US2220186A - Tank construction - Google Patents

Description

NOV. 5, 1940. H. Q WALKER 2,220,186

TANK CONSTRUCTION Filed Deo. 24. 1957 ATTORNEY.

Patented Nov. 5, 1940 UNITED STATES TANK CONSTRUCTION Henry 0. Walker, Warren, Pa., assignor to Hammond Iron Works, Warren, Pa., a corporation of Pennsylvania Application December'- 24, 1937, serial No. 181,549

9 Claims This invention relates to tanks or reservoirs for containing or storing materials such as liquids, and has particular reference to storage tanks of the type adapted to accommodate rela- 5 tively large bodies of oil, petroleum or other viscous liquids, yespecially those liquids Whose specic gravity is less than that of water.

More specically the invention relates to the bottom construction of such tanks and to a manner of constructing and the arrangement of a bottom in the tanks to aiord a strong, durable and substantially water-tight construction.

The prime object of the invention is to provide a method of rendering fit for utilization again,

l liquid holding tanks thebottoms and/or lowermost Wall portions of which have become leaky and are no longer water-tight as a result of rusting, erosion or corrosion.

Another object is toprovide a method of installing, in tanks that have become leaky at the bottom or adjacent thereto, a false or replacement bottom in a manner that will aiord a substantially water-tight construction, and at the same time to determine that the structure actually is substantially water-tight.

A further object is to provide a novel bottom construction for liquid holding tanks or the like that is strong, durable and substantially watertight.

A still further object is to provide a liquid holding tank having a false or re-built bottom constructed in a novel manner and that is strong, durable and substantially water-tight.

Petroleum and its products are usually stored in'steel tanks above ground. In most locations the steel tanks are set directly on the ground. These tanks are generally constructed of plates of structural steel, the plates running in thickness from of an inch upwards. The plates forming the bottom are joined together in a watertight manner by riveting, bolting or welding and the edges of adjoining plates are generally lapped. The walls of the tank are generally constructed of rings made up of a number of plate sections, the lowermost ring being joined to the bottom by means of an annular angle iron, all joints being made Water-tight in any suitable manner.

In tanks of this sort corrosion difficulties are 5o encountered most frequently at the bottom and at the joint between the bottom and the walls of the tank and cause considerable annoyance necessitating expensive repairs and in many cases necessitating razing of the tank and erection of a completely new one. The reasons for these corrosion troubles being confined primarily to the bottom portion of the tank arel several. First, there is the fact that any water in the tank or body of oil contained therein will gravitate naturally to the bottom and will there attack the bot- 5 tom plates and cause oxidation and rusting. Furthermore, the bottom is aiected on its underside by the humus acids in the soil upon which it rests. To these causes are added the contributing chemical eiects of the various acids in the 10 oil itself.

Having in mind the above enumerated corrosion difficulties, it is a primary purpose of the present invention to provide a method of effecting repair or replacement of a corroded tank bot- 15 tom in an eminently satisfactory and economical manner and to obviate the necessity for completely rebuilding the bottom or replacing the entire tank structure.

The invention possesses other objects and fea- 20 tures of advantage, some of which, with the foregoing, will be set forth in the following description. In the accompanying drawing, for the purpose of example, there has been illustrated the best embodiment of the invention now known 25 to me, but such embodiment is to be regarded as typical only of-many possible embodiments, and the invention is not to be limited thereto.

In the drawing:

Figure 1 is a top plan view of an oil storage 30 tank showing one manner of arranging the individual steel plates comprising the replacement bottom according to a form of the invention.

Figure 2 is a top plan View similar to Figure 1 but showing a storage tank rectangular in cross section.

Figure 3 is an enlarged sectional perspective view through part of the bottom and side Wall of an oil storage tank showing the replacement bottom of the present invention in position and 40 illustrating the method of constructing the same. Figure 4' is a vertical sectional view similar to Figure 3 and showing a modified detail of the construction.

