External rust, stripping & painting steel tanks [Archive] - ScubaBoard - Scuba Diving Forum - Diving Social Network

View Full Version : External rust, stripping & painting steel tanks


Sponsored Link

Fishkiller
January 20th, 2002, 12:43 AM
I was looking at my plane white LP121 steel tank and thought hey paint it like a Watermellon, get it O2 Chicken cleaned and use it for a EANx tank. I will just go down to the store and get some spray paint and tapeto give it a two tone design, then give it a clear coat over it all.. Now the question is do I need to have it hydro'd again??

Rick Murchison
January 20th, 2002, 01:15 AM
There are two issues with paint on tanks.
(1) Paint hides stuff. Realize that any time you paint you potentially provide an area for undetected rust or corrosion. Not such a big deal with AL tanks, but some serious rust can grow under paint on steel. For that reason use a paint with a rust inhibitor in it - and clean the tanks clean, clean, clean and make sure they're absolutely completely totally dry before painting - and don't paint on a humid day.
(2) Temperature - many paint processes - especially commercial - involve baking on the paint. This is an ABSOLUTE NO-NO with scuba tanks. It weakens the metal and can and HAS resulted in tanks exploding and killing people during fills. For this reason, fill stations may be reluctant to fill any tank that isn't factory painted with a color they can recognize as a regular factory color.
Painting at room temperature with epoxy or spray paint doesn't warrant a hydro, unless your prep has involved sanding - sanding the tank warrants a hydro. You may have to get a hydro after painting anyway before the fill station will fill it - the last guy I know of who brought in a baked tank to be filled swore it wasn't, and the tank blew - and most folks in the tank filling business know it. So if they insist on a hydro first even though your paint job is obviously not baked, go on and bite the bullet - after all, it's their tail on the line when they're filling.
Rick

trymixdiver
March 9th, 2002, 10:03 PM
I need to touch up my tanks. I just got hydros and the new stamps have damaged the paint.

I want to prime the bare metal first, should i use oil or water based primer ?

Andy

trymixdiver
March 10th, 2002, 12:00 AM
i gess i should use the same type of paint OMS used, water based or oil based.

Does anyone know if OMS tanks come painted with oil or water based paints ?

ANDY

schmisl
March 20th, 2002, 08:53 PM
To refurbish a steel tank could you sandblast the tank and use Rustoleum cold galvanizing compound paint?
Anyone ever do it this way?

Thanks

Campana
March 20th, 2002, 09:10 PM
I would strip it with stripper, clean it up, and paint it. I wouldn't take a chance on losing any material. You might bead blast it or something. Stripper works fine. Then put your cold galvanizing on it and paint it with some good paint. I've got one painted John Deere Green that looks pretty snappy, and a red rustoleum painted one. Actually it's quite easy. I think people obsess too much about painting tanks, just do it.

As far as cold galvanizing, FredT knows the best kind, but I can't remember. I'll write it down this time. I got some that is supposed to be "marine" but it's pretty lame.

Now that I mention it, FredT knows about everything, but don't ask him about politics. Really.

Dave

douhunt
April 7th, 2002, 10:04 PM
not to be a smart a**, but i would not worry about painting it. It's for diving and its gonna get beat up.

jusitn

Thomas Ivey
April 8th, 2002, 02:57 PM
The OMS product (Faber) uses a two-component epoxy paint. It is my understanding that OMS sales a touch up kit, due to if this area goes un-attended it could develop external oxidation, once this starts it is difficult to stop. I would check with your local OMS dealer.

Stoo
September 15th, 2002, 08:54 PM
I occassionally dive with an OMS 98. The tank is 5 years old, never been in salt water. I have used an OMS boot on it always. I just took the tank in for a visual and learned that the coating under the boot has completely corroded away. Even though the tank hadn't been in water for 2 weeks, there was still a significant amount of water trapped there.

I sent a note to OMS a couple of weeks ago, but haven't heard back from them... don't really expect too. This tank probably only has about 50 fresh water dives on it and it appears to be toast. It is dissappointing that a company with OMS' reputation hasn't addressed this...

Has anyone else had similar problems? I generally dive twin Scubapro 95s with boots. These tanks probably have 400-500 dives on them and show no sign of corrosion.

I also use an OMS 46 for O2. I removed this boot as well and found a large amount of water there as well.

I know that boots aren't generally a great idea, but I dive from a small boat with fiberglass deck, and I want the boot to protect the boat...

I'd be interested in hearing from others who have had similar problems...

Stoo

Waterlover
September 15th, 2002, 09:08 PM
OMS recently lost a lawsuit over their paint problems from 1998. I have the same problem with 2 98's but they want to charge me to repaint them so I am going to do it myself eventually or sell them and get PST tanks. I just keep touching up the bad spots and peeling the paint as it flakes off....I don't have the link to the lawsuit but it was on Mid Atlantic diver group on Yahoo. Good Luck

large_diver
September 16th, 2002, 10:41 AM
My OMS 98 is 2 years old and so far no problems.....but I take the boot off after every dive, rinse the tank and boot, and then let the tank and boot dry before putting the boot back on.

My LDS has told me several stories similar to yours -- "lightly" used OMS tanks with nasty corrosion under the boot. The LDS tried contacting OMS.....OMS ignored them. Now the LDS no longer sells OMS gear.....

Stoo
September 16th, 2002, 11:40 AM
large_diver once bubbled...
OMS ignored them. Now the LDS no longer sells OMS gear.....
Funny that companies just don't see the connection between lackluster service and declines in business...

Thanks for the feedback folks. I don't really expect them to replace the tank... so I guess I will... just not with OMS...

S

FredT
September 16th, 2002, 01:20 PM
WAy back when on anther board....
As a side note Luxfer no longer has the same replacement policy for neck cracks.

FT

JProsser99 wrote on 4/25/97 rec.scuba.equipment:
>
> Seem to have missed the original metal tank coatings post which I did not
> see listed now. Looks like I missed a good post: can someone forward me a
> copy of it? Thanx! (jay’s address removed)

It's available on Deja news archive.

HTTP:\\www.dejanews.com

but you _asked_ for it so here goes.

-------------Start quoted text--------------------

Carl Heinzl wrote:
>
> >Now Carl - what's wrong with OMS tank? I was about to buy one tomorrow.
> >Seriously!
>
> I too was going to buy some OMS tanks before I found out all this. Ok
> this is from memory as some of this stuff is till put away in boxes.
>
> 1) Their buoyancy characteristics aren't as good as pressed steel.
>
> 2) I forget what type of galvanizing they do, I think it is sprayed on,
> but it is NOT hot dipped galvanized like pressed steel (and that is a
> big one).
>
> There was more but I don't remember it off the top of my head. Pick up
> tanks that are *hot dipped* galvanized though.
>
> Perhaps others can expound on this more fully than I.
>
> -Carl-

Carl,

I don't have an OMS tank and know of no incidents of coating failure (or success for that matter) with them, but I am relatively familiar with coating technology.

