US1167949A - Rigid piece of metal insulated against electrolysis and corrosion and the process of making the same. - Google Patents

Description

. P. M. lSTEWART.' RIGID PIECE OF-METAL INSULATED AGAINST ELECTROLYSIS AND CORROSION AND THE PROCESS 0F vMAKING THE SAME. A

1,167,949., Patented' Jan'. 11, 1916.

APPLICATIONYFILED SEPT. 16. 1912.

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- f; amarres rarnnfr einen :PEREZ M. STEWART, 0F NEW YORK, N. Y., ASSIGNORF ONE-HALE T0 HAROLD' H. ROBERTSON, OF SEwlCKLEY, PENNSYLVANIA, AND' ONE-HALF T0 GERTBUDE F.

STEWART.

RIGID PIECE 0F METAL INSULATED AGAINST ELECTROLYSIS AND ORROSION AND THE PROCESS 0F MAKING THE SAME.

Specification of Letters Patent. Patented Jan. 11, 1916.

' Application led September 16, 1912. Serial No. 720,492.

To all 'whom it may concern:

Be it known that I, PEREZ M. STEWART, a citizen of the United States, and a resident of the borough of Manhattan, city, county,

and State of New York, have invented anL representing like parts.

This invention relates to a novel process of insulating rigid pieces of metal against; electrolysis and corrosion and to the productJ lof suchprocess.

The process is especially applicable for treating large pieces of structural steel, such as beams, girders, etc., employed in the construction of buildings, bridges, and the like,

whereby said steel structures are insulated` and thereby protected against electrolysis and corrosion.

Prior to this invention many methods have been devised and many compositions have been used for coating steel, with a view to absolutely excludingmoisture,which it was well known, must be excluded in order to protect steel from electrolysis and corrosion, but'these methods and compositions havenot been successful. No paint has as yet been devised which will absolutely accomplish this purpose. Linseed oil which is the vehicle for practically all paints designed for protective coatings, is recognized by those skilled in the art to have several fatal defects. Even when the coat of linseed oil is skilfully applied, voids are bound to occur which will allow the entrance of moisture to attack the coated surface. In-

order to avoid this objection, pigments have water, is sealed in by the paint in ordinary painting, thus leaving the lilm of moisture to continue its electrolytic action with the metal, producing rust underneath the paint.

T he so-called protective coating of linseed oil in combination with many of the lead and zinc pigments is not a stable compound and after a comparatively short time a chemical change analogous to saponification takes place. It is therefore but a brief time before moisture due to condensation removes the oily compound leaving the pigment, which, 1n itself, is not a protective coating, and is generally a rust promoter. This is the action commonly spoken of as chalking. One of the chief characteristics of pure linseed oil is the fact that it oXidizes, but it is not generally known that after this oXidation reaches a certain stage the compound thus produced is soluble in water.

Cushman and Gardner in their recent book on Corrosion and Preservation of Iron and Steel have this to say with regard to bituminous compounds: From the standpoint of the] electrolytic theory of corrosion, it has repeatedly been stated in the foregoing pages that a natural insulator or nonconductor of electricity should be Well adapted for the protection of iron. In view v of the truth of this general principle, it would seem that bituminous f compounds were peculiarly Well adapted for the purpose. Unfortunately, many materials. which are well adapted for the protection of iron from one point of view are too prone to fail from another. As a matter of fact, most bitumens will not stand free exposure to atmospheric conditions, water and sunlight. It is a significant fact that in the cases in which bitumens have been-successfully used, it has been under conditions in 'which the material was not, so to speak, normally eX- posed to sunlight and the atmosphere. To sum up the discussion of the use of bituminous paint and .compounds as protective coats for iron, the authors wish to reiterate their opinicn that in special cases, and if properly selected, there are no better materials available.

