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US4620402A Expired / Lapsed US ⏱️ 0.0 years remaining

Penetrating roofing fastening and sealing system

Assignee: Bridgestone Firestone Inc
•
Filing: 1985-01-22
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Granted: 1986-11-04
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Expires: 2005-01-22
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Abstract

Abstract A penetrating roofing fastening and sealing system for securing a flexible sheet, having a plurality of apertures, to the upper surface of a roof via the use of a plurality of spaced penetrating fastening and sealing devices, each of which includes upper and lower retainers, wherein the latter are anchored to the roofing surface and the elastomeric sheet has a continuous peripheral portion, adjacent each aperture, confined between opposing flange portions of the upper and lower retainers, the retainers being clamped together in a sealing relationship with the interposed sheet portion. A method for securing and sealing the flexible sheet to the roofing substrate is also presented.

Inventors

  • 👤 Heinz W. Beneze

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-01 20:52
CPC Classifications
E; E04; E04D; E04D5/00; E04D5/14; E04D5/144; E04D5/145

Claims Analysis

Total Claims: 26
Claim 1
Independent Claim 289 words
A penetrating, fastening and sealing device for both mechanically securing a flexible elastomeric sheet, of a range of thicknesses, to the upper surface of a roof, and sealingly engaging said sheet, wherein said sheet is provided with an aperture of a first predetermined area and shape, said device comprising a combination: (a) a rigid lower retainer, having an area greater than said sheet aperture area, adapted to be passed through said sheet aperture so as to underlie and completely cover said aperture, said lower retainer having a bottom surface and an upper surface, with the center portion of the lower retainer being stepped having an area and shape generally corresponding with those of said sheet aperture and having an outer peripheral surface adapted for locating the corresponding peripheral wall portion of the sheet that defines said sheet aperture, said upper surface of the lower retainer further including a continuous outer flange portion adapted to underlie a corresponding portion of a lower surface of said sheet, and said bottom surface of the lower retainer overlying said upper roof surface and said center portion being aligned with and extending into said sheet aperture; (b) means for anchoring aid lower retainer to said roof upper surface; (c) a rigid upper retainer, having an area greater than said sheet aperture area, adapted to overlie and completely cover said aperture, thereby confining a continuous peripheral portion of said sheet, bordering said sheet aperture, between said upper and lower retainers; and (d) separate fastener means engageable with a center portion of the upper retainer and extending from said upper retainer into a center portion of the lower retainer for drawing said retainers perpendicularly against each other to sealingly secure the elastomeric sheet between said retainers.
Claim 2
Dependent Claim 289 words
A penetrating, fastening and sealing device for both mechanically securing a flexible elastomeric sheet, of a range of thicknesses, to the upper surface of a roof, and sealingly engaging said sheet, wherein said sheet is provided with an aperture of a first predetermined area and shape, said device comprising a combination: (a) a rigid lower retainer, having an area greater than said sheet aperture area, adapted to be passed through said sheet aperture so as to underlie and completely cover said aperture, said lower retainer having a bottom surface and an upper surface, with the center portion of the lower retainer being stepped having an area and shape generally corresponding with those of said sheet aperture and having an outer peripheral surface adapted for locating the corresponding peripheral wall portion of the sheet that defines said sheet aperture, said upper surface of the lower retainer further including a continuous outer flange portion adapted to underlie a corresponding portion of a lower surface of said sheet, and said bottom surface of the lower retainer overlying said upper roof surface and said center portion being aligned with and extending into said sheet aperture; (b) means for anchoring aid lower retainer to said roof upper surface; (c) a rigid upper retainer, having an area greater than said sheet aperture area, adapted to overlie and completely cover said aperture, thereby confining a continuous peripheral portion of said sheet, bordering said sheet aperture, between said upper and lower retainers; and (d) separate fastener means engageable with a center portion of the upper retainer and extending from said upper retainer into a center portion of the lower retainer for drawing said retainers perpendicularly against each other to sealingly secure the elastomeric sheet between said retainers.
Claim 3
Dependent Claim 58 words
The penetrating, fastening and sealing device of claim 1 wherein said upper retainer is of a third predetermined area and shape, said upper retainer having an upper surface and a planar lower surface, with the center portion of the upper retainer being stepped having an area and size generally corresponding with those of said lower retainer center portion.