There are 3 commonly used methods for galvanizing in production operations. Normally flame spray is not one of them, but it may be used if there was a concern for the heat treatment of the tank. The normal methods and some of the differences are: (all dimensions in inches)

1. Hot Dip
This process involves mechanically or chemically cleaning the object to be coated to bare steel, sometimes preheating the object, and then dipping the object into a tank of molten zinc. The zinc will form a metallurgical bond with the steel similar to a brazed joint where a small percentage of each metal goes into solution in the other forming a bond at the atomic level. The amount of coating remaining on the object is dependent on zinc pot temperature, withdrawal rate and any mechanical removal done as the hot coated object is removed from the tank. Normal coating thickness is often in excess of 0.005". Air knives and mechanical wipers are used on some products to limit film thickness in critical areas. A multiple dip process can obtain heavier coatings in excess of 0.030”.

++Hot Dip normally provides the best adhesion, heaviest film thickness, and least pinholes in the coating of any method.
++ Pinholes tend to self-seal when in contact with water.
+Can be done in an automated process on a production line with minimum labor involvement.
+Process quality control is easy to monitor and has relatively wide acceptable levels for the critical variables.
-Energy intensive as the entire object must be heated to above the melting point of zinc and the molten zinc must normally be maintained at plating temp round the clock to provide production throughput.
-Expensive USA EPA and OSHA requirements for zinc fume scrubbing and worker contact can run up the costs significantly over previous years.
-Effectively prohibits any heat treatment step requiring soaking at or below the zinc pot temperature from being effective. Normal realities involved in heat treatment of steel will usually prohibit engineers from incorporating the galvanizing process into the middle of a heat treatment process following the hot forming of the tank itself since beginning and end of day in process work will have different time constants. This limits material choices.
-(For the manufacturer) thin films are often difficult to maintain with this process. This uses more zinc and thus adds cost to the product. This heavier minimum coating I consider a + for scuba tank owners. Makes it much harder to get a tank off spec on the thin side.:-)

2. Electrogalvanized
This is simply an application of zinc to the surface of the steel by the electroplating process. The object to be coated is etched to remove any surface contamination and immersed in a chemical bath with an applied voltage. The coating drops out of solution on the surface to be coated. The bond is normally at the metal crystal and/or surface irregularity level. Normally used where the required coating thickness is measured in parts of a thousandth of an inch to 0.002". Heavier coatings can be obtained at longer bath dwell times but thick (.005 and up) single coat electroplate of _any_ metal has a tendency to bond failure and will often chip off during localized impact. Coating will preferentially be deposited on sharp outside corners and be thinner in valleys. This may be a problem at tank necks. The process is relatively cold and does not limit heat treatment choices. Coating variables include bath chemical concentrations, dwell time, current density per square inch, temperature, and driving voltage.

+Well understood and developed technology.
+(For manufacturer) Easy to maintain constant coating thickness with minimal material usage.
+Can be set up as part of a production line with limited impact to start and end of day work in progress.
+No constraints on heat treatment/wider material selection.
-More variables and relatively narrower acceptable bandwidth for quality control purposes. Monitoring equipment is more maintenance sensitive than that needed for HD.
-Chemical baths often require treatment as hazardous waste during disposal driving up costs.
-Coating can have unbonded areas not immediately visible on inspection and pinholes do not normally self heal as rapidly as HD, if at all.
-Chemical baths require a similar level of US OSHA and EPA safety hardware and pollution control as HD.

3. Impact coating.
This process involves placing zinc (or other metal powder) in a tumbler along with the parts to be coated and an appropriate transfer medium (ceramic chips, steel balls, etc.) if required and running the tumbler for several minutes up to several hours or days. The coating is applied in a _very_ thin coat by being cold welded to the object by repeated impacts as the parts and transfer media roll around inside the tumbler drum. This process can also provide a limited deburring action. Often used with nuts, bolts and other small solid parts.

+Minimal material usage as unapplied powder and transfer media can be reused batch to batch.
+Minimal energy consumption.
+Time and transfer media wear are the only variables not totally controlled up front. Effectively no problem for quality control.
-Only relatively thin coatings <~0.0005" can be applied.
-Applicable to batch processing only.
-Difficult with scuba tank sized objects.


4. Flame spray or metal spray process:
The fourth type of coating is relatively rare in production but has gained widespread use in the maintenance industry for building up worn shafts at seal and bearing points and applying expensive protective coatings or hard surfacing at known wear points on otherwise lower cost items. Shafts and electrical contacts are two applications that come immediately to mind. I see no reason why a scuba cylinder _couldn't_ be coated this way, and a couple of reasons why it would appeal to the manufacturer. As far as the process path goes normally the material to be coated is mechanically cleaned to near bare metal at the start of the process. The process itself involves an oxy-acetylene, oxy-hydrogen, or other high temp torch impacting the surface to be plated and adjusted to provide a slightly reducing (oxygen starved) flame. The metal to be plated onto the surface is powdered and introduced into the base of this flame. Any surface oxidation on the part is removed by reducing any metal oxides on the surface back into the parent metal as the excess fuel in the torch consumes the oxygen from the metal oxides. It's possible to melt or soften the very surface of most metals without transferring much heat to the core of the product by controlling the torch temperature, flame velocity, and time the flame is in contact with any spot on the object to be coated. The coating metal powder is melted by the torch between the introduction point and when it contacts the softened or melted surface of the object and forms a good atomic level bond with it. Coating thickness is controlled by the speed of the torch, amount of powdered metal introduced, and torch path. Thickness can be as low as tenths of a mil (0.0001") up to several inches depending on the material deposited and number of passes involved. The variables in a production operation would normally be tracked by automated machinery and include powder particle size, fuel/O2 mix ratios, flame velocity, distance to surface being coated, powder feed rate, object temperature and cooling, etc. An example of an uncontrolled variable would be any transient jamming in the powder feed tubing. Provided the quality control is tight enough, and the coating is thick enough, a metal-sprayed zinc coating should be about the same as a hot dipped coating galvanized one. The greater number of critical variables in the process and the natural stinginess of production foremen (must minimize costs you know) combine to create a greater potential for coating failure in the field than in HD.

