US 2330306 A
Description (OCR text may contain errors)
C. E. MURPHY ENAMELED TANK Sept. 28, 1943.
2 Sheets-Sheet 1 Filed Nov. 25 1940 INVENTOR. C//WE/f /J f wf ATTORNEY.
Sept 28, 1943 c. E. MURPHY ENAMELED TANK Filed Nov. 25, 1940 2 Sheets-Sheet 2 INV Alk.
f4 VMH www m ,w m f. a Q w Patented Sept.. 28, 1943 STATES PATEN ortica ENAMELED TANK Application November 25, 1940, Serial No. 367,075
` becomes perforated by the corrosion and a leak results destroying further usefulness of the tank for its intended purposes. For a number of years it has been the practice to galvanize the tanks walls to resist such corrosion, lbut because the tank is a closed container, at the time that the coating is applied, it is next to impossible to produce a continuous solid galvanized coat on the inner wall by any known 'galvanizing method; and a single uncoated spot will corrode and become perforated in as short a time as if there were no coating at all.
The useful life of the usual galvanized hot Water tank therefor is little if any longer than that of an ungalvanized one.
Metals and allo-ys having corrosion-resisting properties have been proposed for the Walls of such tanks to prolong their life but such tanks are too expensive for the general market.
The cheapest and most practicable known fabricating process for making the tank Walls, is to make the Walls in pieces from sheet steel and to join them together; and to render such a steel tank corrosion proof, it has been proposed to coat the tank walls, particularly the inside Wall, with vitreous enamel, that is to say enamel formed by ring and fusing dried enamel slip. The tank walls may be variously constructed but the applying of the enamel coat presents difoulties. The enamel coat must be absolutely complete and solid so as not to expose even a single uncoated spot of the steel wall ho-wet er small to the corrosive action of the hot water; and for this reason, if welding' be used in joining the steel parts of the Wall, the welds must be contrived in some manner so that the enamel as applied will not contact the Weld itself, because if it does it will not form-solidly thereover, with the one exception of electric flash welding the flash of which has been tooled ofi down to solid metal.
Again, if parts of the wall are joined by rivet,- ing. spot welding, roll welding, etc., so that one part overlaps another with intermediate crevices, foreign matter which unavoidably nds its Way into said crevices, or which is produced therein by (Cl. 22o-55) the welding operation, will vitiate the enamel coat during the formation thereof so that it will not formsolidly or completely thereover. And if the joints between wal1pieces are not perfectly rigid, one part will have movement relative to another when the tank is subjected to internal pressure, and even if suchrelative movement is so slight as to be imperceptible Without delicate measuring instruments, it still is suicient to crack the glasslike brittle enamel coat thereat and admit the corrosive hot water to the steel of the wall.
The general market and manufacturing facilities and economies demand a hot Water tank of the form comprising an elongated cylindrical body and -heads at each end of the body. If the body wall of such a tank, which lfor the sake of economy -must be made of as thin metal as practicable, comprises any portions which are gen,- erally planar, or out of round, they tend to become mo-re truly cylindrical under the internal pressure and this deformation Vwill crack the enamel; or if there are any curved wall portions of any shape which under pressure become straightened out by the longitudinal pressure on the heads which tends to stretch the body, their deformation also Wlll crack the enamel. Cracking of the enamel at any point on the inner wall of the tank will start corrosion thereof.
It follows therefore that a successful enameled hot water tank cannot be arrived at by taking just any known steel-walled tank and attempting to coat it with enamel.
After many experimental attempts to make such a tank I have found that the above indicated problems can be solved and herein I have described the preferred construction and method of making such a tank.
The preferred construction comprises a cylindrical tubular Ibody of relatively thin steel with a ash-Welded lc-ngituidinalv seam tooled off down to solid metal and the' body trued up to cylindrical form; a heavy ring of steel surrounding the outside of the body andwelded to it near each end. and the ends of the body anged and coined over the rings; a pair of dishe'd peripherally flanged heads of outwardly curved or generally ellipsoidal sectional form at eachy end of the body and of suiiciently thick sheet steel to resist deformation by internal tank pressure; and means to sealedly attach the heads to the ends of the body through the agency of the rlngs.-
With'the body parts thus made separately, they can each be enameledy separately and the enamel coat thoroughly inspected for imperfections before the parts are assembled in the completed tank; and the formation of a perfect enamel coat is facilitated during the enameling process;
and all liability of enamel cracking during assembly or by internal pressure after assembly is avoided. n
Ihe present invention relates particularly to means by which the enameled heads of such a tank are attached to the enameled body.
