Repair on 2 1/2 pipe

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Have a small home no-option fix-it project.  Small holes have opened in an old painted 2-1/2inch pipe supporting a deck.  These holes are getting larger with time and eventually will affect the structural strength of the support.I have capability to stick or MIG weld (Stickmate 235LX or MM211).  Not a welder by any stretch of the imagination, and have only done minor repairs and building a few simple home projects of angle and tube steel.I can use the MIG on 120 vac or perhaps run a temporary circuit (i.e. lay a wire on the basement floor from the outlet to the post and install appropriate socket and plug) to operate the stick or MIG at 220 vac.  Capability exists to run a permanent 220 50 amp circuit to that location but doubt seriously I would ever again need service at that location.  I have a 4000 watt generator but don't expect that is sufficient power since it is limited to 30amps at 120 vac or 20 amps 220 vac.The pipe orientation is obviously vertical and my limited experience is for flat welding.  I would prefer get this repair done before next spring, do not have the option to have it done for me, and currently have the benefit of nice dry weather.I need to prep the area but do not want to remove any metal that is actually supporting the deck, so I will limit prep to wire brushing the area.  There does not appear to be any thinning of the surrounding pipe wall and the end of the pipe needing the repair is within 2-4 inches of where the end is buried in concrete, so I must limit the general heating of the pipe.Those are the conditions;  what do you suggest as to how I approach and do this work?  What should I know ahead of time and any hints? Stick or MIG, uphill or downhill, current, rod, cooling for base of column (and how?).
Reply:I think this problem is larger than you think.  Holes dont generally just appear, and from where you say the holes are, it seems like moisture getting down the bottom of the pipe.Pics of the structure would help.Im thinkin' Acrow prop., cut section out and replace.  Bracket on the bottom and bolt to existing conc. footing.Pics, pics pics.
Reply:Originally Posted by ragatpinbookmarked and b back l8er, bro, :-)
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Reply:The top is capped with a flat plate.  I have seen the apparent generation of these holes for many years; a very odd occurance.  Holes started as indentions in the surface, then finally developed into through holes.  Thought perhaps when pipe was fabricated, existing holes were just filled and the covering, whatever it was, finally wore away.   I have looked for a source of moisture and have found nothing.
Reply:there is probably more rust than you can see, more holes waiting to appear. but since you dont have lots of options...pics would help...temporary shore the deck so it doesnt drop when you cut out the bad steel..dig out the base, cut and remove..use the welder you think you are better with..that pipe doesnt have much wall, 1/4" max..zero in some spots , it seems..if you aint comfy welding that butt joint, maybe build some base for the pipe with a piece of 4" to nest the 2-1/2 into, that way  you can fill the 4" with some nonshrink grout and get the support that way...
Reply:Originally Posted by mrmikeyHe took note of this page (bookmarked) and he wil be back (b back)  later (l8tr), don't 'ya just love acronyms LOL.
Reply:Chris,I urge you to consider replacing this pipe support, instead of repairing it.  The holes you can see already compromise the integrity of the pipe support.  The damage you can't see makes the whole situation unpredictable.  The risk of your deck collapsing, with people standing on it, warrants a more conservative approach.The pipe is corroding do to moisture that becomes trapped inside the pipe.  This is a common occurrence where inadequate drainage isn't designed in, i.e. weep holes are not made in the pipe.  Basically, what happens is that the pipe is sealed at one or both ends.  Somewhere there is a small defect, a crack or pinhole, that allows air to move in and out of the pipe.  The defect may be too small to see.  But, as the pipe warms up, due to sun or just ambient temperature changes, the air inside of the pipe rises in pressure and is pushed out of the pipe.  When the temperature drops, outside air is drawn into the the pipe.  This air movement brings a fresh, steady supply of moisture into the inside of the pipe.  This moisture condenses on the inside of the pipe, and causes the pipe to rust through from the inside out.You're looking at a 'tip of the iceberg' type problem here.  Even if you patch the holes you can see, corrosion will still occur and new holes will continue to form.  You have no idea just how thin the pipe walls are, and how long before that pipe could buckle.I recommend that you shore up the deck and cut out the pipe.  Replace it with a new piece of pipe, and purchase a new section of pipe that is coated on the inside with a corrosion preventative.  You might also look into galvanized pipe, if you can find it in the right size/wall thickness.  Next you need to do some reasearch and find out the best place and size for some drainage holes in the pipe.  Another option might be to fill the pipe with concrete or some other substance that displaces the air inside the pipe.  Some internet searches should yield some good possibilities  for this, i.e. concrete, foam, something that doesn't degrade over time...Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:I have to agree with Dab on this. Holes usually don't just "Appear...." Whether there is electrolosys, moisture incursion, or weathering issues...there IS some kind of problem that is not going away with some small patch work. A sight hole cored in can help you see what's going on. But once you start exploratory surgery, usually you find terminal cancer, whether it's flesh or steel.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Spammer. Hit several tens (hundreds?) of boards in the last day. All minimal length ambiguous messages, same links in sig.
