CWI Welding Safety and Health Hazards

Question 1

Under OSHA, an atmosphere is considered oxygen-deficient when the oxygen concentration falls below:

Accepted Answer

19.5%

Answer

OSHA defines an oxygen-deficient atmosphere as one below 19.5% oxygen by volume. Inert shielding gases such as argon can displace oxygen in confined spaces and create this hazard.

Question 2

Under NFPA 51B, how long should a fire watch generally be maintained after hot work is completed?

Accepted Answer

30 minutes

Answer

NFPA 51B requires a fire watch for at least 30 minutes after hot work finishes. This allows time to detect smoldering fires.

Question 3

Acetylene should not be used at a pressure above which value because it becomes unstable?

Accepted Answer

15 psig

Answer

Free acetylene becomes unstable and can decompose explosively above 15 psig, so regulators for it are limited to that pressure.

Question 4

Which fume constituent from welding stainless steel is of particular concern as a carcinogen?

Accepted Answer

Hexavalent chromium

Answer

Welding stainless steel can produce hexavalent chromium (Cr VI), a recognized carcinogen. It calls for adequate ventilation or respiratory protection.

Question 5

When moving a compressed gas cylinder, which practice is required?

Accepted Answer

Keep the valve protection cap in place and secure the cylinder

Answer

Cylinders must be moved with the valve protection cap installed, and they must be kept secured. A damaged valve can turn a cylinder into a projectile.

CWI Practice Test

CWI Practice Test

CWI Welding Safety and Health Hazards