It is among the objects of this invention therefore:
To provide generally an improved construction of enamel-coated tank for containing fluid such as hot water under pressure;
To provide improved means for attaching an enameled tank head to an enameled tank body;
To provide improved means for attaching an enameled tank head to an enameled tank body which allows for variation in the dimensions of the head and body which occur during the manufacture thereof;
To provide an improved construction of clamping device or means for clamping the enameled peripheral ange of a tank head upon the enameled peripheral flange of a tank body with sealing gasket material therebetween to effect an improved internal pressure-proof and leak-proof juncture between the head and the body;
To provide in connection with a head clamping construction such as referred to above, improved cover means to cover and conceal the same.
Other objects will be apparent to those skilled in the art to which my invention appertains.
My invention is fully disclosed in the following description taken in connection with the accompanying drawings in which,
Fig. 1 is a side elevational view partly broken away of a tank embodying my invention in one form;
Fig. 2 is a top plan view of the embodiment of Fig. 1;
Fig. 3 is a fragmentary longitudinal sectional View to enlarged scale of a part of the tank of Fig. l illustrating in the preferred form a means of attaching a head to a tank body and a cover element for covering the attaching means;
Figs. 4 and 5 are views similar to Fig. 3 illustrating a modification and the mode of operation thereof to compensate for dimensional variations which may occur in the construction of the parts of the tank;
Fig. 6 is a view similar to Fig. 3 illustrating another modification;
Fig. 7 is a view illustrating a modification of a bolt device which I may employ, one form of which is shown in Figs. 4 and 5; Y
Fig. 8 is a view taken in the direction of the arrow 8 of Fig. 7;
Fig. 9 is a view similar to Fig. 7 illustrating another modification; f
Fig. 10 is a view taken in the direction of the arrow IIl of Fig. 9;
Fig. 11 is a view similar to Fig. 3 but illustrating another modification;
Figs. 12 and 13 are views illustrating the mode of operation of the modification of Fig. 11 to compensate for dimensional variations which may occur in the construction of the parts of the tank; Y
Fig. 14 is a view illustrating steps of the process which may be employed in the formation of a clip device shown in Fig. 11;
Fig. 15 is a view similar to Fig. 3 showing the head-'attaching means of Fig. 3 for the head at the opposite end of tank;
Figs. 16, 17 and 18 are other views similar to Fig. 3 showing other modications.
Referring to the drawings, Figs. 1 and 2. wherein I have illustrated one form of a tank embodywhich are the conduits 4--4 connected to the head 2.
The body I is preferably constructed by rolling a sheet of steel into the form of a hollow cylinder and ash welding the abutting edges thereof together at a longitudinal joint indicated at 5 in Fig. 3. A heavy steel ring 6 is tack Welded or spot welded to the outer wall of the body I inwardly of the end of the body and then the end of the body is bent and, coined over the ring 8 to form a ange l.
'I'he ring 6 has preferably a corner 8 which is coined into the metal of the wall where the flange 1 joins the cylindrical body I, and the cylindrical body I is then trued up to remove any planar or out of round portions. Rings 6 and flanges 1 are provided on each of the opposite ends of the body I, and by the fabricating process employed, when the opposite end heads 2 and 3 have been attached to the body wall through the agency of the rings 6, and internal pressure exerts longitudinal tension in the Wall I, there is no part of the wall which is out of round or which tends to straighten out in the axial direction, and deformation is prevented, for the purposes referred to.
After the flash has been trimmed off from the weld 5 down to solid metal and any other roughness on the wall of the body I flange 'I or ring 6 has been removed, the body flange and ring are coated with a coat of vitreous enamel 9.
