US2631360A

US2631360A - Method of repairing articles having a corrosion-resisting lining

Info

Publication number: US2631360A
Application number: US678144A
Authority: US
Inventors: Elbert A Sanford; Ernest F Holtz
Original assignee: Pfaudler Co Inc
Current assignee: Pfaudler Inc
Priority date: 1946-06-20
Filing date: 1946-06-20
Publication date: 1953-03-17
Anticipated expiration: 1970-03-17

Description

March 17, 1953 E. A. SANFORD ETAL 2,531,360

METHOD OF REPAIRING ARTICLES HAVING A CORROSION-RESISTING LINING Filed June 20, 1946 arzra INVENTORS AG/ZAS Eatented Mar. 17, 1953 METHQDDF REPAIR/ENG ARTICLES HAVENG .A ;COBH-O. SIDN-;RESI STING LINING ,Elbert A.

Sanford, Irondequoit, and Ernest F.

Holtz, Rockville Centre, N. Y., assignors to The 'Pfaudier 60,, Rochester, -N. Y

of NewYork a corporation Application June 20, 1946, Serial Elm-678,144

-7-Olaims. '1

This invention relates to .;corrosi on.- resisting articles, such as containers, pipes, fittings, agitators, bafiles, and the like, having a metal base and a protective coating of glass, vitreous enamel, or other resistive materiaLand to methods of repairing such articles, ,one object of the invention being to provide an 'improvedandmore efild nt n durabl m thod o th cha a described.

A other objec is the provision of th a m hod adap ed to be readi and co ve ly mp ed e ther conne t on th th original manufacture o th art cle o in t c rse o repairsmadepnthe article at 'itsplace of installation.

hnotherobject is to provide ,an improved and more efiipientmethod pirepairing such articles, particularly where itended for-thehandling of acids or other highly corrosive substances.

To these and other ends the invention resides in certain method steps, all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.

TInthe drawings:

"Fig. :1 is a sectional -vi ew of a portion of an article such as a container-wall havinga metal base and a glass coating containing :a pittedportionto'be protectively covered-or repaired;

Fig. 2 is a similar view-showingthe pitted porgtion enlarged by grinding, as a first step in the method attire-invention;

1 'ig.3 shows the further step of drilling and tappingayhole in the metal base attheground awayportion;

Fig. fi -shows a threaded plug screwedinto the tapped hole-and the ground away portion covered bvcem n 'Fig. 5 shows the-application-oi agasket applied about the plug over the cement'with-a flange-and not on the plug for pressing the gasket against the oa n Fig. 6 is atop plan view-of the-partsshownin Fig. isasectional view, "but showinga somewhat modifiedmethod of constructionin-which the plug "is "provided-with an integral fiange -f-or "showing amodified'construction;and

*Fig. 1=1 is-asectional-vieW-similar'to Figs'l, but showing a further modification.

away,

In the manufacture of containers and other articles having on the suriace thereof a corro mr s i e lining, or c in o glas vitreous enamel, or other corrosion resistant coating, applied by fusing to the metal base, the final inspection Olf the articles may disclose imperfections or small pits in the coating which themost improved methods are unable to entirely prevent. It also happens that in the use of such articles, particularly for handling highly corrosive substances, such pits may develop, accompanied bymoreorless corrosionloi the base metal underneath, so as to require repair for the-purpose of maintaining equipment in operation.

Various methods have been employed foreliminating or repairing such imperfections as, for example, the flame spraying of precious :metals or the drilling of a hole at the pit with undercut sides and filling it with a-plug cf :cohesive gold, but such repairs have not always provenwhol-ly satisfactory for some of the combinationsofeorrosive materials handled in such equipment.

In accordance "with the method of -my invention, a pit such as'indicated on an exaggerated scale at Iii, Fig.1, in-aglass coating-H ona-metal base i2, withor-without accompanying corrosion of the metal base, is preferably enlarged .by

grinding away the edges of the pit and the under:

base, as by means of an abrasive wheel or point, such as a B-shaped abrasive stone of Carborundumor Aloxite, mounted on a rotary spindle. By -means of such a tool, the edges ..-of the coating about the pit vrare smoothly round along with a-portion of the "basell Lover-a portion, as indicated l in generally circular area ,or

generally in a somewhat exaggerated may at 1-3,

'Fig. 2. By this step, the discontinuity :of the coating is left with .soundedges and :a .substan.-

tial area of the metal base is exposed for :the next step of drilling for the receptionlof the-inac- -ture plug hereafter described.

