US1867736A - Corrosion protection - Google Patents

Description

July 19, 1932.- w. vH. FINKELDEY CORROSION PROTECTION Filed July 3o, 1929 ATTORNEY Patentd July 19, 1932 i posed to the elements, for example, transmis- UNITED STATES PATENT WILLIAM H. FINXELDEY, or NEW nocHELnE, NEW YORK, AssIcN'on Tov srNeMAsTER a BREYEB, INC., or NEW YORK, N. Y.,- a CORPORATION on NEWYORK conRosIoN rno'rEc'rIoN Application filed July 30, 192.9. Serial No. 382,220.'

This invention relates to the protection of metal structures against corrosion and more particularly to an improved means and method for preventing rusting or corrosion of therivets, bolts or other vconnecting means used in the fabrication .of galvanized structural steel towers, tanks, and similar structures.

The' increased use of steel structures exsion line towers, sub-station switching structures, tanks, steel supporting structures for power lines used in railroad electrificatlon, etc., has made the problem of protecting all parts of such structures from corroslon one of great importance. One methodwhich is widely used is to paint the structures with a suitable protective coating. However', the general shape and design of these structures makes the application of a satisfactory paint coating `extremely difficult. This, coupled with the fact that frequent painting isI necessary to prevent. rusting, makes this method of protection expensive. Also many of these structures are yused to support wires carrying high voltage electricity so that palnting themA while the current is on is very danger` ous and it is oftenextremely inconvenient if not impossible to turn the current oli' to p ermit safe paintin IAs a consequencez'mc coatings applied y the hot-dip-galvamzmg process have been widely used to protect exposed structural steel from corrosion.

In order to apply a protective coating of zinc to steel by either the hot-dip process or by electro'deposition it is necessary to cleankthe steel surface free from all oxides and scale by immersing it in suitable pickling liquids usually consisting of dilute solutions of sulphuric or hydrochloric acid. If the piece is to be coated by the electro-deposition process it must be suitably immersed in a tank containing the plating bath. If it is coated by the more widely used hot-dip process, the surface of the steel is usually fluxed by dipping the article in-suitable solumolten zinc.

tions before it is ,immersed in the bath of The application of the foregoing`processes to completely or partly fab-v ricated 'steel structures, immersed in their final form, is precludedl because of their ung `wvieldy size and shape and also because of the difficulty of properly nickling the steel surfaces in and near the minute recesses between the pieces of assembled metal and the further diificulty of depositing a protective coat- .1

ing of zinc on these same areas. In the hotdip process, such .fabricated structures also tend to warp out of shape when subjected to the relatively high temperature of the zinc bath and it is diilcult to bring theml back Jinto shape again. Because of these limita;-

tions it has been the practice to galvanize the separate .pieces before assembling them, where galvanized steel structures are required. Where the parts are galvanized separately and subsequently' assembled someprovision must be made for protecting the bolts or nuts used to connect the several parts. It isIV apparent thatv galvanized rivets could not be satisfactorily used because, if applied hot,

. the heat would remove the zinc coating and,

if-applied cold, the coating would be broken by the pounding necessary to upset the head of the rivet. To avoid thls diiiiculty, use has sometimes been made' of rivets of non-corrosive materials. The use of such rivets, however, is unsatisfactory, because of the diculty in upsettin the heads of the rivets and because ofthe added expense resulting from the increased cost of the metal. It has also beenv proposed to vuse ordinary black iron rivets and protect them by spraying the exposed heads with metallic zinc or other metal. In this case the rivet must be cleaned of all rust and scale insome manner, as by sand blasting, before the sprayed coating is applied. This is an expensive operation which must be applied to small scattered areas and which often results in the removal or destruction of someof the protective coating around f the rivet. As a result it has been the practice to use galvanizedbolts in assembling the galvanized sections.

. In a riveted structure the upsetting of the 5 head also upsets the shank with the result lill the hole, so there is always a certain amount of celarance between the shank of the bolt and the edge of the hole which makes possible slight motion and reduces rigidity Aof the joints; and in the second place, there is always the possibility that nuts originally drawn tight will loosen with time, especially if the structure is subject to vibration. This is especially true where galvanized bolts are used because it is common practice to undercut the threads on the bolt shank to allow for the thickness of the zinc coating. The zinc coating is seldom of uniform thickness, so that the nuts frequently fit the threaded portion of th'e shank loosely, even when drawn up as tightly as possible.