The heads 2 and 3 may be alike except in some cases as to a diierent number of conduits 4 connected thereto. I'he head 2 as shown in Figs. 1 and 3 is generally of hemi-ellipsoidal crosssectional form having a peripheral flange I0 lying substantially in a plane transversely of the head and continuing peripherally into a depending skirt II. The flange I0 has a circular series of bolt perforations I2 therein the series being substantially concentric with the axis of the head.
The head including the ange I0 and skirt II are coated inside and out with a coat of vitreous enamel I3, the perforations I2 being provided either before or after the enameling process.
By making the body separate from the two heads and enameling the three parts separately, the formationA of an unbroken solid coat of enamel is facilitated inasmuch as oxygen-containing air is free to flow over all the surfaces being enamel-coated. This free ilow of air facilitates drying the wet enamel slip uniformly and without sweating and during the firing of the dried slip the essential presence of oxygen on all parts of the surfaces of the pieces is readily attained. Forming the pieces separately permits a thorough inspection of the enamel coat thereon for accidental imperfections.
To assemble the head with the body, a sealing gasket I4 is laid on the ange 1, and the head flange I0 superimposed thereon and the head flange is clamped upon the body flange with the gasket therebetween by the following means.
Bolts I5 are projected downwardly through the perforations I2 and their lower ends are threaded into washers or plates I5 overlapping and bridging the under side of the enameled ring 6 and the lower termination of the skirt 1. The bolts I5 are then turned by their heads I1 and by the clamping action exerted between the heads and the plates I6, the head flange I is drawn down tight upon the body flange I to effect a pressureproof and liquid-tight seal at the gasket I4.
'I'he skirt II performs a number of functions. Since the bolts I are radially outward beyond the gasket I4, the latter acts as a fulcrum over which the flange I0 tends to bend and it might bend and crack the enamel on the flange if it were not for the skirt II, but the presence of the skirt prevents such bending because in order for the flange IIJ to bend the skirt II would have to be compressed or deformed, and the skirt II being disposed at right angles to the plane of the flange Ill it acts as a beam of relatively great depth and gives rigidity to the flange I0 and prevents it from bending. This is important because bending of the flange I0 would crack the enamel.
Again, since the gasket I4 is compressible, and since the boltsl I5 must be spaced one from the other in their circular series, the force of the bolt heads I'I would tend to force the flange I0 into the gasket I4 at points opposite the bolts and allow it to remain bulged upwardly at points between the bolts and this would tend to crack the enamel, but the skirt II contributes such rigidity to the flange I0 that this action and enamel cracking is prevented. Again, theskirt II at its lower peripheral edge provides a base upon which the plate or washer I6 engages for the clamping purposes described above. Again, the skirt II covers the bodies of the bolts I5 and conceals them, rendering neat in appearance what would otherwise be a complicated appearing bolted structure.
The under sides of the heads I'I of the clamping bolts, may be generally spherical as indicated in Fig. 3 so that they will engage the perforations I2 on the end edges thereof and thereby prevent mutilation of the enamel as the bolts are turned.
The diameter of the skirt II is made dimensionally such that a space I8 may preferably be left between the bolts and the enamel coat on the ring 6 and so that a space I9 may be left between the bolts and the skirt I I, and the perforations I2 are located on a circle of such diameter that the bolts will extend downwardly between the skirt and the ring so that these spaces I8 and I9 will be substantially equal. v
A number of advantages accrued from the employment of the construction described above which are not apparent without further consider,- ation. In the making of the head 2 by the usual press-forming operation, strains are set up in the metal. When the enamel coat is applied the metal is heated to at least a cherry-red color so that the heads tend to warp. The flange I0 may warp slightly out of a true plane, or if it is all in one plane it may warp slightly out of parallelism with planes at right angles to the axis of the body or of the head itself, and the skirt II may warp slightly out of cylindrical form. Similarly the ring 6 and body I may Warp slightly out of round and slightly out of planar form at the ring and ange '1. Again, the perforations I2 may not lie exactly on a circle or upon a center line circle of exactly pre-selected diameter, and
if accurate die means is used to punch such perforations they may not lie in their pre-selected positions after the head is enameled because ,of the above-mentioned warping which may take place.