Referring particularly to Fig. 3, the numeral 45 5 designates the upstanding side wall of an oil storage tank circular in cross-section, the said wall being constructed of a number of steel plates joined together by riveting, Welding or other appropriate means. The Wall 5 adjacent its lower 50 edge is secured to the upstanding ange of an annular angle iron 6 by means of the rivets 1, and to the horizontal flange of the angle iron 6 is attached the original tank bottom 8 by means 0f the rivets 9. For `convenience in illustration, 65

2 y l annonce* the tank bottom 8 has been shown as a one-piece structure. However, as mentioned above, the tank bottom is generally constructed of lap or butt 'jointed plate sections. Furthermore, the 5 wall 5 and bottom 8 have been shown as riveted to the angle iron 6 but it is understood that they may be secured to the angle iron in any other suitable manner such as by bolting or welding. 'Ihe joints betweenythe angle iron and the bottom 10 and sides also are generally made Water and oil-tight by calking or otherwise, when a riveted or bolted construction is used.

As explained above, the bottom 8 in most instances rests directly upon the ground as will l5 clearly be seen in Fig. 4, and is subjected to various corrosive attacks bothfrom the constituents of the soil on the underside and from the water and possibly other contents of the tank on the upper side.

The useful span of life of storage tanks `constructed as above is definitely limited and is generally determined by the condition of the tank bottom. This may s ometimes.be repaired but such repairs are diilicult and expensive and in any event the bottom will eventually become so corroded as to preclude eifective repair and thus necessitate complete rebuilding of the tank even though the upper walls may be perfectly satisfactory for vcontinued service. The present invention completely eliminates these dinlculties by providing a method and a construction whereby a complete replacement or false bottom may bebuilt into the tank with a minimum of eort and expense and will provide ineiect a completely rebuilt bottom that is water-tight, durable and highly eflicient,

Referring again to Fig. 3, it is assumed that the bottom 8 of the tank has become so corroded as to render it no longe efficient. The

tank is completely drained of its contents and upon the upper side of the bottom 8 is spread a uniform and homogeneous layer or foundation I0 of sand, fine gravel, cinders, or other loose aggregate. The thickness; of the layer I8 may be any that is desirable, but in the present embodiment is generally built up so that its top surface is approximately level with the highest point on the upper heads II of the rivets 9 so that the heads II will serve as steps or foundations upon which the outer periphery of the false bottom may solidly rest.

The foundation I0 having been laid firmly in, place, there is now constructed upon the upper surface thereof, a replacement or false bottom I2 which is preferably composed of individual plate sections I3 joined to one another in a Vwater-tight manner by welds Il. These plate sections-are preferably lap-welded to one another as shown in Fig. 4, butmay, of course,

be butt-welded as seen in Fig. 3. The false bottom I2 may, of course, consist of a single unitary steel member. However, a steel shape of that character would be extremely diiicult and expensive to obtain so that the bottom I2 is generally constructed, in situ, of the individual plate sections, as just described. Fig. 1 shows the manner in which the plate sections adjacent the outer periphery of the member |2'may be cut or sheared to conform to the contour of the inner wall of the tank.

The thus fabricated false bottom I2 is substantially circular in shape and of `a diameter just slightly less than the inside diameter of 'the tank adjacent its bottom so that the outer u peripheral edge of the member I2 lies closely adjacent to and approximately parallels the inner wall of the tank, with the underside ofthe false bottom I2 adjacent its periphery resting iirmly upon the heads II of the rivets 8 as here-v` inbefore explained. The outer edge of the false 5 bottom I2 at its upper side is now intermittently welded to the inside face of thev vertical flange of the annular angle iron 6 or the inside of the wall 5 of the tank as th'e case may be by means of the interrupted llets I5, leaving an unwelded l0 area I6 of substantial extent between eachilllet, for the purpose presently to be described.