It is an object of my inventionto avoid the above diiiculties by providing a novel means and method for protecting rivets and thus make possible their use in assemblinggalvanized structures. A further object is to provide suitable means for applying such protection, Other objects will become apparent. y

In describing my invention. reference will I be made to the drawing, in which Figure 1 represents a cross-sectional view of a portion of a riveted structure to which my invention has been applied'. v

Figures 2 and 3 are plan and elevation views, respectively, of the cover applied to protect the head of the rivet.

Figure 4t represents a cross-sectional view of a modification of my invention. and shows a ring of solder in conjunction with the metal cover.

Figure' is aperspective view of the ring of solder.

Figure 6 is a cross-sectional Aview of a soldering iron suitable for applying the metal cover.

Figure 7 is an end elevation of the head of the iron shown .in Figure 6.

In the several figures, the numeral (l) represents a piece of structural steel material to be fastened to a similar piece (la) by means of rivets.(2). vvEach of the structural steel members (l) and (la) is preferably galvanized before assembling. whereby a coat of zinc, indicated at (3), is applied. The black rivet (2) is inserted and headed ,in the usual of the rivet completely fills the holes (5) and (5a) through which it passes.

After driving the rivet (2), the zinc cap (6), which vhas been pre-formed to fit over the rounded head of the rivet, and which has a continuous .iange (7) adapted to be connected to the surface of the zinc coating (3), is applied and lixed to the zinc coating by some suitable means, such as by soldering, brazing or welding. In applying thel zinc cap' I prefer to lirst apply to the pre-formed zinc cap, a layer (8) of lead-tin solder, extending completely around the rim (7). The surface of the zinc coating (3) to which the cap is to be soldered should be cleaned by some suitablemeans, such as a wire brush or emery paper or an electrically operated brush or polishing tool. A suitable flux is then applied to the cleaned portion of the zinc `surface and the cap (6) is placed in position over the head of the rivet.

A copper soldering iron (9) having a. head (l0), shaped to lit over the zinc cap and having a continuous end surface (l1), positioned' to contact with the fiange (7), may be used to melt the solder (8) on the zinc cap. This soldering iron (9) is heated by an electric heating element (l2) which surrounds the stem of the iron and which is attached to a refractory material (13) by which it is sur.

rounded. This refractory material may be enclosed in a metal sheath (14) containing a suitable heat-insulating material (15). The

' soldering iron (9) should be removable so that y it can be replaced by other irons having heads shaped to be used with caps of different sizes and configuration.

The heat conducted to the head of the soldering iron will melt the solder (8) which extends around the rivet between the flange and the zinc coating (3), with the result that the head of the rivet will be hermetically sealed within the cap (6). The shape of the iron will permit simultaneous heating of all the solder around the rivet and the pressure of the iron will assure a snug lit by the melt at the other end ofthe rivet (2) and, since the stem (4) of the rivet its tightly within the holes (5) and- (5a) in the structural steel elements (l) and (1a) the atmosphere to which the fabricated article is subjected will be excluded from contact with the rivet.

The liuXes commonly used in soldering zinc surfaces maybe used, for example, powdered -rosin, killed acid (muriatic acid in which metallic zinc has been dissolved) or other special soldering lluxes. In some cases I prefer to use a special iuXing` material which is in grease form', since it aids in'holding the cap in position while the soldering iron is being applied. This is particularly applicable when placing the cap on a horizontal or verl 1,867,236 i p f 3 ticalsurface from which it would'fall if released.

The solder used ifor fixing the cap to the metal surface surrounding the rivet, may be -applied in the form of a'ring (16), as shown 1n Figures 4 and 5. When in this form, the ringv (16), which Vis preferably sha ed to follow the center line of the flange (7 ai), is placed around the head of the rivet (2a) and the .capi (6a) is applied so that the flange (7a) rests upon this ring. The soldering iron lis then applied to the flange (7a) to nelt the solder of the ring. If-desired, the ring (16) may be a hollow tube of solderenclosing a suitable luxing material, thereby avoiding the necessity ofl applyingthe lluX, by a separate operation.