By means of the above-described.construction which includes the spaces I8 and I9, considerable tolerance in the dimensions and shapes referred to is permitted and therefore although, out of a number of heads and bodies, no two heads and no two bodies may be exactly alike, any two heads may be mounted as described upon any of the bodies, and thus complete interchangeability is provided not withstanding that the allowable tolerances are very great, both as to accuracy in making the parts in the first instance and as to warpage due to subsequent heating.
While the warpage referred to is` not of sufcient degree to cause the Wall or head to deform under pressure in use and crack the enamel coat, it may be enough to interfere with assembly of the parts, if such tolerances are not provided.
If desired, the joint structureabove-described in connection with Fig. 3 for the upper head may be made still more neat in appearance by the following means. A sheet metal cover 20 is pressformed or spun from sheet metal, which may be light in gage, and comprising a planar cup bottom 2| and a cup skirt 22. A large perforation 23 is made in the cup bottom. After the head has been attached to the body or after the tank has been installed, or brought to the' place of installation, the perforation 23 is telescoped over the upwardly curving part of the head as shown with the skirt 22 depending around and covering allof the parts of the joint and the cup bottom .2l may rest upon the heads Il of the bolts to support the cup-form element as a joint cover. The cup-form element 20 may be externally plated or plated and polished if desired or it may be enamel-coated and of the same or of a dillerent color from the external enamel 9 and I3 giving a very neat and ornamental appearance to the entire structure, and since the head 2 is enameled separately from the body I, it may have a different color from that of the body.
In Fig. 15 this same joint structure of Fig, 3 is illustrated for the lower head 3 and a cup form cover device 24 may be provided having a skirt 25 with the bottom of the cup resting upon the ends of the bolts l5 as shown in Fig. l5. The cover device may be put on before the head is attached.
In Fig. 6 is illustrated a modification of the clamping means. Here instead of the bolt I5 and plate or washer I6 of Fig. 3, a J-bolt 26 is used, the short leg 21 of the J engaging the under vside of the enameled ring 6, the long leg of the J extending upwardly through the perforation in the flange I0 and having threaded thereon aconstruction is the same as that of Fig. 3 except that the bolt in this case 29 is projected downwardly through the flange I 6 with the head 30 of the bolt resting on the flange, and with a nut 3| on the lower end of the bolt below the plate or washer I6, and the nut having if desired a rounded or spherical under side as shown at 32 in engagement with the plate I6. The plate I6 is in this case provided with a perforation through which the bolt extends loosely and as the nut 3| is drawn up tight, the plate will assume the right angle position with respect to the bolt indicated in Fig. 3 or will rock one way or the other into bridging and clamping engagement with the skirt II and ring 6 as shown in Fig. 4 or Fig. 5 depending upon whether in the inal assembly the combined thickness of the ring 6 and flange 1 and the packing washer I4 brings the lower side of the ring 6 below or above the peripheral edge of the skirt II.
Instead of the bolt and nut arrangement of Figs. 4 and 5 the bolt and nutarrangement of Figs. '7 and 8 or that of Figs. 9 and 10 may be employed the construction and mode of operation of which it is believed will be apparent without further description from the above-detailed description of Figs. 4 and 5.
In Fig. 11 is illustrated a further modification which in addition to the above-described tolerance advantages has a centering action and an inter-locking action. As shown in Fig. l1 the ring, in this case 6A has the under side 33 thereof formed generally conical sloping inwardly upwardly, the ring on the opposite end of the body sloping inwardly downwardly as will be understood. The clamping plate 34 has a main body portion 35 engaging the lower edge of the skirt Il and for average tolerances being horizontally disposed and has an-angularly oset end portion 36 engageable with the under side 33 of the ring 6A. A nut 31 rounded on its under side and engaging the plate 34 is threaded on the bolt 38. When the nut is drawn tight, the plate 34 bridges the skirt II and ring 6A as described above and the offset portion 36 of the plate interlocks with the ring. When all of the plates and bolts have been drawn up circumferentially of the structure this interlock prevents lateral shifting of the head with respect to the body and centers the head with respect to the body. If an accumulation of the above-mentioned tolerances causes the plate body 35 to take up an inclined position, the plate may assume the position of Fig. 12 or that of Fig. 13 as described above.
