US3777497A - Storage tank for offshore storage of liquid and method of constructing and installing same - Google Patents

Storage tank for offshore storage of liquid and method of constructing and installing same Download PDF

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Publication number
US3777497A
US3777497A US00250732A US3777497DA US3777497A US 3777497 A US3777497 A US 3777497A US 00250732 A US00250732 A US 00250732A US 3777497D A US3777497D A US 3777497DA US 3777497 A US3777497 A US 3777497A
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Prior art keywords
tank
side wall
storage tank
roof
water
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Expired - Lifetime
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US00250732A
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English (en)
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N Edwards
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PITTSBURGH-DES MOINES Corp
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Pittsburgh Des Moines Steel Co
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D88/00—Large containers
    • B65D88/78—Large containers for use in or under water
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S220/00—Receptacles
    • Y10S220/901—Liquified gas content, cryogenic

Definitions

  • ABSTRACT A storage tank for offshore storage of liquid such as .oil and the like and the method of constructing and installing same, wherein the storage tank has a side wall with the shape of a frustum of a hollow right circular cone and an enlarged diameter base or lower end and a reduced diameter top or upper end having a roof thereon, the frusto-conical configuration of the side wall of the tank substantially reducing the forces acting on the tank from a surrounding body of water or from wind or the like, and further resulting in a low center of gravity of the tank and a large water plane area so that the tank is inherently stable for towing in a body of water.
  • a further type of prior art offshore oil storage tank has an open bottom and a cylindrical side wall and is commonly referred to as a shallow water tank. These tanks are often designed as a double wallled cylinder extending from the bottom of the body of water to the surface thereof and several feet above the surface of the body of water. Such storage tanks may or may not be equipped with a stiffened dome roof, as desired.
  • cylindrical tanks are typically constructed on shore and then towed to the offshore site, and lowered in the body of water until they rest on the floor of the body of water.
  • steps of towing the tank to the site and lowering it to the floor of the body of water are quite complicated and difficult to accomplish due to the geometry of the tanks which in some cases necessitates that the tanks be towed on their side and then righted at the site prior to lowering the tanks to the floor of the body of water.
  • Such designs and methods require complicated and expensive equipment, and accordingly, the cost of such offshore oil storage facilities is quite large.
  • the offshore storage tank of the present invention has a configuration which economically and effectively overcomes these problems inherent in prior art storage tank constructions.
  • the tank has essentially the shape of a frustum of a right circular cone with a roof thereon.
  • a tank construction is better able to withstand the hydrodynamic pressure exerted thereon from ocean waves, since the stress resultants at a given location on any tank are proportional to the radius of curvature of the tank at that point and the pressure at that point. Large pressures and large radii of curvature accordingly result in large stresses.
  • the pressures acting on the tank due to waves and the like are obviously largest near the surface of the body of water, and it is in this vicinity that the tank of the present invention has the smallest radius of curvature and thus presents the least projected area.
  • the tank of the present invention has a large radius of curvature near the base of the tank.
  • the tank of the present invention has the shape of the frustum of a hollow right circular cone, or stated differently, is frusto-conical in shape
  • the tank has a large diameter at its base, and this large diameter enables the tank to resist overturning or tipping much more readily than prior art cylindrical tank constructions, since hydrodynamic loads applied to a tank near the surface of a body of water tend to act normal to the wall of the tank and, accordingly, in the present invention, wherein the wall of the tank is frusto conically shaped, these loads or forces tend to act in the direction of the foundation centroid and therefore have a smaller moment arm than those which, for example, act on the walls of a right circular cylinder as in the prior art.
  • the tank of the present invention is much more stable during towing than most other tank designs which have been proposed in the prior art. This is due to the larger diameter of the tank of the present invention at the towing water plane than conventional tanks of cylindrical configuration and similar capacities. This enlarged diameter at the towing water plane enhances stability of the tank. Also, the center of gravity of the tank is much lower than the center of gravity of conventional tanks. In fact, preliminary studies indicate that while towing a tank constructed in accordance with the present invention at a 30 foot draft, the center of gravity of the tank is actually below the center of buoyancy, and the tank is accordingly inherently stable in that configuration and all subsequent configurations.
