US2192248A - Spot-testing of coating metals - Google Patents

Description

March 5, 1940. N. P. \IEEDER SPOT-TESTING OF COATING METALS Filed Aug. 6, 1938 F IC. 1.

INVENTOR ...NICHOLAS P. VEEDER ATTO RNEY Patented Mar. 5, 1940 SATES sro'r-rnsrmo or oon'rmo METALS Nicholas i. Veeder, St. Louis, Mo., assignor to Granite City Steel Company, Granite City, 111., a corporation of Delaware Application August 6,

'1 Claims.

This invention relates to improvements in testing coating metals, and more particularly to improvements in processes and means for the determination, for example, of the weight of zinc coating on galvanized steel sheets or the like.

Methods have been known and practiced for a number of years past by which there may be approximately determined the weight of galvanizing or spelter on steel sheets of the types used for roofing, siding, culvert pipe and for many other purposes. One method heretofore used, but with indifierent success, consists briefly in subjecting a more or less definite area of the coated metal under test, to the action of an inorganic acid, such as a hydrochloric solution of a suitable strength. The reaction is so conducted that the hydrogen evolved is collected and volumetrically determined, whereby there is obtained an approximation of the weight of spelter, usually expressed as a value representing the number of ounces of zinc coating per square foot of galvanized sheet.

Numerous variations of the acid process have been attempted, and as a result of numerous experiments, the process or method generally employed is that outlined by the American Society for Testing Materials, reference being made to the standard specifications for zinc-coated sheets, serial designation A-93, such specification being under the jurisdiction of A. S. T. M. Committee A-5. It is to the improvement of processes of the general type referred to, and the improvement of apparatus for spot testing of galvanized sheets and other metal coated materials, that the present invention is particularly directed, and has for its major object.

Among the objects of the present invention, more particularly stated, is the improvement of apparatus for the spot testing of coating metals, in such a manner as considerably to reduce the time required for each test, as by facilitating the application of the test element or die to the sheet of metal subjected to the determination.

Another object of the invention is attained in a method and equipment for the noted purpose, which enhances the cleanliness of procedure, in that it confines the zone of acid reaction strictly to the predetermined area of test, and thus preventing spoilage of uncontrolled areas of the metal coating, beyond the restricted test area.

Yet another object of the invention arising out of the improved apparatus and method, is attained in an improved technique enabling successive tests with the same test-chamber or die, while the die and remaining itemsof test apparatus, re-

main substantially in situ, requiring only a trans- 1938, Serial N0. 223,550

lation or shifting of the sheet under test, from spot to spot, without movement of any part of the testing apparatus per se,and so resulting in a substantial saving of time between successive spot tests.

Yet another object of the invention is attained in an improved chambered test die, together with mounting and holding elements associated therewith, which serve to enhance the uniformity and comparable nature of spot tests under various conditions, and which render the accuracy of the tests less dependent upon smooth planer surfaces of coated metal subjected to the tests.

The foregoing and numerous other objects will more clearly appear from the following detailed description of a presently preferred embodiment of the improved apparatus, as well as the method or process practiced thereby, all as considered in connection with the accompanying drawing, in

which: i

Fig. 1 is a front elevation of the assembled spot-testing equipment, as set up in readiness for a test of zinc or like coating on a section of metal sheet; Fig. 2 is a view of a portion of the apparatus and sheet under test, as it would appear when viewed from a horizontal plane, and along line 2-2 of Fig. 1, and Fig. 3 is a vertical section through the test die and a portion of a sheet under test, as these elements would appear when viewed along line 3-3 of Fig. 1.

Referring now by characters of reference to the drawing, there is provided as a convenient major support for the apparatus, a table surface 5 or the like, on which is mounted and to which is attached, a clamp base 6, provided with an upstanding bracket 1, apertured for a pivot pin '8, engaging one arm of a C-type clamp, indicated generally at 9, the lower leg of the clamp being indicated at H), and serving to carry a screw-threaded element l5 working in threaded engagement with the free end or arm of the jaw ll) of the clamp. The head of the screw l5 constitutes a hub Hi from which projects a plurality of radially disposed actuating arms ll. The threaded shank I5 of the screw assemblyis provided atits upper end with a ball terminus 20, operating in a socket-forming structure 2! located beneath and centrally of a clamp platen 22, the arrangement being such that the screw I5 may be threaded up while the clamp platen 22 is held against rotation, and in engagement with the under surface of the sheet or section thereof under test, all as will more clearly hereinafter appear.

