Abstract: Method for reflow soldering respectively desoldering of circuit boards by using infrared radiation from radiator groups in a furnace. The circuit boards are introduced into the furnace on a timed belt or work piece carrier and maintained motionless during the prewarming, soldering respectively desoldering and cooling down phase. For prewarming for a first given time the radiator groups are operated with reduced operating current. For reflow soldering respectively desoldering the operating current of the radiator groups is switched for a second given time to a maaximum given stage and subsequently turned off completely. The soldered respectively desoldered circuit boards are cooled in a laminar air stream from ventilators for drawing off the solder vapors; the ventilators are initially operated with reduced number of rpms until the solder solidifies and then at the maximum number of rpms. Subsequently, the circuit boards are moved out of the furnace.

Abstract: Diffusion bonding of aluminum alloy objects of different sizes and shapes are greatly improved when the surface of the object is exposed to a high energy source which causes a heat treatment or melting and rapid quenching or solidification at the surface. Such treatment results in the formation of finer grains at the surface which enhances the strength of a diffusion bond.

Abstract: This invention relates to an improved process for application of a metal-comprising coating to a metal-comprising surface without using a flux. The metal-comprising surface must be wettable by or become wettable upon contact with a bath of the metal-comprising coating. Application of the coating is carried out in an environment which is inert at least with respect to the coating material during the time period of its application to the metal-comprising surface, and preferably inert with respect to both the coating material and the metal-comprising surface. The inert environment temperature is sufficiently low that no damage is done to the metal-comprising surface and no damage is done to other materials adjacent to the metal-comprising surface.

Abstract: In a method of dust-free and vacuum-tight interconnecting of ceramic aluminum-oxide components in a protective gas atmosphere the components are interconnected by heating and the use of a solder. Soldering the components is effected in a protective gas consisting of a mixture of air and nitrogen. A copper/silver solder from which individual constituents diffuse into the surfaces of the components during the soldering procedure is used as the soldering material.

Abstract: Apparatus for performing an operation with molten solder, such as soldering or desoldering a component mounted on a substrate such as a PCB including an enclosed reservoir, the reservoir including a contained space above the molten solder; a hollow nozzle for receiving solder from the reservoir; an element for conveying the molten solder in the reservoir to the nozzle; and a source connected to the contained space for introducing a pressurized gas into the space to raise the solder through the conveying means to a predetermined level within the nozzle and maintaining said solder at said predetermined level to thus effect the operation with the molten solder and then removing the gas to return the solder to the reservoir. The gas is pulsed at least during the time the solder approaches and reaches the predetermined level. The apparatus includes a plurality of different size hollow nozzles for receiving solder from the reservoir where the nozzles are removably attachable with respect to the reservoir.

Abstract: A turbine blade spar wall surrounds a coolant plenum of the blade and is cast with an intermediate thickness exceeding its final or design thickness. The outer surface of the spar wall is machined to form a plurality of incomplete holes extending to bottoms located at the final thickness dimension of the spar wall. A pre-formed sheath of porous metal is fit closely around the spar wall outer surface with coolant pores in the sheath communicating with the incomplete holes. A high pressure inert gas is introduced into the coolant plenum concurrently with application of compressive forces to the sheath as both the sheath and the spar wall are raised to a high temperature whereby the sheath is diffusion bonded to the spar wall. The inert gas pressure in the coolant plenum reinforces the spar wall against the compressive forces.

Abstract: A method of cladding a nonaluminum core with at least one aluminum cladding strip by preheating both the core rod and the strip with the former being preheated to about 1000.degree. F. to 1300.degree. F. and the latter being heated to about 600.degree. F. to 1000.degree. F. Cleaning the core rod and the strip and passing them through a controlled environment chamber containing a reducing or neutral gas. Lubricating the bonding roll grooves to provide a substantially continuous coating of lubricant thereon. Galling of the aluminum strip or strips to the bonding rolls is resisted as a result of this process.

Abstract: Method for flushing the inside surface of a pipe in the vicinity of a welded seam, where a flushing gas is fed to the pipe with laminar flow, characterized by the feature that the laminar flow in the pipe is transformed into a turbulent flow in front of the welded seam.

