"If you are having trouble with porosity on a carbon steel welds, add a little 309L to it. As long as it isn't the root or the cap most x-ray guys can't tell the difference in the density. I'm telling ya it works."

"Hmm, seems like everyone here lives in a utopian vacuum. Must be nice making every weld on clean new pipe and tubes which have been placed in the optimum position for yet another of your textbook perfect welds. Crawl in a 50 year old boiler with 1500 welds 3 deep and an inch off the floor and pull your prima donna card then. If you can't make the shots on rotten tubes you can pull out the bag of tricks or go home but no one cares if you complain."

"The utility knows the boilers are worn out, the contractor and Q.C.'s know that the base metal is boiling porosity into the new weld metal and still the shots are made. You can inform anyone you want to but if you can't make the shot you'll be whining at the house. Thats the real world sorry if you don't like it."

"you can tell there are some peolpe that have never been in a boiler, fab shop welders don't know what they are talking about. This trick is what we call  "the Magic Wire" , tube and pipe welders in the field have been doing it for years. Its is 309L after all!!! Mean't to be welded to carbon steel. I'm not a metalurgist, but from what I have seen stainless steel is better than carbon steel in the wear department. Not to mention its in the middle of the weld. I have been doing boiler tube leak repairs for years and this will hold for years. See what you come up with when you have water and air leaking out of a crack you want to repair. When you are using 2 mirrors and arm lenght deep in the economizer. Next you will tell me a little XX18 downhill welding is bad too. I guess all those old timer tube welders didn't know what they were doing with those 50 year old pad welds."

"If porosity continually shows up in carbon weld metal after several attempts at grinding it out its generally garbage being pulled out of the base metal. This would be a rejectable defect. 309L wire is used to join dissimilar metal (carbon-stainless mostly). This is not an easy way out of doing a good job. This is a COMMONLY used way to prevent porosity from continuing throughout the weld when joining old boiler tube and pipe back together if it is a recurring issue. I don't believe any of the people responding to this post have much if any experience with heavilly heat cycled power piping. Would Kahunna walk off a job if there was diesel pouring out of a heavily magnetized line tie-in? Probably why he became an inspector, most of them can only preach the code, its a different world outside the books."

      "Hmmm, this has been an interesting thread and caused me to re-evaluate my stance on this practice. After seeing some of the initial responses to this "trick" I did an informal survey of the welders I have worked with past and present (boilermaker & pipefitter). ALL have been in this situatation when working with old tubes/pipe after remachineing. Out of 17 responses only 1 said they wouldn't/haven't used this repair. All are top manual/automatic welders. The QA/QC people I work around all know and have seen this done in the field with and w/o supporting documentation. The final straw was when I spoke with an Ohio State welding engineer who works for a large east coast nuclear/fossil power generating co. He had been a boilermaker in while in school and said that they had done this many times themselves. No this doesn't make it right but does add validity to the over 65 309L dm PQR's I've seen where I work. To the shop welders and QC gurus who reponded so negatively to this thread, I'm sorry that you feel that smart ass responses and holier than thou attitude on a message board is the only outlet you have to vent your frustrations. Its not my job to make a call as to what to is the proper filler material to put in a joint but MANY times plant personnel and contractor QC leave it to the welders to select rod (laziness?). Considering the condition of the many coal fired units I've worked in, lack of maintenance and engineering interest show (and help me earn a good living)."

Thank you for the helpful tip on how to weld old, dirty, corroded boiler tubes. And let me apologize for those posters that appear to be venting their frustrations or using language that isn't professional.

I don't believe anyone here believes for one moment that it is wrong to make a weld on carbon steel with a type 309 austenitic welding rod. I don't doubt that this technique is a "tried and true" method for solving the problem described in the post.

The problem is that the welder made the statement, "As long as it isn't the root or the cap most x-ray guys can't tell the difference in the density." The implication is that he made the change in filler metal without the knowledge of "upper management" and without a qualified welding procedure to support him actions. In other words, it appears that in his mind it is acceptable to stray from the approved procedures as long as you don't get caught. The implication is that he knew he was doing something wrong.

