USDA 

 

THERMAL PROCESSING 

TRAINING 

Module 16. Closures for Metal 

Containers 

Thermal Processing for Meat and Poultry 

Products Training 

1 
THERMAL PROCESSING 

TRAINING 

Container Integrity 

Primary Intent Of Part 9 CFR 431.2 

 To prevent product adulteration due to 

leakage during cooling and handling after 

retorting. 

2 
Sanitary (Open Top) Can 

THERMAL PROCESSING 

TRAINING 

3 
 

 

 

 

 

THERMAL PROCESSING 

TRAINING 

Can Manufacturing Plate 

 Tin coated steel plate 

 Tin free steel plate 

 Temper indicates the hardness of the metal 

plate; T1 = very soft, T5 = very hard 

 Base weight = plate thickness/.00011 

 Plate characteristics affect double seam 

characteristics 

4 
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SidtSeam 

Facrorv 

Doubl~Snlt'L 

Factory Finished Can 

THERMAL PROCESSING 

TRAINING 

5 
 

Metal Cans 

THERMAL PROCESSING 

TRAINING 

6 3-PIECE SOLDERED 3-PIECE WELDED 2 PIECE DRAWN 
Seams 

THERMAL PROCESSING 

TRAINING 

7 
Half-Size Seam Table Tray 

THERMAL PROCESSING 

TRAINING HALF SIZE SEAM TABLE

TRAY

8 
End (Lid) Curl 

THERMAL PROCESSING 

TRAINING 

9 
 

 

 

THERMAL PROCESSING 

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Double Seam 

 Formed by joining body of can with end 

 Body flange interlocked with end curl 

 Formed in two operations 

10 
THERMAL PROCESSING 

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Double Seamer Head 

 First Operation Roll 

 Second Operation 

Roll 

 Seaming Chuck 

 Can 

 Base Plate 

11 
 

 

 

THERMAL PROCESSING 

TRAINING 

First Operation 

 Contoured groove of seaming roll 

(narrow/deep) forms the seam profile 

 End curl is interlocked with body flange 

 Faulty first operation will result in a faulty 

finished seam 

12 
, · 

se.quenoe 10f op 

onto a cah bod 

ls Operation 

·e1D1ingRnU 

+ 

First Operation 

THERMAL PROCESSING 

TRAINING 

13 
,• • •• • .,J • • • ' • • 

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. 2 . After Start ·Of 1st O eratio,n Seam · .··· •., 

' • • • • • ~ • ~ • p • 

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Double seam1hg rs pe:rtormed in two operations, ; .. ·: : · ._.... -' .: •_.: ·:- · · · • · _. 

The iirst ope.ratinn roll cur 1s the end hook . · · · .. · -__ : ~ •\.· ·_._·_ . · .. ·: : ·. . : .... ··. _· ~--: .. around the inside ofthe body hoo to: provl:de · .'. ;. ·. ;· :·· . · __ · :~ _; :-._··: · _._-·:' ·. · .. ·,·. · ..- ; ·i ·· · • ·. ..·.:-... •,. · • 

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First Operation 

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14 
 

 

 

 

 

 

Complete First Operation 

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 Body Hook (BH)

approximate parallel to 

Cover Hook (CH) 

 BH tucked down in CH 

radius 

 CH rounded and 

adjacent to or touching 

can body wall 

 Wrinkle created in CH 

at end of hook 

15 
4, Finished Double ~earn : . -,. 

2nd Operation ···' .. Seaming 

~eamln~ Roll i . Chuck ' . ' 

 

 

 

 

Second Operation: 

(Seaming Roll Contour Shallow & Flat) 

THERMAL PROCESSING 

TRAINING 

 Flattens and 

tightens the hooks 

 Irons out CH wrinkle 

 Seaming compound 

forced into voids of 

seam 

16 
Second Operation 

THERMAL PROCESSING 

TRAINING 

17 
t 

BOD 

HOO 

WIDTH 

T HICK ESS 

OVE 

LA 

C 

COVER 

OOK 

Double Seam Measurements 

THERMAL PROCESSING 

TRAINING 

18 
 

THERMAL PROCESSING 

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Double Seam Measurements 

The most critical measurements to a can’s 

double seam are: 

 Overlap 

 Tightness 

19 
 

 

 

 

THERMAL PROCESSING 

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Overlap 

 The degree of interlock between the 

body hook and cover hook 

 Formula when using a micrometer 

BODY HOOK + COVER HOOK + END 

THICKNESS (.010 IN.) − SEAM 

WIDTH 

20 
 

THERMAL PROCESSING 

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Tightness 

 Degree of cover hook wrinkle after double 

seaming 

 Tightness rating indicates relative freedom 

from wrinkles 

21 
Canco 4-head Double Seamer (Can Spin Type) 

THERMAL PROCESSING 

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22 
Seaming Rolls and Chuck 

THERMAL PROCESSING 

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23 
 

THERMAL PROCESSING 

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Juncture Area 

 Location where double seam crosses welded 

side seam 

24 
Juncture Area 

THERMAL PROCESSING 

TRAINING Droop at Crossover 

3-piece soldered can 

25 
Juncture Area 

THERMAL PROCESSING 

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26 
THERMAL PROCESSING 

TRAINING 

Can Seam Defects 

27 
0 

 

