Abstract: Systems and methods to improve an industrial heater are disclosed. The heater comprises a horizontal cylinder oriented parallel to the ground and may encase an interior recess running the length of the heater. The heater may be divided into a plurality of sections or zones. One or more mid-rings may support the structure of the heater, and may be disposed at the intersections of adjacent sections or zones. A plurality of interior boards and/or insulation layers may line the interior façade, and may be configured to overlap each other and/or interlock together. The interlocking structure may be absent of any gap or space to prevent heat loss from the interior recess. One or more heat strips may be configured in a sinusoidal pattern. The strips may be mirrored on the opposite side of the interior recess, and may be configured to elongate in the direction opposite of gravity.

Abstract: Embodiments include a heating device for heating a workpiece, comprising a furnace defining a closed space insulated from exterior and surrounded by a heat insulator, a heater disposed in the furnace to heat a workpiece, at least one support element for supporting a workpiece in the furnace, and a base holding the at least one support element. The base may comprise a mounting portion, a support element retaining portion for each support element, the retaining portion horizontally offset from the mounting portion, and a reinforcement portion configured to increase the strength of the base against deformation due to a load of the workpiece and/or support element applied through the support element retaining portion.

Abstract: An improved method and apparatus for cooling the under-car channel of a tunnel kiln while minimizing migration of air between the above-car and under-car channels involves controlling or equalizing the mass flow of cooling air directed through the under-car channel and in particular through individual undercarriage cooling zones which can match individual heating zones of the tunnel kiln.

Abstract: A thermo-insulation article for a heat absorptive element, e.g., a water-cooled pipe, in a furnace has two parts joined to form a member for covering the pipe. Each part has an interconnected reticulated metal structure embedded in a refractory material. A thermo-insulating mat mounted over inner surface of the parts has a thermal conductivity lower, e.g., equal to or less than 25% lower, than thermal conductivity of the refractory material of the part. In one non-limiting embodiment of the invention, the thermo-insulating mat has a thermal conductivity equal to or less than 0.15 Btu's/hour/ft/degrees Fahrenheit, and the refractory material has a thermal conductivity in the range of 0.30-0.60 Btu's/hour/foot/degrees Fahrenheit. A surface of the mat is embedded in the refractory material and, optionally, a protective layer covers outer exposed surface of each of the mats to protect the mats during shipping and handling.

Abstract: An improved method and a skid member for minimizing the temperature difference between a skid-contacting region and other regions in a hot material to be heated such as a slab or billet within a reheating furnace and a skid apparatus using the same. The skid member has at least one ventilation channel for restraining heat transfer toward a lower portion of the skid member for supporting or carrying the hot material in the reheating furnace and allowing passage of hot gas through the same to reduce the temperature difference between a contact region and a non-contact region of the hot material.

Abstract: A duct to receive duct wrap is provided with a plurality of posts at different locations on and upstanding from the post to protrude through the duct wrap. Wrap retainers fit onto the post over the duct wrap securing the duct wrap on the duct.

Abstract: A pair of composite refractory tiles for insulating fluid-cooled structural members of a metallurgical furnace of the type for re-heating metal billets and slabs. The refractory tiles are a composite of a cast refractory shell which extends radially from an outer surface of the tile inward, at selected portions, to an inner surface for contacting the furnace member. In portions of the refractory tile, where contact with the furnace member is not made, a ceramic fiber insulating blanket fills a hollow between the cast refractory shell and the furnace member. Incorporating the ceramic fiber insulating blanket into each tile decreases furnace heat loss as compared to solid cast refractory tiles of comparable thickness. Attachment assemblies, which contact the fluid-cooled structural members, have a plurality of spaced anchoring wires which extend into the cast refractory shell and maintain proper alignment of each tile with the furnace structural member.

Abstract: In a metallurgical furnace of the type for re-heating metal billets and slabs, a pair of composite refractory tiles for insulating fluid-cooled structural members of the furnace. The tiles are a composite of a cast refractory shell which extends radially inward at selected portions to contact the furnace member. Attachment assemblies are embedded in the cast refractory shell and maintain proper alignment of each tile with the furnace structural member. In portions of the tile where contact with the furnace member is not made, a ceramic fiber insulating blanket fills a hollow between the refractory shell and the furnace member. Incorporating the ceramic fiber insulating blanket into each tile decreases furnace heat loss as compared to solid cast refractory tiles of comparable thickness.