Claim 4
Dependent Claim 59 words
The penetrating, fastening and sealing device of claim 2 wherein said upper retainer center portion also has an outer peripheral surface adapted to matingly engage with the outer peripheral surface of said lower retainer center portion, said lower surface further including a continuous outer flange portion adapted to overlie a corresponding portion of the upper surface of said sheet.
Claim 5
Dependent Claim 60 words
The penetrating, fastening and sealing device of claim 3 wherein said upper retainer lower surface flange portion is of the size and shape so as to overlap, at least a circumferentially continuous portion, of said lower retainer outer flange portion to thereby confine said continuous portion of said sheet, bordering said aperture, between said upper and lower retainer flange portions.
Claim 6
Dependent Claim 32 words
The penetrating, fastening and sealing device of claim 1 wherein said lower retainer stepped central portion is provided with at least two circumferentially spaced apertures adapted for receiving said means for anchoring.
Claim 7
Dependent Claim 39 words
The penetrating, fastening and sealing device of claim 1 wherein said lower retainer stepped central portion is provided with a threaded central aperture adapted to cooperate with said separate fastener means for drawing the retainers perpendicularly against each other.
Claim 8
Dependent Claim 40 words
The penetrating, fastening and sealing device of claim 1 wherein said upper retainer also includes a central boss portion having a stepped central aperture which is adapted to receive separate fastener means for drawing the retainers perpendicularly against each other.
Claim 9
Dependent Claim 23 words
The penetrating, fastening and sealing device of claim 1 wherein said upper retainer is provided with a plurality of radially directed stiffening ribs.
Claim 10
Dependent Claim 428 words
A penetrating, fastening and sealing device for both mechanically securing a flexible elastomeric sheet, of known thickness, to the upper surface of a roof and sealingly engaging said sheet, wherein said sheet is provided with an aperture of a first predetermined area and shape, said device comprising in combination: a rigid lower retainer; means for anchoring said lower retainer to said roof upper surface; a rigid upper retainer adapted to mate with said lower retainer; and means for clamping said upper and lower retainers together, (a) said lower retainer being of a second predetermined area and shape, said second area being greater than said sheet aperture area, said lower retainer having a planar bottom surface and a planar upper surface, a stepped center portion thereof having an area and shape substantially corresponding with those of said sheet aperture, said center portion also having an outer peripheral surface adapted for locating the corresponding peripheral wall portion of the sheet that defines said aperture, said upper surface further including a continuous outer flange portion adapted to underlie a corresponding portion of the lower surface of said sheet, said lower retainer being adapted to be passed through said sheet aperture, via temporary elastic deformation of said sheet adjacent said aperture, so that said planar bottom surface overlies said roof upper surface and said stepped center portion is aligned with said sheet aperture; (b) said upper retainer being of a third predetermined area and shape, said third area being greater than said sheet aperture area, said upper retainer having an upper surface and a planar lower surface, a stepped center portion thereof having an area and size substantially corresponding with those of said lower retainer center portion, said upper retainer center portion also having an outer peripheral surface adapted to matingly engage with the outer periheral surface of said lower retainer center portion, said lower surface further including a continuous outer flange portion adapted to overlie a corresponding portion of the upper surface of said sheet, said lower surface flange portion being of a size and shape so as to overlap, at least a circumferentially continuous portion, of said lower retainer outer flange portion and thereby confining a continuous portion of said sheet, bordering said aperture, between said upper and lower retainer flange portions; (c) said clamping means including separate fastener means engageable with a center portion of the upper retainer and extending from said upper portion into a center portion of the lower retainer for drawing said retainers perpendicularly against each other to sealingly secure the elastomeric sheet between said retainers.
