CA2030811A1

CA2030811A1 - Container seal testing method and system and testable container structure

Info

Publication number: CA2030811A1
Application number: CA002030811A
Authority: CA
Inventors: Christopher J. Farrell
Original assignee: Individual
Current assignee: Rexam Beverage Can Co
Priority date: 1989-04-05
Filing date: 1990-04-05
Publication date: 1990-10-06
Also published as: EP0436676A1; AU635018B2; EP0436676A4; KR920700398A; IL94020A; IL94020A0; AU5433490A; JPH04503113A; WO1990012302A1

Abstract

ABSTRACT

Methods and systems for testing the seals of container lids to the top portion of container bodies are provided. Testing the integrity of the seal is achieved by injecting fluid under pressure under the lid portion of the container and detecting if the lid bulges outwardly with respect to its at-rest position prior to injecting fluid. A
container adapted to having the seal tested for leakage is also provided.

Description

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ll I CONTAINER SEAL TESTING METHOD AND SYSTEM
AND TEST~E~LF~ CONTAINER STRUCTURE

; sackqround of the Invention Field of the Invention The present invention relates to the testing of the . integrity of the seal securing a container lid or closure on a container body and a container structure whose seal is adapted to be tested.
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Description of the Related Art At the present time comestibles such as yogur~, ¦
cheese spread or other perishable items, are often packed in containers of various types, such as bowls, trays and other containers which are opened by peeling off their lids. The containers may have any shape and configuration, for example, cylindrical, rectangular, oval, oblong, etc. One type of container has a bowl-like body, a bottom wall and a flexible lid.
The lid usually is, but need not be a multl-layer sheet or laminate, pre erably flexible in the form of a thin, flexible disc. The lid may consist of layers of p'as_ic which are laminated on opposite sides of a layer o' aluminum foil.
The bottom layer of the lid is usually a heat-sealable or adherable plastic. The cont.ainer body is filled and its lid is placed on a top surface usually the flange, of the :
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¦l container body. The outer peripheral portion of the lid, at its bottom face, is hermetically sealed or adherecl to the I flange.
¦ If the lid-flange seal has even a tiny hole, void or I interruption micro-organisms may enter the container and spoil ¦l the food or other perishable product. Such spoilage may cause ¦i consumers to reject the brand of the product in the future.
Il The consumer may resent having the inconvenience of discarding ¦¦ the container or returning it to the store. In addition, the - li spoiled food, if eaten, may cause illness, and may also ~I seriously damage the reputation of the manufactu_er and/ox j~ food producer or packer.
i! Food manufacturers are aware of the danger of , spoilage due to seals which are not hermetic, and seek to i prevent such faults by quality inspection of their filled i containers. Generally, such quality inspectlon in the case of high acid food products includes testing for faulty seals by ~; pulling a few containers from the production line and visually testing them for leakage. That type of quality control, based -on a statistically meaningful random sample, is well adapted to detect machine errors which cause faulty seals on all the containers in a product~on run. However, statistical quality control is not well adapted to detect random faulty seals, for example, a pin hole in the seal of one container out of a 1~ production run of 10,000 containers.

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It is reali~ed that it would be preferable for high I acid foodstuffs and it is generally required for low acid l sterilized, i.e., retorted shelf-stable foodstuffs, to test i each and every container, which is called ~100~ testing~. The ideal is to test each container twice, called "200~ testing".
Such testing for retortable containers would preferably be accomplished before and after the filled, sealed container and ¦ its contents are sterilized. For filling, sealing and packing .! operations high speed is preferred. To be compatible with i such filling, sealing and packaqing systems, seal integrity testing systems should run at similar high speeds.
The seal area of containers of low acid foods having ~¦ a heat-sealed lid are presently being individually visually 100% inspected rather than automatically tested by machine, due to the difficulty of such testing at the requisite high ¦ speeds of production. Several leak detection systems have ¦ been in development to solve the problem of high speed automatic testing of package seal integrity in a non-destructive way. Electronic, thermal and pressure differential systems have been proposed. However, for one reason or another there are problems with each Oc these systems and none is totally successful in addressing all the needs of a fullv commercial testing system. The system should be fast and must be sensitive, non-destructive, automatic, reliable and accurate.

