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  1. #1
    Join Date
    Oct 2004
    Location
    Melbourne, Australia.
    Posts
    51

    Default Oxy welding/heating galvanised mild steel

    I have a bracket attached to our house, which is one of those generic television aerial brackets, it’s galvanised. It doesn’t hold an aerial, it holds our telephone lines coming from the power pole across the road.

    With some recent bad weather we had a tree go down and pull on the telephone cables, bending the bracket, but thankfully, not doing much other damage.

    My first thought was to whip the bracket off, hit it with oxy to make it soft, then press the flat base back to flat, as well as pull the tube back to its original orientation.

    Then I started thinking about the galvanisation and what problems there may be. I have oxy welded gal before outside in a very stiff breeze and only for a small piece, our Hills Hoist in fact.

    My worries were more in line of, how if anything, will heating and bending/flattening galvanised mild steel, affect the metal?

    The Hills is still happily holding the next generation of children as they swing when they think we aren't looking.

    Thoughts?

    Hills Antenna &amp TV Systems

    The link directs to various brackets, click on, "Curved fascia Brackets" which is pretty much what I'm talking about.

    Mick.

  2. #2
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,540

    Default

    If you heat the tube with the oxy you will more than likely melt the zinc off (melting point of a few hundred degrees). If that happens, there goes your corrosion protection. Galvanising will protect a bare spot up to around 20c size but after that the protection fails. The steel is nothing special and should take heat without changing drastically. Personally I'd be trying to straighten it up cold if I could - more effort required but the galv should not take significant damage.

    To restore protection you will either need to re galvanise or paint the bracket. You could probably get away with some Wattyl Kilrust (primerless top coat) provided conditions are mild (away from the coast, area will not have water pooling around it when it rains)

    Michael

  3. #3
    Join Date
    Oct 2004
    Location
    Melbourne, Australia.
    Posts
    51

    Default

    I pretty much knew the protective coating would run off, but wasn't too sure if doing so may have had a bad effect on the metal underneath.

    With the amount of bend the flat fascia piece has taken, it will require some strength or heavy bashing to flatten it, same with the bent tubing. Hence the thought of gentler persuasion via heating.

    Amazing how strong telephone cabling is.

    Many thanks for your input.

    Mick.

  4. #4
    BobL is offline Member: Blue and white apron brigade
    Join Date
    Feb 2006
    Location
    Perth
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    7,182

    Default

    To bend steel using an oxy will require a near red heat temperatures. This means the zinc will burn (oxidise) rather than melt and this will make a choking white smoke and although not life threatening it is quite debilitating, it will literally take your breath away. If you decide to go this way make sure you have good ventilation.

  5. #5
    Join Date
    Oct 2004
    Location
    Melbourne, Australia.
    Posts
    51

    Default

    Bob, thanks for the warning, I had this issue when welding up the aforementioned Hills Hoist many moons ago with the oxy.

    It was an extremely windy day and perfect for such an exercise, although the pidgeons in the trees near the back fence weren't too enthusiastic about the odour and took off.

    My thoughts on this repair will be to use two electric fans, one at the side, the other towards the rear and in the same direction of any prevailing breeze and done in the backyard.

    The first time I experienced the choking white smoke, as you call it, I was flabbergasted. Needless to say, one whiff and I knew it was trouble.

    I'll keep you all informed as to how successfull the repair, is or isn't.

    Mick.

  6. #6
    Join Date
    Jul 2009
    Location
    Melbourne
    Posts
    133

    Default

    I had a similar issue with a truck that caught my cables and bent the bracket. As it's before the cable termination in your home. It was up to the phone provider. The came in and replaced the whole thing. Not sure what issues you could cause by working on it yourself. The guy that replaced it said there had to be certain tensions on the lines and height limits he had to follow. I just left it with them.

