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API by CCE > 653 & 650 - P4 (50Q) > Flashcards

653 & 650 - P4 (50Q) Flashcards

1
Q

In regard to installation of primary and secondary seals, if the roof rim thickness is less than _____ inch thick, it shall be replaced.

A

0.10

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2
Q

If it is necessary to replace a roof rim, the new roof rim shall be a min. thickness of:

A

3/16”

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3
Q

The min. thickness of new roof plates shall be:

A

3/16” plus any corrosion allowance.

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4
Q

Rim-mounted primary and toroidal seal systems can be removed, repaired, or replaced. To minimize evaporation losses and reduce potential hazards to workers, no more than:

A

1/4 of the roof seal system should be out of an in-service tank at one time.

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5
Q

In the event roof live loads exceed 25 pounds per square foot (loads caused by insulation, vacuum on the tank, snow loads), the plate thickness shall be:

A

Based on analysis using proper allowable stresses

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6
Q

Where tank foundations true to a horizontal plane are specified and concrete ringwalls are not provided, the tolerances are as follows:

A

The foundation under the shell shall be level with plus or minus 1/8” in any 10’ of circumference and within plus or minus ½” in the total circumference measured from the average elevation.

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7
Q

When a tank is reconstructed, the weldability of the steel shall be:

A

Verified

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8
Q

When a tank is reconstructed, the welder or welding operator’s identification mark shall be hand or machine stamped adjacent to and at intervals along the completed weld not exceeding:

A

3’ along completed welds

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9
Q

In lieu of stamping complete welds:

A

A record may be kept that identifies the welder or welding operator employed for each welded joint

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10
Q

The ____________ do not require welder identification.

A

Roof plate welds and flange-to-nozzle-neck welds

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11
Q

What type of tank settlement can often be predicted in advance, with sufficient accuracy from soil tests?

A

Uniform settlement

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12
Q

What type of tank settlement does not induce stresses in the tank structure? It does cause problems with piping and other attachments to the tank from outside.

A

Uniform settlement

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13
Q

What type of tank settlement generally rotates the tank in a tilted plane?

A

Rigid body tilting

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14
Q

What type of tilt of a tank will cause an increase in the liquid level and, therefore, an increase in the hoop stress in the tank shell? It also can cause binding of seals on floating roofs.

A

Rigid body tilting

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15
Q

What type of tank settlement is characterized by settlement of a tank at different rates at different locations? This results in non-planar configurations which induces additional stresses in a tank shell.

A

Out-of-plane settlement

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16
Q

What type of tank settlement leads to a lack of circularity at the top of the tank, and may induce improper functioning of the floating roof? Also, flat spots may develop on the tank shell.

A

Differential settlement

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17
Q

What allowable stress is used for API 653 eval. of riveted tank shell thickness?

A

21000 psi

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18
Q

The selection of a lapped patch repair plate thickness to reinforce areas of deteriorated shell plates or to repair small shell leaks shall be based upon design that conforms to the applicable standard of construction and API 653, using a joint efficiency not exceeding:

A

0.35

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19
Q

The minimum dimension of a lapped patch repair plate is:

A

6”

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20
Q

When calculating the maximum allowable hydrostatic test stress for a new tank shell, the:

A

Gross plate thk., Including any corrosion allowance, shall be used in the calculation.

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21
Q

When the service of an aboveground storage tank is changed:

A

The effects of normal and emergency venting shall be considered.

22
Q

The thickness to be used for each shell course when checking the design for a reconstructed and relocated tank shall be based on measurements taken within _____ days prior to relocation.

A

180

23
Q

Measurements to verify the dimensional tolerances of a reconstructed aboveground storage tank shall be taken:

A

Before the hydrostatic test of the tank

24
Q

The most common stray current and the potentially most damaging to aboveground storage tank bottoms is:

A

Direct current

25
Q

When a SS or copper material is connected to a CS tank, _________ corrosion may occur.

A

Galvanic

26
Q

Current, in galvanic corrosion, is considered to flow:

A

From the more active metal (anode) to the less active metal (cathode)

27
Q

Electric current takes the path of _____ resistance.

A

Least

28
Q

A cushion of new _______ may provide many of the same advantages as a concrete cushion for reducing corrosion and eliminating the need for cathodic protection.

A

Asphalt

29
Q

The projection of the bottom plate beyond the outside toe of the shell-to-bottom weld shall be at least _____ inch.

A

0.3750

30
Q

Corrosive soil beneath a high resistivity foundation material (for example concrete or asphalt that has cracked) may contaminate the foundation fill by:

A

Capillary action

31
Q

In certain cases when considering protecting a tank bottom, internal cathodic protection in conjunction with a _____ may be applicable.

A

Lining

32
Q

If large particle sizes are used in the cushion beneath a tank bottom, differential aeration ______ may result at points where the large particles or debris contact the bottom.

A

Corrosion

33
Q

The major reason for inspecting an aboveground storage tank for deterioration due to corrosion is to:

A

Determine the physical condition of the tank; find & measure the extent of corrosion.

34
Q

Tank-to-soil potential measurements are typically taken with:

A

The current applied

35
Q

A lapped patch is rectangular in shape (8” x 12”). The lapped patch is to be located midpoint of a third shell course plate. What minimum radius (if required) should the corners be?

A

2” radius

36
Q

What is generally considered the normal service life of a properly selected and applied internal tank bottom lining?

A

10-20 years

37
Q

A thin film tank bottom lining is considered to be ____ mils or less.

A

20

38
Q

A thick film tank bottom lining is considered to be greater than ____ mils.

A

20

39
Q

Define forced-curing of an internal tank lining.

A

It is the acceleration of curing by increasing the temperature above ambient, accompanied by forced air circulation.

40
Q

A holiday is ____________

A

a discontinuity in a coating film that exposes the metal surface to the environment.

41
Q

Generally, thin-film linings may be applied to:

A

New tanks and to bottoms of storage tanks that have experienced minimal corrosion.

42
Q

If caustic is stored in an aboveground storage tank, what would be the most likely problem found and where?

A

Caustic embrittlement resulting in cracks in welds and HAZ’s around connections for internal heating units or coils.

43
Q

When checking for pits, bulges, and depressions during an internal inspection of the shell and bottom of a tank using a flashlight, the flashlight beam gives best results when held:

A

Parallel and close to the surface to be inspected.

44
Q

Abrasive blasting prior to installation of an internal tank lining should not be performed if the temperature of the steel surface is less than ____ above the dew point.

A

5F

45
Q

In actual thickness determination of corroded areas, according to API 653 what two thickness measurements are the same?

A

t 1 and t avg

46
Q

Prior to determining the need for cathodic protection of an aboveground storage tank:

A

A full evaluation of tank history is advised.

47
Q

A butt-weld constructed aboveground atmospheric storage tank with a bottom shell course that measured 1” thick when it was originally built was inspected 10 years after it was put in service. A general thickness of 0.87” was measured on the bottom course during the inspection. What is the corrosion rate?

A

0.013” per year

48
Q

Lapped patch repair plates are an acceptable form of repair for butt-welded, lap-welded, and riveted tank shells, but only when:

A

Specified by the tank owner

49
Q

A successfully operating cathodic protection system can usually be determined by measuring the minimum voltage across the structure-electrolyte interface relative to a saturated copper-copper sulfate reference electrode. This measurement should be a minimum of how many volts?

A

-0.85 volts

50
Q

A deep anode ground-bed uses impressed current anodes installed in a vertical hole typically:

A

50’ or more

API by CCE (13 decks)

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