"Make sure you rotate your three rings while you are checking your risers!"

[riggerrob 643]

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It's not defective materials, the materials are perfectly good that can wear or be subject to damage over time.

If it chips due to abuse, that is one thing. If it chips under normal use, that is defective materials. If it is offered on a rig, it should be durable enough to survive several thousand openings.

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Cadmium plating does not last. It can get scraped off by sewing too close to hardware. Any time a piece of webbing rubs on cad-plated hardware, the cad-p[lating rubs off. ANy time you slap two pieces of hardware together, cad chips off.


The nickle-plated hardware used by Strong Enterprises may be prettier, but I see a little iron oxide in the corners.

From what I heard ... environmentalists did not try to ban cadmium, they just made it prohibitively expensive to dispose of the toxic waste that remains after cad-plating.

Nothing in the parachute industry is designed to last forever.

[Hooknswoop 19]

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If it chips under normal use, that is defective materials.

Cadium plated hardware has always chipped under normal use, like the paint on your car. It isn't like only some of the cadium plated hardware chips, it all does. It's 'normal'. If you can make cadium plated hardware that doesn't chip, you could probably make some money.

Canopy fabric gets porus with use, line sets wear out with jumps, cadium plating flakes off with use, closing loops fray. It's all normal wear and tear.

Derek

[tso-d_chris 0]

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Cadium plated hardware has always chipped under normal use,

I've never seen this before on any high jump number rig, though I've never looked for it specifically. Tomorrow, I will look on a rig or two with over 5000 jumps. If I find chipped cadmium, I'll concede the point. If not, I stand by the argument that it is defective materials.

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[Hooknswoop 19]

Attached is a pic of a bunch of Cadmium plated hardware, some newer than other pieces. All of them have some of the plating worn off. You have too look close, but the steel underneath is a slightly different color than the plating. You can take a knife and scrape the plating off. It just isn't that durable. On leg strap buckles, the friction adapter scapes the plating off where it slides, the 3-rings hitting each other removes the plating, etc.

I think the only reason hardware was ever plated was because TSO-C23b required it; "3.1.2 Fitting Materials: Fittings shall be fabricated from carbon steel, alloy steel, or corrosion-resisting material. Fittings made from metals that are not corrosion-resisting shall be plated or otherwise protected, to resist corrosion during the normal life of the parachute. The use of dissimilar metals, especially brass, copper, or steel in intimate metal-to-metal contact with aluminum or aluminum alloy, shall be avoided, whenever possible."

Derek

[bob.dino 1]

That picture isn't high-enough resolution for me to really see the problem. As a layperson, I'm not certain if I'm looking at dithering related to the size of the image or the damage at issue here.

Could you post a closeup on one of the pieces please? Thanks.

[kallend 2,027]

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Well I certainly don't have the expertise that Bill Booth does but here is another angle. I don't think that stainless hardware are affected by the hand oils on the hardware so in my opinion feel free to spin the hell out of them.

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I disagree. Chlorides (as in sweat) are known to depassivate the protective layer of Cr2O3 on many grades of stainless steel, leading to pitting and in the worst case, to stress corrosion cracking.

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The only sure way to survive a canopy collision is not to have one.

[sundevil777 102]

Quite right, more correctly called CRES, for corrosion resistant steel.

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[Hooknswoop 19]

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That picture isn't high-enough resolution for me to really see the problem. As a layperson, I'm not certain if I'm looking at dithering related to the size of the image or the damage at issue here.

I can;t post a larger pic. I tried taking several to get a better shot, but because of the size limitations, couldn't get anything better. Take a look at any cadium plated hardware that has seen some use. Look carefully and you'll see some of the plating is worn off.

Derek

[tso-d_chris 0]

I had the opportunity to check some well used standard rings. There was absolutely no sign of chipping. The plating was admittedly polished, but having not been used for at least a year, it is unlikely the plating was completely worn off. Without more than a visual inspection, though, it is impossible to know with my limited knowledge of chemistry. I am inclined to believe, however, that the Florida air would have caused visible corrosion if the plating had been worn completely off.

At this point, judging by what I have actually seen in my short skydiving career, I have to maintain my position that a chipped ring is an example of defective materials, possibly from a fault in the plating process.

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[adamUK 3]

Stress corrosion cracking is only really an issue for austenitic stainlesses and some duplexes when exposed to stress, an environment containing chlorides (and these usually have to be dried to the surface of the metal) and most importantly temperatures between 70 and 140 degrees C for a fair old period of time. This is why they tend to appear at welds or heat-affected zones or other highly stressed regions. It's highly unlikely a 3 ring system would not be susceptible to cracking in this way.

