Ask X3What does 49 CFR 178.46 (Specification 3AL seamless aluminum cylinders) require?
Generated guidance. Confirm the source and its applicability before you act. How we check sources.
As a motor-carrier owner, here is what 49 CFR 178.46 requires for Specification 3AL seamless aluminum cylinders:
* Size and Service Pressure: Cylinders must have a maximum water capacity of 1,000 pounds and a minimum service pressure of 150 psig.
* Materials: You must use only permitted heat-treatable aluminum alloys (specifically Aluminum Association alloy 6061). Starting stock must be cast stock (or traceable to it), of uniform quality, free from weakening defects (like seams, cracks, or laminations), and properly identified by alloy, producer's cast number, solution heat treat batch number, and lot number. All starting stock must be 100% ultrasonically inspected for internal defects.
* Manufacturing: Cylinder shells must be manufactured using the backward extrusion method with a clean, smooth, uniform surface. Welding or brazing is strictly prohibited. Bases must meet specific thickness and contour requirements. New designs must pass rigorous prototype pressure-cycling and destruction tests.
* Wall Thickness: The minimum wall thickness must keep wall stress within safe limits (not exceeding 80% of the minimum yield strength or 67% of the minimum ultimate tensile strength at the minimum test pressure). Cylinders with an outside diameter greater than 5 inches must have a minimum wall thickness of 0.125 inches.
* Openings: Openings are permitted only in the heads, must be circular, must be threaded (using approved taper or straight threads meeting specific standards), and must meet strict size and separation (ligament) requirements.