Abstract: A boiler tube protector having a cylindrical or semi-cylindrical shape and adapted to be attached around an outer peripheral face of a boiler tube with mortar, which boiler tube protector includes a plurality of ceramic bodies closely arranged along their parting planes, wherein the parting planes includes a restraining portion for restraining slippage of each of the ceramic bodies.

Abstract: Water-cooled pipes of the type utilized to support steel workpieces in reheat furnaces and the like are insulated by preformed, rigid refractory members. Threaded studs are welded to opposing surfaces of the pipe or the web between a pair of pipes. The pipe(s) are then covered by a ceramic fiber blanket. A pair of the refractory members, each of which contains an aperture through which one of the studs is received, is positioned so as cover the pipe(s) and blanket. Nuts are fastened to the studs to hold the refractory members in place. The refractory members are sized and positioned so that gaps exist between them so as to allow for thermal expansion. These gaps may be filled with blanket insulation or heat-resistant plastic. The remaining portions of the apertures are also filled with heat-resistant plastic.

Abstract: The two piece rider assembly consist of a base piece that is welded to the skid pipe of a steel slab reheat furnace and a top piece that is removably attached to the base piece. The base piece has a cut out slot divided into three sections. The center section has strait walls and the front and back sections have walls that slope into the cut out to reduce the cross sectional distance. The cut out is open at the front section. The top piece has two protrusions with dove tail looking cross sections that fit into the front and back sections of the cut out slot of the base piece. The tip of the dove tail protrusion is wider than the neck of the cut out slot in the base piece so that upward movement is prevented when they are engaged. The protrusions are separated by at least the distance of the front section of the cut out slot of the base piece.

Abstract: Rider bar assembly for a product support beam of a reheat furnace of the type suitable for reheating steel product such as slabs, blooms, bar stock and semi-finished products. The assembly has a rider bar which defines an upper contact surface on which a product to be heated is receivable, a base component which has an upper region with which a lower region of the rider bar is contiguous and support means by which the base component and the rider bar thereon are mountable on a product support beam of the furnace in which the product is to be reheated. The rider bar is formed of a high temperature resistant, solid ceramic material which is a low porosity and which has sufficient compressive strength for supporting part of the load of the product when the letter is received thereon and also on the rider bar of other assemblies mounted on the same and other beams.

Abstract: A carrying device for supporting a charge in a reheating furnace is disclosed. The carrying device has several tubular supports through which coolant flows, said tubular supports being provided with high-temperature-resistant riders. Each rider has a top section and a bottom section. The bottom section is limited by sides which are inclined towards each other in the direction of the head section and form protruding steps with the latter. Plate-shaped heat insulation elements supported by support cams are inserted in the resulting recesses. The plate-shaped elements, which are not subject to wear from the movement of the riders, cover the sides of the bottom section of the rider and provide heat insulation for the bottom section. Thus the bottom section is protected against wear-promoting overheating and heat is also prevented from passing from the charge to the bottom section. On the contrary, the plate-shaped elements radiate heat to the charge, thus avoiding the formation of cold charge areas.

Abstract: A kiln assembly (10) with a tunnel kiln (12) having an entrance (14) and exit (16). Two parallel guideways (18) are provided extending through the kiln (12), each adjacent a side wall of the kiln (12). A plurality of car members (20) are movable respectively along either of the guideways (18) carrying support members (24) extending therebetween. Ware is loaded on to the support members (24) at the entrance (14), and is unloaede at the exit (16), are provided. Return guideways (22) are provided extending around opposite sides of the kiln (12) such that the car members (20) from the respective guideways (18) pass around opposite sides of the kiln (12) in a different spacing from when travelling through the kiln (12).

Abstract: A furnace for molding glass blanks includes a housing having a series of electrical heating stations and a rotary door adapted to receive glass blanks for processing. The furnace also includes a rotary turntable for receiving the glass blanks and a steering coil positioned to direct the glass blanks in a spiral pattern as they are heated at the electrical stations, a paddling platform for manual shaping, and a pressing station for pressing the glass blanks into a predetermined configuration.