 

 

 

Can Seam Defects: First Operation Too Loose 

THERMAL PROCESSING 

TRAINING 

 Formation of cover hook 

and overlap may be 

affected 

 Possible cause— 

improper setting of first 

operation seaming roll, 

worn seaming roll, wrong 

groove profile 

28 
Can Seam Defects: Loose First/Normal Second Operation 

THERMAL PROCESSING 

TRAINING 

29 
T 

 

 

 

 

 

THERMAL PROCESSING 

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Can Seam Defects: First Operation Too Tight 

 Results in flattened seam 

bottom, sharp seam and 

poor cover hook 

 One possible cause—tight 

setting of first operation 

seaming roll, worn seaming 

roll, groove profile too 

narrow 

30 
I.: 

L· t lJ 

~ 0 

Can Seam Defects: Tight 

First/Loose Second Operation 

THERMAL PROCESSING 

TRAINING 

31 
 

 

Can Seam Defects: Short Cover Hook 

THERMAL PROCESSING 

TRAINING 

A short cover hook may 

result in short overlap: 

Possible Causes: 

 Loose first operation roll 

 Excessive lifter pressure 

 Excessive countersink 

depth 

32 
 

 

THERMAL PROCESSING 

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Long Cover Hook - May Result In Reduced 

Overlap (Possible Cause): 

A long cover hook may 

result in reduced 

overlap: 

Possible Cause: 

First operation 

seaming roll set too 

tight. 

33 
LO G 

HOO 

Mushroomed Flange 

THERMAL PROCESSING 

TRAINING 

34 
 

 

 

Can Seam Defects: Loose Second Operation Seam 

THERMAL PROCESSING 

TRAINING 

Possible Causes: 

 Folds of metal may not 

be pressed together

tightly enough 

 Cause may be 

improper setting of or 

worn second operation

seaming roll 

35 
Loose Seam 

THERMAL PROCESSING 

TRAINING 

36 
 

 

Can Seam Defects: Broken Chuck 

THERMAL PROCESSING 

TRAINING 

Possible Causes: 

 Portion of chuck lip 

missing 

 Loose seam at that 

point 

 Several possible 

causes of chuck 

damage 

37 
 

 

 

THERMAL PROCESSING 

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Excessively Tight Second Operation 

May cause 

reduction of overlap, 

sharp seam and/or 

compound to 

squeeze out of the 

seam. 

38 
 

THERMAL PROCESSING 

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Insufficient Overlap Possible Causes 

 Irregular can body flange 

 Irregular end curl 

 Poor closing machine adjustment 

39 
E C SS 

COLI T SI K 

DE TH 

 

 

Excessive Countersink Depth 

THERMAL PROCESSING 

TRAINING 

 Results in shortened 

cover hook and 

overlap 

 Excessive baseplate 

pressure or chuck 

set too deep are 

possible causes 

40 
 

 

 

 

Seam Bumps 

THERMAL PROCESSING 

TRAINING 

 Most often on 2-piece 

or welded side seam 

cans 

 Localized increase in 

packer’s end seam 

thickness 

 Distorted body hook 

41 
 

 

THERMAL PROCESSING 

TRAINING 

Seam Bumps 

Possible Causes: 

 Excessively tight finished seam 

 Long body hooks 

 Excessive sealing compound (gasket) in the 

end curl 

42 
Al-SES AM 

 

False Seam 

THERMAL PROCESSING 

TRAINING 

 Seam which is entirely 

unlocked 

 Not always detected by 

visual examination 

 Revealed by teardown 

examination 

43 
False Seam 

THERMAL PROCESSING 

TRAINING 

44 
Damaged Flange and End Curl 

THERMAL PROCESSING 

TRAINING 

 Damaged flange 

 Damaged end curl 

45 
Knock Down Flange 

THERMAL PROCESSING 

TRAINING 

46 
DOOP 

 

 

 

Droop 

THERMAL PROCESSING 

TRAINING 

 Smooth projection of 

the double seam below 

the bottom of normal 

seam 

 Possible causes: 

excessive body hook, 

loose first operation, 

product trapped in the 

seam, too much gasket 

material in end curl 

47 
“VEE” & SHARP SEAM 

“Vee”, Lip, or Spur 

THERMAL PROCESSING 

TRAINING 

48 
 

 

