dark spots on the inside of an alu cylinder

movil · July 9th, 2006, 07:35 PM

Hi all,

inspecting a couple of aluminium cylinders recently I have noticed they both have dark spots on the inside of their walls, including the valve thread. Cleaning the thread with a toothbrush I get a dark powder.

I presume this is some sort of corrosion. Does anyone know what causes it? how can it be removed? what procedure to follow to get the tanks back in O2 service?

any help would be greatly appreciated.

Jorge

tanto · July 9th, 2006, 09:14 PM

oxyde is usually white, haven't seen it dark, unless it's dirt and oxyde...

Ahmed Adly, Marlin Inn DC · July 9th, 2006, 09:58 PM

Quote: (Originally Posted by movil)

Hi all,

inspecting a couple of aluminium cylinders recently I have noticed they both have dark spots on the inside of their walls, including the valve thread. Cleaning the thread with a toothbrush I get a dark powder.

I presume this is some sort of corrosion. Does anyone know what causes it? how can it be removed? what procedure to follow to get the tanks back in O2 service?

any help would be greatly appreciated.

Jorge

Wash the tanks out with some kind of abbrassive stuff like small nuts and some good soap.

After that, if there is anything there, it is some unknown gunk which is not dangerous. Don't worry and fill after the washing.

movil · July 10th, 2006, 04:10 PM

Hi,

thanks to both. I have remembered one detail....both cylinders have had argon in them.....could it be a contaminant from the argon cylinder from the gas manufacturer? It´s odd that these two have these spots while the third one I have doesn´t.....

just wondering.

Jorge

July 9th, 2006, 07:35 PM	#1 (permalink)
movil(Offline) New Member Join Date: Nov 2005 Location: Spain Posts: 37	dark spots on the inside of an alu cylinder Hi all, inspecting a couple of aluminium cylinders recently I have noticed they both have dark spots on the inside of their walls, including the valve thread. Cleaning the thread with a toothbrush I get a dark powder. I presume this is some sort of corrosion. Does anyone know what causes it? how can it be removed? what procedure to follow to get the tanks back in O2 service? any help would be greatly appreciated. Jorge

July 9th, 2006, 09:14 PM	#2 (permalink)
tanto(Offline) New Member Join Date: Mar 2006 Location: italy Posts: 63	oxyde is usually white, haven't seen it dark, unless it's dirt and oxyde...

July 9th, 2006, 09:58 PM	#3 (permalink)
Ahmed Adly, Marlin Inn DC(Offline) New Member Join Date: Feb 2006 Location: hurghada Posts: 849	Quote: (Originally Posted by movil) Hi all, inspecting a couple of aluminium cylinders recently I have noticed they both have dark spots on the inside of their walls, including the valve thread. Cleaning the thread with a toothbrush I get a dark powder. I presume this is some sort of corrosion. Does anyone know what causes it? how can it be removed? what procedure to follow to get the tanks back in O2 service? any help would be greatly appreciated. Jorge Wash the tanks out with some kind of abbrassive stuff like small nuts and some good soap. After that, if there is anything there, it is some unknown gunk which is not dangerous. Don't worry and fill after the washing.

July 10th, 2006, 04:10 PM	#4 (permalink)
movil(Offline) New Member Join Date: Nov 2005 Location: Spain Posts: 37	Hi, thanks to both. I have remembered one detail....both cylinders have had argon in them.....could it be a contaminant from the argon cylinder from the gas manufacturer? It´s odd that these two have these spots while the third one I have doesn´t..... just wondering. Jorge