Ask X3What does 49 CFR 178.68 (Specification 4E welded aluminum cylinders) require?
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As a motor-carrier owner, here is what 49 CFR 178.68 requires for Specification 4E welded aluminum cylinders:
* Design & Capacity: Cylinders must have a water capacity of no more than 1,000 pounds and a service pressure between 225 and 500 psig. They must be made of no more than two seamless drawn shells with a single circumferential weld, and have a minimum wall thickness of 0.140 inch. Cylinders closed by spinning or with longitudinal seams are not allowed.
* Materials: They must be constructed of uniform quality aluminum matching authorized chemical analysis limits (such as alloy 5154), and manufacturers must keep records of intentionally added alloying elements.
* Welding & Attachments: All welding must use the gas shielded arc process. Attachments like neckrings, flanges, and handles can only be welded to the top and bottom of the cylinder, and both the attachment and the cylinder contact point must be made of weldable aluminum alloys.
* Openings: All openings must be located in the cylinder heads or bases and must be fitted securely to prevent leaks.
* Pressure Testing: Every cylinder must undergo pressure testing (using methods like the water-jacket or direct expansion method as outlined in CGA C-1) to at least two times its service pressure, with permanent volumetric expansion not exceeding 12 percent. Additional lot testing and a burst test (hydrostatically testing one cylinder per lot of 1,000 or less to four times service pressure without bursting) are also required.
* Flattening Test: A flattening test is required on a random section from each lot of 200 or less to check for cracking.