API 510 Questions and Answers (ASME VIII – Opening Weld Size)

After completed the Part 5: Exemption of Impact Test, we will continue to try on the Open/Close questions on Module ASME VIII – Weld Size of Openings on Vessel as a part of in-the-exam API 510 Body of knowledge (BOK)

If you don’t know how API 510 Certification scheme, See API 510 Certification Instructions

WELD SIZE FOR ATTACHMENT WELDS AT OPENINGS UW-16
The inspector must be able to determine if weld sizes meet Code requirements. The inspector should be able to:
a) Convert a fillet weld throat dimension to leg dimension or vice versa, using conversion factor (0.7); and
b) Determine the required size of welds at opening (T-c or 1/2 T-min)

Question 1: A nozzle is fitted abutting (i.e. set-on) the vessel wall. What is an acceptable welding method of attaching it?

(a) With a full penetration groove weld through the nozzle wall
(b) With a full penetration groove weld through the vessel wall
(c) With a partial penetration groove weld through the nozzle wall
(d) Both (a) and (c) are acceptable

Explanation: See UW-16 (c) and Figure UW-16.1, a Set-on abutting must be Full penetration, but the Set-in can be partial penetration.

Question 2: By what means/types can reinforcement be added to an opening in a pressure vessel?

(a) By integral reinforcement such as forged inserts
(b) By using separate plates (compensation pads)
(c) By using thicker shell material (a type of integral reinforcement)
(d) All of the above are valid methods

Explanation: See UW-16(c) for definitions of acceptable reinforcement method.

Question 3: A vessel is manufactured from P1 Grade 2 material. It has a shell thickness of 18 mm and is used to contain lethal substances. A set-on (abutting) nozzle of 12 mm thickness is attached using a category D full penetration weld with reinforcing fillet. What is the minimum required throat thickness (T-c) of the reinforcing fillet weld?

(a) 12 mm
(b) 8.6 mm
(c) 6 mm
(d) 12.6 mm

Explanation: See UW-16 (c) and Figure UW-16.1 (a).

Cat D means Nozzle to Shell welds

Question 4: A vessel has a shell thickness of 3/4 in (19 mm). A set-on (abutting) nozzle of 1/2 in (13 mm) thickness is attached using a category D full penetration weld. A reinforcing plate of 1/4 in (6 mm) is required. What welds will be required to attach the reinforcing plate to the nozzle?

(a) A full penetration weld plus a fillet with a 4.2 mm throat
(b) A full penetration weld plus a fillet with a 6 mm throat
(c) A fillet weld with a 3 mm throat
(d) A full penetration weld plus a fillet with a 3 mm throat

Explanation: See UW-16 (c) and Figure UW-16.1 (a-1).

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