Carried by the opposite jaw 25 of the clamp, and above the sheet A under test, is a chambered element which for convenience will be referred to as a test die, indicated generally at 26. Die 26 is of generally cylindrical form, and preferably constructed of a metal closely machined to dimensions, and preferably formed of a metal having high resistance to acid reagents and the like, for example Monel metal. The upper part of the body of die 26 is circumferentially undercut, as at 27, providing thereabout an annular recess for the reception of the paired jaws all constituted by a fuicate end of the arm 25. The ends of the furcations 30 are laterally apertured, and the apertures threaded to receive a pair of screws 31, which extend through openings therefor in the ends of a C-shaped holding member 29. The termini of the furcations 3b are down-turned as at 32 so as, when the clamp is in use, to bear against shoulder 33, defining the lower wall of the recess 2i.

A chamber constituted byan axial bore 34 in the body 26 is preferably of even diameter throughout its length, but for a slightly enlarged or flared portion 35 at its lower end, this flared surface merging into a hat annular face 36 on the bottom of the die or test cup. Surface 36 is preferably machined to a smooth finish, and is provided with a groove 31, constituting a retaining seat for a gasketv All of somewhat compressible and acid resisting material capable of a moderate compressive deformation when the die is clamped to a sheet under test. The location and dimensions of gasket seat 3'! and gasket 66 are preferably such that when the platen 22 of the clamp is threaded up, the sheet A is seated in closing relation to the open end of the die. Prior to and during the test, the gasket ll} will be deformed or squeezed inwardly to an extent that it reaches the shoulder 4i formed where the portion 35 merges with the face 36 of the die. l

It will be understood by those familiar with the testing of coated metal sheets, that the use of a gasket such as til is not necessary in all cases, but that its use for sealingv purposes is sometimes advisable on certain stock, such as" culvert sheet, or other coated flat materials characterized by relatively irregular surfaces. It will, however, appear that, irrespective of whether or not gasket 153 is employed, the area of the test circle is dependably that defined by the circular shoulder i-i, thus standardizing the area of sheet subjected to reaction and test.

The open upper end 45 of the chambered die 26 is closed as by a resilient plug element which may bev a suitable rubber stopper or the like 41 provided with four ports or passages 50, 5|, 52 and 53, which have a purpose to be described.

The various fluid reservoirs and conduits of the apparatus, in its preferred form, include a bottle or other suitable container 5 5, preferably constituting a water reservoir, and a similar bottle or reservoir 55 containing a solution of acid and a suitable inhibitor, the make-up of which is hereinafter particularly described. These bottles are conveniently supported at a suitable height above the test zone, as by a shelf or the like 56, which may be of any suitable form. Delivery of water from the bottle 54 is effected through rubber-connected elements of glass tubing including an inverted L-shaped portion 69, a riser portion BI and an inverted L-shaped portion 62, the latter being provided with a glass stop cock 63 which may be of standard laboratory type. The downturned leg of the tubing element 62 projects through the passage 58 in the rubber stopper 4?, and thus leads into the chamber or bore of the test die. Delivery of the solution in the bottle or reservoir 55, is effected through a glass and rubber tube connection 64, the latter being connected only just prior to test and being provided at its free end with a pinch cock or clamp 65.

As an immediate support for the remaining items of apparatus there is conveniently employed the usual stand 66, provided with an adjustable clamp shelf 51 carrying a leveling bottle i9, connected as through rubber tubing H, to the lower end of a gas burette, the latter being conveniently of 1000 cc. capacity and indicated at T2. The burette is conveniently positioned by adjustable clamps l3 and It, supported by stand Eli. A rubber stopper 15 in the burette is apertured to receive and serves to carry a thermometer H, and is also apertul'ed to receive a glass U-tube 80, the latter being connected through suitable rubber tube junctions with continuing portions 8! and 82, the latter extending through the passage 53 in the plug or stopper 4'1, thence communicating with the interior of the die 25. The tubing section. 85 is branched as at 83, this branch being directed into a separatory funnel 8 5-, the latter being provided with a stopper 135, and having its delivery tube extending through the rubber stopper m, as indicated at 812.

It is of importance in the practice of the present improvement to provide facilities for noroughly and forcibly flushing out the interior of the test die, following a test, but while the die and sheet remain in situ, so as to remove from the reaction chamber the solid and other reaction products, and so as to free the die and test spot of any residual acid and other materials. To enable this flushing or Washing process, it will have been noted that the reservoir or bottle 54 and tubing elements 69, 5! and 62provide the supply. Drainage of the flushing water is accomplished through the tube as, which is conveniently located centrally of the test chamber constituted by the bore 34, and which extends down into the chamber, say to within a distance of inch of the test surface of the sheet section A. The drain tube 9!] is shown as provided with a horizontal leg SH and a down-turned leg 92, leading into a drain hose or the like 93, to a suitable zone of disposal.

