Patent Publication Number: US-8540456-B2

Title: Containment system

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to secondary containment systems typically used in connection with hazardous materials or other materials to be isolated from the environment. More particularly, a deployable modular containment system includes straight and curved members that may be interconnected to form a closed barrier or a dike wall surrounding a primary container or otherwise isolating the selected material. The barrier or dike system may be used to restrict liquid flows of other origins such as a flood or other disaster resulting in an unregulated or diverted flow of liquid. 
     It is known to use secondary containment systems for reducing, if not eliminating, accidental spill of materials being stored or processed. For example, steel drum storage of hazardous materials may require secondary containment under applicable environmental regulations. Military fuel storage may be provided in a primary container surrounded by a secondary containment system. 
     Prior U.S. Pat. No. 4,765,775, assigned to the assignee of the present application, discloses a modular containment system employing interlocking strut and corner members that are staked to the substratum following assembly. Although portable, the strut and corner members are formed of glass fiber reinforced plastics requiring labor intensive and costly construction and results in a rather heavy and difficult to assemble members. The members are provided with integrally formed posts and receivers that are adhesively secured together. Further, the strut and corner members are generally of trapezoidal cross-section and do not resist surge flows as may occur with a major leak or rupture of the primary container. In fact, the outward inclination of the inner barrier wall tends to facilitate overrun and escape of impacting surge flows. 
     Prior U.S. Pat. No. 7,714,825, assigned to the assignee of the present application, discloses a modular containment system employing interlocking strut and corner members that are staked to the substratum following assembly. The members are provided with integrally formed female end sockets for receiving male end members. Again, the strut and corner members are formed of glass fiber reinforced plastics and they are generally of trapezoidal cross-section so as to not resist surge flows. 
     As to be expected, the prior art barrier systems are heavy and raise transportation considerations, especially at remote installation cites and/or tight-fitting tortuous industrial installations wherein the delivery path may be tortuous. In such cases, ease of manipulation for manual transportation and installation is desirable. In all cases, it is desirable that the containment system may be quickly and easily deployed and assembled. This is particularly true in the case of military applications wherein assembly, disassembly and transportation of the system may be provided at different locations by different personnel. Accordingly, it is important that the system components be limited in number and readily assembled to provide a sturdy construction. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, a modular containment system is provided with a limited number of easily assembled straight and corner or curved members. The members are formed of a moldable plastic material. Consequently, the fabrication cost of the members is significantly reduced as compared with prior art barrier systems. 
     As indicated, the members are molded of plastic material, and preferably, the members are rotationally molded and have a generally hollow construction. The members may be formed of any suitably rigid plastic material such as low density polyethylene. Recycled materials may be used to form the members. 
     The members include a top wall extending to opposed side walls that are joined to a base. The length of the member is considered to extend in a longitudinal direction that is generally parallel to the supporting substratum or ground. The members are closed and include opposed longitudinal end walls. Connector ends are provided at the longitudinal ends of the members so that they may be joined end-to-end to form the dike system or barrier. 
     The members are constructed to provide at least one inclined side wall adjacent the contained material. The inclined side wall slopes toward the contained material or into the path of a likely flow of material to be contained. For example, the inclined side wall may extend at an enclosed acute angle relative to the base of the barrier. 
     The inclined angle of the side wall tends to contain and redirect a liquid flow directed toward or impinged upon the member. The inclined angle of the side wall may be up to less than about 90° relative to the base of the barrier and otherwise sufficient to tend to contain and redirect a liquid flow impinging upon the member. In preferred arrangements, the inclined angle is greater than from about 30° to less than about 80°, and more preferably, from about 60° to less than about 80°. 
     In preferred arrangements, the member is hollow and both side walls extend at the same inclined angle relative to the base. The rigidity of the members is increased by forming separate reinforcing ribs in the side wall. In the illustrated embodiment, ribs are provided in each of the side walls and extend along major area portions of the side walls. 
     Preferably, the ribs extend in intersecting angular directions so as to increase rigidity and resist buckling in corresponding directions. Thus, the ribs may be generally disposed in a vertical direction in one side wall and a horizontal direction in the other side wall so as to resist flexure of the member in both vertical and horizontal directions. 
