1. AST fabricated to API 650 (Basic Standard) 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
7. Vertical joints of a 28 mm thick shell of an AST built to API Std. 650 shall be radiographed to the extent as given below :
a. Full
b. Partial
c. Spot
d. Nil
8. In an AST built to API Standard 650, the bottom annular plates have radial weld joints, and are single butt welded with permanent back-up bar, in which case, the extent of radiographing radial joints shall be,
a. One spot on 50% of radial joint
b. One spot on 10% of radial joints
c. Full radiography of all radial joints
d. RT – Nil; only MT of 100% joints is adequate.
9. As per API Std. 650, personnel who perform and evaluate radiographic examinations (RT) shall have a minimum qualification as follows :
a. Shall have a vision of Jaeger No.2
b. Shall be qualified as Level II of ASNT SNT-TC-1A
c. Shall not be color blind
d. Shall have an experience of at least ten years in RT.
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