tractor trailer frame repair. guidance needed!

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I know there are a lot of guys here that work on heavy equipment.  I have a question on frame repair.My brother-in-law has a tractor trailer with hair line cracks in the frame rail. It looks like someone tryed to patch a few of them by running a 7018 over the cracks but it didn't help because the cracks continued to grow since the repair. (That's just what I judge by looking at it, I don't have any background on it)My question is, what would be the proper way to repair them? I'm not sure what kind of metal it is but I assume its high carbon steel because its a tractor trailer. The cracks are in the webbing of the frame rail. Would it be a good idea to just v them out and weld em up with a 7018 or maybe 10018? Then maybe fish plate it? How exactly would WW go about it?Just a little info on meI'm 4G unlimited SMAW certified and still in school. Not much real word experience,  but I can lay it down pretty good with a stick.....but this isn't a bend test in a controlled environment and its kind of critical that I get it right if I am even able to perform the proper procedure, otherwise I will have to pass on the job if it needs something super special.Thanks in advance for your insight!
Reply:Some pics of the cracks would probably help get your answer.                                        MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:I went by there to get pics but he's out. I will try to get some pics tomorrow.From everything I read in our school books about welding allow steel it seems to be a pain with all the ore and post heat. I was kinda just thinking about v ing it out, welding it up and slapping some 3/8s plate on both sides but that may not be the right way to go.
Reply:I think general crack repair advice is to drill it to stop the crack from continuing then perform the repair. I don't normally deal with such but I seem to recall back in the fuzzy recesses of my mind information about stopping cracks from spreading...Here's a bit of general info. http://answers.yahoo.com/question/in...6124917AAsI1RWNow would this work in this case, dunno.
Reply:I'm down with stop drilling the cracks!  Its good practice!So after reading threw the threads here I found that most trailer frames are made of QT100. Guessing that's Quenched and tempered 100000 tensile strength. As far as welding procedure I'm still lost thow
Reply:I seem to remember seeing frames marked as no welding, not sure about that tractor but saw it on a dump truck frame. You may have a bigger problem then you realize on your hands. Keep asking someone here will know, these guys do some top noch welding and repairs.
Reply:Originally Posted by pepiI seem to remember seeing frames marked as no welding, not sure about that tractor but saw it on a dump truck frame. You may have a bigger problem then you realize on your hands. Keep asking someone here will know, these guys do some top noch welding and repairs.
Reply:from what i can find on the web it seems like they use just about any low hydrogen electrode on this metal.one place says to use 10018 on anything thinner than 1/2 inch. so thats probably the route i will go.seems like the main thing is to have it really clean and preheat it to get rid of any hydrogen.every place i found talking about it stressed getting rid of all sources of hydrogen.so i guess unless an expert chimes in to enlighten me i will just clean up the area and grind the cracks all the way threw, preheat it and then put a preheated fish plate on one side of the web to use as a backing plate and then weld it all up, grind it down and fish plate the other side. as far as the fish plates go, i was thinking of using mild steel 1/4 inch and shaping it like a diamond to reduce the chance of more stress cracks.i guess i could make them out of T100 to match the frame but im not sure if i can even get it let alone how much it would cost.
Reply:Originally Posted by jamesyarbroughfrom what i can find on the web it seems like they use just about any low hydrogen electrode on this metal.one place says to use 10018 on anything thinner than 1/2 inch. so thats probably the route i will go.seems like the main thing is to have it really clean and preheat it to get rid of any hydrogen.every place i found talking about it stressed getting rid of all sources of hydrogen.so i guess unless an expert chimes in to enlighten me i will just clean up the area and grind the cracks all the way threw, preheat it and then put a preheated fish plate on one side of the web to use as a backing plate and then weld it all up, grind it down and fish plate the other side. as far as the fish plates go, i was thinking of using mild steel 1/4 inch and shaping it like a diamond to reduce the chance of more stress cracks.i guess i could make them out of T100 to match the frame but im not sure if i can even get it let alone how much it would cost.