Abstract: A walking hearth furnace comprising fixed and walking hearths (1 to 3 respectively 4,5) on the refractory lining of which the work (6) is placed. Slanted surfaces are worked into the refractory lining forming depressions (15) and causing the work to be heated from underneath. The pieces of work are arranged in such a manner that spaces form between them, through which the heat from above can act on the slanted surfaces. Furthermore, the slanted surfaces serve to remove the scale both through the slots between the hearths and through scale chutes (16) which lead downwards out of the depressions (15) and operate in conjunction with scale removal devices (22).

Abstract: A refractory tile adapted for protecting boiler tubes from the corrosive and erosive effects of a hot gas stream comprises an elongated ceramic body covering only that side of a boiler tube upon which the hot gas impinges. The tile is hung on the tube with a threaded stud anchored on the tube and a nut threaded on the stud, urging the tile against the tube.

Abstract: An apparatus useful for sintering unsintered abrasive grain precursor to provide sintered abrasive grain. The sintered abrasive grain can be incorporated into abrasive articles such as bonded abrasives (e.g., grinding wheels), coated abrasives, and nonwoven abrasives.

Abstract: The pusher type furnace comprises an entry chamber (2) associated with a charging device (30) to transfer charge holding devices (a through q) carrying the charges to be heat-treated. The entry chamber is followed by a rectilinear heat treatment chamber (3) and the latter by an exit chamber (4). The entry chamber and the exit chamber may each be separated from the heat treatment chamber by means of doors (15, 16). A pusher device (5) operating in a cyclic mode pushes all charge holding devices in each cycle forward by the length of one charge holding device in the direction of charge travel (X). For separate temperature and atmosphere control in subsequent sections (8, 9 and 10) of the heat treatment chamber (3), two doors (11, 12) are provided.

Abstract: The roller exhibits a support body which is provided with a plurality of support disks. Insulating layers are arranged between the support disks. A heat-resistant cable surrounding the support body in several coils is embedded in each insulating layer. The insulating layer consists of fiber material which is sprayed on at the same time as the cable is wound around the support body. The cable provides a firm and lasting connection of the insulating layer to the support body.

Abstract: A device for carrying a charge in a reheating furnaces comprising at least one skid pipe through which a cooling fluid flows, the skid pipe having at least one rider provided with at least one surface to support said charge running off center in the longitudinal direction of the skid pipe. According to the invention neighboring surfaces are laterally spaced relative to each other and run at least partially to the side of the skid pipe. Charge exposure to the relatively low temperature around the skid pipe is kept at a very low level and charge temperature is therefore very uniform.

Abstract: A device for locking refractory insulation members on support elements in a heat treating furnace, boiler or other piping has a first strap end with a ramp and a second strap end with a raised bearing tab. The ramp engages the bearing tab with an interference-fit to capture the first strap end on the second strap end. The first embodiment of the invention includes a hook insertable in a window. The hook has a deflectable ramp with a bearing edge which engages a lock surface on the raised bearing tab to lock opposing strap ends to one another. The second embodiment of the invention includes an angled edge on the first strap end which engages the raised bearing tab on the second strap end. The first and second strap ends have opposing slots. The first strap end includes a notched back which, when the opposing slots are fully interengaged, receives the bearing tab to capture the first strap end on the second strap end.

Abstract: A heat-resistant material having excellent high-temperature strength and high oxidation resistance at temperatures exceeding 1300.degree. C. The material is a heat-resistant Cr-Fe alloy including at least 60% of Cr and at least 5% of Fe, and having a mean grain size of at least 50 .mu.m and having a melting point of at least 1600 .degree. C., or a composite material composed of the said heat-resistant alloy serving as a metal matrix and a ceramic, and containing up to 40% by volume of a dispersed ceramic phase in the metal matrix.

Abstract: Tall work-supporting elements, riders or buttons, for reheat furnaces increase the unshadowed area of radiation exposure for the under surface of steel workpieces and thereby significantly reduce the "skid mark" phenomena of workpieces. The tall supporting members are secured to horizontal water-cooled skids and have internal flow passageways to receive cooling water.

Abstract: A skidrail system for a reheat furnace including a first skidrail extending within the reheat furnace, a second skidrail extending within the reheat furnace in a skewed relationship with the first skidrail, a plurality of pipe members extending upwardly from the first and second skidrails, and a skid button positioned on an end of each of the pipe members opposite the first and second skidrails. The pipe members have an interior in fluid communication with an interior of the first and second skidrails. The skid button supports a product thereon. A fluid circulation system is positioned in the first and second skidrails and in the plurality of pipe members. This fluid circulation system delivers a cooling fluid in heat exchange relationship with the pipe members. The skid button is supported at least four inches above the first and second skidrail.