The false bottom .I2 having been thus fabricated and resting upon 'its sand -cushion I8 on the heads II of the rivets, there is now provided l5 Ameans for. sealing the new bottom I2 to the inner side of the wall 5 so as to provide a watertight and substantially oil-tight construction and provision is made, in connection with this sealing means, for testing the construction and as- 20 certaining that it is water-tight, or of locating the nature and extent of any points of leakage. Tothis end a sealing ring I1, in the preferred construction taking the form of an inverted angle iron, is placed in position entirely around 25 ,the inside of the tank adjacent the point of conjunction of the side wall 5 and the bottom I2, one end of the sealing ring being contiguous to the inner face of the side wall and the other edge resting uponthe bottom I2.l It will be appar- 30 ent, of course, that the construction is not limited to the specific angle iron shape shown here in, but may take the form of any other suitable metallic shape and may even be a at strip placed at an angle with one edge resting against the 35 side wall and the other against the bottom. The sealing ring II is continuous, of course, and extends completely around the inside of the tank. The horizontal leg I8 oi' the sealing ring II, which parallels the inner surface of the wall 40 5, is now welded to the inner surface of the wall by means of the continuous and uninterrupted fillet I8 which extends completely around the inside of the tank and forms an eiectively sealed joint between the leg I8 and the inner surface 45 of the wall 5. To seal the joint between the edge of the vertical leg 28 and the bottom I2,

vthe said leg is welded to the bottom by means of the continuous and uninterrupted fillet 2| which also extends completely around the joint 50 between the bottom vand the sealing ring and forms an effective water-tight and substantially oil-tight seal. It will now-be apparent that, assuming all of the welds hereinbefore described to have been executed in a satisfactory manner, 55 the tank will now be provided with a new bottom which will be in all respects water-tight and substantially oil-tight. A visual inspection of the various welded areas will generally suice to assure that all joints are water-tight, particu- 60 larly if relatively large amounts of weld metal are used throughout the welded areas However, in order to provide an accurate check on the original inspection, and, particularly if a minimum amount of weld metal is used at the 65 various joints, a method and means -are provided for testing the newly fabricated structure in order to determine beyond doubt that it is actually water-tight.

For this purpose one or more relatively .small 70 holes or openings 22 are drilled through the horizontal leg I8 of the sealing ring I'I. The opening 22 is .then screw-threaded internally and into the same is then screwed the pipe or tube 23 having a corresponding externally screw-threaded end. It 'I5 without na screw-threaded connection, a screw,

threaded connection, however, providinga solid joint more satisfactory for the ensuing test tha most other types of connection. -V

Having now placed the pipe 23 in position so that it communicates with the space 24 between the sealing ring I'I and the wall and bottom of the tank, water or other suitable liquid is now pumped or otherwise forced through' the pipe 23 into the space 24. Using a relatively small amount .of pressure, the liquid will be forced through the spaces between the outer edge of the bottom I2 and the inner surface of the upstanding leg of the angle iron 6 at the unwelded areas I6. Thus it will eventually permeate and saturate the sand cushion I0 and completely fill the space 24. Thereafter continued pressure on this body of liquid exerted through the pipe 23 will force the liquid through any part of the new construction that is not water-tight and will thus appear on the inside of the tank and apprise the observer of any points or localities of leakage. Any Xpoints wheregsuch leakage is observed may then be efectively sealed by welding and the structure effectively made completely water-tight.

Upon completion of the foregoing test, and having observed that there are no leaks, or having remedied whatever leaks may have been observed, the pipe 23 is now withdrawn from the opening 22. The opening or openings 22 arethen tightly sealed preferably by means of screwthreaded bolt 25 if the opening 22 is internally screw threaded. If not, other suitable. plugs or sealing means may be used` such as a metal plug which may be welded into the opening,

The new bottom construction and joint having been thus thoroughly tested and examined and the test openings 22 having been effectively plugged andsealed, there is now provided an oil storage tank having a completely new bottom that is water-tight and substantially oil-tight in every particular and that is satisfactory and eminently t for continuation of its oil storage function.

