Scratched Tanks

Rob H · July 31st, 2006, 10:34 AM

Hi All,

Have just returned from christening a new twinset in Portland. Much to my annoyance and despite padding, the crossbar of the trolley I use to transport the tanks caused the friction marks shown below.

My questions are : should I do something about the scratches (i.e. will they affect the future integrity of the tank at retest?) and if so, what would be the best course of action?

I am based near Cambridge for any practical suggestions regarding cylinder repairs/repaints etc.

Thanks for any advice,

Rob

Chrisch · July 31st, 2006, 10:50 AM

Tanks are pretty tough items. The damage shown should not affect them in terms of testing during the normal lifetime of a steel tank (about 20 years). If you want to apply a little paint to prevent rust that's OK. I've never managed to match colours or finishes so it shows as a repair...

Tanks also get bashed up on wrecks and other normal dive operations..

I guess it depends how much you care about their looks. Not a priority for me.

Chris

**Howard Payne** · July 31st, 2006, 10:57 AM

Doesn't do them any real harm mate -, my new twin 12's are bashed about after only a couple of months. Every scrape tells a story and makes you look dived up!

Rick · July 31st, 2006, 11:13 AM

Lol...I've had a bigger scratch on my erse man!!

You could always see if Phil will replace them for you.....they look condemned to me

Rob H · July 31st, 2006, 11:15 AM

Thanks guys - glad to have some second opinions. Cosmetics are of low importance; as long as the tanks function fine, pass retest and fills are not a problem then I am happy.

Martin Burnard · July 31st, 2006, 11:21 AM

Some of the old cylinders around show just how rough a cylinder can look and still be in service.

They are tough!!

davy · July 31st, 2006, 11:31 AM

If you are worried by that, you better not watch mine, almost no paint left

never a problem, and now on the bottom I also managed to get through the zinc layer about 2 years ago and they are brown of rust now... but it is just superficial and they still passed hydro last month...
It's the inside that really counts and what I want to keep clean.
said cylinders are now 10 and 22 years old...

Don't worry, you'll get plenty of scratches more when you do more boat/cave diving and the scratches just show others how "experienced" you are

lizardland · July 31st, 2006, 11:57 AM

If you have exposed bare metal then there is the chance you can get some pitting. Give it a light sand, cover it with zinc primer and either leave it or put some colour on it.

**Mike Cunningham** · August 18th, 2006, 08:32 PM

Rob,

I think this is the current test spec..... having seen some of the scabby tin foil which does get passed I think that you are ok for at least 10years .....BTW open question is it possible to get tanks powder coated I was thinking black myself...now ducking whilst I get pole axed

Rgds Mike
Visual Inspection (every 2.5 years)
Essentially this test is a detailed visual inspection, both internal and external with the following failure criteria:

Bulge - all fail
Dent - fail if any greater than 2 mm
Wear - reduction of wall thickness greater than 25%
General Corrosion - reduction of wall thickness greater than 20% OR where original surface is not visible
Area Corrosion - (i.e., where corrosion is limited to less than 20% of surface) a reduction of wall thickness greater than 25%
Isolated pitting - Reduction of wall thickness greater than 40%
Thread damage - all physical damage or imperfections (recutting of threads can be achieved up to a maximum tolerance )
Weight Check - Weight of cylinder ( minus valve ) less than 95% of the tare weight stamped on the cylinder

Any cylinder that has been subject to impact damage should be pressure tested before use. If in the opinion of the inspector, any of the above criteria are borderline, then hydraulic testing may also be required.

Divingniknaks · August 19th, 2006, 09:37 AM

Quote: (Originally Posted by Mikey)

.....BTW open question is it possible to get tanks powder coated I was thinking black myself...now ducking whilst I get pole axed

Shame your not nearer to us, as we have guys who will do them any colour your heart desires

Have to say black might not be such a good choice though, I can see the "cool" factor

but you really are gonna disappear underwater.

Cheers

July 31st, 2006, 10:57 AM	#3 (permalink)
Howard Payne (Online) The Voices And The Becks Join Date: Nov 2005 Location: London Posts: 1,900	Doesn't do them any real harm mate -, my new twin 12's are bashed about after only a couple of months. Every scrape tells a story and makes you look dived up! __________________ Eastbourne Sub-Aqua Club 0513 Nitrox & Trimix, Club Boat, Plenty of Good Value Diving, Regular Club Trips & Holidays, Rec & Tech Training, GUE / Hogarthian Friendly Come Try Us!