  • the side wall of the tank in accordance with the present invention is a double wall construction and thus several other advantages. accrue to the tank of the present invention.
  • the width of the wall contributes to the towing stability, and from the standpoint of structural integrity, the double walled construction with concrete between the inner and outer walls eliminates both local and overall buckling of the tank walls due to large external hydrodynamic forces.
  • Conventional tank constructions have to be heavily stiffened with standard structural members to assure against this type of structural failure.
  • the dead weight of the concrete between the two walls of the tank decreases, and in some cases completely eliminates, the uplift on the tank due to the lighter weight of the oil stored therein, and depending upon the foundation conditions and requirements, this can be a very important consideration in the design of the piles used to anchor the tank to the floor of the body of water.
  • a further object of the invention is to provide a storage tank for offshore storage of liquids wherein the tank has a generally frusto conical configuration with a dome roof thereon which can be easily adapted to receive a work platform or the like over the roof.
  • An even further object of the invention is to provide a storage tank for offshore storage of liquid and to the method of constructing and installing same wherein the tank has a frusto-conically shaped side wall and a dome roof, said frusto-conical side wall resulting in the tank having a low center of gravity and a large water plane area, thus enabling the tank to be towed with inherent stability from a construction site to an installation site.
  • a still further object of the invention is to provide a tank having a frusto-conically shaped side wall and a dome roof and wherein lines drawn perpendicular to the surface of the side wall near the upper end thereof extend through the area bounded by the lower end of the side wall.
  • FIG. 1 is a top perspective view with a portion thereof broken away of a storage tank in accordance with the present invention in position in a body of water.
  • FIG. 2 is an enlarged plan view of the tank of FIG. 1.
  • FIG. 3 is an enlarged sectional view taken along line 33 in FIG. 2.
  • FIG. 4 is a fragmentary enlarged sectional view of a portion of the tank side wall in FIG. 3.
  • FIG. 5 is a fragmentary enlarged sectional view with a portion broken away of the tank side wall and foot flange thereon in FIG. 3.
  • FIG. 6 is a schematic sectional view in elevation of a tank in accordance with the present invention being constructed in a graving dock immediately prior to floating the tank.
  • FIG. 7 is a view similar to FIG. 6 of the tank floating on a body of water.
  • FIG. 8 is a view similar to FIG. 7 of the tank being towed in deep water to the site of an offshore facility.
  • FIG. 9 is a view similar to FIG. 8 with the tank at the site of the offshore facility and being lowered toward the bottom of the body of water.
  • FIG. 10 is a schematic sectional view in elevation of a tank in accordance with the present invention installed on the floor of a body of water at an offshore facility.
  • FIG. 11 is an enlarged view in elevation with a part shown in section of a modified and enlarged frustoconical oil storage tank, and showing a dome roof in full lines and a conical roof in phantom lines.
  • FIG. 12 is a schematic sectional view in elevation of a further modified tank in accordance with the present invention with a work platform constructed thereon, and with internal stiffening walls and a bottom.
  • a tank is indicated generally at T in FIG. 1 and comprises a side wall W having the shape of a frustum of a right circular cone with an annular foot flange F on the base thereof and a dome roof R on the top thereof.
  • the tank T is shown in position on the floor or bottom'B of a body of water.
  • a plurality of piles P are extended through the foot flange F into the floor of the body of water to anchor the tank T in position.
  • the upper end of the side wall W and the roof R extend above the surface of the body of water in this particular installation, although the tank could equally as well be completely submerged beneath the surface of a body of water, if desired.
  • the side wall W of the tank is of double wall construction and includes an inner wall 10 and an outer wall 12, each comprised of a plurality of steel plates welded or otherwise suitably joined together.
  • the roof R similarly comprises a plurality of steel plates welded or otherwise suitably secured together and extending upwardly from the upper edge of the inner wall 10.
  • a suitable vent V is provided in the roof R for venting air from the interior of the tank.
  • the inner and outer walls 10 and 12 are in radially spaced relationship to one another and concrete 13 fills the space between the walls 10 and 12.
  • Suitable reinforcing means such as a plurality of reinforcing rods 14 or the like, bent into a zig-zag shape, are welded to the respective inner and outer walls 10 and 12 and are arranged in a criss-crossing pattern as seen in FIG. 1 to reinforce the concrete between the inner and outer walls 10 and 12.
  • a plurality of spaced apart channel members or studs 15 are also welded or otherwise suitably secured to the inside facing surfaces of the inner and outer walls 10 and 12 to prevent shearing action between the concrete 13 and adjacent inner and outer walls 10 and 12.
  • shear members or channels 15 may extend circumferentially around the tank, if desired.
  • the foot flange F comprises upper and lower annular walls 16 and 17 and inner and outer vertically extending annular walls 18 and 19.
