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CWI Welding-Related Calculations practice questions

On-the-job math: unit conversions, heat input, stress and elongation, fillet weld geometry, carbon equivalent and weld metal volume. This domain is about 7% of the exam. Try each question, then open the answer.

Read the Welding-Related Calculations study guide

Question 1

A WPS limits heat input to 40 kJ/in. The welder runs at 28 V and 240 A. What is the slowest travel speed that stays within the limit?
  1. About 0.17 in./min
  2. About 4 in./min
  3. About 6 in./min
  4. About 10 in./min
Show answer

Answer: D. About 10 in./min

Rearrange heat input = V x A x 60 / S to solve for travel speed. That gives S = V x A x 60 / HI. Here S = 28 x 240 x 60 / 40,000 = 10.1 in./min, the minimum speed. Any slower and heat input goes above 40 kJ/in.

Source: AWS Certification Manual for Welding Inspectors (chapter on weld inspection math)

Question 2

A filler metal has a minimum tensile strength of 70 ksi. What is this in megapascals, approximately?
  1. About 10 MPa
  2. About 345 MPa
  3. About 480 MPa
  4. About 700 MPa
Show answer

Answer: C. About 480 MPa

1 ksi is about 6.895 MPa, so 70 ksi x 6.895 = 482.7 MPa, about 480 MPa. AWS metric classifications such as E49XX reflect this (490 MPa).

Source: AWS Certification Manual for Welding Inspectors (chapter on weld inspection math)

Question 3

A tensile specimen has a 2.000 in. gauge length before testing. After fracture the gauge marks are 2.560 in. apart. What is the percent elongation?
  1. 22%
  2. 28%
  3. 56%
  4. 128%
Show answer

Answer: B. 28%

Elongation = (final - original) / original x 100 = (2.560 - 2.000) / 2.000 x 100 = 28%.

Source: AWS B4.0 (tension tests); AWS Certification Manual for Welding Inspectors (chapter on weld inspection math)

Question 4

About how much weld metal is in a 1/2 in. equal-leg, flat-faced fillet weld that is 10 ft long? (Steel weighs about 0.283 lb/in.^3.)
  1. About 0.35 lb
  2. About 4.2 lb
  3. About 8.5 lb
  4. About 15 lb
Show answer

Answer: B. About 4.2 lb

Area = 0.5 x 0.5 / 2 = 0.125 in.^2. Length = 120 in. Volume = 0.125 x 120 = 15 in.^3. Weight = 15 x 0.283 = 4.2 lb. This excludes reinforcement and filler lost as spatter or stubs.

Source: AWS Certification Manual for Welding Inspectors (chapter on weld inspection math)

Question 5

A welder completes a 36 in. weld in 3 minutes. What is the travel speed?
  1. 108 in./min
  2. 3 in./min
  3. 12 in./min
  4. 18 in./min
Show answer

Answer: C. 12 in./min

Travel speed = distance / time = 36 in. / 3 min = 12 in./min. Travel speed is needed to calculate heat input.

Source: AWS Certification Manual for Welding Inspectors (chapter on weld inspection math)

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