Hillbillysmith Posted February 22, 2010 Share Posted February 22, 2010 I had just recently heard about a trick you can do to get rid of porosity on a TIG pipe joint. The comment was that if you were to have any porosity in your weld, you can TIG back over it with stainless filler and just like that, porosity is gone. It will even pass x-ray, radiograph, you name it. Can anyone tell me why this is?? Quote Link to comment Share on other sites More sharing options...
cavala Posted February 22, 2010 Share Posted February 22, 2010 Well I don't know about that but if your getting pinholes your work surface is not clean your tungsten is contamenated or your there is a problem with your shield gas. I'd say work on welding correctly and you won't create more work for yourself, if you can't weld steel without voids then ss won't be much different. Quote Link to comment Share on other sites More sharing options...
HWHII Posted February 22, 2010 Share Posted February 22, 2010 I believe all you are doing is just burning out the original porosity. I am sure when it is reshot the X-ray shading will be different in the area where you added the ss filler because of the density of the material. It will cause the X-ray tech to scratch his head and wonder whats this? It is a practice I think should not be done. You should just grind out the defect repair it correctly and find out what caused the porosity in the first place. ;) Quote Link to comment Share on other sites More sharing options...
BIGGUNDOCTOR Posted February 22, 2010 Share Posted February 22, 2010 It is easy to overheat steel welds with a TIG, and get porosity. I use stainless on most of the steel TIG welds I do when color match isn't a concern. Stainless rod on a steel part comes out really nice, and doesn't bubble as easy as steel rod does. For me, it just runs a lot easier, and I always had plenty of stainless rod available, so I used it. We did a lot of work with the wineries, and food machines, so lots of stainless parts. I am not so sure that the method that you mentioned would pass a strict testing. Quote Link to comment Share on other sites More sharing options...
HWHII Posted February 22, 2010 Share Posted February 22, 2010 It is easy to overheat steel welds with a TIG, and get porosity. I use stainless on most of the steel TIG welds I do when color match isn't a concern. Stainless rod on a steel part comes out really nice, and doesn't bubble as easy as steel rod does. For me, it just runs a lot easier, and I always had plenty of stainless rod available, so I used it. We did a lot of work with the wineries, and food machines, so lots of stainless parts. I am not so sure that the method that you mentioned would pass a strict testing. I do agree with what Bidgundoctor say's here it does work well. If you are going to use this method in a non code application you should use a compadable ss filler alloy for carbon steel like 309L. Quote Link to comment Share on other sites More sharing options...
Thomas Dean Posted February 22, 2010 Share Posted February 22, 2010 If you have to 'cover up' porosity they your intergrety is not where it should be. Fix the problem. Grind out the porosity, sharpen your tungsten, check your shield gas, block of excessive wind. Covering porosity with SS rod will cost you your job. Don't know of any CWI that would let something like that go. Hiding problems only creates more and most often larger problems. Quote Link to comment Share on other sites More sharing options...
200yearstoolate Posted February 22, 2010 Share Posted February 22, 2010 I agree with the last post... do it properly the first time. Take the time to figure out what the problem is and go from there. I don't know what setting you are welding in (personal, industrial, etc.) but think about it this way... If the welders in the manufacturing plant that built your family car used non-approved methods like that to fix their mistakes, would you feel safe driving it? That may be an extreme and slightly off base example, but you get the point. Just remember, any job worth doing is worth doing right the first time. I have Nuclear pipe certification and I can assure you there is no way anything like what you are describing would fly on a job site. Quote Link to comment Share on other sites More sharing options...
Scott Hightower Posted February 27, 2010 Share Posted February 27, 2010 One of my welders in the shop had the same problem. As it turns out he had a fan pointing at himself all day to keep himself cool. The problem is it also disrupted the shielding gas. We took his fan away and his welds were fine. ScottWelders360 Quote Link to comment Share on other sites More sharing options...
Thomas Dean Posted February 28, 2010 Share Posted February 28, 2010 One of my welders in the shop had the same problem. As it turns out he had a fan pointing at himself all day to keep himself cool. The problem is it also disrupted the shielding gas. We took his fan away and his welds were fine. ScottWelders360 Good point Scott. May I suggest that in your welders case that maybe redirecting the fan to blow but not over the immediate weld. Or at least to back it off some to where it is not affecting his welds. I know that in the heat of the summer ANY kind of air movement helps! The hot humid summers in East Teaxas can sap you quick. You might consider also upping the flow rate just a tad on the Argon for the occasional gusts. Oh yea, WELCOME to IFI! Quote Link to comment Share on other sites More sharing options...