The above described method of testing the new bottom construction with water is generally the most convenient where an adequate water supply is available. In addition, other testing methods may be mentioned briey and these will provide an even more accurate check upon the oil-tight characteristics of the welded seams. Where sufficient oil, petroleum or any of its products is available, a quantity of the same may be forced through the pipe 23 and into the sand bed I0 and the space 24 and a static pressure built up against it suicient to force the oil through any openings, even very minute ones. This method will, of course, provide a very accurate test'since it Will reveal any points through which oil could leak. This method also has the further advantage in that it provides the underside of the new or false bottom I2 with a protective coating of oil or petroleum which, of course, will hinder to some extent, the corrosive attacks of water and moisture upon the underside of the false bottom.

Another useful test method, Where neither oil nor water` are readily available, is to smear or coat all seams or Welded areas with a soap solution. Air is then forced or blown through the pipe 23 and beneath the bottom I2 and into the space 24. With a relatively small amount of pressure behind the air, the same will, of course, be

forced through any openings or porous points in the welds and will reveal itself in the form of bubbles caused by contact of the air with the coating'of soap solution. Wherever the bubbles appear, additional welding can be effected and thus assure air-tight seams which will, of course, be water-tight and substantially oil-tight.

While steel oil storage tanks are most generally guration, square or rectangular tanks are sometimes encountered and a plan view of this type of tank is shown in Fig. 2. In that construction it is a relatively" simple matter to lay out and fabricate the false bottom I2 as shown since the plates I3 do not have to be sheared to conform with the inner contour of a curved wall.- In the construction of Fig. 2, the plates are merely laid upon the sand cushion I0 as previously described and then intermittently welded to the side walls of the tank. In this instance the sealing member I1 will preferably be constructed of four straight sections of angle iron, or other preferred metallic shape, one of which sections will, of course, be

laid along each sidewall of the tank and con-` tinuously welded to the corresponding side wall and to the false bottom l2. These strips will, of course, also be welded to one another at their joints 26 in each corner lof the tank and the construction may then be tested for leakage in any of the manners hereinbefore described in connection with the round tank.

It will be appreciated, of course, that, in either shape of tank, the false bottom I2 need not necessarily be welded or joined to the side wall 5 as at I5. In other words, if preferred, the false bottom may be fabricated upon the cushion I0 and the sealing ring I'I may be applied thereafter without any Welding or otherwise joining of the peripheral edge of the false bottom to the side wall, the intermittent weld fillets I5 .serving merely to provide a more rigid and durable structure. The

cushion I0 of loose aggregate material might also in some instances be eliminated without departing from the scope of the invention. In that event it would probably be necessary to place blocks of Wood or other material at scattered points over the original bottom 8 to serve as supporting elements for the false bottom I2 and to prevent any tendency of the same to buckle, the continuous cushion of loose filling material, however, being preferred as it supports the false bottom throughout its entire area and eliminates any stress caused by the weight of the contents of the tank,

In either event the present invention provides a method of installing a completely new bottom in an oil tank, the original bottom of which has become so corroded as to be unt for further service. All fabrication and construction of the false bottom may be effected,l in the field without resort to prefabricated special shapes or structures and a construction results which is strong, durable and highly efficient for continuation of the function for which the tank is adapted. Fursand cushion between it and the false bottom I 2 and an additional sealing ring placed upon the new or additional false bottom and sealed in place and tested in any of the manners heretofore metioned. This procedure may, of course, be continued indeiinitely, depending upon the condition of the side walls l and the capacity of the tank desired.

What is claimed is: v 4

1. In a round tank construction, a bottom and an upstanding side wall substantially perpendicular to said bottom, a layer of loose aggregate material covering said bottom, a round false bottom resting upon said material and having its peripheral edge lying adjacent to and paralleling the inside of said upstanding wall, and a sealing ring between the false bottom and the wall and. continuously welded to each, said sealing ring, said wall, and said false bottom constituting an annular chamber, which chamber is provided with an opening in the connes thereof, whereby a fluid may be introduced into said chamber to reveal any points of leakage in the welding.