     The ribs have a height equal to about one-half of the overall wall thickness of the member as defined by the spaced side walls. Accordingly, the interior surfaces of the opposed side walls are closely spaced and substantially abut at locations between the ribs. The close spacing of the interior surfaces of the side walls results in engagement upon loading and flexure of the member whereby the side walls tend to reinforce each other. 
     An impermeable liner is placed over the joined members to contain liquid. An edge of the liner is secured to the member by a clip that resiliently engages the top wall of the member to trap the liner edge between the clip and the top wall. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a closed dike assembly having straight and curved members in accordance with the invention surrounding a primary container and having parts broken away or omitted for purposes of illustration; 
         FIG. 2  is an elevational view of connected straight members, as seen from the proximal side of the dike assembly, with parts broken away and omitted for convenience of illustration; 
         FIG. 3  is an elevational view similar to  FIG. 2  as seen from the distal side of the dike assembly; 
         FIG. 4  is a sectional view taken along the line  4 - 4  in  FIG. 2 ; 
         FIG. 5  is an isometric view of the connector ends of adjacent members spaced apart for illustration purposes; 
         FIG. 6  is an elevational view showing a straight member connected to a curved member of  FIG. 4  as viewed from the proximal side of the dike; 
         FIG. 7  is an elevational view similar to  FIG. 6  as seen from the distal side of the dike assembly; 
         FIG. 8  is a sectional view taken along the line  8 - 8  in  FIG. 6 ; 
         FIG. 9  is a fragmentary isometric view of three connected members fitted with a spider cable in preparation for further cable installation; 
         FIG. 10  is a schematic top view showing the dike assembly of  FIG. 1  having its members secured together by a cable web including spider cable arrays and straight cables; 
         FIG. 11  is an isometric view showing a resilient clip for securing the liner to the dike assembly; 
         FIG. 12  is a fragmentary isometric view showing the liner being secured to a member forming the dike system using the clip of  FIG. 11 ; and 
         FIG. 13  is a schematic sectional view taken along the line  13 —in  FIG. 1  showing a closable drain valve and a duct for draining the liner. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A closed barrier or dike assembly  10  surrounding a primary container  12  is shown in  FIG. 1 . The primary container  12  is a flexible bladder construction that may contain a fuel to be isolated from the environment in case of container failure or as required by environmental regulations. The primary container may comprise a storage tank (not shown) for industrial liquid supplies such as lubricants, solvents, reactants or any other liquid requiring secondary containment. 
     The dike assembly  10  has a generally rectangular configuration with rounded corners provided by opposed dike walls  14  formed by interlocked straight members  16  extending between and interlocked with corner members  18 . A cable web  20  is provided for securing the members  16  and  18  together as further explained below. 
     For purposes of liquid containment, a liquid impermeable barrier film or liner  22  is disposed between the primary container  12  and the web  20 , along the substratum  23  and over the dike walls  14 . The liner  22  may be secured in place by connection to the dike walls as explained in detail below. 
     The liner  22  is preferably a flexible flat sheet that may be conformed to the interior shape of the dike assembly including the surfaces of the straight and corner members as well as the contour of the substratum  23 . The liner  22  may be formed of a suitable plastic material such as polyamide, polyester or polyurethane with or without reinforcement. For clarity of illustration, the liner  22  is transparent and has been broken away so that only the top left corner of the liner is shown in  FIG. 1 . Of course, the liner  22  may be opaque and/or comprise a fabric/plastic laminate. 
     Referring to  FIGS. 2 through 4 , the straight member  16  extends in a substantially straight longitudinal or horizontal direction to provide the member with a length equal to about 4 feet. The member  16  has a vertical height equal to about 3 feet. The length and height dimensions are not critical. 
     The member  16  has an inclined L-shape including a top portion  24 , a central wall portion  26 , an enlarged base portion  28  for engaging the substratum  23 , and longitudinal end portions  30 . The member  16  is formed by rotational molding and each of the portions  24 - 30  is formed as a continuous plastic wall of the molded part. The portions  24 - 30  are described below. 
