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The requalification of cylinders was formally known as the retesting of cylinders. Requalification is done to ensure that a cylinder is still acceptable to continue to be used as a pressure vessel to transport hazardous material. DOT requalifying of a cylinder and the marking thereof are to be performed by an approved DOT requalification facility that has been issued a DOT Requalifiaction Identification Number (RIN). The requirements for the requalifying of DOT cylinders in the US are identified in Title 49 of the Code Of Federal Regulations (CFR) in part 180, “Continuing Qualification and Maintenance Of Packaging” and any applicable DOT exemption.

The requalifying requirements of any cylinder are specific to the DOT specification and/or exemption to which the cylinder was manufactured. The DOT specification and/or exemption number are stamped on the crown of the cylinder. Cylinders manufactured by Catalina Cylinders are marked with “M4002” on the crown of the cylinders. Cylinders manufactured by Catalina East Division are marked with “M1039” on the crown of the cylinder.

The most basic of the retesting requirements for cylinders manufactured by Catalina Cylinders are identified below.

DOT-3AL Cylinders (Catalina Cylinders and Catalina East Division)

Requalifying required every five (5) years. Requalifying of a cylinder is to be performed five (5) years, as per Table 1 “Requalification of Cylinders” in 49CFR 180.209, after the original manufacturing hydrostatic test date stamped on the crown of the cylinder. Please note the 12 year requalification cycle notated in Table 1 is only for “dry” fire extinguishers as noted in 49CFR 180.209(j). In section 180.205 (c) it states that a cylinder that is filled before the retest date may remain in service until it is emptied of its charge. In other words, a cylinder that currently has a charge when the 5 year retest date occurs does not have to be drained of its charge and retested. The charge can be used and the cylinder retested after the charge has been used.

The requalifying specified in part 180 consists of an internal inspection and hydrostatic retesting of the cylinder at a pressure equivalent to 5/3 the service pressure of the cylinder.

Catalina Cylinders and Catalina East Division are not requalifiers of cylinders to the general public. If you go to this website,, you will find a complete list of DOT approved retesters throughout the country.

There are a few companies that have DOT exemptions to requalify cylinders by Ultrasonic Examination (UE) of the cylinders instead of visually inspecting and hydrostatically retesting the cylinders. In some cases there are benefits to this type of requalifying.

DOT-3AL Cylinders “2 by 2 rule” (Catalina East Division only)

Requalification not required per the note under table 1 in 49CFR part 180.205. The note reads, “Any cylinder not exceeding two (2) inches in outside diameter and less than two (2) feet in length is exempt from volumetric expansion testing.”

DOT-39 Cylinders (Catalina East Division only)

These are non-refillable cylinders and do not require requalifying..

E-7737 (Aluminum DOT-3E) Cylinders (Catalina East Division only)

Requalifying is not required.

Eddy current inspection of the threads in 6061 aluminum cylinders is not required by the DOT and is not mandated as necessary by Catalina Cylinders. Cylinders manufactured by Catalina Cylinders and Catalina East Division have only been manufactured from aluminum alloy 6061, not aluminum alloy 6351, and do not require any special testing or inspection of the neck, threads or shoulder of the cylinders.

All cylinders that have been successfully requalified will have the date of the retest (month and year) stamped in the crown of the cylinder with the RIN of the DOT approved requalification facility stamped between the month and year of the retest date.

If you have any questions with regards to the requalifying of cylinders manufactured by Catalina Cylinders or Catalina East Division please do not hesitate in contacting us directly.