Abstract: A rider for use with lengthwise generally horizontal supports in a furnace is formed from an anchor block and a cover block and a locking means. The anchor block is secured to the lengthwise generally horizontal support surface. The cover block fits vertically onto the anchor block and can be moved forwardly into a locking position which prevents vertical, forward, or lateral movement of the cover block. A locking means between the anchor block and the cover block prevents rearward movement of the cover block. The cover block is replaceable without requiring removal and replacement of the anchor block.

Abstract: The present invention enables a tile or other ceramic wares to have a deep reduced color. A roller hurse kiln 210 includes rollers 214, and a burner mounted in a firing zone adjacent to the outlet so as to provide a reducing gas. The burner has gas injection holes. The injection holes may be circular holes having a diameter of 1 to 5 mm or may be in the form of a slit having a width of 1 to 5 mm. The burner is located 15 to 80 mm above a material to be fired.

Abstract: Thermal insulation members for water cooling pipes in slab furnaces are provided which eliminate the need for welded attachment of the insulation to the pipes. The refractory material is formed for cooperative axial engagement such that a single U-shaped member and a pair of plugs encircles the pipe while in an integrated self-supporting interlock while leaving the upper skid rail unobstructed.

Abstract: The invention relates to a method for increasing the thermal radiation heat transfer between a metallurgical reheat furnace and the object being heated within the furnace by increasing the distance between the water cooled skid pipes and the object itself thereby reducing the shadow effect of the support structure on the object being heated.

Abstract: An insulation sheath for a pipe in a furnace is provided. The sheath has excellent insulation properties together with adequate resistance to the corrosive environment and thermal shock conditions. A pre-formed, substantially C-shaped, elongate member shaped to conform to the pipe over a portion of its circumference, the member comprising an inner layer of bonded insulating material integrally-bonded to a protective outer layer of refractory material. The inner layer is preferably formed of bonded ceramic fibre.

Abstract: Apparatus is provided for decreasing temperature differentials within rectangular metal blooms being heated in a furnace. The apparatus includes elongated internally cooled members located above the blooms adjacent an exit end of the furnace. The longitudinal axes of the internally cooled members are parallel to each other and to the longitudinal axes of the blooms, the latter axes being aligned so as to extend transversely with respect to the direction of movement of the blooms from an entry to an exit end of the furnace.

Abstract: A method for insulating a pipe, including skid pipes for walking beam and pusher type furnaces and the well known over-and-under skid pipe, including providing an appropriately contoured anchor band which can be applied around the pipe, the two ends secured together, each anchor band having a plurality of outwardly projecting prongs. A ceramic fiber blanket is applied around the exposed part of the pipe and then a pliable refractory material is applied around the blanket so that the prongs extend through the blanket and sufficiently into the pliable refractory material to support the refractory material around the pipe. Preferably a preformed insulator laminae comprising a ceramic fiber blanket, a pliable refractory material and a plastic-like film between and secured to them is applied to the prongs to reduce installation time.

Abstract: Refractory tile sections for insulating a pipe, such as a water-cooled pipe, have a pair of refractory tiles with concave faces and outwardly extending flanges. The refractory tiles are placed about the pipe with the flanges confronting each other, with a gap therebetween, and with recesses in the flanges aligned. Refractory connecting members are disposed in the aligned recesses, the connecting members having a bridging section extending across the gap and an enlarged end section in each of the aligned recesses. Refractory mortar secures the connecting members in the recesses and fills the gap between the flanges.

Abstract: Independent installation for discharging, storing and transferring products, such as steelworks products, which comprises fixed beams on which rest the products to be handled, and moveable beams placed between the fixed beams and driven in a rectangular cycle of displacement, each moveable beam comprises, at one of its ends, a discharging arm or fingers so that when a product taken from among those stored on the fixed beams is being transferred, said product rests on the end of said fingers and can be displaced and transferred to a discharging or removal zone in a manner entirely independent of the products which remain stored on said fixed beams.

Abstract: The system comprises at least one coolant-carrying tubular support carrying at least one rider. The latter consists of a heat-resistant cast housing provided with at least one cutout into which a ceramic carrier is inserted. The carrier is of sufficient compressive strength even at a temperature in excess of 1,200.degree. C. The housing remains at a temperature below 1,200.degree. C. and therefore provides a very good support for the carrier which it holds and transfers the loads that occur into the tubular support. The housing is detachably connected with the tubular support by means of a bolt.