Reply:I agree that the problem is bigger than you believe.Including the possibilities for water intrusion Dab mentioned, I'll add one more. Frequently guys will just set the post in the hole and then back fill around the pole with crete. That means that the post, either open or capped can be in direct contact with the ground and water may be entering there. Also concrete itself is porous and will absorb water as well as contribute to corrosion due to lime and chemicals in the mix (as well as the possibility of salt from sand in coastal areas).As already mentioned  you need to brace and support the deck during repairs. Remove and replace the whole column with a new one. Fab a base plate with bolt holes and bolt it to the footing. (Best solution, but probably not the one you want to hear.)As mentioned above you can cut out the damaged section and replace it with a matching  diameter tube You would but weld the two together.If you have the room you can get a tube with an I.D to match the OD of your current tube, then slide the new tube over the old and weld the joint at the "lip". You can add a thick plate with anchors at the bottom to help raise the tube.You could also just cut the pipe higher, weld on a new base plate and raise the height of the footing to match. You could do a nice block pier at the bottom, filled with crete to carry the load of the deck.Another possibility would be to get a tube with a matching ID to the original, taller than the area that needs to be repaired and split it down the middle. Sandwich the old tube with the new tube and weld the vert seam and top and bottom. I'd weld on a new base plate as well to spread the load.If you want an idea of whats going on inside, you can get one of those fiber optic scopes. Depot / Lowes sells them for about $200, and some rental places have them available. Mine requires about a 1/2" / 5/8" hole to insert the end of the scope in. I'd do it above the damaged area and then work the scope down so you can see the whole pipe.I'd weld this with the machine you are most comfortable with, and the most powerful you have available. ( I'd go with the MM211 on 220v from the gen set most likely myself). Better yet, find someone who has the skills to do the welds for you if you are even the slightest bit unsure. Structural welds are not the place for learning and practice. Also I would not just wire wheel the old column. I'd get a sanding disk to strip off the old paint/rust and get down to good metal.A wire wheel does not remove this stuff frequently, it just polishes it up and smears it around. You want to get this as clean and shiny as possible so you get the best weld you can..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:After reading all the responses, I realize I have overlooked what I should not have.  Replace the pipe, and the problem is solved.  I can burn it off flush, replace with the same size pipe, but with a smaller id pipe or protruding ears welded onto the bottom to lock into the existing hole.  I looked closely at the pipe for other soft spots but found none, but...I did not do the search aggressively, must do that now.  Thanks for the comments.  For learning think I need to try the M211 on the pipe while vertical, but I can do at my leisure after I have fixed this problem.
Reply:Pics of side with hole(s) and the reverse showing severe corrosion Attached Images
Reply:Remove and replace.  The structural pipe is rusting out (mostly) from the inside (as already said).Quick test to see how much -other- rot is happening: take an awl/ice-pick and semi-aggresively try to poke through the pipe.  You'll probably be unpleasantly shocked as to how many -other- areas you go through that pipe.  The best laid schemes ... Gang oft agley ...
Reply:Am afraid you are right.    But the strange thing is that all the erosion I see is from the outside, which is why I have been watching it for several years.  I  see this same thing on one of the other posts.  Guess I better put some other temp supports under the deck before I go sticking it with an ice pick .   The engineer in me says there is plenty of wall left to support the deck and the roof above that, but the chicken says the sky might be fallin' soon!  Wish we had a metal scrap yard here.  Lost most of it when we had the fair here in Konxville, then the balance left when the Chinese starting buying up the used world.Take careChris
Reply:I agree that pipe is way too far gone.  Replace it with a new pipe.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op