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14

Technical Services

Possible Solutions

1. Bring material into work space 24 hours prior to usage. This allows the temperatures to stabilize.

2. Store filler material in an oven.

3. Store base material vertically allowing air flow to help the material temperature to stabilize.

Example: If the relative humidity in the weld area is 75%, the base metal and electrode must be no colder than 7.2°F below the air temperature

to prevent moisture condensation.

Relative Humidity vs. Dew Point

Relative Humidity %

∆t °F Air-Metal

∆t °C Air-Metal

87

3.6

1.1

75

7.2

2.2

66

10.8

3.3

57

14.4

4.4

50

18.0

5.5

44

21.6

6.6

38

25.2

7.7

34

28.8

8.8

30

32.4

9.9

26

36.0

11.0

23

39.6

11.9

21

43.2

13.2

18

46.8

14.3

16

50.4

15.4

Many fabricators experience welding problems at different times of the year. Moisture (H

2

O) is a prime source of hydrogen.

At arc temperatures, water breaks down releasing hydrogen atoms that cause porosity in weldments. Shielding gas

supplies are controlled to very low moisture content (-70°F dewpoint or lower). Likewise, the atmospheric conditions

in a fabricating facility need to be controlled to prevent moisture condensation from forming on electrode or base metal.

Atmospheric Conditions Affect Weld Quality