To this end,.a hole M is drilled adjacent the center of the ground away portion which isof larger diameter than :the hole, to avoid. chipping of the edges of the coating .byicontact :With :the drilling tool, and-the hole is tappedaor otherwise prepared, as hereafter described. forsecuringsthe repair plug therein. "The defective portion ,is

thus prepared for the applicationthereto .of ,-.the

repair parts, which will now .be described.

:A metal fracture plug is, preferably 'in :the

iorm of a suitably threaded stud, iislscrewedfinto the tapped hole 14 in the metal base, aseshown in Fig. 4. Theground away :portionaboutthis plug is .then .covered with a layer it .of .noncorrosive, self hardeningcement, which may The a known silicate cement, such as commercially available under the trade designation Penchlor, or a cement of the known synthetic resin type, such as phenol-formaldehyde or resorcinalformaldehyde resin cement. The choice of the type of cement may be governed by the nature of the substances in connection with which the article is employed. Thus, silicate cements as a class are resistant to corrosion by strong acids, but less resistant to water or alkaline solutions, while resin type cements are effectively resistant to water and to weak acids and alkalies, but not to strong oxidizing acids. This cement layer is preferably applied in a heaping quantity, as shown in Fig. 4, to cover the exposed metal and to overlap the edges of the glass lining and form sealing contact with the plug, as shown in Fig. 5, under the pressure of a protective covering comprising a gasket and plug flange, as the latter are pressed down by turning home the plug or its nut, as hereafter described.

While a layer of cement such as described serves to seal in and protect the metal base for a time, we have found that the durability of such protecting cement may be materially increased and the repair made more permanent by applying over the cement a flexible gasket I! of corrosion-resisting material, such as the plastic material sold by the Du Pont Company under the trade designation Teflon, or the synthetic material commercially available under the designation neoprene, or the material known as Tygon, or compressed sheet asbestos packing. Of these, we prefer the plastic sheet material known as Teflon, particularly under highly corrosive conditions, This gasket is preferably in the form of a circular disk, as shown in Fig. 6, of suflicient diameter to sufficiently overlap the edges of the glass coating beyond the layer of cement.

Gasket I1 is pressed into sealing engagement with the glass coating, in one embodiment of the invention, by means of a metal disk l8, centrally apertured for the reception of the plug I5. This disk is preferably dished, so as to have a concave under side toward the gasket l7 and pressing against the gasket primarily at the edges of the disk, so as to hold the gasket tightly against the glass coating. The shape of disk [8 may be varied to conform to a cylindrical or other particular shape of the glass coated surface of the article, for the purpose of obtaining uniform pressure of its periphery on the gasket. The disk is pressed against the gasket by means of a nut l9 threaded on the plug I5, the upper end of which may be notched as at 20 for the reception of a turning tool. Disk I8 is made of material thick enough, say, one-sixteenth (1%) of an inch, so as to resist any permanent set or deformation by the pressure applied to it by nut IS.

Th plug I 5, disk l8 and nut l9 are made of corrosion-resisting metal such as tantalum, palladium, platinum, molybdenum, zirconium, iridium, columbium, Hastelloy, Monel metal, or stainless steel, or the like. Of these, for example, we prefer tantalum for use under intensively corrosive conditions, because of its hi h resistance to corrosives such as aqua regia, and its moderate cost, although molybdenum is likewise satisfactory for many corrosive conditions.

A modified method and construction are illustrated in Figs. 7 and 8, in which the steps and the parts employed are as described above, except that the fracture plug Zl is formed with an integral flange 22, which is concavely dished on its under surface 23 so as to bear with pressure at its peripheral edges against the gasket [1. The upper end of the plug may be formed, as shown, with a portion 24 of square or other angular shape, for engagement by a tool for screwing the plu into place, or may have a screw driver slot in its cap such as shown in Fig. 5. This modification with integral flange is particularly useful for repairs of small size, since it can be turned or formed up economically from expensive material with a minimum of Waste.