Abstract: A method of manufacturing an internally clad tubular product employing a tubular host such as steel, including the steps of plating the internal surface of the tubular host with a low melting point bonding metal alloy, inserting a tubular cladding member, such as of nickel base alloy, into the plated tubular host, circumferentially welding one end of the cladding member to one end of the host member directly and welding the other ends in such a manner as to incorporate a metallic gas reservoir, thus forming a subassembly, evacuating the annular space formed in the subassembly between the exterior of the cladding member and the interior of the tubular host of water vapor and oxygen, assembling a close-fitting full-length tooling mandrel of high thermal expansion material inside the subassembly, heating the subassembly to about 1650.degree. to 2100.degree. F.

Abstract: A method of manufacturing an internally clad tubular product employing a cylindrical host formed such as of a first nickel base alloy including the steps of plating the internal surface of the host with a low melting point bonding metal alloy, inserting a cylindrical cladding member, such as of a second nickel base alloy, into the plated cylindrical host, circumferentially welding one end of the cladding member to one end of the host member directly and welding the other ends in such a manner as to incorporate a metallic gas reservoir, thus forming a subassembly, evacuating the annular space formed in the subassembly between the exterior of the cladding member and the interior of the cylindrical host of water vapor and oxygen, heating the subassembly to about 1650.degree. to 2200.degree. F. thereby melting the bonding metal alloy, and hot extruding the heated subassembly to metallically bond the cladding member to the cylindrical host by means of the mechanism of liquid interface diffusion bonding.

Abstract: Apparatus and method for providing a floating seal for an inert gas solder reflow chamber. The seal floats with respect to upper and lower chucks and is made of a substantially non-deformable material. The seal permits lateral, axial and rotational movement between the lower and upper chucks while facilitating accurate control of bonding pressure. The structure of this floating seal permits use of seal materials which facilitate use of higher melting point solders, some in excess of 350.degree. C., for flip-chip bonding.

Abstract: Device for mutually centering and clamping two pipepieces which are to be welded to one another, which device, for each of the workpieces (50, 51), has a clamping unit on both sides of a welding area (9) provided with an inert gas supply (27). Each clamping unit comprises at least one peripheral row of clamping members which are contained in each case in a clamping groove (36, 39, 42), can be stretched outwards or relaxed inwards by mutual axial approach or distancing of the flanks of the clamping groove and have an outwardly pointing clamping surface for the contact with the bore surface of the workpiece. For achieving an easy method of construction and application, it is provided that the axial extent of the clamping members, lined up in large number at a slight distance, is greater than the width of their clamping surfaces in the peripheral direction. They are preferably formed by the coils of a helical spring (3).

Abstract: A method and apparatus is disclosed for purging air from multiple surfaces of members to be welded together. The apparatus includes a hood with the inert gas entering the hood at about 150 cubic feet per minute at between 2-5 pounds per square inch gauge when handling approximately 21/2 inch diameter tubes. The gas is first evenly spread in the hood to fill the entire cross sectional area thereof and is then moved through a straightening section to provide laminar flow of the gas across the multiple surfaces. An induction coil is moved between hood closure means into the hood to heat the weldable surfaces to a bonding temperature and after the coils have been removed from the hood, the members are urged together to upset the heated surfaces to weld the two members together.

Abstract: A method for continuously producing a powder-filled tubular welding electrode, whereby a metallic band while being fed is formed to a gutter (16) and thereupon to a tube (21), whereby the edges of the gutter are welded together and welding powder is supplied via a conduit (18, 19) to the welded tube, and the welding powder free space of the tube being filled with a protective gas. The object of the invention is to provide a method for continuous production of a tubular welding electrode, especially a tubular welding electrode for welding without external supply of protective gas.

Abstract: A method for joining thin-walled tubular parts (1, 2) of metal by forge/diffusion welding comprising establishing a joint (3) between opposed bounding surfaces (4, 5), the joint having increasing height from one side (7) to the other. During heating of the parts the joint (3) is supplied with an inert or reducing flushing gas, for instance hydrogen, until the oxides are removed from the joint surfaces (4, 5). By subsequently pressing the parts together, complete forge/diffusion welding is obtained. It is also suggested to reduce the cross-section of the parts excentrically in the joint area and press the parts out to their initial cross-section during the forge/diffusion welding. A packer (8) is used to close the joint (3) on the side where the distance between the parts (1, 2) is the greatest. Means (10, 11) are shown for performing the welding under water.

