welding on a steel yacht hull

Discussion in 'Metal Boat Building' started by Andyman, Sep 21, 2010.

  1. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    Concur with Welder/Fitter....your coupon is a fail, sorry.
    As noted, looks like LOP/LOF and lamellar tearing.

    X-ray's need to be shot at very close proximity with the right amount of energy too. Do you know the spec's of the x-ray it produces?

    These might be of use too:

    bend test 1.jpg bend test 2.jpg bend test 3.jpg
     
  2. welder/fitter
    Joined: Jun 2008
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    welder/fitter Senior Member

    Andyman,
    Pay close attention to "Ad Hoc's" attachments. Though it would not address the issues with your coupons, you should be polishing the corners & edges of your coupons. More than a few welders have had their coupons fail guided bend tests because they did not address the non-welding issues, such as mill scale removal on the test plates(root edges & joint faces) and grinding/polishing of coupons.
     
  3. Andyman
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    Andyman Junior Member

    when I took the coupon to the inspector I know he said it was fine. That usually if it doesn't break it's good. Also mentioned that i could use liquid dye penetrate to test my welds for surface imperfections. So what makes you guys say it fails? He is a certified weld inspector at the space center. what qualifications do you guys have in this area?

    Also he was able to tell me the settings to use for the x-ray machine. I'm outta town at the moment but when i get back I'll get back to testing my welds and maybe get some pictures.

    Mike

    Do I really need a backing? i've been doing test pieces without any backing.

    Andy
     
  4. Ad Hoc
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    Ad Hoc Naval Architect

    You need to know what is or is not acceptable and to which standards for professional quality welds before you decide whether your space centre man knows is onions or not.
     

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  5. welder/fitter
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    welder/fitter Senior Member

    Andy,
    I worked as a welding inspector for my father's engineering firm for a few years, in the late 1980s. I've held Canadian Welding Bureau tickets in a few processes/parameters, usually all-position, for many years, which included check-tests for each ticket every two years(I started welding formally in 1982). Where my knowledge runs out, "Ad Hoc's" goes on for volumes!

    But you don't have to trust our opinions.(though why ask?) Take your coupon to the nearest welding school & ask them. If you work in a fab shop that does work to ASME standards, take it to work & ask the welding foreman/supervisor.

    If I understand your question correctly, regarding backing, you don't have to use a backing ring or ceramic backing, unless you cannot access the repair area from the inside. Using either allows you to single-side weld an insert seam.

    Mike
     
  6. welder/fitter
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    welder/fitter Senior Member

    Andy,
    Is the reason that the owner of the boat doesn't want to access the inside of the hull because he has to remove a lot of crap? If you're living in/near an area where more of this type of moon-lighting might be possible, the first thing you'll learn is that every owner wants a quick and perfect job, which is often not possible. Ask him a few questions, such as; "Is it a problem for you if the interior starts to burn?" "Would you prefer to pay me for 10 hours of a perfectly done job that I can guarantee, or 3 to 4 hours of a 'take your chances' job?" Do things right, each & every time, Andy, and the word will be passed around that you take more time with the job than some, but the repairs are always perfect, never need to be re-done.

    Photos would really help us to suggest possible alternatives.
     
  7. pdwiley
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    pdwiley Senior Member

    Good, cheap, fast. Pick any 2......

    You can also use a piece of copper as a backing strip. Might not be approved but it does work, however if I couldn't see or clear the back side of the HAZ I wouldn't touch this job, ESPECIALLY for a friend.

    PDW
     
  8. Brent Swain
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    Brent Swain Member

    How big a boat?

    Major weld failures on boats under a certain size, even those done by beginners , are almost unheard of. In nearly 40 years of cruising and building boats I've never seen one, nor heard of one.
     
  9. Andyman
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    Andyman Junior Member

    I don't know the actual size of the boat so i went and found a picture of it.