Referring further to the gas burette 12, this item of apparatus is preferably provided with a scale or plurality thereof 9 which as is understood, will be downward-reading, and by distinct preference so as to obviate a number of calculations, is of direct-reading type, in that it is preferably graduated toin ounces of zinc per square foot of coated metal. It is a distinct preference that a plurality of such scales be provided, each consisting of a graduated vertical strip as indicated at 94, whose indicia corresponds to a somewhat different temperature, say with a range of five or ten degrees between the different scales, thus minimizing and even obviating entirely, the calculations to correct the burette readings for temperature.

The manner of usage and the technique of test are thought to be fully apparent from the foregoing detailed description of the several items of apparatus, but it may be briefly noted that at the beginning of the test, a sheet or sheet section A is first inserted between the jaws of the clamp 9.

'It is of course understood that, in keeping with prevailing practices, the sheet section subjected to'test ls first carefully cleaned, as by benzol,

alcohol or other suitable cleaning solvent. With the test section A in place as held by screw clamp elements l5, l6, ll, together with platen 22, the sheet section is in the relation of a closure for the bottom opening'of the die. It will have appeared that, due to the unusual depthof opening between the jaws l6 and 25, a considerable latitude of test area is available to the operator, and further that the apparatus offers no restriction, except such: as is practically imposed by the length of the table 5, to, the length of, sheet which may be subjected to spot tests.

Prior to subjection of the test area to the reagent, the stop cock 85, and a stop cock 95 in the drain tube,ili2, are both closed, so as to prevent the escape of envolved gas through the drain. Following this, the connection of tube 33, as by a rubber stopper, into the upper portion of separatory funnel 8b is opened, and the measuring liquid in the burette li. is leveled at Zero by means of raising or lowering the leveling bottle iii. The separatory funnel 84 may next be supplied say with '75 cc. of the acid-inhibitor solution from the bottle reservoir 55, via the tubing 54 and pinch cock 535, for this purpose the tubingfifi being introduced into. the top opening of funnel 8 3. Upon replacement of the connection 83 and associated stopper to close the top of funnel 8t, and re-leveling the fluid in bure'tte '52 if necessary, the apparatus is in condition to begin the addition of the reagent to the test area, it being understood that stop cock 631s kept closed at all times during the test and otherwise, except when opened incident to the flushing operation following the test proper.

The acid-inhibitor solution is now gradually introduced to the chamber in die 26 as by a full opening of the cock 85, whereupon'the acid solution, upon coming in contact with the zinc coating of the test specimen, results according to well known reactions in the evolution of hydrogen. During the time in which there is any evident gaseous evolution from the die it is advisable to keep the measuring liquid in burette l2 level by means of the bottle it, so as to avoid excessive positive or negative pressures in the gas system. It will be noted that the hydrogen evolved within the die has at all times an avenue of free egress, via tubing 52, ti, 8t and into the top of the burette 12. The end point of reaction is indicated by lack of any further movement in the measuring liquid in the burette 12, such cessation of movement indicating completion of the test per se. After again checking the burette liquid for level, a reading 'is taken on the appropriate burette scale corresponding to, or closest approximating the temperature indicated by thermometer Ti. Reaction and reading thus being completed, the acid is drawn from the die by opening the stop cock 9:3 in the drain tube 9l-92, and by raising the leveling bottle 10 to create sufficient pressure to initiate a siphoning action, the acid will be evacuated from the die chamber down tothe point reached by the bent end of tube 90. Upon completion of the acid removal by the drain tubing, and with the drain cock 95 open, cock 63 is now opened, cock 85 remaining closed, with the effect of introducing a flow of pure water from the bottle reservoir El i for the purpose of flushing out the die, and at the same time removing any small amount of remaining acid overlying the test spot. It will be noted that the flushing water is removed nearly as fast as introduced in the die by way of the drain tubing -9I-92. Upon completion of the step of flushing stop cook 63 is closed and the clamp I5-22 may bev loosened to permit removal of the test section of the sheet,

or to enable its displacement to an area desired for subsequent spot test.

- The test reagent preferably employed in the bottle reservoir 55, is preferably made up in a proportion of the order of 800 cc. muriatic acid, with 200 cc, water, to which is added 50 cc. antimony chloride SbClz) solution. The chloride solution is preferably made up in the proportion of 32 grams of the chloride in one liter of concentrated hydrochloric acid. Some variations are of course possiblein the solutions above indicated as preference, but numerous tests have indicated the foregoing proportions to behighly satisfactory for the purpose.

It will be obvious that the method and 8.1).- paratus herein outlined are adapted, with or without minor modifications, to test usage with the sulphuric acid-permanganate reagent sometimes employed as per optional A. S. T. M. specifications, as well as other procedure dependent upon a metal determination on a basis of gas evolution.

