New DOT Hydro Requirements?

[imwright1985]

the eddy currents measure a frequency emitted through the tank some could fail based on oxidization of the metal also try and make sure the whole tank is clean and it should help it pass if needing to get it redone, yes tanks are kinda designed to crack, usually there are seams in the tank around neck and going down a side rather than the tank being cast this area if treated properly should have a heat affected zone which is an area around the welded seams where the metal is softer allowing it to expand through that region and develop a controled crack rather than a random hole or some spot blowing out. That and other principals in the manufacturing of the tank lead to the rule to not heat the tanks beyond a certain temp (i think like 350 degrees F)

 

[DandyDon]

Haha, ever been to Lubbock? They really are good, but are challenged by the local market. Their main business is his construction company, but he teaches & inspect, she runs the shop and sponsors the dive club, plus trips, etc. It's amazing how well they do really.

He injured his leg badly, had to have a few operations, but was back heading to OW check-outs with his big pickup and trailer when a local pulled out right in front of him. The Deputy who worked the wreck found pieces all over the place and was amazed that anyone live, but they all did. They both healed and went back to diving, trips, etc.

The local was hurt the worst. AIG is his insurer and after a year, still dragging feet on settling. But they stay cheerful, doing it all.

 

[DiveSite]

......... usually there are seams in the tank around neck and going down a side rather than the tank being cast this area if treated properly should have a heat affected zone which is an area around the welded seams where the metal is softer allowing it to expand through that region and develop a controled crack rather than a random hole or some spot blowing out. That and other principals in the manufacturing of the tank lead to the rule to not heat the tanks beyond a certain temp (i think like 350 degrees F)

Not sure where you got your info, but aluminum tanks ARE NOT welded. Here is a link to a video that shows a Luxfer tank being made. Tank-Video-Link

 

[mike_s]

the eddy currents measure a frequency emitted through the tank some could fail based on oxidization of the metal also try and make sure the whole tank is clean and it should help it pass if needing to get it redone, yes tanks are kinda designed to crack, usually there are seams in the tank around neck and going down a side rather than the tank being cast this area if treated properly should have a heat affected zone which is an area around the welded seams where the metal is softer allowing it to expand through that region and develop a controled crack rather than a random hole or some spot blowing out. That and other principals in the manufacturing of the tank lead to the rule to not heat the tanks beyond a certain temp (i think like 350 degrees F)

welded seams?

huh?

Tanks aren't welded when made. they are "struck" (pressed) out of a single "puck" of aluminum.

The whole tank is basically formed in one 'strike' then the top/neck is formed in a second step. After that they cut off the top and thread the neck.

no welding is required.


EDIT: see the video that is posted above. shows the process fairly decently

 

[imwright1985]

hmm... will do once internet speeds up and i can do that wont load now, i coulda sworn i had seen seams in tanks before unless im getting something mixed up. should be interesting thanks for the vid divesite. i learn new stuff everyday.

Just got video loaded and watched, pretty neat, musta been the seam where the die for forming the neck meets the extruded sides. thanks for correcting me. nice thing to know and kinda cool watching the tinsle test i love watching the metals snap would be cooler if they zoomed in on the necking area and the fracture surfaces. That means that the metal processing is the control to make the metals soft enough to tear rather than break.

 

[WD8CDH]

Sometimes there are little valleys in the area just below the neck threads from the squeezing process that makes the neck. They may look like seams but they are not. Sometimes they are called folds but they are more like shallow creases.

 

[Rick Christ]

Here we go again,

http://www.scubaboard.com/forums/tanks-valves-bands/269221-tanks-ones-cant-re-hydroed-4.html

I am so tired of hearing all of the self professed experts on this board saying 6351-t6 are bad.

