US 3572662 A
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Description (OCR text may contain errors)
United States Patent  References Cited UNITED STATES PATENTS 2,884,879 5/1959 Corriston.....................
 Inventors Earl L. Weaver;
John L. Freeman, Cook County, Ill. 820,969
XBBBB 6666 9/1962 McCu1lough.... 2/1965 OReilly 12/1965 Balaz et al. l/l970 Dickson Primary Examiner-Charles J. Myhre Appl. No.  Filed May 1, 1969  Patented Mar. 30, 1971  Assignee Dresser Industries, Inc.
Attorneys- Robert W. Mayer, Daniel Rubin, Raymond T.
Majesko, Roy L. VanWinkle, William E. Johnson, Jr. and Roderick W. MacDonald  SKID RAIL SYSTEM 3 Claims, 7 Drawing Figs.
ABSTRACT: A skid rail protection system for a furnace employing a skid rail supported by crossover members and upstanding support members, the skid rail, crossover, and support members carrying a plurality of specially designed, unmortared refractory shapes.
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Patented March 30,1911 3,572,662
3 Q Sheets-Sheet 1 FIG. I
/N EARL L. WEAVER JOHN L. FREEMAN ,zZM M/ Patented March 30, 1971 8 She ets-Sheet 2 FIG. 2
INVENTORS EARL L. WEAVER JOHN L. FREEMAN mfi fim ATTORNEY Patentcd March 30,1971 3,572,662
I Sheets-Sheet S INVENTORS EARL L. WEAVER JOHN L. FREEMAN W W m ATTORNEY SKID RAIL SYSTEM BACKGROUND OF THE INVENTION l-leretofore, the skid rail of a skid rail system has been covered with refractory shapes while the crossover and other supporting members were left exposed to the interior of the furnace in which the skid rail was located. Such a system is fully and completely disclosed in U.S. Pat. No. 3,169,754, the disclosure of which is incorporated herein by reference.
In the operation of a skid rail system, a heavy article such as a steel billet is forced through the furnace by sliding along the skid rails. There is normally a very high coefficient of friction between the heated article being pushed through the furnace and the heated skid rails. This results in a very large amount of vibration being transmitted throughout the skid rail system and particularly to the crossover and other supporting members.
Because the large amount of vibrational stresses encountered in the operation of this system caused a large amount of refractory breakage, it was heretofore thought not to be possible to completely insulate all members of the system.
It is highly desirable to permanently cover all the members of a skid rail system with a refractory because these members are metallic and readily conduct heat away from the interior of the furnace.
SUMMARY OF THE INVENTION According to this invention specialized, unmortared refractory shapes are used on the support members of a skid rail system so that the entire system is covered with refractory. This substantially reduces heat loss in the furnace due to the presence of the skid rail system.
The skid rail system of this invention tolerates normal vibration with minimum damage to the refractory shapes. The specialized shapes of this invention are also easy to install and to replace should repair become necessary. The skid rail system of this invention not only resists the mechanical stresses of operation but also resists attack by mill scale. Heretofore inorganic fiber materials have been employed in an attempt to insulate such systems but these materials were found to breakdown in operation and to rapidly erode under contact with the high velocity gases and slags normally present in furnaces employing skid rail systems. The refractory shapes employed in this invention can be formed from refractories containing at least about 80 weight percent alumina, based on the total weight of the refractory, and which have established capabilities for resisting slags such as iron oxide slags, high velocity furnace gas, and thermal shock.
Also according to this invention there is provided a refractory shape comprising a curved (arcuate) body which has protrusions extending from the top and bottom surfaces of one portion thereof with depressions in the top and bottom surfaces of the remaining portion. The depressions are adapted to receive the protrusions. The depressions are located in the top and bottom surfaces of their portion of the shape in the same position that the protrusions are located in the top and bottom surfaces of the remaining portion of the shape. This refractory shape can be layed about an upstanding member without mortar and when so emplaced will withstand vibrational stresses normally encountered in the operation of a skid rail system.
The skid rail system of this invention and the refractory shapes employed therein have wide use and are particularly useful in the steel industry for reheating slabs or billets preparatory to rolling operations. The-shapes can be used in substantially any situation where a curved refractory surface is desired.
