Old steels denied fills due to store "policy"

[Diving Dubai]

I understand your point but... Are the oils or penetrants used different than other oils? Is there something that makes them more adhesive and harder to clean than other oily contaminates that might get in a tank so that a normal oxygen cleaning process wouldn't remove them? Not trying to be an ass, I'm genuinely curious and don't know. Thanks

Fair question. Happy to answer

Normal oily contaminants are via a compressor so relatively a small amount. Whereas to make a Penetrant inspection or Magnetic Particle, you use a lot more liquid over the area.

These liquids are just a carrier for the dye and the magnetic particles and are specifically designed to have the right amount of viscosity to sit on the material surface, while being "thin enough" to allow them to penetrate very tight fatigue cracks (which are often invisible to the eye) via capillary action

But yes you can wash them off, as you would in a production process prior to anodising or Cad plating etc. If you have laps or burrs in the threads from tooling it will be harder to get the residue out of them.

"Washing" would be via a vapour degreaser or via immersion in a hot alkaline bath for a prescribed amount of time, then a hot distilled water bath to rinse Non of which would generally be done in a local test setting.

So in this case you run teh risk of not getting the component clean afterward.


When we're deciding on which type of test to use to find a particular defect, this would be one consideration.

Another would be the orientation of the defect

For penetrant you need the defect to be open to the surface, you also need to remove surface coatings like paint before test (and reapply afterwards)

Magnetic - Obv component needs to be steel, then you need to have the magnetic flux at 90 degrees to the defect to detect it - but Mag can see subsurface defects

Eddy Current - you need your scans to cross the defect at 90 degree, but you don't need to remove paint

Ultrasonics - you need the sound to hit the defect's side. you need the biggest surface area to get a signal return from

X-Ray you want to look down on the defect so you can "see through" it as you're creating an image from differing densities. if you looked side on you wouldn't see the defect.

X- Ray is the most costly method and requires a purpose made enclosure to put the component inside while you hurl radiation about. Mag and Penetrant are the cheapest and require least operator skill Eddy Current and Ults need no surface preparation, easy to do in the field but require higher skilled operators and teh equipment is costly.

There are other factors too that may become apparent as you try to figure out a procedure but these are the basics.

 

[Ghost95]

Thanks for the reply. I learned some interesting info. It is harder to clean penetrants used in testing. If you found a crack, well then I guess no need to clean the threads to make a bell.

 

[captain]

I find that most older cylinders like these go through long periods of inactivity. People get into SCUBA stop and have a cylinder in the closet for many years. So few are loaded with hydro stamps. Now cylinders for welding and other uses are more likely to have seen many hydros and it stands to reason more fill cycles.[/QUOTE]

Actually no. A diver can fill one cylinder several times on one weekend for half the weekend of the year. By contrast a welding cylinder might get filled only 3 or 4 times a year on average. As a guy who has a welding and cutting rig for personal use I can usually go 5 plus years before needing them filled. Very seldom does a cutting job take more than a minute or two. Large fabrication shops that that use a lot of oxygen have it piped to welding stations from liquid oxygen Dewar tanks.

 

[wedivebc]

I haven't read the whole thread so if this has been covered, apologies.
Metalurgical testing has been around for centuries. The amount of movement in the plastic region of steel tanks is very predictable and is a good indicator of a tanks overall health.
When working on certain diesel engines you can easily measure the torque on a bolt by measuring the stretch of the stud. In fact in some cases no torque spec is given just a bolt length measurement. All this to say, there is very good science to supprt hydrostatic tests and as a compressor owner I have no issue filling old tanks that have passed hydro. The jury is still out on aluminum 6351 tanks but steel tanks last for years and years if they are not overfilled which will cause them to deform.

