STRUCTURAL WORK CONTINUED WITH WELDING

- Suitable electrodes are to be used for the structural steel.

- Generally low Hydrogen electrodes are used for plates more than 20 mm thickness.

- All low hydrogen electrodes shall be baked and stored before use as per manufacturer recommendations.The electrodes shall be re baked at 250 C - 300 degree C for one hour and later on cooled in the same oven to 100 degree C. It shall be transferred to an holding oven maintained at 60 degree C -70 degree C. The electrodes shall be drawn from this oven for use.

-  Minimum pre-heating and inter pass temperature for welding is given below.

-  Thickness of thicker part at the point of welding     Welding with low hydrogen electrode or SAW 

    Up to and equal to 20 mm thickness                                            none 

    Over 20 mm and Up to and equal to 40 mm                                 20 degree C

    Over 40 mm and Up to and equal to 63 mm                                 66 degree C

    Over and Above 63 mm                                                               110 degree C

-  Pre -heating can be done by LPG heating , electric resistance heating or by electric induction heating.

- Temperature can be checked by thermal chalk or putting Thermocouple ( generally Nickel-cromium-Nickel ) . The relation between temperature and voltage is 4.12 mv /100 deg c rise (approximately).

- Sequence of welding to be followed as per WPS and drawings .However a few basics may be noted.

- The direction of welding should be away from restraint point and should be towards open end.

- Butt weld in flange plates and/or web plates shall be completed before the flanges and webs are welded together.

- Generally The beam and column stiffeners shall preferably be welded to the webs before the web and flanges are assembled.

- All welders including tack welders to be tested as per IS codes and identity card to be issued for verification time to time during actual job.

- Carry out Non Destructive examination  RT / UT /LPI  as per requirement.

 A general view of fabrication yard where plates are getting cut into pieces for further fabrication.

 A general view of electrode drying oven . The electrodes are dried here and transported to holding oven.

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