     The top portion  24  has a general rectangular cross-section ( FIG. 4 ) including a top wall  24   a  connected to opposed walls  24   b  that extend respectively to a proximal recess  32  and a distal recess  34  located on opposite sides of the member  16 . For convenience herein, the side of the dike or barrier system adjacent the contained material is referred to as the proximal side and the other side of the dike or barrier system is referred to the distal side. 
     The central wall portion  26  is formed by a proximal side wall  40  and a distal side wall  42 . The side wall  40  includes a plurality of reinforcing ribs  44  extending in a generally vertical or rib direction along a major area portion of the side wall  40 . The ribs  44  are spaced by recesses  44   a  so that the side wall  40  has a corrugated shape as viewed in cross section in  FIG. 4 . Each of the ribs  44  has a generally uniform cross-section extending in the rib direction in the side wall. The specific dimensions and spacing of the ribs  44  may be varied in order to provide a suitable reinforcing strength. As illustrated, the ribs  44  and the recesses  44   a  each have a width of about 4″ and a height or depth of about 1.5″. As shown, the ribs  44  and recesses  44   a  extend into the base portion  28  as further discussed below. 
     The distal side wall  42  is provided with a plurality of reinforcing ribs  46  extending in a generally horizontal direction along a major area portion of the side wall  42  generally corresponding with the area enclosed by the dashed line  45  ( FIG. 2 ). As used herein, major area portion means more than about 50% of the total wall area. Herein, the area enclosed by the dashed line  45  is about 76% of the total area of the side wall  42 . 
     The ribs  46  are spaced by recesses  46   a  so that the side wall  46  also has a corrugated profile when viewed in cross-section. Again, the specific dimensions and spacing of the ribs  46  may be varied in order to provide a suitable reinforcing strength. As illustrated, the ribs  46  and recesses  46   a  each have a width of about 4″, and a height or depth of about 3″ along a major area portion of the side wall  42  generally corresponding with the area enclosed by the dashed line  47  ( FIG. 3 ). 
     In this instance, the major area portion enclosed by the dashed line  47  is equal to about 65% of the total area of the wall extending below the recess  34  to a height generally corresponding with that of the angular wall joint  50  and between the ends  30 . 
     As best shown in  FIG. 4 , adjacent interior surfaces  40   b  and  42   b  of the recesses  40   a  and  42   a  in the side walls  40 ,  42  are closely spaced and substantially abut adjacent the recesses  44   a  and  46   a . These adjacent surfaces  40   b  and  42   b  are spaced apart in accordance with the rotational molding process to allow for resin flow between the mold portions and the interior surfaces as they are formed. In the illustrated embodiment, the adjacent interior surfaces of the recesses are spaced apart a distance of about 0.25″. 
     The spacing of the surfaces  40   b  and  42   b  is sized to provide reinforcing engagement of the surfaces upon flexure of the walls  40  and  42 . In this manner, the walls  40 ,  42  and member  16  are reinforced in response to flexure loading as upon surge loading by fluid impact. 
     Each of the side walls  40  and  42  has a wall thick of from about 0.13″ to about 0.18″. The overall thickness of the central wall portion  26  as measured by the exterior surface extremities of the side walls  40  and  42  is about 5.25″. 
     The base portion  28  has a generally triangular cross-section including an inclined base wall  28   a , a peripheral base wall  28   b  and a lower base support wall  28   c  arranged to engage the substratum  23 . The base portion  28  joins the lower portion of the distal side wall  42 . The inclined base wall  28   a  joins the side wall  40  along an integrally formed angular wall joint  50  generally indicated by the dashed line  52 . In the same manner, the side wall  40  and the inclined base wall  28   a  are integrally formed as part of the rotationally molded one-piece straight member  16 . 
     As illustrated, lower portions of the ribs  44  and recesses  44   a  extend to form the inclined base wall  28   b . In turn, the base wall  28  extends to and joins the peripheral base wall  28   b  and the lower base wall  28   c . The lower portions of the ribs and recesses reinforce the inclined base wall  28   a.    
     With particular reference to  FIG. 4 , the proximal side wall  40  forms an enclosed acute angle “A” relative to the bottom base wall  28   c . The inclined angle of the side wall tends to contain and redirect in a reverse direction liquid flowing against the wall  40  and member  16 . The inclined angle “A” is 70° in the illustrated embodiment, but may range from about 60° to about 80° as discussed above. If the angle is too small, the wall  40  and member  16  may be overly stressed and structurally fail due to loads imposed an impinging liquid flow. On the other hand, if the angle is too large, the liquid will over flow the wall. 