++ Good control of coating thickness and thus of costs.
++ Minimal USA OSHA and EPA requirements since molten metals and hazardous chemicals are not obviously involved. Fume collection on a relatively small flame spray booth would be about it. No, or minimal, hazardous waste since unconsumed powder may be reused or sold as a by-product to impact or electro-platers and die casters.
+ Frees up heat treat and material choices since sidewall core temperature can be controlled to _any_ reasonable point. It should be possible to limit wall core temp to less than 400F during the process. This will allow use of almost any High Strength Low Alloy or alloy steel for tank construction from a heat treatment point of view.
-Complicated quality and process controls are required to provide an acceptable product. Process transients can produce thin spots in an otherwise good coating without being immediately obvious.

The last item is the big kicker! Top management commitment to quality control is MANDATORY for this type of coating to be consistent and suitable for repeated immersion in seawater. Thin or spotty coatings on a few tanks will kill their reputation with the tech crowd. From what you said earlier it sounds like this has already happened. The tech crowd also tend to be a vocal lot with well-formed and entrenched opinions and tend to pass these on to others not of the tech persuasion. Considering that the techies are often opinion leaders in this game it sounds like OMS may have stepped in it big time!

IMNSHO If OMS has developed this reputation the only saving grace it has open to it would be to match Luxfer's neck crack tank replacement policy with their coatings. As it was explained to me if any Luxfer tank fails a VIP due to neck cracks they will replace it, period. No limitation on number of owners or age of the tank. Ship it to them with the PSI inspector’s paperwork and they'll ship back a new tank! If OMS
unconditionally stood by their coatings to the same extent no diver would think twice about buying one. If he got a bad one it would be replaced with a new one. No (hard) questions asked. No proof of purchase or other legal nastiness required. For the price of the postage to get the tank back to them with a VIP inspection report a new one would appear at your door in less than a month!

FT

BTW Not having ever personally dealt with them I have no idea what their warranty currently is.

FredT
September 16th, 2002, 02:06 PM
Have them bead or otherwise externally abrasive blasted in the boot area. Rust fluffs way up when it forms so it may look worse than it really is. The actual pits may be small enough to pass a visual. If so quickly recoat the white metal tank with ZRC.

Not having seen your tanks it may be a long shot, but I have often rehabbed tanks with boot corrosion damage that way. At the very least it won't hurt a garden gong to be cleaned up a bit. Expect the effort to take about 10 minutes a tank to blast, and another few $s for another vip by a PSI inspector. ZRC is about $50 a gallon, which should do several tanks. Given the $s involved in getting new tanks a few $s risked to try and rehab those may be money well spent. Alternately a $10 syphon hose blaster, a bit of beach sand, and a bottle of air routed through your first stage will be enough to do a spot test to see if it's worth pursuing.

BTW if going the ZRC route clean the ENTIRE tank exterior to bare metal and recoat completely. You already know the coating it has is not suitable for what you want it to do, so you might as well replace it with a good one.

FT

Stoo
September 16th, 2002, 03:44 PM
FredT:

Thanks for the insites. I agree that the tank would still pass a visual... for now. I am not familiar with ZRC. Is it a paint of some sort? I am up in Canada, so the stuff might not be available here.

Your comments about the company's commitment is "right on" as well. If they would even have the courtesy to respond, it would go a long way. I've been diving for almost 30 years and have a basement full of highly "experienced" tanks... all of which are quite useable (the joy of fresh water!)... except this one.

S

FredT
September 16th, 2002, 03:56 PM
See :

http://www.zrcworldwide.com/galds.htm

As far as I know it's available almost everywhere, at least in "English" speaking countries.

Surf about on the site for other good info. I've used the stuff for over 20 years. Works GOOOOD where a dip galv can't be done, or to touch up damaged dip galvanizing.

FT

Ray2
September 16th, 2002, 03:58 PM
I've got the same problem with my OMS 85 well maybe .The paint is bubbling up but when I chip this area out to look at it there is no sign of corrosion underneath.Mfg'd in 10-97.Rust does form very quickly on any spot that bare metal exposed and the bubbling seems to be concentrated in the boot area so I check after every dive,salt water only.My PST 95,made in 77 holds up great under the same conditions though.PST may be the way to go.
Ray

Stoo
September 16th, 2002, 04:03 PM
Thanks Fred...

Most of us speak English up here... except our Prime Minister Cretien... he doesn't actually speak either of our "official" languages!

S

Goldminer
September 16th, 2002, 04:04 PM
Stoo once bubbled...
I know that boots aren't generally a great idea, but I dive from a small boat with fiberglass deck, and I want the boot to protect the boat...

I'd be interested in hearing from others who have had similar problems...

Stoo

This winter I was researching a tank purchase and was considering OMS/Faber tanks. I sent them an e-mail asking about corrosion protection and this is how they responded:

>It is an automotive-type paint called "IMRON." It is applied in
>a cold-spray galvanized method.
>The boots do have a drainage hole, however it is recommended
>that you wash off your cylinders after each dive. The warranty
>does not cover corrosion under the boot. That is the diver's
>responsibility.
>
>Safe Diving
>
>>-----Original Message-----
>>From: ----- --------- [mailto:---------_-@hotmail.com]
>>Sent: Sunday, January 06, 2002 8:31 PM
>>To: Info@OMSdive.com
>>Subject: Request for Product Info
>>
>>
>>Dear sirs:
>>
>>I am looking to purchase a couple of scuba tanks and have
>>visited your web site. I saw the following desription of your
>>cylinders: Corrosion Protection (External): Galvanize & Paint
>>
>>I have some questions. Is this hot dip galvanizing,
>>electroplate or some other method? Also are the boots on
>>your cylinders drained to help prevent corrosion?
>>
>>Thank you
>>
>>----- ---------

No matter how well you look after the tank they don't warrant "under the boot". I came to the conclusion that they don't warrant their product adequately and bought PST.

Stoo
September 16th, 2002, 04:26 PM
Goldminer once bubbled...
I came to the conclusion that they don't warrant their product adequately and bought PST.
OMS' website:

"Warranty

OMS Inc. at its sole discretion will repair or replace Ocean Management Scuba Cylinders, proved to have a manufacturing defect, with a service and handling fee of $30.00 per cylinder for a period of up to 180 days from the date of purchase.

This warranty specifically excludes all warranty claims resulting from abuse, misuse, and neglect including but not limited to internal corrosion, impact and abrasion damage, corrosion determined to be caused by failure to remove the boot..."

I don't remember anything like that coming with the tank... even if I had, I would have ignored it, since the tank is only used in fresh water.

What surprised me was the amount of water trapped by the boot on the 96 as well as the 46.

I've been at this for 30 years and have a bunch of old tanks kicking around... all of which are fine. Never removed the boots on any of them.

I recognize that this is beyond their normal warranty terms, and as such I don't really expect them to replace the tank... perhaps some assistance with refinishing would be nice... Hell, I'd be happy if they would just answer my email!


S

Stoo
September 17th, 2002, 04:28 PM
Stoo once bubbled...
Hell, I'd be happy if they would just answer my email!
Still waiting...