It will have appeared that the foregoing method and apparatus for spot testing of coated metal sheets, offers a distinct advantage over the more or less standardized and accepted practice, since the present invention obviates the necessity for sealing off the lower end of the test die, as by plastic materials. It serves further to obviate any specific necessity for cutting and mutilation upon recoating of the test spots, be fully utilized for its intended purpose. Furthermore, the facilities, by use of the apparatus described, for forcibly flushing out the die, and water cleaning the test area, enable the die and the remainder of the apparatus to be kept in situ for successive spot tests. It will further appear that the provision or" a direct-reading burette provided with either a single or multiple scale, efiects a considerable saving in the time heretofore consumed for tabular determination or calculation of gas volume into values indicating extent of coating in ounces per unit area, for example. It will appear that the apparatus and method described fully realize each and all of the several objects hereabove expressed, as Well as those implied from the foregoing description of the preferred assembly of equipment and the practice involved therewith.

Although the invention has been described by making particular reference to details of a se lected embodiment of the invention, the detail of description is to be understood solely in an instructive and not in a limiting sense, inasmuch as many changes may be made within the scope of the claims hereunto appended.

I claim as my invention:

1. In a device for the spot testing of surfacing metals, an open-bottom chambered element, adapted for sealed application to a sheet of metal to be tested, the wall structure of said element being provided with separate passages or ports respectively adapted as a water inlet, an inlet for introducing a reagent, a gas outlet, and a drain outlet, means for supplying the appropriate liquids to said inlet ports or passages, a platen element opposite the open bottom of the chambered element, and means for forcing said elements toward each other with the metal sheet recoated, and the sheet or article formed thereof therebetween and in fluid tight relation to the chambered element.

2. The combination recited in claim 1, characterized in that the said ports or passages are all located in an uppermost wall portion of the chambered element, and a tubing element extending into each of said ports or passages.

3. In apparatus for the spot testing of galvanized steel sheets or the like, a hollow die element forming a reaction chamber, the die element including a body formed of a non-ferrous acid-resisting metal, the die element being provided with a bottom opening adapted to overlie a sheet of the metal under test, and being-provided with a top opening, and a resilient plug or closure adapted to interfit the top opening, the plug being provided with a plurality of fluid inlet and outlet openings for the admission and egress of reagents, water and gaseous reaction products,

and clamping means coacting with the die element, and including a pressure member releasably engaging the sheet under test for holding the sheet in fluid-sealing relation to the bottom of the die element. 7

l. A clamp and die assembly for use in apparatus for the spot testing of metal-coated sheet materials, and including a C-type clamp characterized by upper and lower elongate jaws, adapted to receive therebetween a metal sheet of substantial Width, a clamping screw carried by the lower 'jaw, a chambered die structure pivotally carried by the upper jaw, the die structure having a bottom opening against which a sheet or the like under test is adapted to be maintained in sealed relation for purposes of test, by the clamp screw. I

5. An open-bottom chambered die structure for use in spot testing galvanized sheets or the like, the die being of generally cylindrical form and characterized by a lower wall portion of substantial thickness, surrounding the area of the material under test, the lower face of the die about its bottom opening, being undercut to provide a gasket seat, a gasket so formed'and located in said seat, that when deformed under reasonable compression, the inner diameter of the deformed gasket closely defines a predetermined test area, whereby to seal off said area in substantially fluid tight relation from the portions of the sheet exteriorly about the gasket, a pressure plate'disposable beneath the die structure and sheet under test, and a clamping device releasably engaging the die and plate.

6. In an assembly for the spot testing of metal coated sheet materials, a holder for the sheet under test including a C-type clamp and a screwthreaded holder for a sheet of material under test, a chambered die for the reception of a reagent to react with the coating metal, said die being of open bottom construction and normally disposed in axial alignment with the screw clamp, a plug element in the upper portion of the die, a" plurality of conduits extending through the plug element, and adapted respectively as a water inlet, an inlet for a reagent to react with the metal coating, an outlet for gaseous reaction products and a flushing drain outlet, means connecting a water supply to the Water inlet conduit, means for supplying a reagent to the inlet conduit there for, and means including a burette for entrapping the gaseous reaction products to enable a volumetric determination thereof.

7. The combination as recited in claim 6 wherein the water inlet and reagent inlet conduits are so arranged with respect to the drain conduit, as to enable completion of a test including a volumetric determination of gas evolution, and a Water flushing operation, all without disturbing the test position of the die while in fluid sealed relation to the sheet under test.

NICHOLAS -P. VEEDER.

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