Accordingly, it is an'object of this invention to provide a new and improved skid rail system. It is another object to provide a skid rail system which minimizes heat loss. It is another object to provide a skid rail system which is refractory covered and which refractory covering resists normal mechanical stresses, particularly vibrational stresses, and attack by high velocity gases, slags, and mill scale. It is another object of this invention to provide new and improved refractory shapes which can be employed without mortar.
Other aspects, objects, and advantages of the invention will be apparent to those skilled in the art from the disclosure and appended claims.
FIG. 1 shows a portion of a skid rail system according to this invention.
FIG; 2 shows a cross section of the skid rail and refractory covering taken along the line A-A of FIG. 1.
FIG. 3 shows a cross section taken along the line 8-8 of FIG. 1.
FIG. 4 shows a cross section taken along C-C of FIG. 1.
FIG. 5 shows an elevational view of a support shape according to this invention.
FIG. 6 shows a top view of the shape of FIG. 5.
FIG. 7 shows an alternative method for interlocking the refractory shapes employed in this invention.
More specifically, FIG. I shows a portion of a skid rail system, the portion including one of the plurality of skid rails normally present in such a system. The skid rail itself comprises a member such as pipe 1 having welded to the upper surface thereof a bar 2 which acts as the wearing surface which contacts the slab, billet, etc. Member I can be a conventional 3-inch outside diameter water pipe. Pipe 1 carries a plurality of appendages 3 which are used to carry refractory shapes 4 thereon. Refractory shapes 4 can be those disclosed in US. Pat. No. 3,169,754 and appendages 3 can be the same as the L-shaped hangers shown in FIG. 2 of said US. patent and/or the bolt-type shown hereinafter in FIG. 2.
Running transversely under the skid rail pipe and in contact therewith is crossover member 5 which can also be a conventional water pipe and which can have from a 3-inch to a 10- inch outside diameter. Pipe 5 can have insulation 6, e.g., asbestos, mortared therearound to provide a padding on which the refractory shapes ride and to substantially eliminate any airgap that may exist between pipe 5 and refractory shapes 7, 8, and 9 carried by pipe 5.
Insulation 6 also helps prevent cracking of the refractory shapes caused by a large thermal gradient through the refractory shapes. For example, in operation the outer surface of the refractory shapes is directly exposed to the interior of the furnace and can be at a temperature as high as 2400 F. At the same time, water normally at a temperature of from about to about F. is passing through the pipes of the system, e.g., pipes 1 and 5 as well as support pipe 11. This provides a thermal gradient of from 2400 F. down to about 90 F. if the refractory is in direct contact with the pipe surface. Insulation 6 helps reduce the magnitude of the thermal gradient through the refractory by insulating the refractory from the cool pipe.
Refractory shapes 7, 8, and 9 are not mortared to pipe 5 or insulation 6. Shapes 7 and 9 simply ride on pipe 5 and/or shapes 8 without further attachment. Shapes 8 are loosely bolted by way of bolts 10 to pipe 5.
Bolts 10 can be formed from conventional 304-type stainless steel welded to pipe 5 and can extend downwardly at about a 45 angle from the horizontal.
This particular type of mounting of shapes 7, 8, and 9 snugly fastens the shapes to pipe 5 so that they stay with the pipe during operation even though there is considerable vibration and possibly some distortion of the pipe during operation. However, the mounting allows the shapes to flex with the move-- sion means (better shown in FIGS. 3 and d) for interlocking with arcuate shapes 8. Arcuate shapes 9 are employed in pairs so that each pair covers the lower half of pipes 5 and II." in the same manner that a single crossover shape 7 covers the upper half of pipe 5 and a plurality of crossover shapes 9 cover pipes 5 and I1".
Shapes 7 and 9 are generally U-shaped with the open portion of the U extending downwardly and the curved portion of the U riding on the top of pipe 5. Legs 7 and 9 of the U extend downwardly on either side of pipe 5 for a distance intermediate the top and bottom of pipes 5 and 11", respectively. The legs can extend any desired length. For example, the line of juncture 12 between crossover shape 7 and arcuate shapes 8 can be any place between the top and bottom of pipe 5. Juncture 12 is at substantially the centerline of pipe 5 in FIG. 1.
Legs 7' and 9 can also be extended downwardly to or below the bottom of pipes 5 and 11" and shapes 8 thereby eliminated if desired.
An upstanding support member 11 is provided with two spaced apart upstanding legs 11' joined at their upper ends by a substantially horizontal support portion (pipe) 11". Support portion 11" is in open communication with legs 11 to allow the circulation of water in one leg through the support portion and out the other leg. Support portion 1 1 passes under and in contact with crossover pipe 5 in a substantially parallel relationship as shown in FIG. 1.
