API 653 Question Bank

AST fabricated to API 650 is normally designed not to exceed an operating
temperature of:

a. 260 deg C
b. 100 deg C
c. 90 deg C
d. 21 deg C.

2. Minimum size of fillet welds in the construction or repairs of an AST built to API Standard 650 is:
a. Higher of 6 mm (0.25”) or half of the thickness of thinner plate joined.
b. Higher of 9 mm (0.25”) or one third of the thickness of thicker plate joined.
c. Higher of 5 mm (0.1875”) or one third of the thickness of thinner plate joined.
d. Lower of 6 mm (0.25”) or half of the thickness of thinner plate joined.

3. As per API Standard 650, the overlap at lap-welded joints shall be at least five times the nominal thickness of the thinner plate, but need not exceed,
a. 2” for single-welded lap joints and 4” for double welded lap joints
b. 1” for single-welded lap joints and 2” for double welded lap joints
c. 1.5” for single-welded lap joints and 2” for double welded lap joints
d. 1.5” for single-welded lap joints and 1” for double welded lap joints

4. Calculate by the 1-Foot method the design shell thickness Td in inches, of the following description of tank built to API Standard 650:
H = Design liquid level = 50 feet
D = Nominal Tank Diameter = 180 feet
G = Design Specific Gravity = 0.86
CA = Corrosion Allowance = 0. 0625”
Sd= Allowable stress in design condition, in psi
Shell Material = ASTM A36M
Td = design shell thickness, inch(es)
St= Allowable stress for hydrostatic test condition, in psi
Tt = hydrostatic test shell thickness, inch(es).

Where, Td = 2.6 D (H –1) G + CA
Sd
a. 0.912”
b. 0.850”
c. 1”
d. 0.922”

5. Calculate by the 1-Foot method the hydrostatic test shell thickness Tt in inches, of the above referred tank, when water is used for the test :
Where, Tt = 2.6 D (H –1)
St
a. 0.935”
b. 0.985”
c. 1”
d. 0.922”

6. Maximum Reinforcement thickness of vertical butt joints of a tank shell plate of 28mm, of an AST built to API Standard 650 shall be:
a. 5mm
b. 2.4mm
c. 1.6mm
d. 3mm

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