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. -~: ' Objectives and Features of the Invention It is an objective of the present invention to l provide a system and method of testing the previously dis- I
,j cussed containers, particularly the seal of lids to container bodies in which the seal integrity of every filled container is tested at least once, ideally twice, i.e., 200% testing.
It is a further objective of the present invention that the seal testing be accomplished at a sufficiently high speed so that such testing is fully compatible with the speed of production of the filling operation. ~~
It is a further objective of the present invention that such testing not add appreciably to the per-unit cost of production.
It is a further objective of the present invention that such testing provide a fully accurate test oF each seal and ~e of sufficient accuracy to detect tiny openings through the seal of even pin-hole size.
't is a still further objective of the present invention to provide a container body construction which is particularly adap ed to the testing systems and methods of the present invention.
Tt is a stili further objective -of th.s invention to p ovide an on-line, non-destructive system and method for testing the seal integrity of plastic containers having sealed or adhered covers or lids.

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It is another objective of this in~ention to provide i' the above mentioned method and systems which are automated and I preferably effected at high speeds compatible with high ¦ container fill and seal, line speed.

, Summary of the Invention 'l In accordance with the present invention, there are ;¦ provided methods and systems for testing the seal of container ~1 lids to the top portion preferably a top surface, e.g., lip or ! flange or both of container bodies. Each container, after it is filled and the cover is secured or sealed to the flange, is tested once, optionally twice, i.e., 200~ testing. If any holes are found which extend through the seal, in either of ! the tests the container is rejected.
The container body can be made of any suitable material(s) and can be of any suitable design, shape or configuration and has an upper terminal end portion usually defining the mouth of the container, preferably having an out-wardly extending flange which extends from its top lip. The te-minal end portion may be of any suitable shape, for example, cylindrical, rectangular or oval. A portion of the term nal end portion of the container body preferably a top flattened surface of the lip or flange, is secured to the lid.
The lid or cover can be of any suitable materials or I cons~ruction and preferably comprises a plastic-containing ¦ laminar or flexible sheet. An example of such a multi-layer ?' ,- ' ''.,' .:

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lid would comprise, a bottom layer of plastic polymeric , material for heat-sealing, a core layer of a metal foil and a top layer of plastic polymeric material which preferably may be printed upon. The upper terminal end portion of the I container body has means adapted for the testing of the j present invention. In preferred embodiments, the lip or ¦ flange, preferably the latter, has means for introducing a ¦~ testing medium to or into the seal between the lid and the j surface of the terminal end portion of the container body, ¦i e.g., a peripheral channel which communicates with the I ¦
! lidJseal area of the container body, and means for introducing ,¦ a testing medium into the peripheral channel. The introducing , means can be at least one, preferably two passageways, routes j or openings extending from and through an outer portion, edge or surface of the terminal e~d portion, for example, from and ¦ through the outer side wall of the flange and leading to and ¦ communicating with the channel. In one embodiment each 1 opening is a radially aligned bore, i.e., a round hole, and in ¦ another embodiment each opening is a radial groove.
, The peripheral channel in the lip or flange forms a ! passagewa~ which extends about the inner annular portion Oc the lid-flanse seal. A suitable fluid is pumped, at high pressure, through the routels) or opening(s) into the channel.
_f there is a leak in the seal, the fluid will pass through the leak and into the container, expanding (bulging) the cover upwards. That expansion is detected by suitable means such as " ~

j a linear transducer and the containers whose covers flex or ¦ bulge upwards under the fluid pressure of the test are by suitable means identified and rejected.
The system includes a high-speed automatic machine ! which, in sequence, vertically moves a clamping ring to clamp, for example, the outer portion of the rim or flange of a I¦ sealed container, injects gas through the opening, and then ,¦ lifts the clamp-ng fixture. The faultily sealed container(s) ¦l is or are then rejected from the line. I

jl The above and other objec~ives of the present !¦ invention will be apparent from the detailed description ,¦ provided below, which should be taken in conjunction with the jl accompanying drawings.
ll l Brief DescriDtion of the Drawings Figure 1 is a top plan view of a container body without a lid, showing the preferred first embodiment of the ; present invention;
Fi~ure 2 is a side cross-sectional view taken along line A-A of Figure l;
Figure 3 is a greatly enlarged top sec'ional plan view of a portion of the container body flange shown within the dash-dot circle of Figure l;
Figure 4A is a cross-sectional view ta~en along line B-B of Figure 3;

