Mr. Abhisekh,
" After opening packet at the start of the days work , is it necessary to transfer a pack of electrodes to a portable quiver for holding
at temp 100 deg C to prevent further moisture pick up ? or it is not required as manufacturer says that after opening up to 9 hrs it can be used at 80% / 27 deg C
Electrodes rebaking cycle depends upon which factors? Some client specifies recycling 1 time , some 2 times ... [ As per BIS 13851:1993 , ( R 2006) - Storage & redrying of coverd electrodes before use recommendations- 3 times ] "
Answer:
The very purpose of using E 7018-1 H4 type Vacuum packed Electrodes is to avoid re-backing, as the H2 level is
<4 ml /100 grams of weld and can be used straight after opening the pack.
When not used after breaking the seal and considerable gap of time, re-baking is to be done, as the electrodes would
have picked up moisture by then, due to its exposure to humid conditions.
Without H-4 designation, all low Hydrogen type electrodes may have > 10 ml & < 15 ml of H2 per 100 grams of weld and compulsory re-drying has to be done to reduce the H2 content to <10 ml. by holding them at 300 deg. C for 2 hrs
in the ovens.
The electrodes are held in Holding oven (if required) at 100-150 deg.C, if backed in large quantity and to avoid repeated
re-baking (re-cycling) and damage to flux coating if unused.
Welders are supposed to use portable (kept at 100 deg. C or so) for actual welding. These ovens also know as re-fill ovens
as the electrodes are refilled after every 2 hrs welding work or less.
Sridhar.
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