In accordance with this invention, I have provided a method for producing insulated structural steel shapes orA members or any steel structure, no matter how large, in`

which the steel is insulated by a sheet or layer of asbestos paper against electrolysis and corrosion and in which a bituminous composition is employed to secure the 'asbestos sheet or layer to 'the steel structure and is protected yagainst the injurious action l'of sunlight, moisture vand evaporation on such compounds by the vsheet or layer of asbestos, as Will be described, whereby the bituminous composition remains in its original condition and leffective as an adhesive for an indefinite length of time.

ln accordance With the method employed by me, the steel structure is cleansed and heated, and While the steel is in a heated condition, a layer or coating of iiuxe'd phalt is applied thereto, and almost immefli ately a sheet or layer of. asbestos paper is applied to the asphalt layer, While the latter is in an adhesive fluid condition. The asf bestos sheet may -thenbe coated with paint, cement, or layers of asphalt and felt or paper.

In the accompanying vdrawing I have illustrated one form of protected structural steel member produced by my method and embodying my-invention. i

Figure l is a front vie'wof an 'll column,l

and vF ig:'2,`a transverse detail sectional view of the column shown in Fig. 1 on an en-y larged scale. l

In carrying out my process, the first step of cleaning the surface ofthe steel is' preferably carried out when the structural `shape or member-is at the job, yin the fieldl` or at the place of erection.y All surfaces of the structural shape :are first thoroughly cleaned and heated. The cleaning may be accomplished by Wire brushing, sand blasting or any lother suitable'mechanical or chemical method. The cleaning may also be accompli'sh'edr by burning 'with' one 'or more gasolene torches or any 'kind ofs'uitable gas furnace. `lli-any event thje step of burning or heating shouldvbe lused, since this removes 1shop coat, oil, scale, surface ilin, :moisture and o the'r deleterious yfactors and at the same :time heats the surface of the-member, and

bevappliedeither hot or cold but preferably hot.

The bituminous composition vfor the best' results is a li'uxed'bitumemvthat is, a high grade asphalt having a high melting point, namely about 225? to 250 F., is tempered or -luxed bythe additionof animal fats'or slovvdrying-oils, such'as stearin pitch in theproportion of from 5 'to`10%, which liu'X has'the effect of making thebitumen more durable, tenacious, pliable", and of retaining its elasticityfo'r a 'long timef4 While the coating'of the bituminous composition is still seft, a-layer'or 'sheet of-as'besto's 'paper' is applied With pressure to the coated surface of the metal structure, and this process is repeated until the Whole of one surface of the rigid steel member is covered by the layer of bituminous composition and the layer or sheet of asbestos paper, which lis especially serviceable for the purpose, for

the following reasons: (l) The `sheet of asbestos is not penetrated by the actinic rays of the sun, which have a deleterious effect on the asphalt,.in that they take the llife out of the asphalt and render it liable to crack and expose the steel. (2) The sheet of asbestos normally contains from seven to fourteen per cent. of Water vof its ovvn, that' is, by absorption, and in addition about four per cent. .of water of crystallization, and therefore vthe asphalt coating is practically protected by a Wall Yof `Water in the asbestos sheet, which prevents'the oil in the asphalt from passing through the asbestos sheet and therefore prevents evaporation of the oil and the deterioration of the asphalt coating, Which remains unchanged for-ani'ndefinite length of time. rlhe asbestos sheet'o'rlayer may be painted or otherwise treated on its eXposed surface to Waterproof it, or it may have applied to it additional layers of bituminous composition and asbestos,- felt, lpape-r or cement.

It is preferred to protect the layer or sheet y of asbestos -With paint or other material as described, but it is 'not desired to limit the invention in this vrespect as good -results would be obtained With the plain-asbestos sheet alone.

In the present instance, the I column show-n in the drawing is provided With a plurality o f layers of Vbituminous composition andasbestos.