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' . ~`. , : ' : ~ ' "' ~ .. ' :,, : . . ~', ¦ Figure 4B is a cross-sectional view similar to ¦ Figure 4A but with the lid sealed in place;
! Figure 4C is a cross-sectional view taken along line C-C of Figure 3- !
~¦ Figure S is a side plan view of a portion of a !! flange showing a second embodiment of the present invention;
¦¦ Figure 6 is a top plan view, similar to Figure 3, il but of the second embodiment of the present invention shown in ¦¦ Figure S;
i Figure 7 is a vertical sectional view of à port~on _.
of a flange taken along line D-D of Fig. 3 showing the first embodiment of the invention;
. Figure 8A is a vertical cross-sectional view of a il portion of an apparatus for testing the seal integrity of a ~! plastic container in accordance with the present invention;
¦ Figure 8~ is an enlarged view of a portion of the apparatus of Figure 8A with a container in the apparatus;
I Figure 9 is a vertical cross-sectional view of a ! second alternative appa-atus for testing the seal integrity of.
a plastic container in accordance with the present invention, with a cross-sectional view of a portion of a container taken along line E-E of Figure 10;
Figure 9A is an enlarged vertical cross-sectional view of the embodiment of Fig. 10 taken along line F~F of Fig.
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,,'/~:.)i,l ;~ ' igure 9~ is an enlarged vertical cross-sectional view of an altered embodiment of Figure 9A;
Figure 10 is a top plan view, enlarged, of an ~l optional flange structure of the flange shown in Fig. 9;
Figure 11 is a side cross-sectional view of a third alternative apparatus for testing of the seal integrity of a container and of another embodiment of the container structure;
Il Figure 12 is a side plan view of a portion of the il container shown in a cross-sectional view in Figure 11; ~
ll Figure 13 is a bottom view of a portion of the !i apparatus shown in Figure 11; and ! Figure 14 is a vertical cross-sectional view of a ! fourth alternative apparatus for the testing of the seal j integrity of a container.
Figure 15 is another embodiment like Figure 9A where the lid is sealed to the inside surface of the container side wall.

Brief Description of the Preferred Embodiments As shown in Figures 1-4B, the preferred container of ; the present in~ention includes a flexible lid 10 (Figure 4B) and a container body 11 here shown in the form of a bowl or tub. The container body 11 is preferably formed of one or more suitable plastic resin(s) and has a frustoconical or downwardly and inwardly tapered side wall 12 (round in horizontal cross-sectlon) and an integral bottom wall 13.
Alternatively, and not shown, the side wall may be of any r ` .;

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suitable shape, for example, squared, rectangular, cylindri-~l cal, rounded, barrel-like, etc. in cross section. The upper terminal end portion of the container body has an integral top ~! edge, here shown as comprised of an annular flange or lip 15, which extends radially outward from the top opening 16 of the container body 11.
The flange 15 has a flat top face 17 and includes !l means for introducing a testing medium into or against the ! seal between the lower face of the lid and top face 17, the ,' means being shown as a peripheral or annular channel 18 which~
¦ can but need not be, a groove or score line, which divides face 17 into an inner annular portion 1~ and an outer annular portion 20. The bottom face of lid 10 is secured preferably sealed or adhered, at least to the inner annular portion l9.
Regardless of whether the seal also extends about the outer annular portion 20, only the seal integrity of the seal about the inner portion 19 is tested.
The outer portion 20 of the flange 15 includes means for introducing a testing medium into channel 18. Such means can be a single route or opening but, as here shown, pref-erably it includes two routes or openings 23A, 23B which extend radlally inward from and through the outer side face or edge 22 of the flange and communicate with channel 18.
Openings 23A, 23B need not be positioned as shown, i.e., 180 apart on opposite sides of the flange. They mav be placed in any suitable location or arrangement. The openings 23A, 23B
can be of any suitable type, shape, configuration or ' '' '~

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direction. Preferably they are grooves, slits, cuts or '! channels formed or cut in the flange and preferably they are il radial and perpendicular to the imaginary central axis 41 of ¦ the container body.
In the embodiment of Fi.gures 5 and 6, bores 25A, 25B
! (only 25B is shown) are employed as the openings instead of the grooves 23A, 23B. The grooves 23A, 23B are easier to form 'l in the container body, but should be narrow enough to prevent .j passage of the testing gas between the lid and the clamping ring into the testing chamber, especially when the lidstock is - i thin. The test gas TG introduced through the openings is distributed by channel 18 around and tests the entire periphery of the seal 21 at or between the bottom face of the lid 10 and the flange inner annular portion 19, (See Figure 4B)-In both e~bodiments, when gas TG is injected intothe channel 18 through the openings, the gas will travel through and completely around channel 18 and the seal 21. If there is any hole, void or interruption throush seal 21, even .
a pin-prick size hole or a weakness in the seal which will not withstand the gas pressure, the gas will enter the container and expand, bulge or move the cover upwardly. Such bulging, expansion or movement of lid 10 will be sensed by suitable means, for example, by a linear proximity transducer 26. The defective con'ainer is identified or no4ed by suitable means.
Me~ns, for exampie and preferably, a computer-based digital memory will, in effect, note and remember the position of the ,;~.. , -',,.