I found a old report from PSI, take a look at this

SCUBA Related Incidents
As Reported by PSI-International, Inc. July, 2001

*Injury Codes: 0=None, 1=Death, 2=Severe, 3=Moderate, 4=Minor
Date Location Type Activity Cause Injuries*
1960 Watertow, NY Steel Filling ? 4
1960’s Canada Steel Stored ? ?
1960’s Florida Steel Filling ? 0
1970’s Oregon ? ? ? 0
1971 British Virgin Islands Steel Filling ? 4
1971-72 St. Kitts Steel ? ? ?
1973 Los Angeles, Ca Steel Filling Corrosion 2,3
1974 Grand Bahamas Alum-6061 Filling ? 4,4
1974 Cozumel, Mexico Steel Filling ? 3
1974-75 Anchorage, AK Steel Rigging Corrosion 1,2,4,4
1977 Hawaii Aluminum Filling Fire 4,4
Aug. 1979 Japan Steel Rigging Corrosion 1,2,4,4
1981 Florida Aluminum Filling Heat 2
1981 Florida Aluminum Filling Heat 3,4,4,4,4
1982 Ft. Lauderdale, Fl. Aluminum Filling Crack ?
1983 England ? Filling Metric Valve 0
1983 New York Steel Stored Corrosion 0
1983 England Steel ? Thread Corr. 2
1984 New Guinea ? Filling ? 0
1984 Hawaii Steel Filling Corrosion 4
1984 Hawaii Steel Stored Corrosion 3
1985 U.S. Virgin Islands Steel Filling Corrosion 2,3
1985 Florida Steel Filling Corrosion 2
1986 W. Palm Beach Florida Steel Filling ? 0
1986 Moline, IL Steel Re-valved Pressure 2
1988 Australia Aluminum Filling Crack 2,3,3,4
1988 Virginia Aluminum Filling Altered Drugs 0
1990 Belize ? Filling ? 0
1990 Key Largo, Florida Aluminum Stored Heat 0
1990 Puerto Rico ? Filled ? ?
1991 Cape Town, So. Africa Aluminum Stored ? 0
1991 Roatan Aluminum Stored on boat Fire 0
1991 Latusis ? Stored in Van Burst Disk ?
1992 Hilo, HI Aluminum Filling ? 2
1993 Pooler, Georgia Aluminum Filling ? 2
1993 Pompano, Florida Steel (Vinyl) Filling ? 0
1993 Egypt (Red Sea) Aluminum Filling Overfill 2
1993 Honduras Aluminum Stored Fire 0
1994 Ft. Lauderdale, Fl. Aluminum Filling Crack 2
Aug. 1994 Calgary, Alberta, Can. Steel Filling Overfill/disk 1,3
Jan. 1995 Florida Steel Filling Metric Valve 2,4,4
July, 1996 Alabama Aluminum Filling ? 0
Aug. 1996 Athens, Greece Aluminum Storage Metric Valve 1,3
May, 1997 Fiji Islands (2) Aluminum Boat Fire Heat Damage 0
May 30, 1997 Tjoeme, Norway Gerzat, 5283 Aluminum Storage ? 0
1997 Jeddah, Saudi Arabia Aluminum Filling Cracking 0
1997 Rio De Janeiro, Brazil Aluminum Val Extrusion Metric Valve 0
1997 Cuacao, NA Aluminum Hydro-Retest ? 0
1997 Cuacao, NA Aluminum Val Extrusion Metric Valve 0
Feb. 1998 Auckland, New Zealand Steel Filling ? 0
Jan. 25, 1998 Anaheim, CA Copper In Use ? 0
Feb. 1998 Auckland, New Zealand Steel Filling ? 4,4
Feb. 1, 1998 Riviera Beach, FL Aluminum Filling Cracking 2
June 4, 1998 Joplin, MO Aluminum Filling Heat Treat Paint 3,4
October , 1998 Auckland, New Zealand Aluminum Filling ? 2
April 19, 1999 Campbell River, B.C. Can. Aluminum Filling Cracking 0
May 1999 Cozumel, Mexico Aluminum Filling ? 0
Aug. 9, 1999 San Diego, CA E9791 Filling Valve Extrusion 2
October 2, 1999 Auburn, CA Aluminum Filling Cracking 0
October 19, 1999 Syosset, NY Steel Filling ? 0
March 17, 2000 Key Largo, FL Aluminum Filling Cracking 2
June 8, 2000 Tobermory, Ontario, Can. Steel Storage ? 1
June 30, 2000 Okinawa, Japan Aluminum Filling Cracking 4
Nov. 24, 2000 Hawaii Aluminum Blending ? 3
December, 2000 Rio de Janeiro, Brazil Aluminum Filling ? 1
February, 2001 Osaka, Japan Steel Val Extrusion ? 0
November, 2001 Sebastion, FL Steel Filling ? 1

This is just the ones in the scuba industry, this does not include the industrial side, the medical O2 side, the carbon fiber wrap side, the paintball side or the CO2 side

All tanks fail!! Alum, steel, carbon fiber, 6351-T6 and the new 6061-T6 also FAIL

That is the job of the DOT Retester to try to ferret out the weak ones.

I will check with Mark at PSI tomorrow to see if they have a updated list and if they will release it to me.

 

[DandyDon]

That's all a bit much for me Rick, and the linked thread looks like a challenge for me at the moment. (Heat exhaustion) But thanks.