2. In a round tank construction, a bottom and an upstanding side Wall substantiallyperpendicular to said bottom, a layer of loose aggregate material covering said bottom, a round false bottom resting upon said material, said false bottom having its peripheral edge lying adjacent to and paralleling the inside of said upstanding wall and intermittently welded thereto, and a sealing ring between the false bottom and the wall and 'continuously welded to each, said sealing ring, said wall, and said false bottom constituting an annular chamber, which chamber is provided with an opening in the confines thereof, whereby a fluid may be introduced into said chamber to reveal any points of leakage in the welding.

3. In a round tank construction, a bottom and an upstanding side wall substantially perpendicular to said bottom, a layer of loose aggregate material covering said bottom, a round false bottom constructed of plate sections welded together resting upon said material and having its peripheral edge lying adjacent to and paralleling the inside of said upstanding wall 'and a sealing ring between thev false bottom and the wall and continuously welded to each, said sealing ring, said wall, and said false bottom constituting an annular chamber, which chamber is provided with an opening in the confines thereof, whereby a fluid may be introduced into said chamber to reveal any points of leakage in the welding.

4. A stationary metallic storage tank of large capacity, having a supplemental bottom member within the tank and having an approximate iit around its periphery with the upstanding substantially perpendicular side wall of the tank, a sealing ring having its lower peripheral edge resting upon the top of the supplemental bottom member inwardly from the peripheral edge thereof and welded thereto in liquid-tight sealed relation throughout the length of the periphery of the ring, the upper peripheral edge of the ring resting against the inner face of the peripheral 'side wall of the tank above the supplemental bottom member and welded to the said side wall throughout the peripheral length of the rlng and in liquid-tight relation with said tank wall, the supplemental bottom member, the sealingring and a portion of the tank side wall defining an annular chamber along the periphery of the supplemental bottom member, and a tubular element leading into said chamber through an opening in the contines thereof, whereby a fluidv may'be conducted into said chamber and underneath said supplemental bottom to reveal any points of leakage in the welding.

5. A stationary metallic storage tank of large capacity having a supplemental bottom member within the tank and having an approximate fit around its periphery with the upstanding side wall of lthe tank, means supporting the supplemental bottom above the main bottom of the tank, and a sealing ring having its lower peripheral edge resting upon the top of the supplemental bottom member inwardly from the`peripheral edge thereof and welded thereto in liquidtight sealed relation throughout the length of the periphery of the ring, the upper peripheral edge of the ring resting against the inner face of the peripheral side Wall of the tank above the supplemental bottom and welded to the said side wall throughout the peripheral length of the ring and in liquid-tight relation with said tank wall, the supplemental bottom member, the sealing ring and a portion of the tank side wall defining' an annular chamber around the periphery of the supplemental bottom member, and a tubular element leading into said chamber through an opening in the coniines thereof, whereby a fluid may be conducted into said chamber and underneath said supplemental bottom to reveal any points of leakage in the welding.

6. A stationary metallic storage tank of large capacity, having a supplemental bottom member within' the tank and having an approximate t around its periphery with the upstanding substantially perpendicularsde wall of the tank, a sealing ring having its lower peripheral edge resting upon the top of the supplemental bottom member inwardly from the peripheral edge thereof and welded thereto in liquid-tight sealed relation throughout the .length of the periphery of the ring, the upper peripheral edge of the ring resting against the inner face of the peripheral side wall of the tank above the supplemental bottom member and welded to the said side wall throughout the peripheral length of the ring and in liquid-tight relation with said tank wall, the supplemental bottom member, the sealing ring and a portion of the tank side wall defining an annular chamber along the periphery of the supplemental bottom member, said annular chamber having an opening in the confines thereof whereby a fluid may be introduced into said chamber to reveal any points of leakagelin the welding.v g

7. A tank according to claim 6, with the addition of closure means for said opening.

8. A tank according to claim 6, in which said opening is provided in said. sealing ring.

9. A tank according to claim 6, in which said opening is tapped, with the addition of a closure membervtherefor in the way of a screw element.

HENRY O. WALKER.

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