Fig. 9 shows a further modified embodiment in which the glass coating is ground away as previously described and in which the fracture plug 25, made of one of the above corrosion-resisting metals, instead of being threaded, has its lower end chambered as at 26. A tapered steel head 21 is lightly inserted in the chambered portion of the plug and so crowned and dimensioned as to engage the bottom of the drilled hole I 4, before the plug is fully seated in it. The hole M is undercut and enlarged at its bottom and as the plug is driven home in the hole, the head 27 expands the end of the plug so as to securely anchor it in the hole M. The plu has its upper end reduced and inserted and Welded in an opening in a disk 28 similar to the disk l8 described above, and when the plug is fully seated and secured in the hole in the base, the disk is thereby held pressed against a filling of cement 29, as described above for covering and protecting the ground away area at the pitted portion to be repaired. In the modification of Figs, 7 and 9, a temporary fiangeless plug, if desired, may be releasably located in the hole in the base while applying the cement, to prevent the latter from entering the hole, and then removed and replaced by the permanent plug.

In some instances, also, where both sides of the metal base are readily accessible, as in the repair of single wall vessels, or single wall covers of jacketed vessels, or where corrosion has penetrated so deeply as to materially thin the metal base, the wall is drilled entirely through the base for the reception of the threaded plug which is extended through and. beyond the base to receive a nut and washer for drawing the flange of the plug down against the protecting cement or gasket, or both, as described above. Fig. 10 shows one such modification, generally similar to the method and construction disclosed in Fig. 5, except that an imperforate flange 30 is welded to one end of a threaded plug 3| so as to bear upon a gasket 32 overlying a cement filling 33, substantially as described above. The hole is drilled entirely through the metal base but left untapped and the threaded plug extends somewhat beyond the base to receive a nut 34 and washer 35 for drawing the flange down on the gasket and cement, as described above. In this arrangement, as in the modification of Fig. 5, the

flange may be shaped to fit a curved base and positioned to correspond with such curvature before turning the nut home to draw the flange into place.

Fig. 11 shows a further modification, generally similar to that shown in Figs. 7 and 8, except that here also the hole is drilled entirely through the base, without tapping and the plug 36 extended beyond the base and provided with a nut 31 and washer 38 for drawing the plug and its flange 39 down against the gasket, as described above. s

It has been found sufiicient in some applications to employ the cement "alone, without a gasket, as shown in Fig. 9, whereas in themepair of small pits a gasket alone .has at times been found 'sufiicient without the use of cement, the application of the cement, or the gasket, or both, being governed by the particular conditions of each case.

The invention provides "a method by means of which defects in a vitreous 'coaitingmay'bereadily andconven'iently made, either in perfecting the article as a part of its "originalmanufacture, or as a repair operation on installations in the field. "By suitable choice of the parts and materials, as indicatedabove,.:.a non-.corrosive lining or coating may be perfected, .or efiiciently .repaired, to ;provide substantially permanent protection against corrosive attack.

It will thus be seen that the invention accomplishes its objects and while it has been herein disclosed by reference to the details of preferred method steps, it is to be understood that such disclosure is intended in an illustrative, rather than a limiting sense, as it is contemplated that various modifications in the details of such methodwill readily occur to those skilled in the art, within the spirit of the invention and the scope of the appended claims.

We claim:

1. The method of repairing corrosion-resisting articles having a metal base and a glass coating thereon containing a pitted portion to be repaired, comprising the steps of grinding away said coating at said pitted portion over an area larger in diameter than the diameter of a fracture plug to be inserted at said ground away area, drilling a hole in said base adjacent the center of said area, securing a threaded fracture plug of corrosion-resisting material in said hole, and applying a layer of corrosion-resisting cement on said base at said area to form sealing contact with said plug and overlap the edges of said coating, said plug being provided with a flange of corrosion-resisting material adapted to overlie said cement and the edges of said coating, to press said cement in place and protect said cement and area.

2. The method of repairing corrosion-resisting articles having a metal base and glass coating thereon containing a pitted portion to be repaired, comprising the steps of grinding away said coating at said pitted portion over, an area larger in diameter than the diameter of a fracture plug to be inserted at said ground away area, drilling a hole in said base adjacent the center of said area, securing a threaded fracture plug of corrosion-resisting material in said hole, applying a layer of corrosion-resisting cement on said base at said area to form sealing contact with said plug and overlap the edges of said coating, and applying a gasket of corrosion-resisting material to said plug over said cement and overlapping said coating, said plug being provided with a flange of corrosion-resisting material adapted to bear at its edges on said gasket and hold the same in sealing contact with said cement and coating.

