BAM Chapter 22D: Examination of Containers for Integrity
Bacteriological Analytical Manual (BAM) Main Page
Authors: Rong C. Lin, Paul H. King, and Melvin R. Johnston
For additional information, contact Steven Simpson
BASE PLATE PRESSURE. Force of the base plate that holds the can body and end against the chuck during the double seaming operation. In general, it has the following effect on the seam formation: low pressure, short body hook; high pressure, long body hook.
BODY - The principal part of a container, usually the largest part in one piece comprising the sides. The body may be cylindrical, rectangular, or another shape.
BODY HOOK - The flange of the can body that is turned down in the formation of the double seam.
BOTTOM SEAM - Double seam of the can end put on by the can manufacturer, also known as factory end seam.
CABLE CUTS - Cuts or grooves worn into can ends and bodies by cables of the runway conveyor system.
CAN, SANITARY - Full open-top 2-piece drawn can and 3-piece can with double seamed bottom. Cover or top end is attached with a double seam by the packer after filling. Ends are compound-lined. Also known as packer's can or open-top can.
CANNER'S END - See packer's end.
CAP TILT - Cap should be essentially level with transfer bead or shoulder.
CHIPPED GLASS FINISH - Defect in which a piece of glass has broken away (chipped) from the finish surface.
CHUCK - Part of a closing machine that fits inside the end countersink and acts as an anvil to support the cover and body against the pressure of the seaming rolls.
CHUCK WALL - Part of the can end that comes in contact with the seaming chuck (Fig. 2).
CODE CUT - Fracture in the metal of a can end caused by improper code embossing.
COLD WELD - Weld appears narrower and lighter than normal and may be scalloped. Fails the pull test, possibly exhibiting a zipper or sawtooth type of failure.
CONTAMINATION IN WELD AREA - Any visible burn at one or more points along side seam. COMPOUND - Sealing material consisting of a water or solvent dispersion or solution of rubber and placed in the curl of the can end. The compound aids in producing a hermetic seal by filling spaces or voids in the double seam
COUNTERSINK DEPTH - Measurement from top edge of double seam to end panel adjacent to chuck wall.
COVER - See packer's end.
COVER HOOK - The part of the double seam formed from the curl of the can end. Wrinkling and other visual defects can be observed by stripping off the cover hook.
CRACKED GLASS FINISH - Actual break in the glass over the sealing surface of the finish. Also known as split finish.
CRAWLED LAPS - Occurs when two layers of metal are bent and the outer layer looks shorter because it has a greater radius to traverse than the inner layer, which has a smaller radius, perhaps being bent almost double. Also known as creep.
CROSS-OVER - The portion of a double seam at the juncture with the side seam of the body.
CROSS-SECTION - A section cut through the double seam for the purpose of evaluating the seam.
CRUSHED LUG - Lug on cap forced over glass lug, causing the cap lug not to seat under glass lug.
CURL - Extreme edge of the cover that is turned inward after the end is formed. In metal can double seaming, the curl forms the cover hook of the double seam. For the closure for glass containers, the curl is the rolled portion of metal at the bottom of the closure skirt (may be inward or outward).
CUTOVER - A break in the metal at top of inside portion of double seam caused by a portion of the cover being forced over the top of the seaming chuck. This condition usually occurs at the cross-over. Also known as a cut through by some can manufacturers. These manufacturers refer to a cutover as the same condition without the break.
CUT THROUGH - Gasket damage caused by excessive vertical pressure.
DEADHEAD - An incomplete double seam resulting from the seaming chuck spinning in the end's countersink during the double seaming operation. Also known as a spinner, skidder, or slip.
DELAMINATION - Any separation of plies (laminate materials) that results in questionable pouch integrity.
DOUBLE SEAM - Closure formed by interlocking and compressing the curl of the end and the flange of the can body. It is commonly produced in 2 operations. The first operation roll preforms the metal to produce the 5 thicknesses or folds; the second presses and flattens them together to produce double seam tightness.
DROOP - Smooth projection of the double seam outside and below the bottom of the normal seam. Usually occurs at the side seam lap area.
FACTORY END - See manufacturer's end.
FALSE SEAM - Double seam where a portion of the cover hook and body hook are not interlocked, i.e., no hooking of body and cover hooks.
FINISH - That part of the glass container for holding the cap or closures.
FLANGE - Outward flared edge of the can body cylinder that becomes the body hook in the double seaming operation. For weld cans, any flange crack at or immediately adjacent to the weld is a major defect.
FLEXIBLE CONTAINER - A container, the shape or contour of which, when filled and sealed, is affected by the enclosed product.
HEAVY LAP - A lap containing excess solder. Also called a thick lap.
HOOK, BODY - See body hook. HOOK, COVER - See cover hook.
