Tig welding tips, questions, equipment, applications, instructions, techniques, tig welding machines, troubleshooting tig welding process
Coldman
  • Posts:
  • Joined:
    Mon Dec 15, 2014 2:16 am
  • Location:
    Oz

Got called in on a Friday afternoon a couple of weeks ago by a plant engineer for an urgent repair on a 1940's production machine cast iron base that broke. Shift fab guys were determined to do the repair and not listening to plant engineer who could see they were struggling.
Holy crap what a nightmare! Break was at a previous repair so I had to go with the previous prep which was full 45* bevel on a 3/4" base that took three of us to lift or shift it was so heavy.
When I got there the guys had used grinding discs to clean it up and were proceeding with the repair with oxy/acet and some kind of moly bronze gas brazing wire. They tried preheating with a rose bud off small bottles so the bud kept popping out. The filler wasn't taking and their tacks falling on the floor you can see in the 2nd pic.
The plant engineer said if they let me do it and it didn't work I would get the blame and not them. They liked this idea and stepped away. The whole time I had at least 4 guys with shields on watching over my shoulders at everything I did.

It was nasty, full of old oil, grease, paint and every kind of crud imaginable. Cleaned it all back with a burr and washed with shellite. All I had with me was EZ_WELD (not enough and no good for these gaps and bevels) silicon bronze, 309 wire. The base was huge and no facility to preheat. The plant engineer said it had to be repaired and put back into service immediately and would not entertain slow cooling either. What a mess. I decided to tig silicon bronze. We clamped it together with backing plates while I retacked. It was awful all the way, took many runs to fill it all up fighting the worst crud I've ever seen but got some reinforcement on in the end. Turned it over, gouged with a burr back to filler and did the back side as well. Cast webbing got huge gaps filled in as well. Drilled and tapped holes for fish plates to reinforce the repair in two directions which I asked the fab guys to prepare. As soon is I broke the last arc they pushed me away to dress it up and re-assemble so couldn't take finished pics.
I told the plant engineer I had zero confidence in the repair and I expect it to crack and fall apart at any time as no good procedure was followed, the filler was not my best choice and the prep was awful.
I'm absolutely ashamed of this repair and wasn't going to post it, but sometimes we need to see the ugly as well as the good for constructive criticism and advice. The machine is back in service now for a couple of weeks and hasn't broken yet.
The fab guys said they were impressed with the repair and asked to keep the rest of my tube of silicon bronze.
CI1.jpg
CI1.jpg (122.23 KiB) Viewed 858 times
CI2.jpg
CI2.jpg (75.09 KiB) Viewed 858 times
CI3.jpg
CI3.jpg (41.78 KiB) Viewed 858 times
CI4.jpg
CI4.jpg (60.19 KiB) Viewed 858 times
CI5.jpg
CI5.jpg (123.12 KiB) Viewed 858 times
CI6.jpg
CI6.jpg (112.26 KiB) Viewed 858 times
CI7.jpg
CI7.jpg (65.69 KiB) Viewed 858 times
CI8.jpg
CI8.jpg (61.6 KiB) Viewed 858 times
I think I will write up a better procedure for when this repair might need doing again. Any suggestions?
Flat out like a lizard drinkin'
User avatar
  • Posts:
  • Joined:
    Thu Jan 06, 2011 11:40 pm
  • Location:
    Near New Orleans

There are few thinks I dislike more than repairing someone else's failed repair attempt.

Good on you for not throwing tools and whipping asses.

Steve
User avatar
  • Posts:
  • Joined:
    Thu Jan 06, 2011 11:40 pm
  • Location:
    Near New Orleans

New repair procedure:

Step away from the damage.

Call in the real welder.
Coldman
  • Posts:
  • Joined:
    Mon Dec 15, 2014 2:16 am
  • Location:
    Oz

Agreed.
BTW I stopped climbing down out of my tree and peeling bananas a while back. I seem to scare the tripe out of people just being in proximity. Don't know why with my boyish good looks and witty sense of humour.
These days if I get pushed into a job like that I am very amicable and charge "premium" rates on the bill. Much more satisfying.


Sent using Tapatalk
Flat out like a lizard drinkin'
Post Reply