This should be a clearly visible impression around the inside of the can body which is exposed when the cover countersink wall is removed after stripping the double seam for inspection. This is a very important point of inspection when tearing down a seam. If there is no pressure ridge, or a light pressure ridge, it would indicate a loose 2nd operation seam even though there are no cover hook wrinkles. A heavy pressure ridge may indicate an excessively tight seam. While a pressure ridge heavy at the top and light at the bottom may indicate that an improper 2nd Operation Seaming Roll groove profile is being used for the particular cover and body componets being seamed.
|Probable Cause||Suggested Remedy|
|2nd Operation Seaming Roll setting incorrect.||If the pressure ridge is too light, tighten the 2nd Operation Seaming Roll. If the Pressure Ridge is too heavy, loosen the 2nd Operation Seaming Roll. Check with your can supplier for the proper specifications.|
|2nd Operation Seaming Roll groove profile is incorrect.||Replace the 2nd Operation Seaming Roll with an improved groove profile.|