  • a plurality of cylindrical pile sleeves 20 are welded in vertical relationship between the top and bottom walls 16 and 17 for receiving the piles P therethrough.
  • the upper ends of the side walls 10 and 12 are connected together by an annular, slightly inclined frustoconically shaped ring or wall 21 welded or otherwise suitably secured at its upper and lower edges to the respective adjacent upper edges of the walls 10 and 12 to provide a substantially unitary side wall construction having a pleasing appearance.
  • Suitable vent means such as pipes or the like may be provided at the base or lower end of the side wall W for establishing communication between the surrounding bodyof water and the interior of the tank T, if desired.
  • hydrodynamic forces acting on the tank due to waves and the like in the surround ing body of water tend to act in a direction normal to the surface of the tank as indicated by the arrow f, and these forces accordingly act along a line L extending generally in the direction of the centroid C of the base of the tank T, thus substantially reducing the overturning or tipping effect on the tank due to the hydrodynamic forces acting on the tank from the surrounding body of water.
  • oil is stored in the tank and has in interface I,,, with water therebeneath and an interface 1,, with air thereabove.
  • the roof R has a radius r selected so that the roof continues smoothly upwardly from the upper edge of the inner wall 10.
  • the side wall W has a height H of approximately 100 feet for use in a body of water having a depth h of approximately 90 feet.
  • the tank has a diameter D of approximately 315 feet at the base thereof and a diameter d of approximately 115 feet at the top of the side wall W.
  • the roof R has a radius of curvature r of approximately 81.3 feet, and the plates in the roof have a thickness of about 1. inch, whereas the plates in the outer side wall 12 and the plates in the inner wall have a thickness of approximately onehalf inch.
  • the side wall W has an overall thickness of approximately 40.0 inches, and the foot flange is approximately 9 feet wide and 6 feet high.
  • the piles P are spaced around the foot flange on approximately 4 feet centers.
  • the shear connectors or channel members are spaced approximately 4 feet apart and the reinforcing rods or bars 14 are spaced 3 feet apart.
  • a tank thus constructed can readily store 500,000 barrels of oil or other liquid.
  • FIGS. 6 through 10 the manner or method in which the tank T is constructed and towed to the site of an offshore facility is schematically illustrated, and in FIG. 6, the tank T is shown in a graving dock GD.
  • the graving dock concrete 13 is poured between the walls 10 and 12 to a level of approximately 40 feet to provide ballast, and the graving dock is then flooded. Air is then pumped through a suitable means 22 to the interior of the tank to a pressure of approximately 3.0 psig, and the tank is then floated'and towed with a draft of approximately 18 feet into shallow water.
  • air is vented from the tank T through vent V until the tank assumes a draft of approximately 30 feet and the pressure inside the tank is about 3.0 psig.
  • the tank T is shown at the site of installation of the tank and is illustrated in the process of being lowered in the body of water. Air is vented from the interior of the tank in a controlled manner through the vent V as necessary to effect lowering of the tank.
  • the tank T is shown in position on the floor of the body of water. Once the tank has been lowered to the floor of the body of water as seen in this Figure, concrete is poured to the final depth between the walls 10 and 12 and the piles P are installed through the foot flange F into the floor of the body of water. Oil or other liquid to be stored is then pumped into the tank by suitable means, not shown.
  • the hydrodynamic force f on the tank T at the surface S of the body of water is directed along a line ex tending generally toward the centroid C of the foundation of the tank and the tipping or overturning moment applied to the tank by waves or the like S is accordingly substantially reduced since the moment arm is relatively short because of the direction of the force f toward the centroid C.
  • the tank T could be completely submerged in deper water, if desired, rather than positioned in relatively shallow water with the upper end thereof projecting above the surface of the body of water as illustrated in FIGS. 1 through 10.
  • the tank If the tank is to be installed in deeper water, it would be constructed and towed to the installation site as previously described, but upon arriving at the site, air would be bled from beneath the tank until it became neutrally buoyant and at this stage suitable means would be attached to the tank to lower it in the body of water to the floor of the body of water.
  • suitable means for this purpose is illustrated and described in U.S. Pat. No. 3,621,802.
  • FIG. 11 a modified tank T in accordance with the invention is illustrated, and is substantially identical in construction with the tank illustrated in FIGS. 1 through 10.
  • tank T has a diameter at the base thereof of approximately 365 feet and a diameter at the upper end of the frusto-conical wall W of approximately 50 feet.
  • the frusto-conical wall W is approximately 180 feet high, and the tank is intended to be used in water having a depth of approximately feet.
  • the steel plates comprising the outer side wall 12 are approximately /z inch thick, and the plates comprising the inner wall 10 are approximately of an inch thick.
  • the reinforcing rods 14 are spaced 3 6 inches apart.
  • the foot flange F is approximately 11 feet wide and 8 feet high and the shear connectors or channels 15 are spaced 3 feet apart.