     The inclined base wall  28   a  forms an enclosed acute base angle “B” relative to the bottom base wall  28   c . The base angle “B” may be up to about 45° and is 30° in the illustrated embodiment. The inclined base wall  28   a  reinforces the connection between the central wall portion  26  and the base portion  28 . 
     The stability of the member  16  is further enhanced by maintaining the projection of top portion and the center of mass of the central wall portion  26  within a foot-print corresponding with the base portion  28 . This geometry inhibits the tendency of the member  16  rotate upon impingement of a surge flow. The base wall  28   c  has thickness of about 22″ as measured between its proximal and distal extremities. 
     The longitudinal end portions  30  include longitudinal end walls  60  and longitudinally projecting connector teeth  62 . The connector teeth  62  are arranged at different heights at opposite ends of the member  16  for engagement with corresponding connector teeth on an adjacent member  16  or  18 . 
     It should be appreciated that the surge liquid impacting with and/or resting upon the inclined wall  28   a  further contributes to the stability of the member  16 . That is, weight of such water provides a downward force component pressing the base portion  28  against the substratum  23 . 
     Referring to  FIG. 5 , members  16  are disengaged and slightly spaced to better illustrate the teeth  62  and their staggered heights on opposite longitudinal ends of the members. The connector teeth  62  are integrally formed with the end walls  60  and members  16 . Each connector tooth  62  has a boxlike shape of generally rectangular cross-section. Each connector tooth  62  has generally flat upper and lower walls  62   a  connected by flat side walls  62   b . A tunnel opening  64  is formed by extension of the walls  62   a  through each tooth  62 . The tunnel openings  64  are aligned in a vertical direction for receipt of a locking pin  66  as described more fully below. 
     As best shown in  FIGS. 3 and 5 , a connector shroud wall  66  extends from the distal side wall  42  to cover the teeth  62 . In the illustrated embodiment, the shroud wall  66  integrally extends from the distal right end of the side wall  42 . The shroud wall  66  is hollow. The shroud wall  66  provides additional support for the teeth  62  and increased rigidity at the longitudinal ends  30  to better maintain the alignment of the teeth  62 . 
     Referring to  FIGS. 2 and 3 , the locking pin  68  is a metallic tubular member having an L-shape including a straight leg  70  and an angularly offset handle lock  72 . The leg  70  extends through the tunnel openings  64  in the aligned teeth  62  and secures adjacent members  16  and/or  18  together. The distal recess  34  has enlarged ends  34   a  for receipt of the handle lock  72 . More particularly, the handle lock  72  is rotated into the adjacent distal recess  34   a  with a friction fit to fix the pin  68  against vertical movement. 
     Referring to  FIGS. 6 ,  7  and  8 , the corner member  18  connected to an adjacent straight member  16  is shown. The corner member  18  extends in an arcuate or curved longitudinal direction and is otherwise configured in the same manner as the member  16 . Accordingly, like reference numerals are used for corresponding elements with the addition of a prime designation. 
     The member  18  also has an inclined L-shape including a top portion  24 ′, a central wall portion  26 ′, an enlarged base portion  28 ′ for engaging the substratum  23 , and longitudinal end portions  30 ′. The member  18  is also formed by rotational molding and each of the portions  24 ′- 30 ′ is formed as a continuous plastic wall of the molded part. 
     The top portion  24 ′ corresponds with the top portion  24  but for the curved longitudinal shape. Accordingly, a top wall  24   a ′ is connected to opposed walls  24   b ′ that extend respectively to a proximal recess  32 ′ and a distal recess  34 ′ located on opposite sides of the member  18 . 
     The central wall portion  26 ′ is formed by a [concave] proximal side wall  40 ′ and a [convex] distal side wall  42 ′. The side wall  40 ′ includes a plurality of reinforcing ribs  44 ′ extending in a generally vertical direction along a major area portion of the side wall  40 ′. The ribs  44 ′ are spaced by recesses  44   a ′ so that the side wall  40 ′ has a corrugated shape as viewed in cross section in  FIG. 8 . The specific dimensions and spacing of the ribs  44 ′ may be varied in order to provide a suitable reinforcing strength. As illustrated, the ribs  44 ′ have a width of about 8″ and the recesses  44   a ′ each have a width of about 12″ and a height or depth of about 2.5″. 
