Pipe Wall Thickness and Welding Process

Hello you use a Vee groove because a welder cannot get to the bottom of Vee to weld the root pass very well if the side bevels are to straight. Also straight bevel walls make it hard to tie into the straight side walls during first couple of filler passes. The 37.5 angle used on each bevel has proven to be enough to do the manual welding successful and also not to make the included bevel angle so great as to cause excessive filler metal to be used (a welder can weld it best and fastest with this angle) On very thick manual welds it is best to use a J-bevel or modified Vee groove that incorporates the vee at the bottom so that the welder can get the first few passes in without problem and after enough filler is deposited the bevel wall design becomes straight in order to keep the welding deposit narrower thus speeding up the welding time and reducing the HAZ width. U bott joints are better used for automatic welding IMO

1G=flat welding position for plate and flat for rolled pipe welding tests

2G= horizontal welding position for plate and pipe welding tests

3G=vertical welding position for plate

4G=overhead position for plate welding tests

5G= vertical welding position for pipe welding tests

6G=45 degree incline of the pipe axis welding test.

Most companies use the 6G position to test pipe welders because if a welder qualifies on it the they are qualified on all the other mentioned positions and all fillet welds as well. Also most companies that only weld plate they will usually test on vertical and overhead positions and the this will cover the welders on all other positions.