Operations | Electrode size 1/32 in. | Arc current | Minimum protective shade |
---|---|---|---|
Shielded metal arc welding | Less than 3 | Less than | 7 |
3-5 | 60 | 8 | |
5-8 | 60-160 | 10 | |
More than 8 | 160-250 | 11 | |
250-550 | |||
Gas metal arc welding and flux cored arc welding | Less than | 7 | |
60 | 10 | ||
60-160 | 10 | ||
160-250 | 10 | ||
250-500 | |||
Gas Tungsten arc welding | Less than | 8 | |
50 | 8 | ||
50-150 | 10 | ||
150-500 | |||
Air carbon | (Light) | Less than | 10 |
Arc cutting | (Heavy) | 500 | 11 |
500-1000 | |||
Plasma arc welding | Less than | 6 | |
20 | 8 | ||
20− | 10 | ||
100 | 11 | ||
100− | |||
400 | |||
400− | |||
800 | |||
Plasma arc cutting | (light)** | Less than 300 | 8 |
(medium)** | 300-400 | 9 | |
(heavy)** | 400-800 | 10 | |
Torch brazing | 3 | ||
Torch soldering | 2 | ||
Carbon Arc welding | 14 | ||
** These values apply where the actual arc is clearly seen. Lighter filters may be used when the arc is hidden by the workpiece. |
Operations | Plate thickness—inches | Plate thickness—mm | Minimum* protective shade |
---|---|---|---|
Gas welding: | |||
Light | Under 1/8 | Under 3.2 | 4 |
Medium | 1/8 to 1/2 | 3.2 to 12.7 | 5 |
Heavy | Over 1/2 | Over 12.7 | 6 |
Oxygen cutting | |||
Light | Under 1 | Under 25 | 3 |
Medium | 1 to 6 | 25 to 150 | 4 |
Heavy | Over 6 | Over 150 | 5 |
Code of Federal Regulations
100
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* As a rule of thumb, start with a shade that is too dark to see the weld zone. Then go to a lighter shade which gives sufficient view of the weld zone without going below the minimum. In oxyfuel gas welding or cutting where the torch produces a high yellow light, it is desirable to use a filter lens that absorbs the yellow or sodium line in the visible light of the (spectrum) operation. |