Locate the cylinder neck, shoulder, or collar area
Find the stamped or printed date code on the cylinder
Look for the manufacture date and the last test date
Check the hydrostatic test or retest date if marked
Read the expiry or next test due date if provided
Compare the date with the current date
Refer to the cylinder label, tag, or stamped markings for validity
If the date is unclear or missing, contact the supplier or authorized inspector
Do not use a cylinder that is past its expiry or test due date