As far as pitting goes, it is possible for chlorides to provide localised breakdown of the oxide layer but this would require the presence of an electolyte and would take a considerable exposure time too.

I am not worried about mine...

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[billbooth 10]

I've been asked to comment on this discussion. For me, it is a sore subject. For the first 25 years I was in business, we all used cadmium plated hardware from US Forgecraft, with almost never a problem. Then Forgecraft went out of business, and now the problems seem never ending. The quality of the hardware and the plating have been "all over the place" for the last 5 years. For a while we were rejecting more hardware than we were accepting. We tried nickel plating a few years ago, because we heard that cadmium would soon be "banned", because it is a toxic heavy metal, with terrible manufacturing waste products. (I believe this has now actually happened in Europe) Sometimes it worked well, and sometimes it didn't. There is no danger of this hardware "failing", but chipping of the plating, especially on the harness 3 ring has been a problem. Cadmium plating also wears off, but it usually takes longer.

We have concluded that our best course is to make the transition to all stainless hardware, which has mostly occurred in the sport market. Stainless 3-rings work great. However, the standard designs for friction adapters did not "translate" well to stainless, and slippage has become a problem. Even attempts to use "hang glider inspired" hardware designs has not been entirely successful, especially in the western US, where there seems to be something in the sand that makes stainless slip when the webbing get dirty. We are currently working on refining these designs. As a matter of fact, I just tested some prototypes yesterday. Both the cost and the "frustration" factor has been tremendous, but I believe we are making progress, and I believe that things will be back to "normal" soon, with the added bonus of all that bright and shiny stainless steel gracing our gear.

[rehmwa 2]

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Go ahead and play with your stainless steel riser rings if you must (I do). It won't do any good, but the oil or sweat on your hands won't hurt stainless. By the way, riser rings, when loaded toward failure, "potato chip", they do not "oval". In every case I've seen (with type 17, 1" risers), the riser webbing fails before the rings are damaged. The harness ring, which you can't rotate, is the only ring that will oval. We did have a problem with large (RW-1) harness rings which the manufacturer fail to heat treat, but that was back in 1981.

Thanks for that, I have a pretty ingrained gear check (flap, pud/hacky, leg straps, handles, chest strap, rings, helmut) that I do prior to jump run and I hate to break the routine. I used to avoid the ring spin because of the salts and oils being transferred to the ring attachments and them getting stiff sooner than usual checks - but the old patterns still stick. Right now, all stainless on the new Jav. And the mint 1990 vector still looks great.

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[kallend 2,027]

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Stress corrosion cracking is only really an issue for austenitic stainlesses and some duplexes when exposed to stress, an environment containing chlorides (and these usually have to be dried to the surface of the metal) and most importantly temperatures between 70 and 140 degrees C for a fair old period of time. This is why they tend to appear at welds or heat-affected zones or other highly stressed regions. It's highly unlikely a 3 ring system would not be susceptible to cracking in this way.

As far as pitting goes, it is possible for chlorides to provide localised breakdown of the oxide layer but this would require the presence of an electolyte and would take a considerable exposure time too.

I am not worried about mine...

Sweat is a very effective electrolyte. Contains chloride ions, too.

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The only sure way to survive a canopy collision is not to have one.

[adamUK 3]

..which evaporates readily from the surface of your rig.

[kallend 2,027]

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..which evaporates readily from the surface of your rig.

Chloride ions don't evaporate. The lie in wait for the next humid day. Maybe you haven't visited the humid parts of the US.

I once had to deal with some serious pitting corrosion on SS tubes that had been left in a storage area after getting "damp" and not being cleaned off. We did SEM/EDS on the pits and found chlorides in the corrosion product, all centered on dust particles. Each time it got humid it seems the dust adsorbed moisture and the corrosion got going some more. Cost the company about $50k in tube stock that had to be thrown away.

IMO (as a metallurgist) anyone that ignores the possibility of chloride attack on SS is taking a risk.

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The only sure way to survive a canopy collision is not to have one.

[adamUK 3]

Very true, chloride ions do not evaporate and I would well imagine we don't get as hot and wet as you guys over there.

Naturally chlorides are present in all parts of the envionment so there is a (IMO low) risk of attack however such risk would be minor given the exposure level due to manual handling vs. the benefit of looking at them... After all there's all that pitting corrosion to check for though if I ever start seeing pitting on my watch strap I will have a look at my gear under the stereo.

You don't know what grade of stainless rig manufacturers use? It would be interesting to see if they use a 316 or other more pitting resistant grade. I was tempted to have a look with the metascop if it didn't leave dirty great big black marks on the thing

Good to see some skydiving metallurgist around...