High Temperature Exposure of Aluminum Cylinders

High Temperature Exposure of Aluminum Cylinders 

Aluminum cylinders known to have been exposed to overheating or showing evidence of having been overheated, with overheating being a cylinder metal temperature in excess of 350°F, must be condemned per 49 CFR 180.205 (i) (viii). No testing for acceptance or re-heat treatment is authorized.

In CGA pamphlet C-6.1; Standards For Visual Inspection of High Pressure Aluminum Gas Cylinders, it states that cylinders heated to cylinder metal temperatures in excess of 350°F (176°C) must be condemned.

Common evidence of exposure to overheating that may heat the metal temperature to 350°F (176°C) include:

charring, blistering, or discoloration of the cylinder paint or protective coatings;

distortion of the cylinder;

melting of non-metallic (i.e. plastic, etc.) valve components;

charring or burning of labels;

activation of valve pressure relief device; or

activation of the heat indication system.

Evergreen Midwest recommends that if there is evidence, or it is believed, that a cylinder has been exposed to overheating but the temperature of metal of the cylinder is not believed to have reached 350°F (176°C) for any duration of time, the cylinder must still be subjected to hydrostatic testing or condemned. A cylinder that has been exposed to temperatures great enough to change the temper of the cylinder could show an increase in total or permanent expansion as measured during hydrostatic testing. Cylinders showing unusually high total expansion or exceeding the regulatory limits for the relationship of permanent expansion to total expansion (i.e. DOT = 10% and TC = 6%) should be condemned.

Non-Reversible Heat Indicating Devices

Aluminum cylinders should not be exposed to elevated temperatures, 350°F (176°C) or greater, or the action of fire for any period of time. In section (f) (4) of 49 CFR part 173.34, DOT-3AL and DOT-4E, aluminum cylinders subjected to fire must be removed from service. In CGA pamphlet C-6.1; Standards For Visual Inspection of High Pressure Aluminum Gas Cylinders, it states that cylinders heated to metal temperatures in excess of 350°F (176°C) must be condemned.

The CGA recognizes the effects of high temperature on aluminum cylinders and issued a safety bulletin SB-22; Aluminum Cylinders - Guidelines for a Heat Exposure Indicating System. In this safety bulletin the use of heat indicating devices on aluminum cylinders is only a recommended practice and is not a requirement by the CGA or any DOT specification. However, in some applications, Evergreen believes the use of such devices makes sense. CGA’s safety bulletin SB-22 identifies many applicable parameters of a heat indicating system but does not identify sources of these systems.

Following are a few sources of different types of heat (temperature) indicating systems:

American Thermal Instruments, Inc.

Omega Engineering Incorporated

McMaster Carr

Telatemp Corp.

Evergreen Midwest recommends that when choosing a heat indicating device, make sure you select a non-reversible temperature indicating device and that the device is compatible with the environment in which the cylinder will be used.

DISCLAIMER: The information contained herein is provided as a service to the public and is intended for informational purposes only.  Evergreen Sales and Services Corp. expressly warns that information contained herein may not be completely accurate and/or up to date. Therefore, neither Evergreen Sales and Services Corp. nor any of its affiliates assumes any liability whatsoever for the accuracy or completeness of the information contained herein. The statements herein shall have no force or effect. If you detect any omissions, misstatements or errors, please contact us immediately.