Claim 11
Dependent Claim 428 words
A penetrating, fastening and sealing device for both mechanically securing a flexible elastomeric sheet, of known thickness, to the upper surface of a roof and sealingly engaging said sheet, wherein said sheet is provided with an aperture of a first predetermined area and shape, said device comprising in combination: a rigid lower retainer; means for anchoring said lower retainer to said roof upper surface; a rigid upper retainer adapted to mate with said lower retainer; and means for clamping said upper and lower retainers together, (a) said lower retainer being of a second predetermined area and shape, said second area being greater than said sheet aperture area, said lower retainer having a planar bottom surface and a planar upper surface, a stepped center portion thereof having an area and shape substantially corresponding with those of said sheet aperture, said center portion also having an outer peripheral surface adapted for locating the corresponding peripheral wall portion of the sheet that defines said aperture, said upper surface further including a continuous outer flange portion adapted to underlie a corresponding portion of the lower surface of said sheet, said lower retainer being adapted to be passed through said sheet aperture, via temporary elastic deformation of said sheet adjacent said aperture, so that said planar bottom surface overlies said roof upper surface and said stepped center portion is aligned with said sheet aperture; (b) said upper retainer being of a third predetermined area and shape, said third area being greater than said sheet aperture area, said upper retainer having an upper surface and a planar lower surface, a stepped center portion thereof having an area and size substantially corresponding with those of said lower retainer center portion, said upper retainer center portion also having an outer peripheral surface adapted to matingly engage with the outer periheral surface of said lower retainer center portion, said lower surface further including a continuous outer flange portion adapted to overlie a corresponding portion of the upper surface of said sheet, said lower surface flange portion being of a size and shape so as to overlap, at least a circumferentially continuous portion, of said lower retainer outer flange portion and thereby confining a continuous portion of said sheet, bordering said aperture, between said upper and lower retainer flange portions; (c) said clamping means including separate fastener means engageable with a center portion of the upper retainer and extending from said upper portion into a center portion of the lower retainer for drawing said retainers perpendicularly against each other to sealingly secure the elastomeric sheet between said retainers.
Claim 12
Dependent Claim 30 words
The penetrating, fastening and sealing device of claim 9 wherein the flange portions of said upper and lower retainers are parallel with each other and said lower retainer bottom surface.
Claim 13
Dependent Claim 35 words
The penetrating, fastening and sealing device of claim 9 wherein the opposing surfaces of said upper and lower retainer flange portions are parallel with each other but angled relative to the lower retainer bottom surface.
Claim 14
Dependent Claim 71 words
The penetrating, fastening and sealing device of claim 9 wherein the opposing flange surfaces of said upper and lower retainers are parallel to one another, one of said surfaces being provided with a plurality of radially spaced circularly extending concentric annular grooves while the other of said surfaces is provided with a similar plurality of corresponding raised land areas, said grooves and land areas cooperating to successively clamp said sheet therebetween.
Claim 15
Independent Claim 213 words
A method for mechanically securing and sealing a flexible elastomeric sheet to the upper surface of a roof via the use of a plurality of spaced penetrating fastening and sealing devices, each of which includes upper and lower retainers, means for anchoring said lower retainer to said roof upper surface and means for clamping said upper and lower retainers together, each of said devices being used in conjunction with an aperture through said sheet, said method comprising the steps of: a. spreading said flexible elastomeric sheet over said roof upper surface. b. determining desired locations for said devices on said sheet; c. providing, at said location, said sheet with an aperture; d. passing, at each location, said lower retainer, which is larger than said aperture, through said sheet aperture to underlie and completely cover said aperture; e. physically anchoring said lower retainer to said roof upper surface at each of said locations; f. placing, at each location, said upper retainer, which is larger than said aperture, over said aperture to overlie and completely cover said aperture, thereby confining a continuous peripheral portion of said sheet, bordering said aperture, between said upper and lower retainers; and g. pressing said upper and lower retainers together which results in a continuous sealing relationship with said sheet.
Claim 16
Independent Claim 213 words
A method for mechanically securing and sealing a flexible elastomeric sheet to the upper surface of a roof via the use of a plurality of spaced penetrating fastening and sealing devices, each of which includes upper and lower retainers, means for anchoring said lower retainer to said roof upper surface and means for clamping said upper and lower retainers together, each of said devices being used in conjunction with an aperture through said sheet, said method comprising the steps of: a. spreading said flexible elastomeric sheet over said roof upper surface. b. determining desired locations for said devices on said sheet; c. providing, at said location, said sheet with an aperture; d. passing, at each location, said lower retainer, which is larger than said aperture, through said sheet aperture to underlie and completely cover said aperture; e. physically anchoring said lower retainer to said roof upper surface at each of said locations; f. placing, at each location, said upper retainer, which is larger than said aperture, over said aperture to overlie and completely cover said aperture, thereby confining a continuous peripheral portion of said sheet, bordering said aperture, between said upper and lower retainers; and g. pressing said upper and lower retainers together which results in a continuous sealing relationship with said sheet.