Mainely,Bob Posted February 28, 2010 Share Posted February 28, 2010 If you absolutely have to TIG in a slight cross breeze then a gas lens can help too. Even higher flow thru a lens won`t help you if you got one of those big floor fans aimed at you.Heat must have really got to him to have forgotten about the shield gas. Quote Link to comment Share on other sites More sharing options...
Rutterbush Posted February 28, 2010 Share Posted February 28, 2010 As a weldor, I have done this, but only to ornamental type welds. It fills up the porosity holes and doesn't give too bad of a color match on very small welds. Porosity is a gas bubble which did not escape the molten metal. Trapped gas, usually air/oxygen, creates oxides/scale. This oxide is on the surface layer inside of the porosity. Filling with a stainless filler only covers this oxide layer inside of the porosity. As a CWI, I cannot knowingly allow a weld to be repaired like this. Having tested many weldors and about the same amount of students I have seen the results of welding dissimmilar metals. There are tested and proven welds of carbon steel with stainless steel filler. Of course, these welds were using ER-309, ER-312 or some similar filler which is designed to have compatable chemistry to fully mix with the carbon steel. If the stainless will not become homogenous (mixed/ go into solution)it will tend to tear out under a bend test. I see this time after time when training weldors. I explain that they obviously used a non-compatable filler. When the correct filler is applied to the weldors' next test it usually passes. The X-Ray/Radiagraphs that I've seen can identify something in the weld other than matching filler metal. Anything of differing density will stand out. An X-ray will even show where a different sized stick electrode was used to fill a widening vee groove. Even with matching electrode metal to base metal it will still show a wide bead against smaller beads. This is why, as a CWI, I cannot condone this practice. I should add that if a Welding Procedure Specification is required by the customer it is considered as not being followed by the contractor. This can lead to litigation, law suites, firings, fines, insurance cancelation, hungry children, divorce, etc. Quote Link to comment Share on other sites More sharing options...
arftist Posted March 1, 2010 Share Posted March 1, 2010 Some good suggestions here, but the main reason for porosity when tigging steel is not cleaning the steel enough. Quote Link to comment Share on other sites More sharing options...
Thomas Dean Posted March 1, 2010 Share Posted March 1, 2010 I agree, poor prep can contribute to porosity but there are a multitude of contributing factors for porosity in a tig weld and not cleaning is just one of them. The cleanest material but with poor shielding will cause porosity. The original post was "fixing" porosity with S/S cover. We are not sure How the porosity got there... Quote Link to comment Share on other sites More sharing options...
arftist Posted March 5, 2010 Share Posted March 5, 2010 I agree, poor prep can contribute to porosity but there are a multitude of contributing factors for porosity in a tig weld and not cleaning is just one of them. The cleanest material but with poor shielding will cause porosity. The original post was "fixing" porosity with S/S cover. We are not sure How the porosity got there... I agree with what you are saying, but still, the main cause when welding "steel" is lack of cleanliness. In other words, if you are welding stainless with no problem, and then weld carbon steel and have porosity, it is most likely a result of the surface condition of the steel. I realize what the original posters comment was, that is why I pointed out the cleanliness issue, prevent the porosity rather than repairing it. Quote Link to comment Share on other sites More sharing options...
Thomas Dean Posted March 5, 2010 Share Posted March 5, 2010 I agree with what you are saying, but still, the main cause when welding "steel" is lack of cleanliness. In other words, if you are welding stainless with no problem, and then weld carbon steel and have porosity, it is most likely a result of the surface condition of the steel. I realize what the original posters comment was, that is why I pointed out the cleanliness issue, prevent the porosity rather than repairing it. Me thinks we are on the same page. Especially your last statement of ..."prevent the porosity rather than repairing it." Quote Link to comment Share on other sites More sharing options...
pkrankow Posted March 5, 2010 Share Posted March 5, 2010 On fan placement: Would having a large fan exhaust from the area have less effect on shield gas than having a fan blow into an area? I'm thinking a fairly large fan could be placed close to and past the work (in front of the worker) blowing more or less upwards to create a draft of fresh air across the worker, while slightly farther away at the work piece the air would be coming in from more (all) directions around the work piece. This could act similar to a fume hood, but without the hood. Would this placement provide less disturbance of the gas shield while cooling the welder? Phil Quote Link to comment Share on other sites More sharing options...
