Sunday, 12 May 2013

On with the Oil Tank

Looking back, I realise that pulling those dents out cold was never going to work. The last time I did something like that, I welded the pins in and pulled the dents out hot.

Ho hum. With cracks like this, there was no going back:

So now you are all going to find out what the oil tanks looks like inside...

I decided to do what I should have done all along. Using the trusty hacksaw, I cut down each side of the damaged area. Using a cut off wheel in the Dremel, I cut a short slot, long enough to allow a hacksaw blade to pass through, in the long edges of the damaged area. Then I used a hacksaw blade to remove the damaged area:

The tank is made of 18 SWG sheet. So, taking a piece of cardboard, I cut a template roughly the same size as the hole and attached a loop of masking tape to it. I folded the edge of the card to allow it to fold around the edge of the tank. I then suspended this in the hole and drew around the inside of the hole, onto the card. I now had a card model of the repair patch I would need.

The shape was then transferred to a piece of cold rolled 20 swg sheet, and cut out with the Wiss aviation snips. I folded the edge in the vice, and then used some scrap material to press the joddle into both edges, so that the pieces would sit flush with the original surface:

I've shown it here, held in place with magnets. At this point it is important to dress the edges of the tank, take out any wobbles or dents and make sure that patch sits flat. This is not good enough:

All adjusted; and the butt joints at the short sides have been given a 45 degree weld prep. The panel is tacked in place with the MIG:

Fully welded. a bit messy in places, but I blame the lighting. The lights in my shop are either behind me when I am welding (so I am welding in the dark, with the lights shielded by my body), or if I switch the overhead lights on the sensor in my helmet picks up the brightness and darkens the lens - welding in the dark again:

Dressed with the flap wheel:

There was another weld/dress step as I tested the tank. I filled the tank with water (after it had cooled) and found several holes; these were welded & dressed; I now have two very minor holes left, but the family are complaining about the noise the grinder is making so I had better stop.

Sharpie rings mark the holes!

A couple of days later in a marvellous week at home - I have not travelled anywhere and I have the luxury of a wonderful wife who brings me Martinis in the evening - I'm done with the oil tank. It has taken two more leak test/re-weld/grind cycles to get the tank water tight, but now the repair is invisible as the day the tank was made.

A temporary coat of black hammerite, until we are ready for Phase 2, and we are finished.

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