Claim 17
Dependent Claim 22 words
The method of claim 13, wherein said passing step is accomplished via the temporary elastic deformation of said sheet adjacent said aperture.
Claim 18
Dependent Claim 38 words
The method of claim 13 wherein said passing step includes coinciding said aperture with a stepped center portion of said lower retainer upper surface and placing the bottom surface of said lower retainer on said roof upper surface.
Claim 19
Dependent Claim 31 words
The method of claim 15 wherein the upper surface of said lower retainer includes a continuous outer flange portion that underlies a corresponding portion of the lower surface of said sheet.
Claim 20
Dependent Claim 65 words
The method of claim 16 wherein said placing step includes matingly engaging said lower retainer stepped center portion with a corresponding center portion of said upper retainer lower surface, with a continuous outer flange portion of said lower surface being adapted to overlie at least a continuous portion of said lower retainer outer flange portion, thereby confining a continuous peripheral portion of said sheet therebetween.
Claim 21
Independent Claim 352 words
A method for mechanically securing and sealing a flexible elastomeric sheet to the upper surface of a roof via the use of a plurality of spaced penetrating fastening and sealing devices, each of which includes upper and lower retainers, means for anchoring said lower retainer to said roof upper surface and means for clamping said upper and lower retainers together, each of said devices being used in conjunction with an aperture through said sheet, said method comprising the steps of: a. spreading said flexible elastomeric sheet over said roof upper surface; b. determining desired locations for said devices on said sheet; c. providing, at said locations, said sheet with an aperture of a first predetermined size; d. passing, at each location, asid lower retainer, which is of a second predetermined size larger than said first predetermined size, through said sheet aperture, via temporary elastic deformation of said sheet adjacent said aperture, so that the edge of said aperture substantially coincides with a stepped center portion of said lower retainer upper surface and the bottom surface of said lower retainer overlies said roof upper surface, with a continuous outer flange portion of said upper surface underlying a corresponding portion of the lower surface of said sheet; e. physically anchoring said lower retainer to said roof upper surface at each of said locations; f. placing, at each location, said upper retainer, which is of a third predetermined size larger than said first predetermined size, over said lower retainer stepped portion so that it matingly engages with a correspondding center portion of said upper retainer lower surface, with a continuous outer fange portion of said lower surface being adapted to overlie a corresponding portion of the upper surface of said sheet, said lower surface flange portion being of the size and shape so as to overlay at least a continuous portion of said lower retainer outer flange portion, thereby confining a continuous peripheral portion of said sheet, bordering said aperture, between said upper and lower retainers; and g. pressing said upper and lower retainers together which results in a continuous sealing relationship with said sheet.
Claim 22
Independent Claim 352 words
A method for mechanically securing and sealing a flexible elastomeric sheet to the upper surface of a roof via the use of a plurality of spaced penetrating fastening and sealing devices, each of which includes upper and lower retainers, means for anchoring said lower retainer to said roof upper surface and means for clamping said upper and lower retainers together, each of said devices being used in conjunction with an aperture through said sheet, said method comprising the steps of: a. spreading said flexible elastomeric sheet over said roof upper surface; b. determining desired locations for said devices on said sheet; c. providing, at said locations, said sheet with an aperture of a first predetermined size; d. passing, at each location, asid lower retainer, which is of a second predetermined size larger than said first predetermined size, through said sheet aperture, via temporary elastic deformation of said sheet adjacent said aperture, so that the edge of said aperture substantially coincides with a stepped center portion of said lower retainer upper surface and the bottom surface of said lower retainer overlies said roof upper surface, with a continuous outer flange portion of said upper surface underlying a corresponding portion of the lower surface of said sheet; e. physically anchoring said lower retainer to said roof upper surface at each of said locations; f. placing, at each location, said upper retainer, which is of a third predetermined size larger than said first predetermined size, over said lower retainer stepped portion so that it matingly engages with a correspondding center portion of said upper retainer lower surface, with a continuous outer fange portion of said lower surface being adapted to overlie a corresponding portion of the upper surface of said sheet, said lower surface flange portion being of the size and shape so as to overlay at least a continuous portion of said lower retainer outer flange portion, thereby confining a continuous peripheral portion of said sheet, bordering said aperture, between said upper and lower retainers; and g. pressing said upper and lower retainers together which results in a continuous sealing relationship with said sheet.