The head of the rivet (2a) and the cap (6a) are shown asl crown-shaped and it 1s apparent that square, hexagonal or many other shapes of caps may be used, depending on the conliguration of the heads of the rivets to be covered. For instance, where1the head of the rivet is countersunk into the structural material, the cap may take the form of a flat plate covering the hole in which the head is countersunk. For general use, however, the' :caps lmay be made of standard sizes and shapes to lit the rivets ordinarily used.

The zinc caps may be Astamped from rolled zinc having a suitable thickness to give the desired rigidity and resistance to corrosion. By using a cap having wall thickness of approximately .035 inches, the thickness of the protecting mediun would be from ten to fteen times the ordinary zinc coating which is applied to suc-h articles. This would insure a protection over the head of the rivet which would outlive the protection resulting from galvaniz'ing, so the cap would not have to be replaced during the life of the structure.

Although I have described myinvention as applied to the use of a protecting coat of zinc, it is apparent that it may be usedy withv other protective metals and materials. For instance, a copper or tin protecting cap might be applied in a similar manner. It'might also be desirable to apply a protecting cap of metals dilfering from the coating applied to the -article. Such a modification lof my invention may be used but the precaution must be taken to avoid electrolytic couples resulting from the' union of 'the different metals. i,

It is also apparent that my invention is not limited to the protection of rivet heads, since the protective covering ymay be applied to bolts or other types of construction where similar protection is, desired. One cap may also be used to enclose and hermetically seal several rivet heads, or ,other connecting devices, instead of using a separate cap vfor i each rivet. Many other types of soldering irons may also be used in applying the protective cap, the one described being merely illustrative of a suitable device. For examv ple, the heat may be supplied by a fuel, such vas gas or gasoline, instead of by the electricheating element.

j"Ihe method of fixing the flange of the protective cap to the. material around the rivet may be varied. For instance, this flange might be welded directly tothe surface without the use of solder. In the operation of welding the two surfaces,'or in the soldering of the cap, the heating may be accomplished hyp-making the cap and the heating ironv opposite terminals of anelec-` tric circuit and passing a high-amperage, low-voltage current between theftwo terminals. This current could be regulated to give the proper temperature for the soldering or welding.

My method of protecting the rivet heads avdids the necessity of removing the iron oxide and scale therefrom. The caps can be quickly applied and since the soldering iron is no larger or more cumbersome than the ordinary air-driven riveting hammers, or bucking-up irons, the caps can be appliedwherever a rivet can be headed up.

Although I have described myinvention asl applied to a structure to be Vexposed to atmospheric conditions it is evident that it may be used in other connections Where corrosion is likely to take place.4 For instance, it might be used as a protection against corrosive gases in a chemical plant. Many other.

applications of the invention will be appar-V,

ent to one skilled in the art.

In referring in the specification and claims ioo toa hermetical seal it is intended to mean a seal which will prevent the ingress and egress of moisture and other corroding elements of the air, within the normal limits of the temperature and pressure of the atmosphere,to such an extent as to inhibit corrosion within the seal. i

What I claim is: v f

1. The method of providing a corrosion resistant structural steel structure which comprises providing galvanized structural steel members. securing said members together by riveting` and protecting-said rivets from corrosion by covering the exposed heads of said rivets with preformed corrosion resistant caps and securing said caps to the'face of said structural steel members by ya moisture proof joint. l

2 The method of forming a rigid corrosion resistant fabricated structural steel structure which comprises constructing theV fabricated structure of corrosion 'resistant structural forms and securing such structural forms together lby non-corrosion resistant rivets and protecting theheads of the rivets from corrosion by enclosing the same in corrvosion resistant caps .enclosing the rivet heads and spaced therefrom. and soldering said caps at their edges to the corrosion resist# I ant structural forms.

3. A corrosion resisting fabricated metal structural comprising structural steel members havin a corrosion resistant surface,

rivets rigid y connecting said members, and' an individual pre-formed corrosion resistant protecting cap enclosing the head` of each rivet and spaced therefrom and secured to m the face of the structural member by a mois- -ture proof joint. y In testimony whereof; I have signed my f name to thisspecification this 27th day of July, 1929.

n H. INKELnEY.

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