1. During the internal inspection of a vertical vessel a minimum thickness reading of 1.270” was found on a shell course. The Data Report reflects an original thickness of 1.50”, and allowable stress at 600 degrees of 14,500 psi, full radiography, and a MAWP of 650 psi. The MAWP was based on a retirement diameter of 49.02 inches after the corrosion allowance was expended. Inspection records indicate a corrosion rate of 0.025 inches a year. If the corrosion rate does not change what is the maximum time before the next on stream or internal inspection?
a. 56 years b. 10 years c. 90 days d. 2.815 years
2. A pressure vessel has been measured to have a minimum wall thickness of .235 inch after 5 years of service. The vessel’s original wall thickness was .250. Its minimum allowable wall thickness is .195 inch.
How long until the next required internal inspection per API 510?
a. 13.3 years b. 10 years c. 5 years
d. 6 and 2/3 years
3. During an internal inspection a vessel’s shell was measured and found to have a remaining wall thickness of .486 inches. It was last inspected 4 years ago. The retirement thickness of the vessel shell is .475 inches and its previous thickness was .500 inches Based on this data, per API 510 what is the present corrosion allowance of the vessel?
a. 0.025‖
b. 0.110‖
c. 0.011‖
d. 0014‖
4. In corrosive service the wall thickness used in the MAWP calculation must be the actual thickness as determined by the inspection, but must not be thicker than original thickness on the vessel’s original material test report or Manufacturer’s Data Report __________________.
Fill in the blank;
a. Plus twice the estimated corrosion loss before the next inspection.
b. Minus twice the estimated corrosion loss before the next inspection.
c. Minus three times the estimated corrosion loss before the next inspection.
d. Plus four times the estimated corrosion loss before the next inspection.
5. A weld repair using the preheat and deposition welding methods described in the API 510 is to be performed on a groove type repair in a vessel wall, and will require a welding procedure qualified using notch toughness tests. What would be the allowed depth of repair if the procedure test groove was 2 inches in depth?
a. 2 inches or more b. Less than 2 inches.
c. Not more than 1-1/2 inches.
d. Unlimited thickness would be permissible.
6. The inner wall of a jacketed vessel has corroded down to 0.635 inch; the inner cylinder has a 45” O D in this corroded state, its unsupported length is 120 inches. The vessel operates at an external pressure of 175 psig and a temperature of 300 ºF. The factor A has been calculated to be 00085, using the CS- 2 factor B chart what is the approximate value of Factor B?
a. 17,000 b. 14,500 c. 11,500 d. 9,500
7. A vessel was placed in service on 1/15/60 with an original wall thickness of .875” It lost wall at an average rate of .005” per year until 1/15/75.
Service conditions have changed and this inspection, 1/15/96 the vessel has a present wall thickness of .630”. The previous thickness 5 years ago was .789”. If the present rate of corrosion continues and the
8. Local PWHT per API 510 Specifies that the area to be heat treated shall extend for a given distance from the weld what would be the distance required for the local PWHT of a 10 inch .500” thick nozzle in a 3 inch thick shell?
a. 12 inches in all directions.
b. 3 inches in all directions.
c. 1 inch in all directions.
d. 6 inches in all directions.
9. When averaging a vessel’s corrosion over an area in which circumferential stress governs, the corrosion must be a averaged using;
a. An 8‖ diameter circle.
b. The diameter of the vessel.
c. The most critical element in the corroded area d. The longitudinal weld involved.
10. A vessel has pitting in a small area; the area will fit in an 8 inch diameter circle with its center at the deepest pit. The shell course has a minimum thickness of .740”. The pits within the circle are more than 2 inches apart in any straight line with the following depths;
#1 - .385” #2- .301” #3- .235” #4- .287”, this area cannot be ignored because;
a. The pits are too many in number.
b. The pits are too close together.
c. The square inches of the pits exceed 7 square inches.
d. One of the pits is too deep to allow averaging.
11. When an owner-user chooses to conduct a RBI assessment, it must include a systematic evaluation of both the likelihood of failure and the associated consequence of failure. This likelihood of failure assessment should be repeated whenever what happens?
a. Each time equipment or process changes are made.
b. After it has been in service for 5 additional years.
c. If operations reports any significant upset in the unit.
d. Each time equipment or process changes are made that could significantly affect degradation rates or cause premature failure of the vessel.
12. Preheat and controlled deposition welding, as described in 7.2.3.1 and 7.2.3.2, may be used in lieu of postweld heat treatment (PWHT) where PWHT is inadvisable or mechanically unnecessary. Which of the following describes the circumstances where an alternative to PWHT is allowed?
a. Preheating when notch toughness testing is not allowed and controlled deposition welding when notch toughness testing is allowed.
b. Preheating when notch toughness testing is required and controlled deposition welding when notch toughness testing is not required c. When the pressure vessel engineer has approved the technique or the
API A.I. has approved this method.
d. Preheating method when notch toughness testing is not required and controlled deposition welding when notch toughness tests are required.
13. While inspecting a torispherical head it was discovered to have some severe corrosion and must be evaluated for continued service. This corrosion occurs at a radius 33.256” from the exact center of the head.
The shell diameter of the vessel the head is attached to is 84”. To evaluate this head for continued service what is the greatest distance from the center that the corrosion can be and still be allowed to use the formula for spherical shells given is Section VIII Div. 1 of the ASME
14. If the head in problem number 13 corrosion cannot be evaluated using the spherical formula for shells, what shall be done to evaluate it for continued service?
a. Use finite element analysis.
b. Average the corrosion over the area in an 8-inch diameter circle.
c. Use the appropriate formula from UG-32 for torispherical heads.
d. Call in a pressure vessel engineer per the API 510 Code.
15. What is the remaining life of a vessel corroding at a rate of 0.017 inch per year when the last inspection measured 0.638 inch and the minimum required thickness is 0.513 inch.
a. 4 years b. 10 years.
c. 6.3 years.
d. 7.3 years.
16. In the pulse echo contact method of measuring thickness, the velocity of the material being measured is a function of the material’s physical properties and is usually assumed to be a constant for a
a. its entire thickness b. given class of materials c. all ferrous materials d. all non ferrous materials.
17. Thickness measurement instruments are divided into groups which are ________________
a. Flaw detectors with CRT readout, Flaw detectors with CRT and direct readout, and Flaw detectors with direct readout
b. Flaw detectors with direct and CRT readout
c. Flaw detectors with CRT or Flaw detectors with direct readout
d. All flaw detectors are direct read out, one has a meter the other has a CRT display