  7. #7
    Join Date
    Jul 2003
    Location
    Sydney
    Posts
    493

    Default

    Light up oxi, heat to cherry red, bash straight with hammer on anvil or similar surface.
    If pipe is bent as well, heat up cherry red, slide a round bar inside and bash straight again.
    When cold, paint with galvo paint.
    Bob's your uncle
    Civilized man is the only animal clever enough to manufacture its own food,
    and the only animal stupid enough to eat it.
    Barry Groves

  8. #8
    BobL is offline Member: Blue and white apron brigade
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    Feb 2006
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    Perth
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    Default

    Quote Originally Posted by Marc View Post
    Bob's your uncle
    I could be, I have 26 nieces and nephews

  9. #9
    Join Date
    Sep 2010
    Location
    Lebrina
    Posts
    1,910

    Default

    I am guessing that the tube bend on the bracket has opened out when it was hit by the tree. This will be the most awkward part of your repair trying to rebend the tube without kinking it. If not too severe, you could just cut the base plate off and reweld it on at an angle that will bring the tube back to a vertical orientation.
    I would definitely not heat the bracket to straighten it, use a bigger hammer if need be, the steel is probably only 5mm at most.
    Simpler and better option, Bunnings, about $45 new.
    It would pay to check with your provider as this may be their baby.

  10. #10
    Join Date
    Jul 2009
    Location
    Melbourne
    Posts
    133

    Default

    It is the providers property and responsibility as it is before the termination on your property.

  11. #11
    Join Date
    Sep 2010
    Location
    Lebrina
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    1,910

    Default

    Quote Originally Posted by DocBug View Post
    It is the providers property and responsibility as it is before the termination on your property.
    That being the case. No touchy!

  12. #12
    Join Date
    Jul 2009
    Location
    Melbourne
    Posts
    133

    Default

    Quote Originally Posted by Karl Robbers View Post
    That being the case. No touchy!
    When I reported a similar issue to Optus a while back. They replaced it completely and left the old one in the bin. Let them do it, it's what you pay for as part of your line rental

  13. #13
    Join Date
    Oct 2004
    Location
    Melbourne, Australia.
    Posts
    51

    Default

    Hmm, many ways to skin a cat it seems. All options are being considered, but everything is delayed as the weather is such that climbing up and removing a tile of three with rain happening, isn't on the cards.

    With regard to who owns what, the bracket was placed by us as a solution to getting our slide-on camper underneath when it's on the ute tray, technically, that bracket doesn't exist.

    Once it's off the roof it will be looked at and I'll see just how easy it may or may not be to straighten cold. I have no qualms about purchasing a new one to replace it, however I always try and repair anything as a matter of course.

    Having been raised surrounded by some people who could and did attempt to repair or manufacture whatever they needed, in an era where few people had the means to just go and buy another one, I am always compelled to have a go.

    The missus was brought up in a similar situation in another country, there is however a fine line in the size of the junk pile necessary to allow one to build and/or repair stuff comfortably, and what she considers an unholy mess.

    Mick.

  14. #14
    Join Date
    Oct 2004
    Location
    Melbourne, Australia.
    Posts
    51

    Default

    Took it off today, hit it with a big hammer on the Triton Superjaws, the 6mm steel flat plate was straightened with a bit of an effort and locking in the jaws.

    Filled the tube with dry sand then reversed the Superjaws for the length, then carefully squeezed the tube.

    Those Triton Superjaws are amazing, 1,000 kg of controllable pressure at the touch of your feet. Very versatile piece of equipment.

    Made a plate up from some scrap steel to hand, 3mm thick by 280mm by 165mm, drilled the appropriate holes then placed this plate on the inside of the facia board, used some 10mm by 65mm bolts.

    The whole thing is rock solid and looks like it will be perfect for another 10-12 years, or if another tree grows up and drops a branch, whichever occurs first.

    Many thanks for all the input, having bad weather was a good thing as I thought of the various ways this may be repaired and/or improved; rather than rushing in as is my usual practice.

    Mick.

  15. #15
    Join Date
    May 2008
    Location
    Perth
    Posts
    241

    Default

    Did you give it a coat of cold gal or something similar to protect it from rusting?

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