The plate 34 may be made from a sheet or strip of metal 39 as shown in Fig. 14 by rst perforating it as shown at 40-40 and then shearing it transversely as at 4I- 4I and then bending portions 36-36 out of the plane of the strip, the plate in such event being generally U-shaped whereby it may be assembled with the bolts 38 by lateral movement after the nut 31 has been run loosely on the bolts. The bolts 38 may thus be put in the head loosely before the head is brought to the position to be assembled with the body which shortens the assembly time for assembling the bolts with the head.
Obviously a U form plate with or without the offset portion 36 may be used with others of the forms described and to be described. The inclination from the horizontal of the plates in Figs. 4, 5, 12 and 13 is exaggerated in the drawings to more clearly illustrate the principle.
In the foregoing I have illustrated and described my invention in its preferred embodiments, and inFigs. 16, 17 and 18 I have shown further modification embodiments which I may employ in the practice ot my invention when desired.
As indicated by the construction in Fig. 16, the body I may lat the gasket-engaging end thereof be variously formed. It may terminate without the above-described flange 1 as shown at 42, or the end may be rolled or folded over as indicated in broken line at 43. In the above-describedpreferred forni, the under side of the ring 6 provides a shoulder against which the bridging washer or plate I6 engages and as indicated in Fig. 16, this shoulder may be provided otherwise for example by pieces such as 44, corresponding in number to the plate I6 and welded to the outer wall of the body I inwardly of its end.
In the modification of Flg. 17 the ring 6 and flange 1 are provided as before, the under side of the ring 6 providing the said shoulder, but here the bridging element 45 is in the form of a ring surrounding the body I and the central opening 46 of which is large enough so that when the ring is shifted to one side it may be telescoped over the ring 6 and then centered around the body I whereby it will engage. the under side of the ring 6 as a shoulder, and the bolts 41 are threaded into the body of the ring to effect the clamping action.
In the modication of Fig. 18, a ring 6B is provided over which the flange 1 is bent and into the corner 48 of which it is coined as referred to above. The ring I6 may be welded to the flange 1 as indicated at 49. The ring 6B which surrounds the body I may be of suflicient radial extent as shown to engage both the under side of the ange and the peripheral termination of the skirt in this case IIA, the ilange 1 itself constituting the shoulder means and the ring 6B constituting the bridging means by which the clamping action of the bolts 50 is erfected.
A consideration of the forms of Figs. 16, 17 and 18 in connection with the preceding forms more completely described. show that with respect to the clamping of the head upon the body vo en'ect a seal at the gasket the structure comprises any Iorm for the end of the lbody which engages the gasket a specific formf/ being a ange such as the nange l; and snolder means or some kind on the body which may be tne under side of the ring 6 or the under side of the ,nange l, the latter as in Fig. 18, or separate abutments such as 44 in Fig. 16; bridging means between the skirt of the head and the shoulder means which may be separate washers or plates I6 or which may be a ring as in Figs. 17 and 18. And the various modifications illustrated and described indicate that other forms of body and shoulder means and bridging means may be provided 'by other modications and by changes and combinations of the iorms shown so that my invention is not limited to the exact details of construction illustrated and described but is inclusive of all such modications and changes which come within the scope of the appended claim.
In a tank construction a tubular tank body, a ring surrounding the body adjacent its end and welded thereto, a flange on the end of the body extending outwardly radially over the ring, a head having an annular substantially planar portion opposite theflange, a compressibly yieldable gasket between the annular head portion and the flange, a skirt on the head surrounding the flange and ring and radially spaced therefrom, a circular series of bridging elements bridging the ring and the skirt, and a circular series of threaded bolts disposed in the space between the ring and the skirt and projected through periorations in the planar portion and the bridging elements and provided with heads and nuts to exert a clamping action on the bridging elements and planar portion to clamp the gasket between the head and the flange, a coat of vitreous enamel on the planar portion, and the skirt being sumciently rigid to prevent bending of the planar portion and crack- 5 ing ot the enamel coat by the clamping action at the bolt perforations therein.
CHAIMER E. MURPHY.