Rick Murchison
September 17th, 2002, 05:17 PM
I found some rust under the paint on the bottom of one of my OMS 85's. Made the decision to strip 'em and repaint with clear epoxy so I coiuld see the metal and never again get surprized with rust. I'll say this for the paint - it's tough to get off - regular commercial strippers were marginally effective, and it took a hell of a lot of elbow grease to finally get all the paint and primer off. But now they're repainted with the clear epoxy and I can inspect under the paint visually - haven't had any more rust since repainting, either.
I did a precautionary hydro (2 years early) after stripping 'em, by the way.
Rick

Stoo
September 17th, 2002, 05:21 PM
It sounds like sand blasting would be the way to go. I'm not sure it'll be worth the effort. Pay for blasting. Buy the goop. I can generally get stuff from my LDS at cost... might just get a nice new tank... not OMS this time!

S

pescador775
September 24th, 2002, 05:06 PM
The only way to deal with this junk is to sand blast and metallize the tank. "Metallizing" is a Zinc spray (flame spray) that is almost as tough as hot dip. Paint sticks to its porous surface really well. The paint that was mentioned, ZRC or something, is a zinc paint and is the best choice for finish coat. Double zinc so to speak. Years ago, when OMS first came on the scene I gave them a call. My impression was that they were dodgy and arrogant. I have never owned one of their overpriced tanks. If I want a Faber tank I buy one with the Faber name.

GP
September 24th, 2002, 05:12 PM
Anyone know approximately how much it costs to have a tank repainted? I have a couple OMS/Faber 85's and I'm just curious. One of them needs a hydro next April and both could stand a new paint job. Just wondering if it's worth it and where the best place to have it done is.

Rick Murchison
September 24th, 2002, 05:28 PM
GP once bubbled...
Anyone know approximately how much it costs to have a tank repainted? I have a couple OMS/Faber 85's and I'm just curious. One of them needs a hydro next April and both could stand a new paint job. Just wondering if it's worth it and where the best place to have it done is.
Having stripped and painted two myself last year, I'd charge more than they're worth to do it again! I'm sure a paint & body shop could strip 'em easily and cheaply for you - just make sure everything's "cold" process and non ablative for the metal itself. And get a hydro after you're done, regardless how long the current one's good for.
Rick

FredT
September 24th, 2002, 05:45 PM
pescador775 once bubbled...
The only way to deal with this junk is to sand blast and metallize the tank. "Metallizing" is a Zinc spray (flame spray) that is almost as tough as hot dip.

Check with DOT before flame spray. ANY application of heat to a tank after manufacturer's hydro voids the roll mark and condems the tank. Flame spray bay be an allowed exception, but given their normally anal attitude I doubt it.

FT

pescador775
September 25th, 2002, 02:44 PM
For Pete's sake, give it a rest. Asahi and Faber metallize their tanks at the factory. I personally own 6 tanks that were treated with this method. I know that San Diego Sandblasting has flame sprayed hundreds of SCUBA cylinders. Many CA divers treasured their twin 38's and would have them metallized after the hot dip galvo or OD paint began to bleed. A number of divers made doubles or triples from Navy 40 cf life raft bottles. The hot setup included metallizing.

Imron is good for cars and boats. On tanks it's a joke.

FredT
September 26th, 2002, 02:09 AM
pescador775 once bubbled...
For Pete's sake, give it a rest. Asahi and Faber metallize their tanks at the factory. I personally own 6 tanks that were treated with this method. I know that San Diego Sandblasting has flame sprayed hundreds of SCUBA cylinders. Many CA divers treasured their twin 38's and would have them metallized after the hot dip galvo or OD paint began to bleed. A number of divers made doubles or triples from Navy 40 cf life raft bottles. The hot setup included metallizing.


Metalizing at the factory is done pre-hydro certification and part of the TESTED production process. The "no evidence of external heat" rule is CGA adoped by DOT to prohibit ANY heat damaged tanks from being used. Even a scorched paint spot or a single small arc start mark on a bottle condems it! On most SCUBA tanks I'd not have a problem with the metalizing process, but DOT has known to be a bit wierd on this subject in the past so I suggested you check it out before risking a tank. IF metalizing is going to void the tank down the road, I'd rather just do the cold galv trick.


pescador775 once bubbled...
Imron is good for cars and boats. On tanks it's a joke.

Agree 100%

FT

DocRCH
September 26th, 2002, 05:45 PM
I have a couple of dbl 98s and one set has the rust problem. I wrote OMS and did not hear from them. I also have a couple of 131s and do not see any rust (yet). I understand that both the Scubapro tanks and OMS are made by Faber and the OMS 98 and SP 95 are the same tank. Next time PST.

Robert:doctor:

pescador775
September 29th, 2002, 02:46 PM
Faber tanks are high quality and over spec'd for their pressure ratings. However, there are differences depending on the vendor. The generic Faber tanks are 'flame sprayed' with zinc and painted with urethane. They should hold up rather well. The OMS version of this tank is treated differently, probably for marketing differentiation reasons and cost. Correct this if wrong but I believe that the OMS tanks are primed bare metal and coated with urethane (Imron*). If so, this is hardly better than the US Divers tanks from the late 60's which were painted yellow over bare metal and which totally rusted away in a few years when used in salt water.

trymixdiver
October 1st, 2002, 06:52 PM
I have OMS 112s and a pair of OMS 46s.

I just had there hydros 6 months ago and had NO problems. When i first got these tanks i looked at the boots that came with them and said "thats a dumb design, theres no drainage on these". I put SP boots on the 112's and took a drill to the boots on the 46's to allow for drainage.

like i said i just had VIPs and Hydros and had no problems. There was a little surface rust, but i sanded those few small areas and repainted them.

i do think the coatings are not up to par, but your problems with the rust under the boots is due partly due to the lack of drainage in the boots.

Andy

GP
October 1st, 2002, 07:24 PM
I noticed that one of my OMS 85's has some nasty rust on the bottom boot area. The paint just flaked off over a 2 x 2 inch section. The rest of the tank is fine. Any suggestions on how I can fix this? Do I just sand it down by hand and then repaint the bad spot?

Bill Walton
October 3rd, 2002, 01:58 AM
I have several OMs tanks that I dive as singles. I went and removed all the boots and was inspecting. The boots on all the tanks except one are the same. They are the smooth rubber on the inside w/o any channel to allow evaporation and drainage. There is a hole but no way for water to escape to the hole.

Now, I look at the boot on my newer 112 (bought it this summer, orig hydro is 06/02) which I had not like all that much as it moves around more than the others which has always bugged me until now. It has raised ribs that allow water to drain down to the hole and has a thin gap allowing air to circulate up and evaporate water. It is easy to remove as well.

