Care, Handling, And Storage Of Electrodes

Question 1

Which type of electrode(s) produces a low-hydrogen deposit?

Answer 1

Lime-coated
Last digits: 5, 6 ,8

Question 2

Which electrode should you use if the base metal composition is unknown? Why?

Answer 2

Lime-coated electrode. It reduces the chance of hydrogen-induced cracking.

Question 3

Lime-coated electrodes must be in ___________ (airtight) containers and placed in an _______________ immediately after opening.

Answer 3

Hermetically

Electrode holding oven == Rod oven

Question 4

At which temperature should you set the rod oven at to ensure lime-coated electrodes contain the minimum moisture content?

Answer 4

Approx. 30c-140c (50F-250F) above ambient temperature.

(ASME Section II, Part C)

Question 5

In the case of lime-coated electrodes that have been exposed to air for longer amounts of time, what temperature should you rebake them at?

Answer 5

260c-427c (500F-800F)

Question 6

What should the range of the moisture content be with cellulose-coated rods?

Answer 6

3%-7%

Question 7

What are two weld faults associated with low-hydrogen electrodes that contain excess moisture?

Answer 7

Cracking and porosity.

Question 8

Describe how moisture in lime-coated electrodes can lead to cracking.

Answer 8

Cracking is caused by the excess hydrogen in the rod to dissolve into the weld puddle and adjacent area of the HAZ.

Question 9

Describe how porosity is caused from low-hydrogen electrodes with excess moisture.

Answer 9

Porosity is especially present at the start of the weld because there was not enough heat applied to drive off the moisture. Porosity can also be caused from long arcing or travelling too fast.