It appears that the type of repair being discussed is in a power plant. Most power boilers are covered by ASME and the National Board in which case the repairs have to be approved by an Authorized Inspector if the state has adopted the ASME Boiler and Pressure Vessel Codes or if the client (owner) includes it in the purchase order. Why would anyone in their right mind ask that the requirements of ASME be met? Are they crazy?

Crazy enough to realize the dangers associated with high pressure steam and that using ASME as a basis of facilitating the repair will ensure a certain level of safety. 

Few welders have the training in metallurgy, design, or code requirements to make the decisions necessary to repair a power boiler without jeopardizing the integrity of the system. This isn't intended to be condescending, it is a simple fact.

Does that mean that welders aren't called upon everyday to make unauthorized repairs? Heck no, I know what it's like out there. Owners will ask you to do all sorts of illegal or immoral things just to save a few dollars. Unfortunately, it doesn't make it right and the welder has to know when to say "No". Do you believe for a minute that inspectors aren't asked to look the other way or to let something "slide"? As a skilled tradesman or inspector, you are knowledgeable about what is right, what will work, and what is ethical. Doing what is right is more important than the dollar (there are times when my wife might disagree with that statement).

I am involved in many types of repairs. I have no problem with discussing a problem with the welders doing the work and I take their suggestions into consideration when developing the procedure that will be used. However, once the procedure has been agreed to, I expect the welders to do what is "written". No welder has the right or authority to change the procedure without discussing it with management. If a change is needed, it has to be discussed and agreed to, whether it is a change in the joint design, filler metal, welding process, or technique. Any change that can't be discussed in the "light of day" is simply wrong and the individual making the change without the knowledge of management is placing the company, the owner, his fellow workers, and the public in danger. 

Let me illustrate my points by asking a few questions:
  What type of base metal are the tubes made of?
  What is the base metal specification of the material used to make the tubes?
  What is the P-number of the material the tubes are made of?
  Do the tubes require a post weld heat treatment after welding based on ASME requirements?
  What filler metal is compatible with the base metal and matches the mechanical properties of the tubes?
  Since you elected to weld the tubes with 309 filler metal, what is the expected ferrite number?
  What type of microstructure can you anticipate in the HAZ and weld deposit using the filler metal you selected?
  Is there is a chance the dissimilar filler metal is exposed to an electrolyte (chemically treated boiler water) and is there a potential corrosion problem?
  What are the preheat requirements for the tubes based on ASME code requirements?

I could go on with my list of questions, and again, I mean no disrespect nor do I want to appear to be condescending. It simply that most welders don't have the training or information available to answer those types of questions.

The reason so many comments were made about the use of a qualified welding procedure is that by qualifying the WPS you know what mechanical properties can be expected (if the weld is made using that WPS). If the welder decides to stray from the procedure, there is no way of knowing what the properties of the weld (strength, ductility, notch toughness, etc.) will be. It's a throw of the dice, a gamble that what the welder did will not cause a problem "down the line".

Too much is at stake to allow the welder or anyone to deviate from the procedure that is "approved" by people that (hopefully) have the proper training, knowledge, and experience to make the decisions that need to be made.

Many of us that have become inspectors have a good number of years of welding experience. It isn't mandatory to have experience as a welder to be an inspector, but it certainly has helped me in my career. I had over twenty years of experience burning rod before I took the fork in the road and became an inspector. I still teach welding. I'm leaving in the morning to work with a group of Canadian pipe welders to sharpen their skills on aluminum. Then I will be heading to Georgia the following week to work with some pipe welders that will be welding copper nickel alloys. I freely admit that I don't have the expertise at boiler tube repair that you gentlemen have and it is precisely for that reason I would likely sit down with you to discuss the best way to facilitate the repairs before finalizing the procedure. However, that being said, I would take a very dim view of any welder that took it upon himself to change the filler metal to a different classification or alloy without my knowledge or approval.