In the region wherein crossover pipes 5 and 11" are in contact specialized refractory crossover shapes 9 are employed. crossover shapes 9 are of a length shorter than crossover shapes 7 so that one arcuate shape 8 interlocks with at least two crossover shapes 9. The legs 9' of crossover shapes 9 extend downwardly to a point intermediate the top and bottom of pipe 11" if arcuate shapes 8 are used.
The interlocking of the protrusions and notches of shapes 7 and 9 with arcuate shapes 8 provides a flexiblelocking means for shapes 7 and 9 since they are unmortared to the pipe or to each other. The interlocking also prevents direct impingement of furnace flames on pipes 5 and 11". In FIG. 1, shiplap interlocking is shown, but any conventional type of tongue-ingroove or other protrusion-in-depression interlocking (e.g., FIG. 7) can be employed.
Upstanding legs 11' are covered with support shapes l3. Shapes 13 are employed in a plurality of layers one over the other for substantially the full height of legs 11". There are at least two shapes per layer. Shapes 13 interlock with contiguous shapes in the next higher and next lower layers. A single shape 13 in a given layer interlocks across a joint formed by the meeting of two shapes 13 in the next lower layer. This provides a snugly fitting wall of support shapes about leg 11' without the use of mortar and thereby retains the flexibility required to withstand vibration and distortion of legs 11' encountered in operation. Legs 11 and pipe 11" can be covered with insulation 14 in the same manner and for the same reasons set forth hereinabove with respect to insulation 6.
In the areas where pipe 1 crosses pipe 5 and legs 11' meet with pipe 5, there results an open joint wherein the refractory shapes carried by each of the pipes do not meet one another and thereby leave a substantial portion of the pipes exposed to the interior of the furnace. These open joints can be filled with a monolithic refractory 15 thereby providing continuous refractory coverage of all the pipes of the system. If desired, refractory shape fastening openings 16 can also be filled with monolithic refractory to prevent direct flame impingement and corrosion of the metallic appendages 3 and used to attach the refractory shapes to the pipes.
The refractory shapes and monolithic refractory employed in this invention can vary widely as to composition and can include both basic and nonbasic refractory compositions. The composition of the refractory shapes and monolithic refractory employed can differ from one another or can be substantially the same. It is presently preferred that high alumina, i.e., at least 85 weight percent alumina based on the total weight of the shape or monolithic refractory, be employed throughout the system.
FIG. 2 shows pipe 1 with a pair of C-shaped refractory shapes fixed thereto by means of bolts 17, washers 18, and nuts 19. Insulation can be inserted in the airspace 25 between shapes 4 and pipe 1 if desired.
FIG. 3 shows pipe 5 in contact with pipe 11". FIG. 3 also shows crossover shape 9 with its legs 9' extending on opposite sides of pipes 5 and 11" with the ends of legs 9' terminating intermediate the top and bottom of pipe 11". The ends of legs 9 carry a protrusion 20 and notch 21. The pair of arcuate shapes 8 which cover the bottom half of pipe 11" carry on the upper edge of each shape 8 a notch 22 and a protrusion 23 which mate with protrusion 20 and notch 21, respectively, of legs 9 thereby providing the interlocking of shape 9 with the pair of arcuate shapes 8. Insulation can be provided in airspace 26.
FIG. 4 shows crossover shape 7 with legs 7 extending intermediate the top and bottom of pipe 5 and interlocking with a pair of arcuate shapes 8 in the same manner discussed hereinabove with respect to FIG. 3. Insulation can be provided in airspace 27.
FIG. 5 shows a support shape 13 which is in the form of a half circle. The shape has top and bottom surfaces 31 and 32, respectively, flat ends 60,61 and inner and outer curved faces 62,63 (FIG. 6). The left half of shape 13 as pictured in FIG. 5 contains protrusions 30 extending from the substantially flat top and bottom surfaces 31 and 32, respectively, of the shape. Bottom protrusion 30 is aligned substantially vertically under top protrusion 30. The right half of shape 13 as pictured in FIG. 5 contains depressions 33 in said top and bottom surfaces. Depressions 33 are sized to receive protrusions 30 thereinto. Bottom depression 33 is aligned under top depression 33 in the same manner that protrusions 30 are vertically aligned.
