porosity in tig root (6g 3"carbon) ???

[jjb]

hello there could someone help me im puzzled was doing 6g carbon test today and got porosity in the bottom section of pipe only. Was using 2.5mm landing edge 4mm gap gas 15cfh 2.4 lanthana (blue) ran at 105 amps free hand torch angle back 5 deg all mill scale ground back please does anyone know what im doing wrong???

[zapster]

Originally Posted by jjb

please does anyone know what im doing wrong???

You did not post any pics..
We are not mind readers...


...zap!

[aevald]

Hello jjb, as Zap said, pictures are certainly worth a thousand words. In lieu of that; how old is the pipe? After cleaning back the inside and outside edges of the groove is there still any evidence of rust or pitting? Does the pipe have a layer of rust prohibitive on it that is fairly thick at all?

There are many surface conditions that could contribute to porosity and it's formation in a weld deposit. Pitting that is still visible even after cleaning could harbor oxides(rust) that could cause porosity. The pitting could also contain chemicals or other surface contaminants that could cause off-gassing when heated that could lead to porosity. The rust preventative agents on some pipe can melt when heated and run down and contaminate a weld pool from the backside(rootside) of a weld joint as welding is progressing. Your mention of this occuring on the bottom of the pipe might support this train of thought some. In a fairly extreme case contamination of filler rods could result in porosity, yet I doubt that is the case here.

Using gloves that have oil or other chemicals on them from metal processing equipment might be suspect. Metal preparation with comtaminated abrasive wheels, stones, flap-wheels, or other sorts of items such as brushes, etc. should be considered. You really need to look at your process and procedure that you have used to make these welds and systematically rule out points of contamination. Good luck and best regards, Allan

[jjb]

sorry zapster
about the pictures wasnt realy thinking about taking any pictures when i was doing the test was more inclined to grind out the porosity out and finish the test.

[zapster]

Originally Posted by jjb

sorry zapster
about the pictures wasnt realy thinking about taking any pictures when i was doing the test was more inclined to grind out the porosity out and finish the test.

That's OK..

You are excused this time..

...zap!

[jjb]

thank you for your reply allan will definitely put into use.thank you

[Showdog75]

Wind and/or a slight breeze can do it. This is usually the cause when I get porosity as I know how to properly clean my material.

[Donoharm]

take your foot off the gas hose/leads next time

[Showdog75]

Originally Posted by Donoharm

take your foot off the gas hose/leads next time

This will do it as well. Another thing is if you have your welding machine backed up to you or other machines blowing on or near you it can gas your weld.

[ironman715]

Also if you rest your hand/thumb on the gas valve that can limit the flow or even shut the gas off momentarily.

'Mike

[shovelon]

I don't remember what 6g is but I hate it already.

ER70-S6 can help with the porosity, but you may be getting a lack or gas coverage on the opposite side or perhaps over penetrating, or lingering in the area.

I remember back in school many moons ago, to keyhole it with lots of gas, electrode straight up and down with no tilt with 70s6. Hot, fast, and driving that rod in to allow the deoxidizers to work before they foul out.