  • the most noticable difference in this modification is that the roof R has a radius of curvature of about 33 feet as compared with a radius of curvature of approximately 81 feet in the first described embodiment.
  • the construction and principles of operation of this tank are the same as that of tank T. Also, due to the difference in size, there are slight differences in the amount of draft of the tank as it is being towed.
  • the tank T is constructed in a graving dock GD as previously described, and concrete is poured between the inner and outer side walls 10 and 12 to a of about 40 feet to provide ballast.
  • the graving dock is then flooded and the tank pressurized with air to a pressure of approximately 4.0 psig, and the tank towed into shallow water.
  • the tank floats with a draft of approximately 20 feet and the bottom edge of the tank is spaced approximately 10.0 feet downwardly below the air-water interface within the tank.
  • part of the air is vented from the vessel until the vessel assumes a draft of approximately 35 feet, at which point the bottom edge of the tank is spaced approximately 25 feet below the air-water interface in the tank.
  • the pressure of the air in the tank at this point is then about 5.0 psig.
  • the tank is towed to the installation site and air is then vented from the tank in a controlled manner until the tank rests on the sea floor. Concrete is then poured to the final depth between the wall 10 and 12 and the piles P are installed.
  • the tank T in FIG. 1 1 could be provided with a conical roof R", illustrated in phantom lines, rather than the dome roof R illustrated in full lines, if desired.
  • the roofR would simply comprise an extension of the side wall.
  • FIG. 12 a further modified tank T" is shown and a work platform or the like 23 is shown constructed on top of the tank T.
  • the platform 23 is supported by means of a plurality of vertically extending supports 24 connected to the tank T at the upper end of the side wall W.
  • a floor or bottom 25 of reinforced concrete or the like is in the tank T" to provide weight to the tank and to provide a mat type foundation and is secured to the lower edge of the side wall W of the tank.
  • a plurality of vents V extend through the wall W for establishing communication between the interior of the tank and the surrounding body of water.
  • a plurality of radially extending internal stiffening walls 26 of reinforced concrete or the like are secured to the inner surface of the wall W of the tank T and to the floor or bottom 25.
  • the platform 23 comprises or forms the roof for the tank, but a dome roof R, shown in phantom lines, or any other suitable roof could be provided, if desired.
  • the work platform could be constructed on top of the tank irregardless of whether the tank extends above the still water level or not.
  • Each of the tanks described herein could be provided with a bottom and/or internal stiffening walls, and a work platform and/or vents, if desired.
  • tanks as illustrated and described herein have been described as comprising a plurality of steel plates welded together, and as having particular dimensional relationships, it is to be understood that any suitable material could be used in constructing the tank and that the specific dimensions of the tank may be varied so long as the inventive concept of the invention is realized.
  • the pile anchoring of the tank to the sea floor is not necessary in all situations, and as an alternate, the total weight of the tank could be adjusted such that the weight of the tank maintains the tank on the sea floor and resists all wind, waves and currents.
  • This weight could comprise, for example, the floor or bottom 25 seen in FIG. 12.
  • a storage tank for storage of liquids in a body'of water comprising a unique side wall having substantially the shape of a frustum of a right circular cone and with an upper end thereof above the surface of the body of water and a lower end thereof fixed to the floor of the body of water, an annular, outwardly extending foot flange integral with the lower end of the side wall, a plurality of circumferentially spaced piles extending through the foot flange into the floor of the body of water fixing the tank to the floor of the body of water, said side wall comprising a pair of spaced apart, substantially coextensive, parallel inner and outer walls, reinforcing means fixed to the opposed, confronting interior surfaces of the parallel inner and outer walls and joining the inner and outer walls together, suitable ballast means in the space between the parallel inner and outer walls and substantially filling same, and a rigid, concavo-convex roof fixed on the upper end of said side wall above the surface of the body of water and closing the upper end of said tank, said roof comprising a
  • frusto-conically shaped wall is connected between the adjacent upper ends of the inner and outer side walls.
  • each of said inner and outer side walls and said roof comprises a plurality of steel plates welded or otherwise suitably secured together in edge-to-edge relationship.
  • a storage tank as in claim 8 wherein the upper diameter of the side wall is about 1 15 feet, the lower diameter of the side wall is about 315 feet, the height of the side wall is about feet, the roof is dome shaped and has a radius of curvature of about 81 feet, and the annular space between the inner and outer side walls is about 40.0 inches, said tank having a capacity of about 500,000 barrels of liquid.
  • a storage tank as in claim 16 wherein the bottom provides a mat foundation, and the weight of the tank is sufficient to resist movement of the tank.

