Tube to Tubesheet Joint Welding

[uglyspec]

When welding tube to tubesheet joints in the vertical 3G position, what is the proper weld progression? Can I start at one point and weld 360 degrees around the tube to completion (uphill then downhill.) Or should I start at the bottom and weld upward 180 degrees stop, then start at the bottom again and weld the other half of the tube 180 degrees?

Thanks!

 

[david339933]

Assuming Sec IX qualification....check out QW-288.1(h)

 

[pradipgoswami]

Are you talking about Manual T#TS welding or automatic one. If automatic welding equipment will involve all 360 Deg rotation. Manual is always better to do with 3G upwards position.
Covering whole 360 degree is a lot difficult for larger dia tubes.
I've seen welders welding up to 3/4" OD tube in one go. However I found that for tube typically 1" or 1/1/4 inch dia many welders prefers to weld this in 2 sectors(typically 9PM to 3 AM & 3AM to 9 PM ) or as convenient.

Thanks.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299

 

[uglyspec]

Pradip,

I am referring to manual GTAW with the addition of filler metal to create a strength weld. Tube diameters are typically either 5/8" OD or 3/4" OD.

When you use the term "one go" are you referring to welding the tube joint in one continuous pass 360 degrees around? If so, in the 3G position at some point you will be welding slightly downhill during with a single continuous pass. Do you agree?

I have heard downhill welding is not permitted on tube to tubesheet joints.

Thanks

 

[pradipgoswami]

I would like to Clarify the point in a better way.

Manual T#TS welding requires special skill. Often welders develop this skill over years of continuous T-TS welding practice. Some welders could manage such welding with at least one-start stop point, however many welders prefer multiple start stop points. More start/stop may lead to defects or unevenness in T#TS welds.

With the advent of Automatic T#TS equipment, machines are programmable for each quadrant thus may mean that welding may be finished faster with little start -stop.

Here're some videos for general guidance in you tube:-

https://www.youtube.com/watch?v=HK7whwc25PY

https://www.youtube.com/watch?v=tyaq52-pluI

Search for more videos to get the good ideas.
Thanks.


Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299