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Re: [MW:17850] Regarding baking of low hydrogen electrodes

By Materials & Welding
Dear Sridhar,
                   thanks for swift reply,now its clear to me.

--
Thanks & Regards
Shashi


On Fri, May 31, 2013 at 12:46 PM, c sridhar <sridhar305@yahoo.com> wrote:
After  breaking the seal and considerable gap of time, re-baking is to be done for LH type electrodes,
as the electrodes would have picked up moisture by then  when exposed to the humid conditions. 
 
All low Hydrogen type electrodes may have > 10 ml  & < 15 ml of H2 per 100 grams of weld (except for
H4 type LH  electrodes, where it is less than 3 to 4 ml. of H2 ) and re drying  to be done  to reduce the H2 level   to < 10 ml.by holding them at 300 deg. C for 2 hrs. in the oven. 

Drying should be done only once and prolonged drying  (or) more drying cycles will whither the flux
coating and may produce cracks  on the coating surface and make the electrodes unusable.
 
The electrodes are then 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 the coating if  unused for any prolonged
period like unforeseen circumstances, holidays etc

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 re-filled after  every 2 hrs. of welding work or less. 
 
Sridhar.
 
 
From: shashi <slpo1980@gmail.com>
To: materials-welding@googlegroups.com
Sent: Friday, 31 May 2013 11:44 AM
Subject: [MW:17843] Regarding baking of low hydrogen electrodes

Dear experts,
                        I have query regarding baking of low hydrogen electrode, is there any universal rule/standard governing these as in some project rebaking is not allowed whereas in some project re-baking can be done only 1 or 2 times.

Query1: how many time can we bake the low hydrogen electrodes, if over baked what will be the consequence.
 
Query2: after baking we transferred to holding oven maintain at 150 ° C,  how long we will keep electrodes at these temperature

Regards
shashi

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