Claim 23
Dependent Claim 419 words
A penetrating, fastening and sealing device for both mechanically securing a flexible elastomeric sheet, of known thickness, to the upper surface of a roof and sealingly engaging said sheet, wherein said sheet is provided with an aperture of a first predetermined area and shape, said device comprising in combination: a rigid lower retainer; means for anchoring said lower retainer to said roof upper surface; a rigid upper retainer adapted to mate with said lower retainer; and means for clamping said upper and lower retainers together, (a) said lower retainer being of a second predetermined area and shape, said second area being greater than said sheet aperture area, said lower retainer having a planar bottom surface and a planar upper surface, a stepped center portion thereof having an area and shape substantially correspondng with those of said sheet aperture, said center portion also having an outer peripheral surface adapted for locating the corresponding peripheral wall portion of the sheet that defines said aperture, said upper surface further including a continuous outer flange portion adapted to underlie a corresponding portion of the lower surface of said sheet, said lower retainer being adapted to be passed through said sheet aperture, via temporary elastic deformation of said sheet adjacent said aperture, so that said planar bottom surface overlies said roof upper surface and said stepped center portion is aligned with said aperture; (b) said upper retainer being of a third predetermined area and shape, said third area being greater than said sheet aperture area, said upper retainer having an upper surface and a planar lower surface, a stepped center portion thereof having an area and size substantially corresponding with those of said lower retainer center portion, said upper retainer center portion also having an outer peripheral surface adapted to matingly engage with the outer peripheral surface of said lower retainer center portion, said lower surface further including a continuous outer flange portion adapted to overlie a corresponding portion of the upper surface of said sheet, said lower surface flange portion being of a size and shape so as to overlap, at least a circumferentially continuous portion, of said lower retainer outer flange portion of said sheet, bordering said aperture, between said upper and lower retainer flange portions; (c) said clamping means pressing together said upper and lower retainers into a continuous sealing relationship with said sheet; and (d) the opposing surfaces of said upper and lower retainer flange portions being parallel with each other but angled relative to the lower retainer bottom surface.
Claim 24
Dependent Claim 419 words
A penetrating, fastening and sealing device for both mechanically securing a flexible elastomeric sheet, of known thickness, to the upper surface of a roof and sealingly engaging said sheet, wherein said sheet is provided with an aperture of a first predetermined area and shape, said device comprising in combination: a rigid lower retainer; means for anchoring said lower retainer to said roof upper surface; a rigid upper retainer adapted to mate with said lower retainer; and means for clamping said upper and lower retainers together, (a) said lower retainer being of a second predetermined area and shape, said second area being greater than said sheet aperture area, said lower retainer having a planar bottom surface and a planar upper surface, a stepped center portion thereof having an area and shape substantially correspondng with those of said sheet aperture, said center portion also having an outer peripheral surface adapted for locating the corresponding peripheral wall portion of the sheet that defines said aperture, said upper surface further including a continuous outer flange portion adapted to underlie a corresponding portion of the lower surface of said sheet, said lower retainer being adapted to be passed through said sheet aperture, via temporary elastic deformation of said sheet adjacent said aperture, so that said planar bottom surface overlies said roof upper surface and said stepped center portion is aligned with said aperture; (b) said upper retainer being of a third predetermined area and shape, said third area being greater than said sheet aperture area, said upper retainer having an upper surface and a planar lower surface, a stepped center portion thereof having an area and size substantially corresponding with those of said lower retainer center portion, said upper retainer center portion also having an outer peripheral surface adapted to matingly engage with the outer peripheral surface of said lower retainer center portion, said lower surface further including a continuous outer flange portion adapted to overlie a corresponding portion of the upper surface of said sheet, said lower surface flange portion being of a size and shape so as to overlap, at least a circumferentially continuous portion, of said lower retainer outer flange portion of said sheet, bordering said aperture, between said upper and lower retainer flange portions; (c) said clamping means pressing together said upper and lower retainers into a continuous sealing relationship with said sheet; and (d) the opposing surfaces of said upper and lower retainer flange portions being parallel with each other but angled relative to the lower retainer bottom surface.