     The distal side wall  42 ′ is provided with a plurality of reinforcing ribs  46 ′ extending in a generally horizontal direction along a major area portion of the side wall  42 ′. The ribs  46 ′ are spaced by recesses  46   a ′ so that the side wall  46 ′ also has a corrugated profile when viewed in cross-section. Again, the specific dimensions and spacing of the ribs  46 ′ may be varied in order to provide a suitable reinforcing strength. As illustrated, the ribs  46 ′ and recesses  46   a ′ each have a width of about 4″, and a height or depth of about 3″. 
     In the member  18 , the recesses  46   a ′ are interrupted by a central located vertically extending rib  74 . The rib  74  is positioned above a tunnel drain opening  76  extending through the base portion  28 ′ of the member  18 . That is, the inclined base wall  28   a ′ and the distal side wall  42 ′ extend through the base portion  28 ′ to form the drain opening  76 . 
     As best shown in  FIG. 8 , the adjacent interior surfaces of the recesses  44   a ′ and  46   a ′ are closely spaced and substantially abut in the same manner as the described above with respect to the interior surfaces of the recesses  44   a  and  46   a . Similarly, each of the side walls  40 ′ and  42 ′ has a wall thickness of about 0.13″ to about 0.18″. The overall thickness of the central wall portion  26 ′ as measured by the exterior surface extremities of the side walls  40 ′ and  42 ′ is about 5.25″. 
     As described above, the base portion  28 ′ has a generally triangular cross-section including an inclined base wall  28   a ′, a peripheral base wall  28   b ′ and a lower base support wall  28   c ′ arranged to engage the substratum  23 . The base portion  28 ′ joins the lower portion of the distal side wall  42 ′. The inclined base wall  28   a ′ joins the side wall  40 ′ along an integrally formed angular wall joint  50 ′ generally indicated by the dashed line  52 ′. Similarly, the side wall  40 ′ and the inclined base wall  28   a ′ are integrally formed as part of the rotationally molded one-piece straight member  18 . 
     As illustrated, lower portions of the ribs  44  and recesses  44   a  extend to form the inclined base wall  28   a ′. In turn, the base wall  28   a ′ extends to and joins the peripheral base wall  28   b ′ and the lower base wall  28   c ′. The lower portions of the ribs and recesses reinforce the inclined base wall  28   a′.    
     With particular reference to  FIG. 8 , the proximal side wall  40 ′ forms an enclosed acute angle “A” relative to the bottom base wall  28   c ′ and the inclined base wall  28   a ′ forms an enclosed acute base angle “B” relative to the bottom base wall  28   c ′ in the same manner as described above with respect to the member  16  in order to obtain similar containment of liquid flow. 
     The stability of the member  18  is enhanced in the same manner as in the case of the straight member  16  by maintaining the projection of top portion and the center of mass of the central wall portion  26 ′ within the foot print of the base portion  28 ′. The lower base wall  28   c ′ in contact with the substratum  23  is provided with a gross wall radial dimension of about 22″ as measured from its proximal to its distal extremities along a radius of the curve of the member  18 . 
     The longitudinal end portions  30 ′ include longitudinal end walls  60 ′ and longitudinally projecting connector teeth  62 ′. As described above, the connector teeth  62 ′ are arranged at different heights at opposite ends of the member  18  for engagement with corresponding connector teeth on an adjacent member  16  or  18 . 
     The connector teeth  62 ′ are integrally formed with the end walls  60 ′ and member  18  as described above with respect to the member  16 . Further, the teeth  62 ′ are shaped and constructed in the same manner as the teeth  62  and include aligned tunnel openings  64 ′ for receipt of a locking pin  68 . 