I love these tanks but just recently got a PST lp 120 and have to admit I like the coating much more than the oms. This is diheartening for me as I am getting ready to assemble my first set of doubles and had planned on doubling the 112 and just buying another single tank. I like the pst 104 but that would call for another two tanks. I already have two 98's I could band together, but am afraid it would be too short--I am 6'1".

pescador775
October 3rd, 2002, 01:30 PM
Let's see, you are afraid to band together two humungous 98 cf lp tanks because they are too SHORT?? You are 6'1". Unless your legs are only a foot long don't worry about it. You've been reading too much stuff from U.Pug.

TheAce
December 20th, 2002, 08:54 PM
I just bought a Faber 15liter 16.2kg 200bar mfg date 02/2000 second hand in EXCELLENT condition.

I understand that these tanks suffer from rust problems especially in the boot area.

My tank has a net and a boot. One of those tight fitting boots with a small round hole in the bottom.

In the store, the seller recomended me to keep the net OUT of the boot as he says he has seen bad cases of rust caused by the net. So bad that it makes it difficult to remove the net because of so much rust. Looks bad, but I did what he said.

He also applied greese to the bottom of the tank and recomended me to remove the boot once every 3 months or so.

I wanted to add a folding handle to the tank but again, he said that it'll only create one more place that can rust and recomended not to install one.

I think I might change the boot. Any recomendations on which boot to buy? Can you point me to a place on the net to buy it from?

Any tips on how to minimize the risk of the tank rusting? Care and maintenance tips?

And last, do you know this tank? opinions?

Thanks!

Dryglove
December 20th, 2002, 09:00 PM
TheAce once bubbled...
I just bought a Faber 15liter 16.2kg 200bar mfg date 02/2000 second hand in EXCELLENT condition.

I understand that these tanks suffer from rust problems especially in the boot area.

My tank has a net and a boot. One of those tight fitting boots with a small round hole in the bottom.

In the store, the seller recomended me to keep the net OUT of the boot as he says he has seen bad cases of rust caused by the net. So bad that it makes it difficult to remove the net because of so much rust. Looks bad, but I did what he said.

He also applied greese to the bottom of the tank and recomended me to remove the boot once every 3 months or so.

I wanted to add a folding handle to the tank but again, he said that it'll only create one more place that can rust and recomended not to install one.

I think I might change the boot. Any recomendations on which boot to buy? Can you point me to a place on the net to buy it from?

Any tips on how to minimize the risk of the tank rusting? Care and maintenance tips?

And last, do you know this tank? opinions?

Thanks!

The boots come off fairly easily on my faber LP95 tanks.After my diving day or weekend is done i just pull the boot, rinse everything really good in fresh water and dry it off.I then spray a little wd-40 on the boot and tank and slip it back on.I dont normally use the boots on my bp as it interferes with the bp anyhow but do put them on when storing my tanks so i can stand them up in the corner

Ari
December 21st, 2002, 03:53 AM
I think that the idea of using the boot only for storage makes a lot of sense. It does make gearing up a bit more complicated but will surely solve the problem of water trapping.

Draining the boot will, naturally, won't be sufficient, as the edge that causes the rust can not be drained.

I Agree with lal7176 that you must take off the boot after the dive, rinse and let it dry.

Ari :)

Alban
December 23rd, 2002, 10:59 AM
Hi Ace

The handles on tanks can sometimes trap your fingers also check that your first stage doesn't foul it I have seen this with swivel turrets inverted . As has already been said the cylinder needs to be maintained the same as all your equipment , boot off and dunked in fresh water , the netting offers a small amount of abrasion protection but keep an eye on trapping small stones under it . I am not sure on the regs in Iarael but it should be ok to apply a zinc rich paint to the boot area the same to any small chips or scratches clean them and touch up . The steel cylinder has a zinc sacrificial coating which will degrade rarther than the steel this has a paint finish over the top so just give it a visual when washing . As to which boot I would think they are all more or less the same they let the tank stand up and should have drain holes , it's more about taking it off .

Yours Alban :)

ScubaJorgen
January 25th, 2003, 06:59 AM
I've got a Faber tank (200 bar, 15.5 kg, steel, type not known). Dated 1994. Last year I checked underneath the boot. You really get your eyes wet when you see it. ;-0 All rusty. Paint chipped of.


It now appears a pain in the ass. I removed all paint from the bottom of the tank, grinded of the rust and applied paint: a primer and a finishing paint. Just ordinary paint. Was not a solution: paint stays soft underneath the boot and starts blistering immediately.

I removed the paint and applied car paint (acryl). Same problem. I'm wondering what to do next..... :confused:

Anyway, thanx for the advise. Bit late for me though :(

AzAtty
January 25th, 2003, 12:30 PM
For what it's worth, Faber tanks use a "spray coating" galvanizing process. Cold spray galvanizing doesn't protect steel as well as a "hot dip" process. So Faber tanks are a bit more susceptible to seawater corrosion than hot dipped tanks.

For those who don't understand what galvanizing is, zinc, which is highly resistant to corrosion, is electrochemically bonded to the steel tank. The zinc "layer" varies in thickness, depending on the application and the manufacturer's specification, and the thickness of the zinc layer determines the service life of the equipment. For instance, a 5 micron zinc layer gives the galvanized item a service life of approximately 100 years; "service life" being defined as the time to a five percent rusting of the steel surface.

If the tank has already begun rusting, the damage is already done. Merely grinding off the rust and painting the tank won't solve the problem. Indeed, taking a grinder to the tank guarantees that you'll cause further damage to the zinc layer. You're also scraping off layers of steel, which I don't think is such a great idea for a high pressure cylinder.

Applying primer and a paint coat on the metal will not adequately protect the tank, even if you could get the paint to adhere. The other problem is that metal oxidization occurs on a microscopic level, and removing the visible rust does not guarantee that you've eliminated the oxidization problem. Slapping a coat of paint on the cylinder may actually hide a portion of the tank where oxidization is continuing.

If you really want to fix the problem, I would suggest that you check around for companies that provide post-fabrication galvanizing and talk to them about how to clean the tank and reapply the zinc.

Rick Murchison
January 25th, 2003, 01:09 PM
First, I tried the boot-on, boot-off management scenario, but eventually just gave up and now have a wooden rack to stand the tanks in for storage - the boots... are gone.
I ended up stripping my Fabers (OMS's) completely (this is a major job as the paint they use is really hard to get off when it isn't peeling on its own), and repainting with clear epoxy. Now, if any rust starts I can see it immediately and take action.
Rick

MechDiver
January 25th, 2003, 01:39 PM
Rick Murchison once bubbled...
First, I tried the boot-on, boot-off management scenario, but eventually just gave up and now have a wooden rack to stand the tanks in for storage - the boots... are gone.
I ended up stripping my Fabers (OMS's) completely (this is a major job as the paint they use is really hard to get off when it isn't peeling on its own), and repainting with clear epoxy. Now, if any rust starts I can see it immediately and take action.
Rick

Rick,

Could you post details of what you did and products used? Or PM me with info please.