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US00250732A 1972-05-05 1972-05-05 Storage tank for offshore storage of liquid and method of constructing and installing same Expired - Lifetime US3777497A (en)

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US25073272A 1972-05-05 1972-05-05

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4068480A (en) * 1975-11-13 1978-01-17 Kenneth Winans Lefever Liquid storage systems
US4405258A (en) * 1977-10-24 1983-09-20 Dome Petroleum Limited Method for containing oil and/or gas within a blow-out cover dome
US5004051A (en) * 1989-09-12 1991-04-02 Norwegian Contracts A/S Method and means for cleansing and storing drill cuttings from drilling operations in the sea bottom
WO2010048969A1 (en) * 2008-10-28 2010-05-06 Statoil Asa Subsea gravity separator
US20120045285A1 (en) * 2010-08-23 2012-02-23 Oil Well Closure And Protection As Offshore structure
US20140334884A1 (en) * 2010-02-15 2014-11-13 Arothron Ltd. Underwater energy storage system and power station powered therewith
US8894325B2 (en) 2010-05-04 2014-11-25 Oxus Recovery Solutions, Inc. Submerged hydrocarbon recovery apparatus
US20180163359A1 (en) * 2014-11-27 2018-06-14 Gravifloat As Sea bed terminal for offshore activities
US10988905B2 (en) * 2016-10-27 2021-04-27 Gravifloat As Harbour plant and method for mooring a floating body in a harbour plant