~ ~J ~ ~ ~3 identified defective container in the production line and reject it from or after it exits from the testing station.
The testing apparatus, shown in Figure 8A, is a machine to automatically, and at high speed, provide a 100~ i seal integrity test. The embodiment of Figure 8A is only ,1 illustrative of one possible tlesting machine design. Since ¦¦ the testing station should be integrated into or used in or ! with different types of production lines for different con-, tainers and products, it may be constructed using various !i mechanisms. In all cases, however, it will be adapted to --~
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!i provide a 100~ test and preferably utilized twice or at two ¦ locations for a ~00~ test, by injecting gas, under pressure, through the two openings. If only one opening is used, and that opening is blocked, or there is a blockage in the channel ,¦ at the junction of the channel and the opening, the test may appear satisfactory, i.e., a false positive reading because the cover does not bulge, and yet there may be a laak throuyh .~-,, the seal 21. That type of false positive is avoided b~y introducing the gas, simultaneously, through two or more widely separated openings. The gas enters the channel through the two openings each time the seal in egrity is tested. The openings also permit air to ente. and diffuse through the channel acter the container is packed. This tends to help keep the channel dry.
As shown in Figures 8A and 8B, the container, after being filled and having the lid 10 heat-sealed or otherwise . .' ~ ,~,.

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secured or adhered to the flange 15, is automatically posi- j tioned in a suitable testing apparatus by a conventional , transfer mechanism (not shown). In the apparatus, the bottom ! face 29 of the flange 15 rests on the fixed support ledge 30.
~ A vertically movable annular clamping ring 31 is then brought I down to clamp flange outer annular portion 20, and partially ,, but not completely over clamp channel 18, between the clamping ! ring 31 and ledge 30~ The use of O-rings 43 and 44 provides a i gas tight seal and forms an annular gas chamber 32. The gas ! inlet 33 is connected through a solenoid-operated valve~to a~