     As shown in  FIGS. 1 ,  9  and  10 , the assembled barrier or dike  10  may optionally be reinforced by the cable web  20 . To that, the web  20  includes spider webs  80  formed of three spider cables  82  having cable ends joined to closed connector member  84 . The opposite ends of the spider cables are connected to associated triangular connectors  86  as schematically shown in  FIG. 10 . The members  86  are joined to associated members  16  or  18  by passing the end of the leg  68  through the member  86  to trap it between one of the teeth  62  and the base portion  28  or  28 ′ of the member. 
     Referring to  FIG. 10 , straight cables  88  may be used to join the spider webs  80  by attachment to opposed connector members  84 . As also shown, each end of the straight cable  88  may be fitted with a connector member  86  and connected to opposed locking pins  68 . 
     Referring to  FIG. 11 , a resilient clip  90  for mounting an edge of the liner  22  to the dike wall  14  is shown. The clip  22  has a channel or U-shape including a central bight  92  connecting opposed channel legs  94 . Each of the channel legs  94  terminates at a reverse bend  96 . The clip  90  is symmetrical about its longitudinal axis and it may be mounted with either leg adjacent the proximal wall  40  or the distal wall  42 . As described more fully below, the clip  90  is sized to fit over the top portion  24  or  24 ′ of the member  16  or  18  with the reverse bends  96  engaged within the recesses  32  and  34 . The clip  90  has a longitudinal length of about 1 foot, but its length is not critical, a sufficient number of clips may be used to securely mount the liner to the dike walls  14 . To that end, the liner  22  is manually positioned within the dike space and draped over the top portions  24  and  24 ′ of the members  16  and  18 , and secured to the dike walls  14  using a plurality of spaced clips. 
     The clip  90  is formed of glass fiber reinforced resin such as polyethylene, polypropylene, polyvinyl chloride, polystyrene and polyester as well as recycled plastics and/or inert fillers. The clip  90  has a limited range of elastic deformability or flexibility for resiliently engaging the top portion  24  or  241 . More particularly, the clip  90  is sized to receive the top portion  24  or  241  in a tight resilient fit with the edge of the liner  22  trapped between the clip and the top portion. To that end, the bends  96  are spaced apart in the normal state a distance about equal to the thickness spacing between the recesses  32  and  34  to allow the resilient capture of the liner  22  and the frictional fixing of the same to the top portion  24  or  24 ′. 
     Referring to  FIG. 12 , the edge of the liner  22  is positioned over the top portion  24  and mounting of the clip  90  is illustrated. The clip may be positioned above the liner  22  and the top portion  24  with one of the bends  96  positioned in the proximal recess  32  or  32 ′. The clip is then pulled rearward and downward over the opposite side wall  24   a  or  24   a ′ to position the other bend  96  into the distal recess  34  or  34 ′. During this process, the separation of the bends  96  causes the bight  92  to be flexed inwardly to tightly bias the liner  22  against the top wall  24   a  of the top portion  24 . 
     With particular reference to  FIG. 1 , the Dike assembly  10  is provided with a 32′×32′ generally square shape with rounded corners and a 4′ height. The bladder  12  also has a generally square shape and a size of 24′×24′×4′. The filled bladder holds about 10,000 gallons of liquid. The bladder  12  is centrally positioned within the dike assembly  10  so as to about a 4′ space between the filled bladder and the adjacent dike wall  14 . The dike assembly  10  and bladder  12  were positioned on substantially horizontal and level substratum  23  or ground area. 
     For purposes of evaluating the surge flow resistance of the dike assembly  10 , the bladder  12  was filled with about 10,000 gallons of water. The bladder  12  was formed of a plastic material reinforced with a woven fabric. Puncture of a top edge of the bladder with a sharp knife resulted in an immediate tear or rupture of the fabric forming the bladder about 10 to 20 inches long, and a surge flow of the water through the tear and against the adjacent proximal side of the dike assembly occurred with the latter being substantially emptied in less than a minute. 
     The initial surge flow of water impinged on the dike wall and the flow was substantially redirected and contained within the dike assembly. A limited amount of water, estimated to be a few hundred gallons, flowed over the dike wall, and the remaining water was contained. It is estimated that full containment would be achieved with the addition of one additional straight member  16  to each dike wall for this size bladder. In contrast, prior art dike assemblies having vertical or outwardly sloped walls are estimated to result in thousands of gallons of liquid flow over wall in response to such a surge flow. 
     It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.