MD

DocRCH
January 25th, 2003, 06:10 PM
I have not seen where "hot dip" is better than being sprayed. I have seen where the heat of a hot dip may be bad for the steel in terms of its strength. When a metal is made, there are grains in it. Heating a metal such as steel can disrupt these grains change its physical properties.

The problem with scuba tanks is wear against something else. The steel is coated with an organic substance (e.g. epoxy, urethane). Any of these can be worn off. Also, the gaivinizing can be worn off also. Nothing is impervious to wear.

As far as putting something over the damaged areas, look at www.zrcworldwide.com. They have a number of products like www.zrcworldwide.com/galds.htm

Hope this helps, Robert :doctor:

Rick Murchison
January 26th, 2003, 12:42 AM
MechDiver once bubbled...


Rick,

Could you post details of what you did and products used? Or PM me with info please.

MD
Well, when I discovered rust hidden under the paint I decided to strip the tanks - had I known then what I know now I don't know whether I would do it again... what I thought was going to take about two hours took nearly two weeks of meticulous work in my spare time getting off all the paint without damaging the zinc underneath. I used a commercial paint stripper, which had barely enough effect to soften the paint to the point where I could scrape it off a tiny strip at the time with a heavy duty razorblade. I came behind that with some light sanding (zinc is soft and you don't want to remove that - just the paint) and finsihed cleaning with a rotary wire brush. Once cleaned I had 'em hydro'd as a precaution to make sure that (1) the little bit of rust I'd removed was in fact a "little bit" and didn't affect the tank's structural integrity and (2) to make sure I hadn't hurt 'em during the stripping process.
After I got them back from hydro I gave 'em another bath with a mild vinegar solution, rinse with distilled water & dried, then painted with clear epoxy - the old fashioned kind that you mix the hardener in and paint quick before it sets. (to paint them I put some old out-of-service valves in 'em and hung 'em up by those).
Worked out great - I can now see the surface of the tanks through the epoxy, and since it is epoxy it's super easy to fix any dings. So far this coating has been totally successful at preventing any further rust - I've been diving 'em about 14 months since I did it.
Rick

ScubaJorgen
January 26th, 2003, 11:48 AM
Zinc painting
This weekend I asked a local paint specialist. He could sell me zinc paint, though he really advised to sand blast the metal first. That is usually the procedure for applying zinc paint. Just grinding and zinc painting is not sufficient, leaves rust underneath. :hour: Fred, are you still attending this thread?

Epoxy
He advised an expoxy. Paint is micro porous. No protection for rust. Epoxy is not porous.

Since I am not able to sand blast, I am going to paint my tank with epoxy. I'v removed the original paint and rust from underneath the boot by grinding. I grinded the remaining original paint. It is really stuck very well (does not come off), so I leave it there (saves me the Rick-labour :D ) Since I am usually diving in fresh water I hope this is sufficient.

Grinding tanks
I do not think grinding the tank is much an compromis to safety: before you've grinded off one micron of steel, your elbows are worn off. I think recent tanks are thicker than, say, 10-20 years ago (according to the weight difference between my old and my new 12 l tank). My old tank still passes the hydro's. So I think recent tanks are well over-dimensioned. :bonk: Any comments to this statement?

Zinc and tanks
I wondered if my Faber tank was galvanised. As AzAtty bubbled, zinc works electrochemical. The zinc corrodes (redox reaction), the surrounding steel does not. On ships they mount pieces of zinc at regular intervals on the hull. The intervals are larger than a tanks length. Zinc being present prevents steel from corroding. I would expect my tank not to corrode if there was any zinc left on it. :idea: Maybe I should mount a piece of zinc nearby the valve, making good electrical contact to the bare metal of the valve.....

akforsyth
February 28th, 2003, 05:30 PM
Anyone done this before? Have any tips/tricks? Thinking about painting a couple of steels...Make them look purdy again...

Aquamaniac
February 28th, 2003, 05:31 PM
They look a whole lot "purdier" in a dull galv coat.

Paint is for cars.

cudachaser
February 28th, 2003, 06:11 PM
Around 20 years someone here in Florida got the idea to paint tanks with exotic designs and colors...and market his product!

His process included baking the enamal at 350d much like you do when repainting a car. This heating altered the characteristics of the Aluminum significantly. The tanks would rupture during filling. I recall there were deaths.

Many dive shops recall this incident and will probably not fill your tanks if you paint them

Bob3
February 28th, 2003, 06:56 PM
Nice shiny new looking stuff makes ya look like a newbie, I'd just roll 'em around in a gravel parking lot to even out the scratches.
:tease:

akforsyth
February 28th, 2003, 08:15 PM
OK, so I take it most people do not like shiney toys here... How about glass beading a tank. Seen this done before on a steel and it looked really neet. Kinda like the hazy finish the oceanic regulators come with. Anyone do that before?

FredT
February 28th, 2003, 09:42 PM
akforsyth once bubbled...
OK, so I take it most people do not like shiney toys here... How about glass beading a tank. Seen this done before on a steel and it looked really neet. Kinda like the hazy finish the oceanic regulators come with. Anyone do that before?

If the tanks are galvanized under a surface coat almost anything abrasive can wear away the zinc coating before you can stop it. If you intend to blast them you'd do best with an organic abrasive like ground walnut or pecan shells. Glass beads will work, but be QUICK aobut it and don't dwell on any one place very long.

My preferred treatment is just stripping any paint off the galvanizing chemically and then touching up the tank galvanizing with ZRC.

FT

Aquamaniac
March 1st, 2003, 12:29 AM
Peel all the stickers off, Stencil your name on the side, and dive it.
The tank is there to hold gas, nothing else, what does the appearance do? NOTHING!!!!!!!

Bob3
March 1st, 2003, 02:49 AM
I was just yanking your chain, haven't used up my wise@zz quota for the day. :tease:
I've done steel tanks, non-galvanized, with plain old rustoleum appliance white in the spray can. I prefer the zinc chromate for a primer 'cuz the oxide primer makes too thick of a coat.

bobafett21
March 1st, 2003, 10:48 AM
Almost all of the tanks sold by my LDS are painted either yellow or black. Is there anything significant about the way the vendors are painting these tanks?

akforsyth
March 1st, 2003, 12:06 PM
Thanks everyone for the responses...even the smart@zz ones. Why I was wondering is because of a tank with a pretty good gouge out of it, but still passes the tests. I was concerned about oxidation from the outside. Is this a valid concern, or just plain old nothing? TIA

FredT
March 1st, 2003, 12:32 PM
akforsyth once bubbled...
Why I was wondering is because of a tank with a pretty good gouge out of it, but still passes the tests. I was concerned about oxidation from the outside. Is this a valid concern, or just plain old nothing? TIA

If the metal at the bottom of gouge is turning brown, it's a serious problem! If so, then strip at least the rusting area and a coule inches around it, wash it with phosphoric acid, and cold galvanize the gouge.