In; Fig. 2, A represents the first layer of bituminouscomposition, B the layer of asbestos paper, C a layer of bituminous com vposition on the layer B, D a layer of asbestos paper, E a layer of bituminous composition applied to the layer D, F a layerof Waterproof fabric in. the formv of prepared felt, mu slin or linen, Ga layer'of bituminous composition or! mastic. Theprotected I column may be embedded in concrete or other suitable fr'eproof building material J,

ln some" instances itmay be desirableto provide'thesteel structure With a plurality of 'layers of bituminous composition. and sheets or layers of'asbesto's, but in mostcases, it Will be s'uiicientto provide a single'layer of' bituminous composition and a single sheet i ia or layer of asbestos, and render the latter Waterproof by, painting the exterior surface thereof, for in the simpler lconstruction it Will be seen that the steelmember istho'roughly protecte'da gainst electrolysis andcorrosion,

by the layerl of the bituminous'composition and, by the sheet of asbestosv for the 'reasons labove set'forth 'and 'further 'by the additional layer of paint or other waterproof material, I.Which prevents evaporation of the Water p Wall in the asbestos layer, and also prevents `moisture penetrating into the asbestos.

In some cases, as for instance in buildings, it'may be preferred to protect all the surfaces of the steel structur or member, Whereas in the same and other structures, such for instance as bridges and the like,

it may be found suflicient to protect only those surfaces of the steel member which are exposed to the atmosphere. In either case, the surface ofthe steel member covered by the bituminous composition and the sheet i or llayer of asbestos is thoroughly protected from the deleterious Vaction of extraneous `fumes, gases, atmospheric conditions and stray or ground electric currents, and also from interior deterioration, that is, deterioration of the bituminous composition. Claims: 1. The process of insulating structural steel shapes to prevent electrolysis and corrosion, which consists in cleaning and heat- 25. .ing the surfaces of the steel structure to remove scale, dirt, moisture, etc., and to open the pores of the steel, applying to the steel structure thus cleanedand While in a heated 'condition a iiuxed bituminous composition,

.l applying to said coating of bituminous composition While thelatter is soft a layer of asbestosfpaper in its normal condition, and applying'to, the exterior surface of the asbestos paper a waterproofcoating, for the 3.5 purpose specified.

l2. The process of insulating structural steel shapes yto prevent electrolysis and corrosion, which consists in cleaning and heat-y ing thefsurfaces of the steel structure to re- A 40n move scale,l dirt, moisture, etc., and to open the pores of the steel, applying to the steel structure thus cleaned and while in a heated condition a iiuxed bituminous composition, and applying to said coating of bituminous composition While the latter is soft a paper in its normal condia` sheet of insulating material which is imprevious to sunlight and in its normal condition. Y

4. As an improved article of manufacture,

a rigid piece of corrodible metal havingits outer surface free from deleterious substances protected'by alayer of bituminous composition applied to the ysaid surface, and penetrating into the pores thereof, and a layer of asbestos paper adhesively secured to the rigid metal structure'by said bituminous coating which penetrates one surface of the asbestos layer, substantially as described.

5. The process of insulating a rigid piece of metal, vvhichconsists in cleaning the rigid article, coating the rigid article thus treated with a layer of bituminous composition, applying to the bituminous layer While soft a layer of asbestos, folding the layer of asbestos about the coated rigid article to envelop the same, and pressing the asbestos layer into firm contact With the rigid article.

6. The process of insulating a rigid piece of metal,which consists in cleaning the rigid article, coating the rigid article thus cleaned .While in a heated condition with adhesive material, applying to the metal article thus y coated and While the coating of adhesive ma- '1 cured thereto by said bituminous coating which penetrates one surface of the asbestos layer.

8. As an improved article of manufacture,

a rigid piece of corrodible metal having its outer surfaces free from scale, dirt, oil and moisture and protected by a layer of bituminous composition ,applied to the said surfaces and penetrating into the pores thereof, and a, layer of fibrous insulating material enveloping said rigid metal structure and adhesively secured theretoby said bituminous coating. a

9. As anwimproved article of manufacture,

a rigid piece of corrodible metal having its outer surfaces free from .deleterious substances and protected by a layer of adhesive lmaterial applied to'said surfaces, and a layer of fibrous insulating material enveloping said rigid structure and secured'thereto by said adhesive coating.,

In testimony whereof, I' have signed my name to this specification in the presence of twoy subscribing witnesses.

PEREZ M. STEWART.

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