 

Cocked Body 

THERMAL PROCESSING 

TRAINING 

 Can body blank out 

of square causing 

unevenness at lap 

 Can manufacturing 

defect 

49 
 

 

 

Sharp Seam 

THERMAL PROCESSING 

TRAINING 

 Sharp edge at the top 

inside portion of seam 

 More easily felt with finger 

nail than seen 

50 
 

 

 

Cut Over 

THERMAL PROCESSING 

TRAINING 

 Seam that is sharp 

enough to fracture 

the metal at the top 

inside portion of 

seam 

 Several possible 

causes 

51 
.!Inspect for 

meta.I bacture, 

- %, p ate reduction 

------- metal fracture· 

Cutover and Fracture 

THERMAL PROCESSING 

TRAINING 

52 
'AD H AD OR R 

..---------

11 

 

 

Deadhead (Spinner) 

THERMAL PROCESSING 

TRAINING 

 Incomplete seam 

caused by chuck 

spinning in countersink 

 Caused by grease/oil on 

chuck, insufficient pin— 

gage setting, no second 

operation, insufficient 

base plate pressure 

53 
Double Seam Skip 

THERMAL PROCESSING 

TRAINING 

54 
 

 

Can Body Buckling 

THERMAL PROCESSING 

TRAINING 

 Buckled or twisted 

condition under finished 

double seam 

 Possible causes: 

excessive base plate 

pressure, chuck set too 

low 

55 
 

Misassembly 

THERMAL PROCESSING 

TRAINING 

 Referred to as 

misplaced cover 

 Can body and end 

improperly aligned in 

closing machine 

56 
JUMPED SEAM 

AREA ADJACENT 

0 lAP IMP'RESS,ION 

CAN BODY SI DE 

SEAM LAP IMPRESSION 

 

 

 

 

Jumped Seam Or “Jump-over” 

THERMAL PROCESSING 

TRAINING 

 Seam not rolled tight 

enough next to 

juncture 

 Caused by jumping 

of seaming rolls after 

passing over top of 

juncture area 

57 
 

Cut Seam 

THERMAL PROCESSING 

TRAINING 

 Outer layer of double 

seam fractured 

 Possible causes: 

damaged chuck, 

excessive seaming 

compound (gasket) 

material in end curl 

58 
 

Fractured Embossed Code 

THERMAL PROCESSING 

TRAINING 

Results when metal of can has been cut through 

at the code mark. 

59 
 

Swollen Can 

THERMAL PROCESSING 

TRAINING 

Possible Causes: 

 Under-processing 

 Post process leakage 

 Hydrogen swell 

 Incipient spoilage 

60 
 

Panelling 

THERMAL PROCESSING 

TRAINING 

Caused by inadequate 

pressure control during 

cooling in the retort 

61 
Corrosion 

THERMAL PROCESSING 

TRAINING 

62 
Internal Can Corrosion (Pinhole Development) 

THERMAL PROCESSING 

TRAINING 

63 
Damaged Coating 

THERMAL PROCESSING 

TRAINING 

64 
Open Weld At Side Seam 

THERMAL PROCESSING 

TRAINING 

65 
Dents 

THERMAL PROCESSING 

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66 
THERMAL PROCESSING 

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Evaluating Double Seam Integrity 

67 
 

THERMAL PROCESSING 

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Evaluation of Double Seam Integrity 

 Inspections must be performed by a trained 

technician 

 Inspections must include visual and teardown 

examinations 

68 
 

 

 

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Good Seam Formation 

 Cannot be judged purely by mechanical 

means or measurement 

 Requires experience and skill which cannot 

be quickly imparted 

69 
 

 

 

 

 

 

 

THERMAL PROCESSING 

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Visual Inspection Requirements 

9 CFR 431.2(b)(1) 

 At intervals of sufficient frequency, the 

container closure inspector must visually 

examine either the top seam of a can 

randomly selected from each seaming head 

or the closure of any other type of container 

being used. 

 Measurements/recordings should be made at 

intervals not to exceed 30 minutes. 

70 
Visual Can Inspection 

THERMAL PROCESSING 

TRAINING 

71 
 

 

 

 

 

 

THERMAL PROCESSING 

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Visual Inspection Requirements 

 For double-seam cans, each can should be 

examined for gross defects such as cutover or 

sharpness, skidding (deadheading), false 

seam, droop at the crossover or lap, and 

condition of the inside of countersink wall for 

evidence of broken chuck. 

 Must record the observations made and any 

corrective action taken. 

72 
Visual Can Inspection 

THERMAL PROCESSING 

TRAINING 

73 
 

 

 

 

THERMAL PROCESSING 

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Visual Inspection Requirements 

 Additional visual closure inspections must be 

made immediately following a jam in a closing 

machine, after closing machine adjustment, or 

after start-up of a machine following a 

prolonged shutdown. 