Steels are hard to hurt if galvanized, but the painted only bottles are simply a recoat job waiting to happen.

FT

sailnj
March 2nd, 2003, 09:08 PM
I'd paint them bright yellow so if you die it will be easier to find the corpse.

No really, I don't think there is anything wrong with painting the tanks if you feel like it and have some time and money to burn. If so use a one or two part polyurethane paint. You can get this stuff from your local paint store usually (it's used mostly for commercial and industrial work) or at a boat store like West Marine . They sell quarts of Interlux two part stuff which will work good and is pretty indestructable. It also dries to a perfect gloss if applied right, which shouldn't be a problem on a little tank.

One thing - don't spray it - DEADLY in that form.:boozer:

fgray1
June 9th, 2003, 07:38 AM
I just bought a set of doubles, OMS 112 when I got home I noticed that the covering on the tank at the bottom was chipping and under it was a little rust not alot just some suface rust.
I scrapped the loose coating off cause I figured that was better than leaving a place for water to collect and rust the tank even more. I removed the rust with a wire brush and sanded the bottom by hand with a vibrating sander. My question is. Should I get the tanks hydro redone, It's not due for another 4 years.
I would like to protect the surface again. But don't know what I should use. I don't want to end up with the same thing happening again. I know your not surpose to bake the cylinders cause that will weaken the metal. I will be using these tanks as singles with boots on them so they should'nt get scrapped and chipped again on the bottom.

totterfield
August 19th, 2003, 12:02 PM
Hi, i`ve recently bought a 15ltr cylinder, hasd 4 years of test left on it which is great, but it does have some rust on it, what would be the best thing to do with the rust, i wan`t to kind of get rid of it. i`ve been advised to to use a use a wire brush to get rid of the rust in a small section, then use some sort of silver pen to protect the metal, what sort of pen, where do i get them???

The larger biuts of rust i`ve been advised to use the wire brush again, then use an emulsion paint over the metal as an under coat, then gloss over that. the worst of the rust is in the boot location. what does this sound like??? any better ideas or tips that i could usae would be greatfully recieved, thanks Tom

fgray1
August 19th, 2003, 03:30 PM
I just had the same problem and this is how I solved the problem
I removed the rust with a wire brush. and sanded it by hand with 400 grit wet sand paper. went to the local auto parts store bought plasti coat auto paint. Not enamal paint (oil base)
This is the paint they use to match the factory paint on the cars.
choose a color that comes as close to the tank color as possible.
I did about 7 coats of primer wet sanding betwwen each coat letting each coat dry completely before the next coat is added. Most IMPORTANT is all the rust must be gone. If not you will have a problem later. After the primer has dried completely I did about 7 coats of the main color also wet sanding between each coat so as to get good adheartion to the previous coat. When your all done painting let it set in a warm place for at least a week to dry completely. After that you can put the boot back on and if you did it right have no more problems. If you get nervous you can have the tanks Hydroed again. Thats what I did. But the bottom of the tanks are the thickest part of the tank. As long as you only wet sand and wire brush the tank and there are no deep pits you should be fine. DO NOT USE ANY POWER TOOLS ON THE TANK. NO GRINDERS OR POWER SANDERS.
Remeber always remove the boot after diving and rinse and dry the tank before storing it. Leave the boot off if possible till the next time you go diving. The rust was caused because the boot was not removed.

mrducks
August 19th, 2003, 08:54 PM
are u diving in fresh or salt water with your home paint job?

totterfield
August 20th, 2003, 04:07 AM
I just had the same problem and this is how I solved the problem


How long ago did you make this repair job??? and it`s worked fine you say.
After you`ve used the wire bruch and wet sanded it, would you use like a rust killer to make sure or is this not nessesary?? cheers again
Tom

fgray1
August 20th, 2003, 07:25 AM
I did the repair June 03 I dove salt and fresh water with them.
I've had no problems but I remove the boots and dry the tanks now. The paint from the Auto parts store is poly coat mixture if I'm not mistaken. Make sure all the rust is gone before you start painting. It took me about 2 weeks to do the job right waiting for the coats of paint to dry completely before the next coat was added. Total cost of the job was about $20 for paint and sand paper . Then just for peice of mind I had the tanks hydroed again and they passed with flying colors. These were my first tanks I did so I did alot of research before attempting it. I first tryed enamel paint but it never got hard or dried competely. In the sun it would soften up from the heat so I figured that would be a problem. I redid them this way after more research. I did read were someone used epoxy based paint (appliance paint) and had no problem with that. I decided for the poly based paint because it's what used on cars and I had more color choices. The best thing I can tell you is do alot of research and make up your own mind as to what makes sense to you. You can tell hows full of it when you read the post.

fgray1
August 20th, 2003, 07:32 AM
I did'nt answer about the rust killer.
I did the firt try with enamal paint but I thought about it and changed my mind after I remove the enamal paint and redid them with poly. I decicded that if I used the rust killer again I maybe might get lazy and not remove all the rust and I was worried about the paint sticking to the rust killer so I just made sure I removed all the rust and started with a nice clean surface. I figured if It chips or I scratch it it's an easy repair as well this way.

FredT
August 21st, 2003, 07:46 AM
Instructions are here:

http://www.scubaboard.com/t34414/s.html

FT

northcoastdiver
September 5th, 2003, 07:45 PM
I'm in the process of removing the paint from my old steel 72. The paint is coming off good, however a grey coating is also starting to come off. Is this the galvanized coating, or could it just be a grey primer or something like that? I'm not using any abrasives, just an aircraft grade paint remover.

Rick Murchison
September 5th, 2003, 08:05 PM
I don't know about every zinc application process, but hot dipping isn't susceptable to removal with paint stripper. It's probably a primer.
Still, I'd keep a mighty close eye on it for rust.
Rick

northcoastdiver
September 5th, 2003, 11:16 PM
You were right, it was primer. I thought I was going to get off easy with this one, because the paint came right off. But now the primer is coming off VERY slowly with the stripper. I haven't tried using a wire brush or anything else, I guess I'm too worried about taking too much off. There's a pretty good galvanized coating underneath, and I don't want to mess it up. I wish whoever painted it in the first place would have left it alone.

gto1
February 1st, 2004, 12:14 PM
PUWDER COATING steel tanks any thoughts?