! high pressure gas supply (not shown). After the container 11 I is clamped in position but before the pressure chamber 32 is pressurised, the proximity transducer 26 is read. At a parametric time during or after pressurization of chamber 32, !! the transducer 26 is read again. If a difference greater than !l a predetermined amount is sensed then this container will be earmarked for automatic reject-on by simple means (not shown) after pressure release and the lifti~g of clamping ring 31.
In the embodiments of Figures 1-8, a circumferen.ial channel 18 with openings 23A, 23B or 25A, 25B leading to circumferential channel 18 is employed in the flange 15 of container 11. ~he circumferer.tial channel 18 may collect food due ~o splashing or otherwise during the filling operation, or collect dirt during processing or storage. This is unsightly '¦ and unhygenic. One possible and preferred solution is in a ,~ secondary operation, after testing, to cut of f flange portion i il 20 with or without, preferably with all of the residual portion of the channel, that is the portion of the flange which forms the bottom of channel 18. To avoid this extra operation, an embodiment which dispenses with the circumferential channel 18 is desirable and preferred. One such embodiment is shown in Figures 9-10 in which the radial i slots 23C penetrate further in towards the container axis 41 and further than the inner edge of clamping 31. In Figure 9, ¦ a vertical section is shown taken along F-E Figure 10 of such i a container embodiment here shown in a testing apparatus~ ~
!I Test gas conveyed inwards by c~annel 23C moves around the il circumference of the container in the natural channel provided by unsealed area of lid 10 between portions 19' and 20', of Fig. 10.
The embodiment, illustrated in Figures 11, 12 and 13 does not use a peripheral channel or one or more individual grooves. In this embodiment, the flange 15" has a raised inner annular portion 19~ and a depressed or offset outer annular portion ~0". This ou~er portion can merely be a slopinq outer portion or edge as shown in Figure 11. The testing apparatus, par'lv shown in Figure ll, operates in the same manner as the apparatus of Figure 8A. The container is t-ansferred into the apparatus with its flange 15" positioned on fixed ledge 30". The lid 10', about its outer edge, preferably is held by vacuum up against the clamping ring 31' ; when the clamping ring 31' is lowered. The vacuum is applied, :' ' G
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,' ~, 3 ,3 ~ , ,j for example, through holes 46 ln clamping ring 31'. The ¦ testing gas TG, shown by arrow TG, from chamber 32" enters the gap 47 between the bottom face of the outer edge portion of 1 lid 10' and outer depressed annular portion 20". The gas ¦ tests the peripheral seal holding cover 10' to the inner ¦ annular portion l9n. As previously mentioned, preferably the ¦ seal is tested again at another location. After the seal ! integrity tests are completed, the container preferably is i transferred to another station (not shown) where the bottom il face of cover lO' at its outer edge may be secured or sealed ¦1 to, for example, the outer annular portion of the flange, here j shown as 20 n, ¦ The embodiment illustrated in Figure 14 uses a ¦¦ conventional container having container body 11 n t flange I portion lS" and lid 10" whose bottom face, at its outer i! peripheral edge, is sealed to the top flat face of flange lSn.
The flange 15" does not have a channel, groove or hole. The integritv of the seal is tested by gas TG when the clamping ring ~l" is lowered near to or onto the lid 10" and a vacuum ~i is applied to hole 46". An outer chamber 32" is temporarily I formed by the clampins -ing 31". When the gas from ou'er chamber i2"space is pressurized, ring 31" is li'ted slightly.
~ If there is a hole in the seal, gas will enter the container !, and cause the lid 10" to bulge outward, activating a transducer (not shown). The clamping ring, of the type shown in Figure 13, uses vacuum V. After the seal integrity is tested the vacuum is shut off, the .: I
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rin~ 31" is lifted frorn the lid lO~ and the container is I¦ removed from the testing apparatus.
,l¦ Modifications may be made in the above-described ¦¦ embodiments within the scope oi- the claims. For example, the container body shown in the drawings is bowl-shaped. However, I¦ alternatively, the container body may have arcuate or rounded ¦¦ portions or straight or flat sides and be triangular, rectangular, or have more than four side walls, As additional : examples, the container body may be a right-sided cylinder, or ' .
cone shaped. It may be formed from one layer or -- --~j multiple-layers of plastic or plastic and foil. It could also !I be a suitable composite material.
The flange 15 is shown, in the drawings, as a flat 1 annular member, having a channel therein, which extends '! horizontally outwardly from the top of the container body, perpendicular to the imaginary axis of the container body.
i Alternatively, and not shown, the flange may extend outwardly at an incline or obtuse angle to the axis, or the flange may be parallel or downwardly angled relative to the axis, for example, an upward or downward extension o~ the side wall of the container body. The flange may also extend inwa-d, i.e., toward the axis.
The embodiments, described above, show the flange 15 ; as an integral portion of the container body. Alternatively, and not shown, the flange may be a separate ring which is welded or otherwise connected to the body.

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The container body terminal end portion need not Il include a flange. Instead, the channel 18 may be formed in ¦l the upper edge or lip of the container. For that purpose, the ¦¦ lip may be thickened compared to the container body's side ¦l wall.
he lid or cover 10 is described, in one embodiment, 11 as a multi-layer flexible sheet. The cover may be of a single ¦~ layer. It may be semi-rigid and need not be formed using a !l plastic film or laminate. It may be injection molded. The j cover, however, must be able to flex, bend, bulge or expand 1 due to the pressure o~ th~ testing gas to an extent as to be ¦! detectable by the testing apparatus employed and properly 1 attributable to a seal leak.
i The channel 18 and the grooves are shown as being ! U-shaped with square bottom corners. Alternatively, and not jl shown, the channel and grooves may have other cross-sectional ¦ shapes including rectangular, square, hemi-spherical and V-shaped. One peripheral channel is shown, however two or more channels, each communicating through grooves or bores to the side wall, may be utili~ed. There may be many grooves, openings or bores in the flange outer annular portion.
In the above-described embodiments, the cover is heat-sealed or otherwise adhered to the flange. Other sealing methods may be used, for example, a plastic cover may be spin ` welded to a container body, or the seal may be 'ormed ultra--~ sonically. The adhesive, for example, may be a heat set or a i ~old_se~.~

