge of the butt weld attaching the replacement shell plate shall be at least the greater of ______ times the weld size or 10 inches from the edge of the fillet weld attaching the bottom shell course to the bottom, except when the replacement shell plate extends to and intersects the bottom-to-shell joint at approximately _____.
8
90°
The RBI assessment shall be performed by a team including inspection intervals _______.
Not to exceed 10 years
The current edition of the standard (such as API standard or UL standard) that applies if the tank were built today.
Current Applicable Standard
Experience shows that once a tank has demonstrated the ability to withstand the combined effects of ______ (highest stresses) and ______ without failing, the risk of failure to brittle fracture with continues service is ______.
Maximum liquid level
Lowest operating temperature
Minimal
For circular reinforcing plates, blend-grind the periphery attachment weld from the ______ position to the ______ position.
4 o’clock
8 o’clock
Each newly deposited weld or any cavity resulting from gouging or grinding operations shall be ______ examined over its full length.
Visually
Advantage of thick film un-reinforced linings
Fast curing and can be put back in service after 24 hours @ ambient temperature
No welding of any kind shall be performed when the surfaces to be welded are wet from rain, snow, or ice; when rain or snow is falling on such surfaces; or during periods of high winds unless:
The welder and the work are properly shielded
The minimum light intensity shall be
100 foot candles (fc)
Corrosion rates for soil corrosion increase with _______.
Increasing metal temperature
Thickness to be used for each shell course when checking tank design shall be based on measurements taken _______ days prior to relocation
180
No known tank failures due to brittle fracture have occurred at shell metal temperatures of ______
60°F or above
For existing shell plates 1/2” thick and less, this spacing may be reduced to _____ inches. For shell plates of unknown toughness not meeting the exemption criteria of Figure 5.2, the edge of any verticle weld joint attaching a replacement plate shall be at ____ inches or ____ from the edge of a weld joint in the bottom annular ring or weld joints in bottom plates under the tank shell.
6
3
5t
In all reported incidents of tank failure due to brittle fracture, failure occurred either shortly after erection during:
Hydrostatic testing or on the first filling in cold weather, after a change to a lower temperature service, or after a repair/alteration
Roof plate welds and flange-to-nozzle-neck welds ________.
do not require welder identification.
If a tank shell thickness is no greater than _____, the risk of failure due to brittle fracture is minimal.
0.5”
To minimize evaporation losses and reduce potential hazard to the workers, no more than ______ of the roof seal system should be out of an in-service tank at one time.
1/4
Roof plates corroded to an average thickness of less than _____ in any _____ area or roof plates with any holes through the roof plate shall be repaired or replaced.
0.09”
100 inches²
When the corrosion rate is not known, the maximum interval shall be _____.
5 years
Corrosion rates may be estimated from tanks in similar service based on thickness measurements taken at an interval not exceeding ________.
5 years
For unknown material an allowable stress value of the lesser of ______ yield strength or ______ tensil strength shall be used.
2/3
2/5
Shall not be used
Pan-type floating roofs
The welder or welding operator’s identification mark shall be hand or machine stamped adjacent to and at intervals not exceeding _______.
3 feet
The minimum diagnostic length of each radiograph shall be _____.
6 inches
Each scanning operators should receive a minimum of _______.
40 hours of training
The nameplate shall indicate, by means of letters and numbers _______.
Not less than 4mm (5/32 in.) high
Industry experience and laboratory tests have shown that a membrane stress in tank shell plates of at least ______ is required to cause failure due to brittle fracture.
7 ksi
To minimize burn through, the first weld pass to equipment or piping less than _____ thick should be made with _____ or smaller diameter welding electrode to limit heat imput.
1/4 inch
3/32 inch
Hot Tap Minimum Spacing between nozzles
R=tank shell radius in inches
T=shell plate thickness in inches
√RT
For tank shells of unknown toughness the nozzle/hot tap connection shall be
Limited to a maximum diameter of NPS 4
Rim-mounted primary shoe seals and toroidal seal systems can be _______, _______, or ________.
removed
repaired
replaced
The rate of underside corrosion on tanks decreases significantly when the ph of the sand is ______.
Greater than 8ph
