DOT Advisory: Aluminum Alloy 6351-T6
How to read Aluminum or Steel Cylinder Markings
1. Cylinder Specification consisting of three sections:
DOT – Department of Transportation
3AA – Specification of type and material of cylinder construction.
2265 – Service Pressure in psi.
2. 12345 – Cylinder serial number (See Note A)
3. Gas Inc. – Identifying symbol (See Note A)
4. Manufacturing Data:
4-70 – Date of manufacture and original test date.
XX – Inspector’s official mark.
+ - Cylinder qualifies for 110% filling.
5. YY – Manufacturer’s identifying symbol.
6. Retest Markings:
4-75 – Data of first 5 year hydrostatic retest
ABC – Retester identifying symbol.
+ - Cylinder requalifies for 110% filling.
* - Cylinder qualifies for 10-year retest interval.
7. Neck ring owner’s identification.
Notes:
A. Serial number and identifying symbol may be that of purchaser user or manufacturer.
B. “Spun” or “Plug” must be stamped near DOT mark when an end closure in the finished cylinder has been welded by the spinning process or effected by plugging.
C. Markings “5” and “6” are usually shown diametrically opposite other markings on the cylinder neck.
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DOT “E” Number Look-up site.
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