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The gas used in the test is preferably air, pref-~~ erably ho~ air, to help dry the channel, or it may be an inert ¦¦ gas such as nitrogen, helium or argon.
Figure 15 is a ~ertical section through an alternate ,¦ embodiment of the container of this invention whose lid is `' sealed to the inside surface oE the container side wall. More Il particularly, Figure 15 shows a container 61 having a side ,¦ wall 6 , an outwardly flared or stepped marginal end portion i! 64 having a passageway opening 63 therethrough. The container l! is sealed by a lid 66-recessed into the container body and Il sealed about its peripheral marginal edge portion at 68 (lower !i seal) and 69 (upper seal). The upper seal is optional. In ! this embodiment the testing fluid is injected through opening 63 and tests seal 68.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A container comprising a container body and a lid sealed thereto, said container being adapted to have said seal tested for leakage, wherein:
said container body has a side wall, a bottom wall, a top opening and a top peripheral surface extending from about said top opening;
said top surface having a top face, divided into inner, central and outer peripheral portions; said lid being sealed about said container top surface by a would-be hermetic seal about said inner and outer peripheral portions, and at least one fluid passageway opening in said container in communication with the unsealed central peripheral portion and the ambient atmosphere exterior of said container.

2. A container according to claim 1 wherein said passageway opening is in said container body, preferably in the form of a groove or bore.

3. A container comprising a container body and a lid sealed thereto and having a marginal edge portion, said container being adapted to have said seal tested for leakage, wherein:
said container body has a side wall, an imaginary axis, a bottom wall, and a top peripheral surface extending outwardly from, about and defining a top opening;
said top surface having a top face, a side surface and a peripheral channel in said top surface or an annular depressed outer surface area; said lid being sealed to said container top surface by a would-be hermetic seal about said top surface inward of said channel or depressed outer surface area;
in conjunction with said channel said top peripheral surface outward of said channel having at least one opening leading from said side surface to and communicating with said channel, and in conjunction with said channel or said depressed outer surface area, said lid marginal edge portion extending outwardly beyond said channel or outwardly over said depressed outer surface area.

4. A container body as in claim 1 or 3 wherein there are two openings preferably in the form of bores or grooves which extend radially inwardly in relationship to said axis, and preferably are positioned opposite from each other separated by about 180°.

5. A container body according to claim 1 or 3 wherein said top peripheral surface comprises a flange having at least one opening leading from said side surface to and communicating with said channel.

6. A container as in claim 1 or 3 wherein said lid is sheet or a multi-layer laminate which includes a layer of metal foil.

7. A container comprising a container body and a lid sealed thereon said container being adapted to have said seal tested for leakage, comprised of:
a flexible lid having a marginal edge portion, a top exposed face and a bottom face whose marginal edge portion includes a sealable plastic material;
a container body;
said container body comprising a bottom wall and a side wall having a top terminal end portion which at least partially defines a top opening in said container body;
said seal being the seal of a portion of said top terminal end portion of said side wall to said lid marginal edge portion, said side wall terminal end portion having at least one opening therethrough above said seal.

8. A container according to claim 7 wherein there are two of said seals, one disposed axially lower than the other, said opening(s) being positioned between said seals.

9. A container according to claim 8 wherein said seals are between said lid marginal edge portion and the inside surface of said side wall terminal end portion.

10. The method of testing the integrity of the seal of a lid to a container, comprising the steps, in sequence, of:

(a) providing a filled container body having a side wall, a bottom wall, a top opening and a top peripheral surface extending from about said top opening;
said top surface having a top divided into an inner peripheral portion and preferably an outer peripheral portion preferably comprised of an unsealed area, or a depressed annular peripheral portion or an annular channel with at least one fluid passageway opening leading from the outside of the container through said container side wall to said annular channel.

(b) sealing a flexible lid having a marginal edge portion onto said container top surface inner peripheral portion by a would-be hermetic seal and not sealing said lid outer marginal edge portion to said top surface or to said outer peripheral portion;

(c) applying a vacuum clamping ring to the top face of the lid at said marginal edge portion; and (d) testing the integrity of said seal by injecting a fluid under pressure under the vacuumed-clamped lid marginal edge portion about said outer peripheral portion or by injecting said fluid through said at least one opening if there is a said annular channel, and detecting if the lid bulges outwardly with respect to its at-rest position prior to injecting said fluid, due to fluid penetrating said seal into said container.

11. A method as in claim 10 wherein said detection occurs by detecting a bulge in the lid caused by leakage of gas into the container.

12. A method as in claim 10 wherein said container body has two of said openings and the injection of fluid is simultaneously through both openings.

13. A method as in claim 10 wherein said container body has two of said openings and including the further step of drying said channel.