Rebake of low hydrogen electrode

[jabir]

I want to know, how many times we can rebake the low hydrogen electrode.

[wgadmin]

Since the re-baking causes the coating to become fragile and flake or break off while welding, or there is a noticeable difference in handling or arc characteristics, such as insufficient arc force (some welders have claimed that they have faced difficulties during welding with re-baked electrode), it is recommended re-baking of electrodes to be done no more than once.

Moreover, even though in lots of cases the re-baking depends on the user’s procedures that are based on good engineering practice and although some manufacturers say that most electrodes can be re-baked at least 2-3 times, some codes do not allow re-bake more than once (i.e. AWS D1.1, par. 5.3.2.1).

In order to eliminate the necessity of re-baking you could establish procedure for strict electrode management. Since electrodes tend to pick up atmospheric moisture, immediately after opening of their hermetically sealed package, they can be maintained dry by storing in a holding oven or refill flask (portable holding oven) at a temperature as specified by the electrode manufacturer and the relevant electrode specification (i.e. the ASME II, Part C, SFA-5.1, Table A.3 and the SFA-5.5 Table A.2 specify typical storage and drying conditions for electrodes). With any other storage condition, the electrodes must be dried in a drying oven (the range of the temperature and the time duration are specified by the manufacturer and the relevant electrode specification) and then they shall be stored in a holding oven as already described, where they could be kept for a long period without any fear of over-drying.

[Logosweld]

Once electrodes are exposed to the atmosphere for time periods greater than
the limits set in the timetable, they must be rebaked. To rebake SMAW
electrodes after they exceed the limits for exposure, complete the following
steps:
1. Bake all electrodes with low-hydrogen coverings conforming to
ANSI/AWS A5.1 for at least two hours at temperatures between 500°F
(260°C) and 800°F (430°C).
2. Bake all electrodes with low-hydrogen-coverings conforming to
ANSI/AWS A5.5 for at least one hour at temperatures between 700°F
(370°C) and 800°F (430°C).
Note After completing the baking process, the time limits are once
again in effect as listed in the table. Electrodes shall not be
rebaked more than once.
Results After completing these steps, the electrode is ready for reuse
according to the listed time limits.