Thomas Dean Posted March 5, 2010 Share Posted March 5, 2010 Depends on much air is being moved. Air movement is air movement no matter what direction and if it's too much across the welded area then you will have a problem. All I can suggest is to try it and see, You may also place a burning rag (read smoking rag or whatever) and see how much of the smoke is blown. If it is not too bad then your shield gas should be OK. Just some thoughts... Quote Link to comment Share on other sites More sharing options...
plain ol Bill Posted March 7, 2010 Share Posted March 7, 2010 Like many other boiler tube welders I had a few tricks up my sleeve and a few in my "trick bag". Some short lengths of 309SS were one. You can fight porosity in welding old burnt up tubes to new material for hours and not get it right. Finally get in the trick bag and you can fix it real quick with a little 309. They will pass any X-ray exam I have ever seen. Sometimes what the CWI don't know don't hurt him! Sometimes the CWI is the dumbest ass on the job too. Quote Link to comment Share on other sites More sharing options...
Rutterbush Posted March 10, 2010 Share Posted March 10, 2010 Hillbillysmith, Metallurgical studies have shown that when a weld bead is deposited the base metal and filler metal blend at an approximate 50/50 mix. Note that I have rounded off to 50%. This number can vary. That is 50% base metal and 50% filler. This could leave 50% that does not blend. If a second bead is welded on top of the first there is another 50/50 blend. If a third bead...it continues everytime a bead is deposited. The blending "can/could" mask the non conforming filler. So, if a 309 or 312 or other stainless designed for welding non matching metals is used to fix a porosity, then the stainless could be overlooked on x-ray. Then there are the x-ray techs who are also qualified weldors and may have a sharper edge than their colleages. Quote Link to comment Share on other sites More sharing options...
ArtWerkz Posted March 11, 2010 Share Posted March 11, 2010 All that it takes is a breeze of 5 mph to be blowing across the puddle to remove shield gas and create porosity. Quote Link to comment Share on other sites More sharing options...
pkrankow Posted March 11, 2010 Share Posted March 11, 2010 It sounds like different applications have different "passing x-ray" standards. What passes on a boiler may be different than what passes for general structural welding. Are the standards and requirements different for different jobs? Phil Quote Link to comment Share on other sites More sharing options...
HWHII Posted March 11, 2010 Share Posted March 11, 2010 It sounds like different applications have different "passing x-ray" standards. What passes on a boiler may be different than what passes for general structural welding. Are the standards and requirements different for different jobs? Phil Phil to answer your question yes. The main codes are AWS American Welding Society and ASME American Society of Mecanical Engineers, API American Protroleum Insitute. API is the proubably the most allowing for defects. Most all refere back and forth to AWS and ASME for different applications. It is a bit like law books it can take a bit of reading to get the right answer. Quote Link to comment Share on other sites More sharing options...
Rutterbush Posted March 13, 2010 Share Posted March 13, 2010 Boiler Code will be Boiler and Pressure Vessel Code - Section IX As stated further up in an earlier reply, it may be spelled out in a Welding Specification Procedure, (I've added the following)Procedure Qualification, or a Specification for X-ray interpretation as to what is allowed or not allowed. If the specific job does not have any of the above, then it is generally left to the engineer in charge or a qualified someone he/she may designate. Quote Link to comment Share on other sites More sharing options...
pkrankow Posted March 14, 2010 Share Posted March 14, 2010 Ah, that's clear as mud or tax code then. Phil Quote Link to comment Share on other sites More sharing options...
Rutterbush Posted March 14, 2010 Share Posted March 14, 2010 Tax code... yeah, I agree. Unless a person works with A welding code on a regular basis it can almost be indecipherable. On top of that, the American Welding Society has just stopped publishing an updated code every two years. They had massive complaints about purchasing that $500.00 book for few and minor changes. Plus all of the specifications which are available. The AWS now replaces the book every five years. Best comparison that I can come up with is Englands driving code has everyone driving on the left side of the road. The USA has everyone driving on the right. Italy, hmmm, you hold your breath, close your eyes and go. Every body has their way of doing things. With a little modification to your driving habits you may be able to adapt to Englands driving code and visa versa.Very roughly the same as welding codes. Then there are those who think they know better because they've done it that way for years, kinda like Italy. Quote Link to comment Share on other sites More sharing options...
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