Abstract: A heating apparatus comprising a heating chamber the inside of which is heated to a fixed temperature and which is provided with an entrance and an exit through which articles to be heated are taken in and out of the heating chamber, a support on which the articles are supported inside and outside of the heating chamber, a conveyer which moves vertically and horizontally so that the top surface of the conveyer is above and below the top surface of the conveyer is above and below the top surface of the support and that the conveyer reciprocates in the direction in which the articles are conveyed, and a pair of doors for opening and closing the entrance and exit of the heating chamber, whereby the articles are successively moved over a fixed distance by the conveyer toward the heating chamber, thereby providing a heating apparatus with a simple structure in which articles such as semiconductor devices are conveyed to the heating chamber without vibration and then properly heated in the heating chamber.

Abstract: Printed circuit boards, assemblies and the like are heated uniformly from edge to edge or to a desired lateral temperature profile while being conveyed through a heating area. The conveying systems reliably conveys circuit boards and the like through the heating area without dropping them. A rail heater is provided to heat rails supporting conveyors having pins to hold circuit boards and the like. A control for the rail heaters controls the temperature of the rails so the circuit boards are positively supported on the conveyors and have a uniform temperature profile or desired temperature profile from edge to edge.

Abstract: Printed circuit boards, assemblies and the like are heated uniformly from edge to edge or to a desired lateral temperature profile while being conveyed through a heating area. The conveying systems reliably conveys circuit boards and the like through the heating area without dropping them. A rail heater is provided to heat rails supporting conveyors having pins to hold circuit boards and the like. A control for the rail heaters controls the temperature of the rails so the circuit boards are positively supported on the conveyors and have a uniform temperature profile or desired temperature profile from edge to edge.

Abstract: A low cost, improved convective heat transfer furnace is disclosed which includes a cylindrical casing to which is attached blanket insulation and the casing is closed at its ends to define a closed end cylindrical furnace enclosure. An annular fan face plate is positioned within the enclosure to define a pressure zone on one side and a work zone on the other side. A paddle wheel fan in the work zone develops a large mass of circumferentially swirling wind which is initially formed as a stationary swirling mass without an axial force component but which under pressure travels axially in the form of a swirling annulus through the non-orificing annular space. The under pressure zone established by the central opening in the fan face plate causes the swirling wind annulus in the work zone to expand radially inwardly and uniformly impinge the complete surface of the work in an effective heat transfer manner before being recirculated back to the pressure zone.

Abstract: The invention is directed to an arrangement of high thrust burners with control systems for a heating furnace which heat metal or similar product, in order to erase developing cold skid marks. The location of these burners is specified, transversely and longitudinally as well as their position with the product face. This invention considers the flow of gases inside of the furnace and the necessary burner characteristic required for the application of these burners to the developing skid marks and the reasons for the specifications. The burners are required to be such that the maximum available heat in the flame is applied at the spot required in order to heat those spots at a faster rate than the cooling effect of the water cooled parts, which are the initial causes of the cold spots. Moreover, it is specified as to the control systems and to the part in which they play in the operation of the skid mark erasure burners.

Abstract: A drum dryer for use in the manufacture of bituminous concrete asphalt is provided with a jacket including a layer of ceramic fiber insulation bonded too an outer sheath of aluminum, the jacket being wrapped the outer peripheral surface of the wall of the drum and secured in place with bands of stainless steel strapping so as to reduce to a minimum heat loss due to dissipation of heat from the outer peripheral surface of the drum wall, thereby enabling conservation of energy, while affording protection to personnel and equipment in the vicinity of the dryer drum against excessive heat. Weather seals are provided for inhibiting the entry of ambient moisture between the jacket and the outer peripheral surface of the wall of the drum.

Abstract: The present invention relates to a heat-resisting supporting member, such as a skid button, for supporting a heated material, such as a steel plate, in a high-temperature atmosphere within a heating furnace and the like and provides a heat-resisting supporting member in which a peripheral surface of a lower corner portion of a supporting aggregate formed of heat-resisting alloys with single ceramics, ceramic particles or ceramic bars dispersed therein or heat-resisting alloy-impregnated ceramics formed by impregnating air-pores of porous ceramics with heat-resisting alloys is coated with heat-resisting alloys so as to be capable of being welded to other members while the remaining peripheral surface of the supporting aggregate is coated with a shock-resisting substance formed of heat-resisting alloys, heat-resisting alloys with ceramic particles dispersed therein or heat-resisting alloy-impregnated ceramics.