    Also had the chance to do some more bend tests and i think i got a keeper. The bend in the picture is of a root bend, I TIGed(for the hell of it) the back of the root then MIGed the front, cut into the back of the weld and MIGed over that. Also got to thinking and I'm wondering if I'm using the correct former and correct guides. I used the equation with the smallest results outta my book since they weren't really labeled. Figured that would be my safest bet. Anyways my former is 1-1/4"dia and the spacing between my guides is 1-3/4" let me know what you think.

    Welder/Fitter
    you got it right. he didn't wanna access the inside because all the crap inside it.

    PDW
    Why isn't copper as a backing not approved?
    I'm considering using a backing now. Found it a little easier this last set of test i did when i had the tig weld acting as a backing. Question is though how do i hold it up there?

    Looks like I'm delayed for awhile anyways the owner travels a lot for work and he is only gonna be home 4 days out of this month. He still has quite a bit of work to do before he wants me to come in. So I have some time to see if i wanna do this or not
     

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  10. welder/fitter
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    welder/fitter Senior Member

    Andy,
    Can you use "paint" or a similar program & mark the areas in the photo you want to replace/repair?

    When I enlarged your coupon photo, all I could see was blurred, but in the non-enlarged version it looks like a major improvement.

    As PDW says, you don't want to be working on an area that is backed with insulation, fixtures, etc., because the whole thing could go up in flames. Assuming that you take this into account, you can use fairly thin material or material of a similar thickness to your insert(replacement) material. depending on room, your backing strip should be about an inch to an inch & a half wide(1" to 1 1/2"). you lap the strip to the inside surface of the hull cut-out (after you've cleaned up the existing edge, of course & pre-fit the backing ring), clamp it in, and tack it in(small tacks). The insert should be of a size that there is about a 1/4" to 5/16" gap between the existing edge and the insert's edge on all sides. Don't forget that the corners must be radiused. Then you weld up the seam, making sure that you get into the edges on each side of the seam. The only problem with this repair is that we have to go back to PDW's comments because you will still need enough access from the interior of the boat to be able to paint the completed job. I'd recommend having the owner of the boat read this thread, as it will give him a greater appreciation for why you need to access the inside of the hull. Sure, he could simply have you weld doubler-plates(patches) onto the exterior surface of the hull & overlap the edges enough to not worry about doing more than pre-priming the plate then painting the outside, but it would be a pretty shabby looking repair, imho.

    For smaller repairs; tears, pinholes, etc., you can use a piece of old gouging rod, if you have any laying around the shop, or a welding rod for filler, but you should be able to fill a 1/4" or smaller diameter pinhole with just your wire, without creating too much heat, just do a lot of stop & start. Once again, you'll want enough access to at least spray some zinc oxide on the interior surface.

    If it were me, I'd do my best to convince the guy to let me do it properly, including removing portions of the interior. Anything less is really half-assing the job.

    Best of luck with it!
    Mike
     
  11. Andyman
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    Andyman Junior Member

    Mike

    i was referring more to how to hold the backing up since i can't exactly use clamps unless i tack something to the haul to clamp to or tack a clamp on the haul.

    Do i really need a 1/4 - 5/16 gap? all my tests have been with a 1/16 gap.

    Took another picture on the bend and went out and got some pics of the boat. I believe he said he wanted to replace all the spot that have white paint on them.
     
  12. Andyman
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    Andyman Junior Member

    forgot pics

    #1: I think he said he was gonna open this whole up more

    #2&3: I think I'd be replacing this hole area that is shown in #3

    #4: cutting a hole out much like in #1

    #5: small whole almost above the water line.
     

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  13. Andyman
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    Andyman Junior Member

    more pics

    1: i think I'm replacing the rusty area to the left and maybe the patch that's on the right.
    2 & 3: I think i'm replacing both areas in #2. in #2 you can kinda see the the crack in the area on the right #3 is a close up of that.
    the rest: might be replacing these areas
    and another pic of the bend
     

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  14. wardd
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    wardd Senior Member

    what is the actual plate thickness where you plan to weld?

    cann you cut back to full thickness?
     

  15. Andyman
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    Andyman Junior Member

    3/16 is the thickness
     
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