Druid
February 1st, 2004, 06:57 PM
PUWDER COATING steel tanks any thoughts?


Don't do it.

The heat needed to powder coat a metal object will anneal the steel and soften it - not a property you want in a compressed air cylinder.

FredT
February 1st, 2004, 08:14 PM
While I doubt the heat (generally 300-400°F for most polymers) applied would damage the steel druid's correct. ANY tank exposed to heat is DOA as far as the US DOT is concerned.

That same temp will permanetly kill the metal strength of an Aluminum bottle.

FT

D-Diver
May 7th, 2004, 01:36 PM
Hi Guys,
OK, 1 more time here..;) I bought a new pst E-7 and my local bodyman told me that as on newer cars the body panels
are hot dipped galvanized andproper cleaning and epoxy primer is all thats really necessary to paint the tank especially as it is new. No heat will be used.

I want paint!!! Unless of course there is a downside other
than I'll look like a newbie which I am. Can anyone ( especially the old salts...much respect here) give me a valid reason why I shouldn't do it? I've read the threads about
refinishing rusted tanks and looking like a newbie but somehow I've missed a single reason not to have the tank
properly painted!!! Or should I just try to get enough bottom time in that sponges and anemones start growing on it.... :eyebrow: and I can pass 4 a hermit crab?

I plan on removing the boot regularly and paying close attention to the condition of the paint, and after paying over 2 grand in gear whats another 30 4 a hydro......So please help me out here with something other than the worn seasoned look is the way to go line. I wore starched utilities as a former US Marine 2....lol!!!
Thanks guys!!!!!!
D-Diver...Newbie OW

captain
May 7th, 2004, 07:47 PM
Down side is that it will get scratched up no mater how careful you are. To me a scratched up paint job looks worse than the galvanize and adds no protection to the tank.

Captain

Fireboat57
May 8th, 2004, 01:22 PM
D-Diver: you wanted a good reason to not paint your PST E-7's --- I wrote to PST and here is what they said:


Subject: Painting Steel scuba cylinders

I just purchased a couple of PST scuba cylinders and want to know what your stand is on painting them. I figure that since you built them you would be the ones to ask the question of.


Thanks - Toby

Original Message-----
From: Thomas Ivey/PST Scuba [mailto:t.ivey@verizon.net]
Sent: 30 January, 2004 8:55
Subject: RE: Painting Steel scuba cylinders



Painting will only cause you problems, our product is designed with a zinc coating only.



Best regards,

T.Ivey
Scuba Product Manager
E-mail: tivey@pressedsteel.com
Web:pstscuba.com

jgarysmith
July 17th, 2004, 02:26 PM
Can you paint PST E series tanks. I know most serious divers love the dull gray finish they become, but I don't. Personally I like the finish of OMS Painted tanks. I just want Prefer the smaller HP size. Anybody done this or know about painting them. How hard is it? Thanks :dazzler1:

SDAnderson
July 17th, 2004, 03:08 PM
Hot dip galvanized surfaces which are intended to be the final finish (i.e., Pressed Steel Tanks) have a treatment which paint does not very well adhere to. Google "painting galvanized surfaces" for about a million relevant hits.

It's not that people necessarily love the matte galvanized finish, however in the battle between form and function, many will choose the latter. There isn't much of a middle ground, unfortunately.

FrankT
August 13th, 2004, 08:22 PM
What stripper would be safe to use on a PST tank that someone painted a light coat on with a can of spray paint? I tried some MEK on a rag, and it works, but seems like a stripper would be faster and do a better job.

Ben_ca
October 26th, 2005, 08:09 PM
You were right, it was primer. I thought I was going to get off easy with this one, because the paint came right off. But now the primer is coming off VERY slowly with the stripper. I haven't tried using a wire brush or anything else, I guess I'm too worried about taking too much off. There's a pretty good galvanized coating underneath, and I don't want to mess it up. I wish whoever painted it in the first place would have left it alone.

Sorry to revive an old thread but I think I have the same thing as northcoastdiver.

The top orange layer was a rubberized coating that peeled off relatively easily... then there is some white powder corrosion and then seems like another layer... primer maybe? some of it flaked off near the hydro stamp. Could it be a galvanizing coat? The corrosion under the orange rubber paint/covering is white and not rust so that makes me think it's something like that. Besides the parts that have flaked off near the hydro stamp it is pretty much intact so maybe a ZRC touch up?

Thanks in advance,

Ben

http://www.scubaboard.com/gallery/showphoto.php/photo/34188/cat/533

http://www.scubaboard.com/gallery/showphoto.php/photo/34187

http://www.scubaboard.com/gallery/showphoto.php/photo/34186

Can't seem to embed the pictures sorry

FredT
October 26th, 2005, 10:54 PM
That tank is hot dipped, with adhesion failure at the stamp. Wire brush the stamp and ZRC coat the area a couple of times.

FT

Ben_ca
October 26th, 2005, 11:32 PM
That tank is hot dipped, with adhesion failure at the stamp. Wire brush the stamp and ZRC coat the area a couple of times.

FT

Thanks Fred... That's what I thought... I'm supprised to see that the coating is that thick. Should I do it before or after hydro? or does it matter? It's actually cleaning up really nicely... all the white spots are superficial and come off with a little elbow grease

FredT
October 27th, 2005, 09:33 AM
Do it after, that way you protect the "new" stamps as well. Don't forget to "feather" the edges of the failed coating. The failure was probably due to the WAY oversize hydro stamps used, and a bit of excess exuberance on the part of the guy swinging the maul when that hydro was done. I've seen that symptom before.

The white spots don't matter corrosion wise as long as the coating under it is sound.

Ben_ca
October 27th, 2005, 06:55 PM
Do it after, that way you protect the "new" stamps as well. Don't forget to "feather" the edges of the failed coating. The failure was probably due to the WAY oversize hydro stamps used, and a bit of excess exuberance on the part of the guy swinging the maul when that hydro was done. I've seen that symptom before.

The white spots don't matter corrosion wise as long as the coating under it is sound.

The white spots are pretty much gone... came off pretty easily with a wire brush. I'll post some before and after pictures soon.

Anyone in Northern CA with some ZRC to spare?

inletsurf
November 21st, 2005, 04:03 PM
For those who don't understand what galvanizing is, zinc, which is highly resistant to corrosion, is electrochemically bonded to the steel tank.


Zinc is highly susceptible to corrosion and is the reason why it is typically the #1 sacrificial metal used in marine applications. Maybe you ought to do some research? Here's a link which may help you to understand it better.
http://www.corrosionsource.com/handbook/galv_series.htm

Sponsored Link

Search Engine Friendly URLs by vBSEO 3.6.1