July 31st, 2006, 11:13 AM	#4 (permalink)
Rick(Offline) Jock Exley Join Date: Nov 2005 Location: Falkirk/Stratford UK Posts: 730	Lol...I've had a bigger scratch on my erse man!! You could always see if Phil will replace them for you.....they look condemned to me __________________ Forget Everything And Remember http://phreaticzone.thedeepstop.com/ http://www.dublinbaydiving.com/

July 31st, 2006, 11:21 AM	#6 (permalink)
Martin Burnard(Offline) New Member Join Date: Nov 2005 Location: Plymouth, UK Posts: 614	Some of the old cylinders around show just how rough a cylinder can look and still be in service. They are tough!! __________________ I once enjoyed a sado-masachistic frenzy of total tintintabulation leading to a state of metampsychosis... or did I make that up? www.bananafrogcars.co.uk

July 31st, 2006, 11:57 AM	#8 (permalink)
lizardland(Offline) LCS Join Date: Nov 2005 Location: Evidently Chickentown Posts: 1,004	If you have exposed bare metal then there is the chance you can get some pitting. Give it a light sand, cover it with zinc primer and either leave it or put some colour on it. __________________ Can you imagine drifting along in the sea with your mouth open and a load of f***ing plankton going in? You'd like it, would you? www.westons-cider.co.uk The Lot isn't the only place to dive: http://www.lulu.com/content/613554

August 18th, 2006, 08:32 PM	#9 (permalink)
Mike Cunningham(Offline) DIRX Supporter Join Date: Aug 2006 Location: UK Essex Posts: 27	Rob, I think this is the current test spec..... having seen some of the scabby tin foil which does get passed I think that you are ok for at least 10years .....BTW open question is it possible to get tanks powder coated I was thinking black myself...now ducking whilst I get pole axed Rgds Mike Visual Inspection (every 2.5 years) Essentially this test is a detailed visual inspection, both internal and external with the following failure criteria: Bulge - all fail Dent - fail if any greater than 2 mm Wear - reduction of wall thickness greater than 25% General Corrosion - reduction of wall thickness greater than 20% OR where original surface is not visible Area Corrosion - (i.e., where corrosion is limited to less than 20% of surface) a reduction of wall thickness greater than 25% Isolated pitting - Reduction of wall thickness greater than 40% Thread damage - all physical damage or imperfections (recutting of threads can be achieved up to a maximum tolerance ) Weight Check - Weight of cylinder ( minus valve ) less than 95% of the tare weight stamped on the cylinder Any cylinder that has been subject to impact damage should be pressure tested before use. If in the opinion of the inspector, any of the above criteria are borderline, then hydraulic testing may also be required.

July 31st, 2006, 10:50 AM	#2 (permalink)
Chrisch(Offline) Hogarthian Heretic Join Date: Dec 2005 Location: Montpellier, France Posts: 106	Tanks are pretty tough items. The damage shown should not affect them in terms of testing during the normal lifetime of a steel tank (about 20 years). If you want to apply a little paint to prevent rust that's OK. I've never managed to match colours or finishes so it shows as a repair... Tanks also get bashed up on wrecks and other normal dive operations.. I guess it depends how much you care about their looks. Not a priority for me. Chris

July 31st, 2006, 11:15 AM	#5 (permalink)
Rob H(Offline) New Member Join Date: Apr 2006 Location: Sheffield, UK Posts: 27	Thanks guys - glad to have some second opinions. Cosmetics are of low importance; as long as the tanks function fine, pass retest and fills are not a problem then I am happy.

July 31st, 2006, 11:31 AM	#7 (permalink)
davy(Offline) DIveR Join Date: Nov 2005 Location: Belgium Posts: 292	If you are worried by that, you better not watch mine, almost no paint left never a problem, and now on the bottom I also managed to get through the zinc layer about 2 years ago and they are brown of rust now... but it is just superficial and they still passed hydro last month... It's the inside that really counts and what I want to keep clean. said cylinders are now 10 and 22 years old... Don't worry, you'll get plenty of scratches more when you do more boat/cave diving and the scratches just show others how "experienced" you are

August 19th, 2006, 09:37 AM	#10 (permalink)
Divingniknaks(Offline) Resident purveyor of shiney kit.... Join Date: Nov 2005 Location: Midlands UK Posts: 1,040	Quote: (Originally Posted by Mikey) .....BTW open question is it possible to get tanks powder coated I was thinking black myself...now ducking whilst I get pole axed Shame your not nearer to us, as we have guys who will do them any colour your heart desires Have to say black might not be such a good choice though, I can see the "cool" factor but you really are gonna disappear underwater. Cheers __________________ Phill ----------------------------- Salvo Lights, DirZone Gear , Frog Wings Dive ? http://www.divingniknaks.com