Pressure Piping and the ongoing issue of welding downhand vs. uphand.

[bigreddog]

I've run into the issue of downhand pipe welding (SMAW), using 7018, and the reasons why it's bad, and how some inspectors just don't care. I've usually chalked it up to the skill of the welder, and the circumstances of positions etc. Could someone please clarify for me if there are any code requirements to this anomaly? I've scoured SEC IX, B31.3 etc etc and I really couldn't find much. I know the difference between uphill/downhill and that the downhand thing is more or less a trade term, but I would really like to put this issue to bed. Thanks!

 

[BigInch]

Put it to bed? Why? When you need speed and your welder can control the arc at that speed and you get the quality you want ... go for it. When you need higher quality, thicker throats and have all day to do it ... go uphill.

Production -> downhill, Speciality-> Uphill

Downhill Advantages
---------
Faster speed.
Smaller fillet legs.
Lower overall heat input due to faster speed.
Less distortion due to lower heat input.

Disadvantages
--------------
Harder to control arc track at faster speeds.
Possibility of greater number of slag inclusions.

Independent events are seldomly independent.

 

[BigInch]

PS no code issues, other than qualifying the procedure, whatever that might be.

Independent events are seldomly independent.

 

[21121956]

Hello everybody:
Here you can find some ingredients to start a good discussion: thread794-187838.

El que no puede andar, se sienta.

 

[stanweld]

Whereas E7018 is classified under SFA 5.1 for V- up progression per Table 1 Note [1], The WPS and the welder must be qualified with vertical down progression to permit same in production.

Because welding with E7018 with downward progression will no doubt be done with smaller diameter electrodes at lower current settings than when used in upward progression, deposition rates will be lower even though travel speed will be higher. If you want to weld downhill with low hydrogen electrodes, use E7048.

 

[bigreddog]

stanweld, that's exactly the answer I was looking for. Thank you for the info.