3. The method of repairing corrosion-resisting articles having a metal base and a glass coating thereon containing a pitted portion to be repaired comprising the steps of grinding away said coating at said pitted portion over an area larger in diameter than the diameter of a fracture plug to be inserted at said ground away area, drilling and tapping a hole in said base adjacent the center of said ground away area,

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screwing a threaded :fracture plug of corrosionresisting material in said hole, applying a layer of corrosion-resisting cement on said base at said ground away area-to form sealing contact with said plug and overlap the edges of said coating, applying a gasket of corrosion-resisting material to said plugover said cement and over-- lapping said coating, applying to said plug :a metal flange of corrosion-resisting :material adapted to bear on said gasket 7 and screwing "a nut'of corrosion-resisting material :on said plug against said flange to press said gasket ,into sealingcontact'withsaid cement and coating.

'4. The method of repairingcorrosion-resisting articles having a metal base and a glass .coating thereon containing a pitted portion to be repaired wmpr-ising the steps of grinding away said coating at said pitted'portion over an area larger in diameter than "the diameter of a fr-acture plug to be inserted at said ground away area, drilling a hole through said base adjacent the center of said ground away area, passing a threaded fracture plug through said hole, applying-alayer of corrosion-resisting cement on said base at said ground away area to form sealing contact With said plug and overlap the edges of said coating, applying a gasket to said plug over said cement and overlapping said coating, said plug having fixed thereon a metal flange adapted to bear on said gasket and screwing a nut on said plug on the side of said base opposite said. coating, to press said flange against said gasket and said gasket into sealing contact with said cement and coating, said plug and flange and nut being made of corrosion-resisting material.

5. The method of repairing corrosion-resisting articles having a metal base and a glass coating thereon containing a pitted portion to be repaired, comprising the steps oi grinding away said coating at said pitted portion over an area larger in diameter than the diameter of a fracture plug to be inserted at said area, drilling and tapping a hole in said base adjacent the center of said area, applying a layer of corrosionresisting cement on said base at said area to form sealing contact with said plug and overlap the edges of said coating, applying a gasket of corrosion-resisting material over said cement and overlapping said coating and screwing in said hole a threaded fracture plug of corrosion-resisting material provided with an integral flange having a concave under surface adapted to bear at its edges on said gasket and hold the same in sealing contact with said cement and coating.

6. The method of repairing corrosion-resisting articles having a metal base and a glass coating thereon containing a pitted portion to be repaired, comprising the steps of grinding away said coating at said pitted portion over an area larger in diameter than the diameter of a fracture plug to be inserted at said area, drilling a hole through said base adjacent the center of said area, applying a layer or corrosion-resisting cement on said base at said area and overlapping the edges of said coating, applying a gasket of corrosion-resisting material over said cement and overlapping said coating, passing through said hole a threaded fracture plug provided with an integral flange adapted to bear on said gasket, and screwing a nut on said plug, on the side of said base opposite said coating, for drawing said plug flange against said gasket and said gasket into sealing contact with said cement and coating and pressing said cement into sealing contact'with said plug, said plug and nut being made of corrosion-resisting material.

7. The method of repairing corrosion-resisting articles having a metal base and a glass coating thereon containing a pitted portion to be repaired, comprising the steps of grinding away said coating at said pitted portion over an area larger in diameter than the diameter of a fracture plug to be inserted at said area, drilling and tapping a hole in said base adjacent the center of said area, applying a layer of self-hardening, corrosion-resisting cement on said base at said area and overlapping the edges of said coating, applying a flexible gasket of corrosionresisting material over said cement and overlap- 15 ping said coating and screwing in said hole a threaded fracture plug provided with a flange having a concave under surface adapted to hear at its edges on said gasket and hold the same in sealing contact with said cement and coating and said cement in sealing contact with said plug, said plug and flange being made of corrosionresisting material.

ELBERT A. SANFORD.

ERNEST F. HOLTZ.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 1,285,210 Jones Nov. 19, 1918 "1,636,135 Hughes July 19, 1927 2,020,767 Bullis et al. Nov. 12, 1935 10 2,266,609 Martin Dec. 16, 1941 2,266,611 Martin Dec. 16, 1941 2,354,533 Martin July 25, 1944 2,355,474 Shepard Aug. 8, 1944 FOREIGN PATENTS Number Country Date 2'79 Great Britain Jan. 7, 1915 534,439 Great Britain of 1941