FIG. 6 shows the top surface of shape 13 containing top protrusion 30 and top depression 33. It can be seen from FIG. 6 that top protrusion 30 is located in the left half of shape 13 in the same relative location that top depression 33 is located in the right half.
Thus, referring to FIG. 1, a second upper shape 13' can be placed on top of shape 13 of FIG. 6 so that the bottom depression of 13' mates with the top protrusion of 13. Shape 13' then extends across joint 35 to shape 13" so that the bottom protrusion of 13 mates with the top depression of 13". Thus, 13' locks 13 and 13" together without mortar.
More than one protrusion 30 and depression 33 can be employed on each surface of each shape so long as they are located to provide for the interlocking of shapes in one layer by shapes in the next higher layer.
In a preferred embodiment, all the refractory shapes and monolithic refractory employed contains from about 82 to about 88 weight percent A1 0 up to about 5 weight percent combined total of the group of Ti0 Fe 0 CaO, MgO, Na20, and K20, the remainder being substantially SiO Skid rails shapes 4 have a wall thickness of about 2 inches while crossover shapes 7 and 9, arcuate shapes 8, and support shapes 13 have wall thicknesses of about 2%inches. Crossover shapes 7 and arcuate shapes 8 have a length of about 12 inches. Crossover shapes 9 have a length of about 3 inches so that four crossover shapes 9 are employed with two pairs of arcuate shapes 8 in the region where pipe 11" contacts pipe 5. Support shapes 13 are half circles so that two shapes are employed in each layer along the height of legs 11'. Pipes l1 and 5 are wrapped with asbestos insulation. Crossover shapes 7 and 9 interlock with arcuate shapes 8 along the full length of arcuate shapes 8 using shiplap interlocks.
FIG. 7 shows shapes 7 and 8 locked together by mating protrusions 70 and of shapes 7 and 8 in recesses 81 and 71, respectively, of shapes 8 and 7. This type of interlock can be disposed on the sides or on the top and bottom of pipe 5. This type of interlock can also be used on shapes 9 and 8 and/or shapes 13.
Reasonable variations and modifications are possible within the scope of this disclosure without departing from the spirit and scope of this invention.
1. In a skid rail system which contains at least one skid rail supported by transverse crossover members and upstanding support members, said crossover members passing under and in contact with said skid rail, said support members having at least two spaced apart upstanding legs openly communicating with and joined at their upper ends by a substantially horizontal support portion, said support portion being substantially parallel with, passing under, and being in contact with said crossover member, the crossover members carrying a plurality of adjacent U-shaped refractory shapes, where said crossover member is not contacted by said support portion, said unmortared crossover shapes riding on the crossover member so that the arcuate portion of the U rests on the upper portion of the crossover member and the sides extending downwardly on either side of the member a distance intermediate the top and bottom of the member, thereby leaving a lower area of the member exposed, where said support portion contacts said crossover member, said unmortared crossover shapes riding on the crossover member with their sides extending downwardly a distance intermediate the top and bottom of the support portion, thereby leaving a lower area of the support portion exposed, the lower ends of each crossover shape sides having notch means and protrusion means, the exposed lower areas of said crossover member and support portion being covered by pairs of curved shapes carried by said crossover member and support portion, said curved shapes being unmortared and meeting each other along a line in said exposed area, each curved shape carrying notch means and protrusion means, each arcuate shape interlocking its notch means and protrusion means with the notch means and protrusion means of said lower ends of said crossover shape sides.
2. The system according to claim 1 wherein the regions where said support portion contacts said crossover member each arcuate shape is substantially longer than each crossover shape so that each arcuate shape interlocks with at least two crossover shapes, in the regions where said crossover members do not contact said support portion each arcuate shape is of a length substantially the same as each crossover shape so that a single arcuate shape interlocks with a single crossover shape, and said crossover members and support members are covered with insulation to provide padding for said shapes and to substantially eliminate any airgap between said members and the refractory shapes surrounding said members.
3. The system according to claim 1 wherein said interlocking means on said support shapes comprises inone-half of the shape at least one protrusion on the top of the shape and at least one similar protrusion on the bottom of the shape, each bottom protrusion being aligned under each top protrusion, in the remaining half of the shape at least one depression on the top of the shape sized to receive said protrusion and located in the remaining half in the same manner said top protrusion is located in the first half and at least one similar depression on the bottom of the shape, each bottom depression being aligned under each top depression.