This particular defect has a few names, such as “Vee”, “Spur“, “Pin Lip” and other names.

In actuality, this is the visual part of a simpler defect called “false seam“. False seams occur when the seam formation is not done correctly, typically due to incorrect 1st operation setup. This issue is particularly nasty as it means that the entire closure is compromised, typically meaning that the can will lose internal pressure, leak as well as expose its contents to potentially harmful outside influences (e.g., pestisides, toxic materials, erosion).

false seam

This problem must never occur on a normal production line!

Steps to detect Vee:

Possible reasons for a Vee:

This is what the defect looks like in a non-destructive scanner – note the “humps” at the bottom Length graph indicating the defect.