Norsemans even badly done!

[knothead]

Originally Posted by Brian Duff

thats on my list

I have one of those lists too.

Please forgive me, but do you mind if I ask one final follow up question?

I agree with this;

Originally Posted by Brian Duff

The observations i have made about the failures of wire tecknic or kearny drawn swages as opposed to rotatry swages have been a result of the crease, fold, or ridge left by the rollers - this site has been the beginig of corrosion on the fitting by my observation.

But I can't truthfully say that I have noticed that the rotary swages last longer. I do lots of inspections, as I am sure you do. I live in Florida and I would say that the average life span of a rig is between 12 and 15 years. I really don't think that one method of swaging has shown to have a longer life than the other. At least here.

The die marks from Kearny or roller swagers sometime will look like a swage crack, but often aren't. Many times, upon closer inspection, they are just little creases, like scratches in the surface that start showing surface corrosion first.

I think that I read earlier somewhere in this thread or the one we were linked to, about swage cracks starting on the outside and moving inward. That doesn't make sense to me.
In my experience, stainless always corrodes where it doesn't get ventilation. Where do chainplates or u-bolts usually fail?
My understanding has always been that as the corrosion builds in the interior of a swage, it acts similar to a rusting piece of re-bar in a brick wall. Swelling with the corrosion (rust) until the internal pressure cracks the wall. Or like a stainless bearing race in an aluminum housing. The corrosion builds up and pushes on the outside of the races thereby increasing pressure on the balls until it seizes up the bearing.

My question is this; Are you convinced that swage cracks show up earlier in a swage made on a good roller swager than they do on a good rotary?

[knothead]

Originally Posted by knothead

I have one of those lists too.

Please forgive me, but do you mind if I ask one final follow up question?

I agree with this;



But I can't truthfully say that I have noticed that the rotary swages last longer. I do lots of inspections, as I am sure you do. I live in Florida and I would say that the average life span of a rig is between 12 and 15 years. I really don't think that one method of swaging has shown to have a longer life than the other. At least here.

The die marks from Kearny or roller swagers sometime will look like a swage crack, but often aren't. Many times, upon closer inspection, they are just little creases, like scratches in the surface that start showing surface corrosion first.

I think that I read earlier somewhere in this thread or the one we were linked to, about swage cracks starting on the outside and moving inward. That doesn't make sense to me.
In my experience, stainless always corrodes where it doesn't get ventilation. Where do chainplates or u-bolts usually fail?
My understanding has always been that as the corrosion builds in the interior of a swage, it acts similar to a rusting piece of re-bar in a brick wall. Swelling with the corrosion (rust) until the internal pressure cracks the wall. Or like a stainless bearing race in an aluminum housing. The corrosion builds up and pushes on the outside of the races thereby increasing pressure on the balls until it seizes up the bearing.

My question is this; Are you convinced that swage cracks show up earlier in a swage made on a good roller swager than they do on a good rotary?

Bump.Bump.

[knothead]

Okay, I see how it is.
I guess you feel that I am so full of crap that I don't even deserve a response to my question.
Message received.
Thanks for the stimulating conversation.

[Brion Toss]

Hi again,
It depends. In the South, corrosion tends to kill things before fatigue does, so the difference in longevity between swage types will not be as marked. But I have observed that roller swages are more vulnerable to fatigue than rotary, and for two reasons: the rotary machine is much less likely to produce deformations and localized stresses that can lead to fatigue; and in the real world, roller swage machines are far more likely to be out of spec or unskillfully employed than rotaries. The latter point has to do with price; roller swages are much, much cheaper, and tend to end up in the hands of people that don't care as much about quality. Yes, I know that there are riggers out there with Kearney's who are utterly skillful and utterly responsible. But that's not the way to bet. In addition, as I understand it a roller is much easier to knock out of spec, particularly when swaging larger diameters.
In my experience, "12 to 15 years" is more than a little pushing it for rigs in warm climates. Partly this is because I think that crevice corrosion will act faster than that, and partly because it occurs simultaneously with fatigue- and chloride-corrosion, as well as galvanic corrosion. Crevice corrosion on the wire works from the inside out, and the the other three types work from the outside in (though there will also be some crevice corrosion going on in fatigue cracks and chloride pits, as well as the corrosion cracks caused by the expansion of the wire in the terminal).
In the North, fatigue tends to kill rigs before corrosion, though again all the forms tend to work in concert. So in both places the longest-lived rigs tend to be the shiniest, strongest, best-tuned, and appropriately-scantlinged ones that also have their terminals' interiors sealed.
Fair leads,
Brion Toss