By the way, who do you think went into the boiler or economizer to discover the cracks, corrosion, and assorted other problems you were hired to repair? It was me that stumbled out of the manhole blacker than the ace of spades with only the whites of my teeth and eye showing through.:)

The bottom line is that most of us, both welders and inspectors, strive to do the right thing, to ensure no one is placed in harm's way by our actions. Most of us do get upset when we see or hear of something that potentially is damaging or could result in someone getting hurt or killed.

Best regards - Al

spgtti: As I am not a pipe welder by trade My opinion "don't mean crap" but I offer this from experience in manufacturing: There are many times that a production foreman will suggest an unorthodox process or even try to intimidate QC people to accept something that clearly they should not, just to keep thier production numbers up, or make a problem "go away". Often they do not have the authority to to decide to continue to run the substandard parts. By refusing to sign off on the documentation they sidestep any responsibility if the questionable practace ever leads to failure or gets caught by someone else down the line, and the liability falls on whoever actually DID the work and inspected it. Yes, LAZINESS might be the motive.

When there is a catistrophic failure and it is traced to your weld..  When your weld is examined and it is found to have a non standard filler metal you may find yourself quite alone.

It the court room, expert wittnesses will be brought forth and testify to the importence of following qualified procedures.

You might tell the jury in your own defence... "I did an informal survey and seventeen boilermakers and an OSU .. thats "The OSU" engineer told me it's ok."....... This will not serve you.

Don't need an OSU engineer to add validity to a PQR... The PQR is all the validity anybody needs... If there were proper PQR's *in place* for the 309 boiler tubes there would be nothing to talk about in this thread.

Next you will say something like..."but MANY times plant personnel and contractor QC leave it to the welders to select rod",,,,,,, But there will be an objection and under cross examination you will be asked how many nuke or boiler projects out there are run without qualified welding procedures  that include filler metal selections made for the welder in advance.

The real "final straw"  may be you standing alone to take the full responsibility for a catistrophic failure.  Those Seventeen boilermakers and Degreed engineer will most likely dissolve away into the ranks of  "shop welders and QC gurus who reponded so negatively to this thread" and not come to your rescue when it really counts.

"of 17 responses only 1 said they wouldn't/haven't used this repair."
Eze 6:8 Yet will I leave a remnant, that ye may have [some] that shall escape the sword  

Good for the one guy......

I weld tubes in coal burners 6 months out of the year the rest i weld pipe ya 309 works but no real reson to use it most tube are 1 1/4 crome 80s or 2 1/4 crome 90s it will take a lot of heat i set the welder between 130 and 160 depending on the machine for 2g weld my expernace if your as hot that its almost scary for you you'll know it but be carefull when you put in the root keep the wire in it or you might a blow a big hole in the tube, also watch for too much argon that mini rig dosent need a s### load of argon if that dont work get out the 90 grinder and the burr bit sometimes you have to grind down and put hole in the root to get all the porisity out but that will usualy get it
also if you been welding tubes long enugh you will know 309 has been used on almost ever outage not that it makes right but most QC on boilers know it goes on
i was on an outage in OH there were 15 repairs to be made they shut the doors fired the boiler up the hell with the bad shots i dont think thats right ether

just to chime in here, I don't think anyone is saying that this process is totally bogus. Making a repair out of procedure without proper documentation is what's at question. If you have supporting PQR's hence a welding procedure than clearly this would acceptable with your employer. But, without going through the testing stages there is no way this could be acceptable to any welding code. I do not believe you'll find this pre-qualified. And as far as carbon to stainless, true, but what grade of carbon and stainless steels are we talking about. You'd be foolish to not think there are limitations on material grades and percentage of stainless deposits involved. As with all filler metals, there is a fit and places this would not fit. The decision is not the welders to make.

Having operated and maintained our 1200 psi super heated steam B&W chemical recovery boiler, I can sat that this thread is SCARY!
Hard to believe there are supposedly legit welders out there who would do this sort of stuff in these circumstances and environments.

I've read this whole thread. All I can say is .... Wow!