Abstract: Disclosed is an improved skid rail used in furnaces, particularly, the furnaces for heating steel pieces for hot processing. The skid rail uses, as the material of the skid members thereof, an oxide-dispersion reinforced type super alloy which comprises certain amounts of Cr, Fe, Al and Ti, and optionally a certain amount of Co, the balance being Ni, and contains fine particles of a high melting point metal oxide such a Y.sub.2 O.sub.3, ZrO.sub.2 and Al.sub.2 O.sub.3 dispersed in the austenitic matrix of the alloy.

Abstract: A steel reheating furnace is characterized by a plurality of elongated, longitudinally extending, heating elements and associated skid rails, the skid rails having primary portions laterally offset with the portions supporting respective of laterally offset first and second areas on the bottom of slabs as they pass through the furnace. The heating elements direct their heat at the respective first areas when the slabs have their second areas supported by the rail portions, and vice versa, whereby to eliminate skid marks caused by the rail portions shielding the slab.

Abstract: An improved walking beam furnace insulation in which the leg openings through the furnace floor are provided with insulation to limit the heat losses therethrough and such insulation includes an insulating cap secured to the leg within the furnace and positioned to engage the insulating material surrounding the leg openings in the furnace floor during a substantial portion of the time. Additionally a pipe is secured to said leg to circulate water therethrough.

Abstract: A method, and a kiln, by and in which to fire ceramic tiles (8), or similar items, which are taken along a given path each stage of which is singular in terms of temperature level and other parameters governing the firing cycle. Travelling forward along the path, the tiles are subjected to a succession of alternating forward and reverse movements (30, 31) sequenced in such a way that each passage forward is followed by a shorter movement in reverse.

Abstract: A walking beam type reheating furnace which is provided with a furnace housing, stationary beams fixedly mounted in the furnace housing, first movable beams arranged on the charge side in the furnace housing, second movable beams arranged separately from the first movable beams on the discharge side in the furnace housing and a steel workpiece transfer device capable of transferring a steel workpiece which is placed in a zone where the first movable beams are located to a predetermined position in the vicinity of a separating portion of the first and second movable beams by passing the steel workpiece over the stationary beams and the first movable beams, wherein the first and second movable beams can be independently driven from each other.

Abstract: A drum dryer for use in the manufacture of bituminous concrete asphalt is provided with a jacket including a layer of ceramic fiber insulation bonded to an outer sheath of aluminum, the jacket being wrapped around the outer peripheral surface of the wall of the drum and secured in place with bands of stainless steel strapping so as to reduce to a minimum heat loss due to dissipation of heat from the outer peripheral surface of the drum wall, thereby enabling conservation of energy, while affording protection to personnel and equipment in the vicinity of the dryer drum against excessive heat.

Abstract: An improved heat transfer arrangement for use in a unique multi-function, industrial heat treat furnace which employs a sealed, closed end, heat exchanger shell member containing the work. The heat transfer arrangement includes a totally contained, internal recirculation system which develops an especially configured annular jet stream that produces highly efficient, convective heat transfer with the shell member. After heat transfer between the entrained gases in the jet stream with the shell member has occurred, the jet flow is reversed at one end of the shell and impinged against the workpiece, the spent stream being reformed into the annular jet at the opposite end of the shell member.

Abstract: Straight and arcuately curved superheater tube shields of refractory material comprising a pair of elongated half shields of identical interchangeable interfitting and interlocking size and shape, each half shield having a semicircular sidewall of corresponding straight or arcuate shape of predetermined radius of curvature extending between opposite ends and to inner diametrically opposite inner sides lying in a central plane and the plane of curvature. A number of mating camming portions with inclined camming surfaces are precisely spaced adjacent each of the inner sides so that one of the half shields may be turned end for end relative to and assembled to the other about a correspondingly shaped superheater tube by a relatively short axial movement and engagement of the inclined camming surfaces whereby the half shields are pulled together to close the joints therebetween and interlocked about the superheater tube. A refractory cement may be applied to attach the half shields to the tubes.