 

[mictrik]

Actually no. A diver can fill one cylinder several times on one weekend for half the weekend of the year. By contrast a welding cylinder might get filled only 3 or 4 times a year on average. As a guy who has a welding and cutting rig for personal use I can usually go 5 plus years before needing them filled. Very seldom does a cutting job take more than a minute or two. Large fabrication shops that that use a lot of oxygen have it piped to welding stations from liquid oxygen Dewar tanks.

What you say makes sense, thank you. I do see more older welding cylinders but if they are filled that infrequently then I imagine in makes little difference. In general I do not have an issue filling a "clean" well maintained cylinder in current hydro. The only exception being the aluminum 6351 cylinders which I have found cracks in too many times for my liking.

 

[JahJahwarrior]

I like Force E and have bought several wetsuits from them, and used them for fills a few times. I get most of my gas in cave country, where all the shops know me by name and say hi and ask how I'm doing and never give me crap about my tanks or ask for cert cards, but Force E and Pura Vida are both good local shops and I support them all when I can.

I don't have any tanks older than 20 years at this moment. I absolutely don't think anyone should fill an aluminum tank made from a bad alloy. As a previous fill station tank monkey, I refused to fill any of those tanks, even in hydro or with VE. But I think it's silly to not fill steel tanks that are in hydro and vip regardless of age--with an exception for tanks which look severely rusted and enough time has passed since last hydro that rust could have damaged the tank and someone could have vipped it poorly.

I'm sad to see that Force E has such a silly policy, but I also bet that older tanks are a small part of their fills and their insurance might play a role here.

I also think it is silly for a shop to make you carry tanks inside, but maybe cave country has spoiled me. In general, getting fills in recreational shops is a drag. Atleast they aren't as bad yet as Divers Direct. They make you use a cart to carry tanks to the very back of the shop. Their fill box won't fit large steels, like LP120s. And now, they require NITROX band sticker to do nitrox fills.

It's super frustrating when shops have these policies that don't really matter, especially when they are otherwise a great shop, but I'm glad you were able to get the fills at PDC and they are also a great shop.

 

[boulderjohn]

I'm sad to see that Force E has such a silly policy,

I just want to remind people who are not reading this thread carefully that whether or not Force E has this policy is in dispute. I do not question Ana's account--I am sure her experience was genuine. However, when I personally asked them about that policy, they absolutely denied it, saying that there is no age limit whatsoever on steel tanks. I was with a couple of employees when I asked, and when I told them about this thread, they were very surprised. I got the feeling that they would enter this thread and straighten things out, and I have to wonder why they did not.

 

[Ana]

I just want to remind people who are not reading this thread carefully that whether or not Force E has this policy is in dispute. I do not question Ana's account--I am sure her experience was genuine. However, when I personally asked them about that policy, they absolutely denied it, saying that there is no age limit whatsoever on steel tanks. I was with a couple of employees when I asked, and when I told them about this thread, they were very surprised. I got the feeling that they would enter this thread and straighten things out, and I have to wonder why they did not.

This happened on a Sunday, and yes it did happen.
I could not get either of the employees present to tell me what was the policy, just that my tanks were to old. That response, actually lack of response, is what prompted me to go to their website, and ask what was their policy, they responded with a question: How old were my tanks?
That pissed me off to high levels, because the age of my tanks should not have anything to do with their policy, how about telling me what is the blessed policy.

My contact with them stopped at that point, can't remember if they send any more messages to me but if they did I deleted them. I checked and they do not need any of my dollars, they get dollars from other people and it is perfectly fine.

 

[boulderjohn]

I have written to them and hope to get a definitive response soon.

 

[boulderjohn]

I got the complete fill policy from Force-E headquarters. Here is the part relevant to this discussion:

All cylinders for fills must have a valid and current visual inspection sticker and hydrostatic inspection stamped into the tank. *Foreign Hydro’s are filled for export only.

Force-E will no longer fill 6351 alloy cylinders, or Luxfer older than 1989; nor will Force-E fill 72 cubic feet steel or steel with fill pressures below 2400.​