Flame-straighten plate butt weld

Double-V coplanar butt weld - slight imbalance of weld shrinkage forces left small angular distortion about weld-axis.

Flame-straightened as follows

The weld was "flushed-off" with an angle-grinder, presenting a "silver" metal surface. Making the temperature easy to see.

Suggest

use a powerful stoichiometric oxy-fuel flame
wear clear glasses not tinted glasses conventionally used for oxy-fuel cutting

Latter point is so can see the first onset of low-red glow of the steel under the flame, and maintain that resulting temperature.

Apply the flame at one end of the weld which had the angular misalignment. It should take seconds to come to just-red, and the just-red spot under the nozzle is "striped" along the weld-joint.
Quite quick.

To increase angular correction, "stripe" again.

Result - as seen under rule - good flatness. Happy.

The colour patina indicates perfect temperature for flame-straighening.

(R. Smith, 16Mar2021)