IMPROPER POUCH SEAL - A defect (e.g., entrapped food, grease, moisture, voids, or fold-over wrinkles) in that area of the closure seal that extends 1/8 inch vertically from edge of seal on food product side and along full length of seal.
IRREGULAR WELD WIDTH - Any obvious irregularity in weld width along length of side seam.
JUMPED SEAM - See jumpover.
JUMPOVER - Double seam that is not rolled tight enough adjacent to the cross-over; caused by jumping of the seaming rolls at the lap.
JUNCTURE - The junction of the body side seam and the end double seam, or that point where the 2 seams come together. Also known as the cross-over.
KNOCKED-DOWN FLANGE - Common term for a false seam where the bottom of the flange is visible below the double seam. A portion of the body flange is bent back against the body without being engaged with the cover hook.
LAP - The section at the end of the side seam consisting of 2 layers of metal bonded together. As the term implies, the 2 portions of the side seam are lapped together to allow for the double seam, rather than hooked, as in the center of the side seam.
LID - See packer's end.
LIP - Projection where the cover hook metal protrudes below the double seam in one or more "V" shapes. Also known as a vee.
LUG CAP - Closure with raised internal impressions that intermesh with identical threads on the finish of the glass container. It is a closure with horizontal protrusions that seat under angled threads on the glass container finish.
MANUFACTURER'S END - End of the can that is attached by the can manufacturer.
NOTCH - Small cut-out section in the lap designed to facilitate the formation or the body hook at cross-over.
OPEN LAP - A lap that is not properly soldered or has failed by separating or opening because of various strains in the solder.
OVERLAP - Distance the cover hook laps over the body hook. Any observable loss of overlap along the side seam is a critical defect.
PACKER'S END - End of the can attached and coded by the food packer. Also known as the canner's end.
PLATE - General term for tinplate, aluminum, and the steel sheets from which cans are made. It is usually tin plate, which is black plate with tin applied to it.
PRESSURE RIDGE - Impression (chuck impression) around the inside of the can body directly opposite the double seam.
PULL-UP - Term applied to distance measured from the leading edge of the closure lug to the vertical neck ring seam.
SAWTOOTH - Partial separation of the weld side seam overlap at one or more points along the seam. If observed after performing the pull test, it is considered a critical defect.
SEAM NARROWING - A steadily visible narrowing of the weld at either end of the weld side seam is a critical defect.
SEAM THICKNESS - Maximum dimension of double seam measured across or perpendicular to layers of seam.
SEAM WIDTH (LENGTH OR HEIGHT) - Maximum dimension of double seam measured parallel to folds of seam.
SECURITY - Residual clamping force remaining in the closure application when gasket has properly seated after processing and cooling.
SEMIRIGID CONTAINER - A container, the shape or contour of which, when filled and sealed, is not affected by the enclosed product under normal atmospheric temperature and pressure, but which may be deformed by external mechanical pressure of less than 10 psi (0.7 kg/cm2) (i.e., normal firm finger pressure).
SIDE SEAM - The seam joining the 2 edges of the body blank to form a can body.
SKIDDER - Can with incompletely finished double seam because the can slipped in the seaming chuck. In this defect, part of the seam will be incompletely rolled out. The term has the same meaning as deadhead when referring to seamers that revolve the can. Also known as a spinner.
SOFT CRAB - Colloquial term used to describe a breakdown in the packer's can resulting in a hole between end and body.
SPINNER - See deadhead and skidder.
STRIPPED CAP - Lug closure applied with too much torque, which causes lugs to pass over glass lugs. May have vacuum but has no security value.
TIGHTNESS - Degree to which the double seam is compressed by the second operation roll. Tightness is determined primarily by the degree of freedom from wrinkles in the cover hook. Tightness rating is a percentage that ranges from 100 to 0, depending on the depth of the wrinkle: 100% indicates no wrinkle and 0% indicates a wrinkle extending completely down the face of the cover hook. A well-defined continuous impression around the circumference of the can in the double seam area indicates a tight seam. This impression is known as a pressure ridge.
TOP SEAM - Top of packer's end seam.
UNEVEN HOOK - Body or cover hook that is not uniform in length.
WELD CRACK - Class I corrosion products plus any observable seam crack, and any cracks that extend 25% or more across the width of the weld at any point along the weld seam are considered critical defects.
WELD PROTRUSION - Protrusion of the weld in excess of 1/16 inch beyond the leading or trailing edge of the can body.
WRINKLE (COVER HOOK) - A waviness occurring in the cover hook from which the degree of double seam tightness is determined.
ZIPPER - Gross separation of the side seam overlap along all or any part of the side seam. If observed during pull test, it is a critical defect.
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Hypertext Source: Bacteriological Analytical Manual, 8th Edition, Revision A, 1998. Chapter 22.