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3339512A (en) * 1966-06-17 1967-09-05 Siegel Gilbert Multiple storage and redistribution facility
US3429128A (en) * 1967-04-21 1969-02-25 Chicago Bridge & Iron Co Offshore storage structure
US3472033A (en) * 1966-10-26 1969-10-14 H J Gruy & Associates Inc Fluid storage apparatus
US3675427A (en) * 1969-11-25 1972-07-11 Arcadia Refining Co Underwater storage device
US3686811A (en) * 1970-02-09 1972-08-29 Charles W Hayes Spaced multi-wall construction unit
US3708987A (en) * 1971-07-23 1973-01-09 J Roulet Concrete reservoir for underwater use

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3339512A (en) * 1966-06-17 1967-09-05 Siegel Gilbert Multiple storage and redistribution facility
US3472033A (en) * 1966-10-26 1969-10-14 H J Gruy & Associates Inc Fluid storage apparatus
US3429128A (en) * 1967-04-21 1969-02-25 Chicago Bridge & Iron Co Offshore storage structure
US3675427A (en) * 1969-11-25 1972-07-11 Arcadia Refining Co Underwater storage device
US3686811A (en) * 1970-02-09 1972-08-29 Charles W Hayes Spaced multi-wall construction unit
US3708987A (en) * 1971-07-23 1973-01-09 J Roulet Concrete reservoir for underwater use

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4068480A (en) * 1975-11-13 1978-01-17 Kenneth Winans Lefever Liquid storage systems
US4405258A (en) * 1977-10-24 1983-09-20 Dome Petroleum Limited Method for containing oil and/or gas within a blow-out cover dome
US5004051A (en) * 1989-09-12 1991-04-02 Norwegian Contracts A/S Method and means for cleansing and storing drill cuttings from drilling operations in the sea bottom
US8597506B2 (en) * 2008-10-28 2013-12-03 Statoil Petroleum As Subsea gravity separator
NO345024B1 (no) * 2008-10-28 2020-08-24 Equinor Energy As Undervanns gravitasjonsseparator
US20110259901A1 (en) * 2008-10-28 2011-10-27 Statoil Petroleum As Subsea gravity separator
GB2476763B (en) * 2008-10-28 2012-10-17 Statoil Petroleum As Subsea gravity separator
WO2010048969A1 (en) * 2008-10-28 2010-05-06 Statoil Asa Subsea gravity separator
GB2476763A (en) * 2008-10-28 2011-07-06 Statoil Petroleum As Subsea gravity separator
DK178669B1 (da) * 2008-10-28 2016-10-24 Statoil Petroleum As Undersøisk gravitationsseparator
US10894660B2 (en) 2010-02-15 2021-01-19 Yehuda Kahane Ltd Underwater energy storage system and power station powered therewith
US20140334884A1 (en) * 2010-02-15 2014-11-13 Arothron Ltd. Underwater energy storage system and power station powered therewith
US9309046B2 (en) * 2010-02-15 2016-04-12 Arothron Ltd. Underwater energy storage system and power station powered therewith
US8894325B2 (en) 2010-05-04 2014-11-25 Oxus Recovery Solutions, Inc. Submerged hydrocarbon recovery apparatus
US20120045285A1 (en) * 2010-08-23 2012-02-23 Oil Well Closure And Protection As Offshore structure
US10633815B2 (en) * 2014-11-27 2020-04-28 Gravifloat As Sea bed terminal for offshore activities
US20180163359A1 (en) * 2014-11-27 2018-06-14 Gravifloat As Sea bed terminal for offshore activities
US10988905B2 (en) * 2016-10-27 2021-04-27 Gravifloat As Harbour plant and method for mooring a floating body in a harbour plant

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JPS4954915A (da) 1974-05-28
JPS5247575B2 (da) 1977-12-03
DK138594C (da) 1979-05-07
GB1384360A (en) 1975-02-19
DK138594B (da) 1978-10-02

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Effective date: 19810107

Owner name: PITTSBURGH-DES MOINES CORPORATION

Free format text: CHANGE OF NAME;ASSIGNOR:PITTSBURGH-DES MOINES STEEL COMPANY;REEL/FRAME:003849/0081

Effective date: 19810107