Claim 25
Dependent Claim 457 words
A penetrating, fastening and sealing device for both mechanically securing a flexible elastomeric sheet, of known thickness, to the upper surface of a roof and sealingly engaging said sheet, wherein said sheet is provided with an aperture of a first predetermined area and shape, said device comprising in combination: a rigid lower retainer; means for anchoring said lower retainer to said roof upper surface; a rigid upper retainer adapted to mate with said lower retainer; and means for clamping said upper and lower retainers together, (a) said lower retainer being of a second predetermined area and shape, said second area being greater than said sheet aperture area, said lower retainer having a planar bottom surface and a planar upper surface, a stepped center portion thereof having an area and shape substantially corresponding with those of said sheet aperture, said center portion also having an outer peripheral surface adapted for locating the corresponding peripheral wall portion of the sheet that defines said aperture, said upper surface further including a continuous outer flange portion adapted to underlie a corresponding portion of the lower surface of said sheet, said lower retainer being adapted to be passed through said sheet aperture, via temporary elastic deformation of said sheet adjacent said aperture, so that said planar bottom surface overlies said roof upper surface and said stepped center portion is aligned with said aperture; (b) said upper retainer being of a third predetermined area and shape, said third area being greater than said sheet aperture area, said upper retainer having an upper surface and a planar lower surface, a stepped center portion thereof having an area and size substantially corresponding with those of said lower retainer center portion, said upper retainer center portion also having an outer peripheral surface adapted to matingly engage with the outer peripheral surface of said lower retainer center portion, said lower surface further including a continuous outer flange portion adapted to overlie a corresponding portion of the upper surface of said sheet, said lower surface flange portion being of a size and shape so as to overlap, at least a circumferentially continuous portion, of said lower retainer outer flange portion of said sheet, bordering said aperture, between said upper and lower retainer flange portions; (c) said clamping means pressing together said upper and lower retainers into a continuous sealing relationship with said sheet; and (d) the opposing flange surfaces of said upper and lower retainers being parallel to one another with one of said surfaces being provided with a plurality of radially spaced circularly extending concentric annular grooves while the other of said surfaces is provided with a similar plurality of corresponding raised land areas, with said grooves and land areas cooperating to successively clamp said sheet therebetween.
Claim 26
Dependent Claim 457 words
A penetrating, fastening and sealing device for both mechanically securing a flexible elastomeric sheet, of known thickness, to the upper surface of a roof and sealingly engaging said sheet, wherein said sheet is provided with an aperture of a first predetermined area and shape, said device comprising in combination: a rigid lower retainer; means for anchoring said lower retainer to said roof upper surface; a rigid upper retainer adapted to mate with said lower retainer; and means for clamping said upper and lower retainers together, (a) said lower retainer being of a second predetermined area and shape, said second area being greater than said sheet aperture area, said lower retainer having a planar bottom surface and a planar upper surface, a stepped center portion thereof having an area and shape substantially corresponding with those of said sheet aperture, said center portion also having an outer peripheral surface adapted for locating the corresponding peripheral wall portion of the sheet that defines said aperture, said upper surface further including a continuous outer flange portion adapted to underlie a corresponding portion of the lower surface of said sheet, said lower retainer being adapted to be passed through said sheet aperture, via temporary elastic deformation of said sheet adjacent said aperture, so that said planar bottom surface overlies said roof upper surface and said stepped center portion is aligned with said aperture; (b) said upper retainer being of a third predetermined area and shape, said third area being greater than said sheet aperture area, said upper retainer having an upper surface and a planar lower surface, a stepped center portion thereof having an area and size substantially corresponding with those of said lower retainer center portion, said upper retainer center portion also having an outer peripheral surface adapted to matingly engage with the outer peripheral surface of said lower retainer center portion, said lower surface further including a continuous outer flange portion adapted to overlie a corresponding portion of the upper surface of said sheet, said lower surface flange portion being of a size and shape so as to overlap, at least a circumferentially continuous portion, of said lower retainer outer flange portion of said sheet, bordering said aperture, between said upper and lower retainer flange portions; (c) said clamping means pressing together said upper and lower retainers into a continuous sealing relationship with said sheet; and (d) the opposing flange surfaces of said upper and lower retainers being parallel to one another with one of said surfaces being provided with a plurality of radially spaced circularly extending concentric annular grooves while the other of said surfaces is provided with a similar plurality of corresponding raised land areas, with said grooves and land areas cooperating to successively clamp said sheet therebetween.

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USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1989-11-03 1990-05-05 1990-11-04 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1993-11-03 1994-05-05 1994-11-04 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1997-11-03 1998-05-05 1998-11-04 $7700.00 Window Closed / Lapsed

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