 All pertinent observations must be recorded. 

 When irregularities are found, the corrective 

action must be recorded. 

74 
 

 

 

THERMAL PROCESSING 

TRAINING 

Visual Inspection Requirements 

Regular observations must be maintained 

during production runs for gross closure defects. 

Any such defects must be recorded and 

corrective action taken. 

75 
 

 

THERMAL PROCESSING 

TRAINING 

Visual Inspection Requirements 

Immediate Corrective Action Required When: 

• Sharp cut-overs/fractures 

• Heavy cut-over at crossover 

• Severe droop at cross-over 

• VEES or LIPS 

• False seam 

• Distorted seam 

• Skidding or deadheading 

• Fractured code 

76 
 

 

 

THERMAL PROCESSING 

TRAINING 

Teardown Examination for Double-seam Cans 

9 CFR 431.2(b)(2) 

 Must be performed by a qualified individual 

 Must be performed at intervals of sufficient 

frequency on enough containers from each 

seaming head to ensure maintenance of 

seam integrity 

77 
 

 

THERMAL PROCESSING 

TRAINING 

Teardown Examinations 

Should Perform Teardown Examinations: 

 At the beginning of production 

 Immediately after severe jam 

 After adjustment or changes to seaming 

machine 

78 
 

Teardown Examinations 

THERMAL PROCESSING 

TRAINING Seam Teardown Equipment 

79 
 

 

THERMAL PROCESSING 

TRAINING 

Micrometer Measurement System 

 Three measurements made 120° apart 

excluding the side seam juncture 

 Body hook, cover hook, width, thickness, 

juncture rating (USDA) and tightness are 

required 

80 
Marking Seam for External Measurements 

THERMAL PROCESSING 

TRAINING 

81 
Can Seam Micrometer 

THERMAL PROCESSING 

TRAINING 

82 
 

 

THERMAL PROCESSING 

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Teardown Measurement Procedure 

External measurements (seam width, thickness 

and countersink) 

followed by 

Internal measurements (body and cover hooks, 

tightness, pressure ridge and juncture rating 

83 
Cover Hook Wrinkle 

THERMAL PROCESSING 

TRAINING 

84 
TIGIHTNESS (WRINKLE) RATING IN% 

100 90 80 70 60 50 

I 

40 30 20 10 0 

- - -

FORMER #0 

WR INKLE 

#1 LESS THAN 50% WRINKLE"' #3 

Cover Hook Wrinkle Rating 

THERMAL PROCESSING 

TRAINING 

85 
Pressure Ridge 

THERMAL PROCESSING 

TRAINING 

86 
 

 

THERMAL PROCESSING 

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Optical Measurement System 

 Cuts should be from at least 2 different 

locations 

 Body hook, overlap, thickness, tightness, and 

juncture rating are required 

87 
Seam Saw 

THERMAL PROCESSING 

TRAINING 

88 
Cutting Cross Section of Double 

End Seam With Seam Saw 

THERMAL PROCESSING 

TRAINING 

89 
Seam Projector 

THERMAL PROCESSING 

TRAINING 

90 
MEASURING DOUBLE SEAM ON SEAM PROJECTOR

Measuring Double Seam on Seam Projector 

THERMAL PROCESSING 

TRAINING 

91 
 

 

 

THERMAL PROCESSING 

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Interpretation of Inspection Results 

 Resample if results are unsatisfactory, then 

assess severity of defect 

 Timeliness of corrective action depends upon 

severity of defect 

92 
 

THERMAL PROCESSING 

TRAINING 

Teardown Inspection Results 

If critical factor measurements are beyond 

adjustment tolerance limits, immediate 

adjustments must be made. 

93 
 

 

THERMAL PROCESSING 

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Teardown Inspection Results 

Shut the line down immediately and adjust 

double seamer if: 

 Cut overs 

 False seams 

 Severe droops 

 Skidding/deadheading 

 Fractured embossed code 

94 
 

Records 

THERMAL PROCESSING 

TRAINING 

Can Seam Evaluation: 

 All visual 

examinations and 

measurements must 

be recorded 

 Must record defects 

and steps to correct 

problems 

95 
 

 

THERMAL PROCESSING 

TRAINING 

Evidence of Container Defects 

Needed for Regulatory Action 

Plants Need Documentation when: 

 Seam defects occur 

 Product contains viable microorganisms or is 

spoiled 

 Deviations from Part 431 

96 
 

 

THERMAL PROCESSING 

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Regulations and Guidelines 

 9 CFR 431.2—LACF Regulations 

 Reference Manual—Guide to Inspection of 

LACF Manufacturers, Part 3, Container 

Integrity 

97 
Questions 

THERMAL PROCESSING 

TRAINING 

Questions?

98