Abstract: A heat exchanger and a method of manufacturing a heat exchanger by brazing metal members mainly made of Al or Al alloy is disclosed. The heat exchanger has a plurality of brazed metal members, at least one of the brazed metal members being made of brazing sheet clad with a brazing material. The brazed portions of the metal members or the whole surface of the heat exchanger are coated with a corrosion-resistant fluoride flux consisting essentially of 25-40% KF, 38-54% AlF3 and 3-30% ZnF2 by weight which forms a corrosion-inhibiting metallic film.

Abstract: A method of manufacturing an internally clad tubular product employing a tubular host such as steel, including the steps of plating the internal surface of the tubular host with a low melting point bonding metal alloy, inserting a tubular clad member, such as of nickel base alloy, into the plated tubular host, circumferentially welding one end of the cladding member to one end of the host member directly and welding the other ends in such a manner as to incorporate a metallic gas reservoir, thus forming a subassembly, evacuating the annular space formed in the subassembly between the exterior of the cladding member and the interior of the tubular host of water vapor and oxygen, heating the subassembly to about 1650.degree. to 2000.degree. F. thereby melting the bonding metal alloy, and hot rolling the heated subassembly to metallically bond the cladding member to the tubular host by means of the mechanism of liquid interface diffusion bonding.

Abstract: In a process for wave soldering a work-piece in an atmosphere consisting essentially of air wherein (i) there is a first portion of the solder wave in which fluid motion can be observed, said first portion including an active dross forming area and (ii) there is a second portion of the solder wave, which is the last portion of the solder wave with which the work-piece comes into contact, the improvement comprising (a) subject to step (b), replacing the atmosphere in contact with at least about 50 percent of the surface of the active dross forming area with an inert gas; and (b) preventing the atmosphere in contact with the surface of the second portion from becoming inert regardless of whether the first and second portions overlap.

Abstract: The invention concerns preventing oxidation of printed circuit board metal surfaces as a result of heat produced in a solder bath arrangement and reducing thermal stress defects from occurring in the circuit carrier being soldered. An enclosed reaction chamber is provided with the solder bath and supplied with a pressurized atmosphere of inert gas which gas seals the reaction chamber from ambient air. The inert gas is discharged from jets against the solder side (the connector post side) of the printed circuit boards at a point upstream of the solder bath and the inert gas is at a temperature substantially higher than the solder bath temperature.

Abstract: A solder reflow process including vaporized fluorinated organic liquid such as FC-70 is dehumidified by pressurizing the vapor chamber with dry nitrogen and blowing the dry nitrogen against the conveyor belt and article to be soldered as they pass through the inlet throat.

Abstract: The method comprises the steps of: digging out a continuous groove (13) in the wall of the tubing at the location of the tapping point to be made, said groove being slightly shallower than the thickness of the wall, thereby leaving a membrane (14) of metal at the bottom of the groove between the inside of the tubing and the outside atmosphere; placing a sealed isolation unit on the tubing, said unit covering a wide area which is at least equal to the area delimited by the groove; breaking the metal membrane so as to make an opening in the wall of the tubing; removing the cut out portion of the wall; welding on a blind tail pipe; and removing the sealed isolation unit. The invention also provides a groove-digging device, and a membrane-breaking punch device (600).

Abstract: A toll for melting solder on the contacts of a surface mounted electronic component and on the corresponding contacts of a printed circuit substrate to which it is to be soldered or from which it is to be de-soldered. The tool includes a conduit for conducting hot gas to the contacts. A diverter located in the interior of the conduit deflects hot gas away from the top of the surface mounted component and confines the hot gas to the periphery of the component.

Abstract: The method of bonding silver-based contact is disclosed. A silver-based contact is brought into contact with a support, at least the surface of which is made of a cupreous material, with a pressure of less than 1 kgf/cm.sup.2 exerted therebetween. The contact and support are heated in a non-oxidizing atmosphere at a temperature of more than 700.degree. C.

Abstract: Method for directly bonding copper foils having a copper oxide layer to oxide-ceramic substrates by heating the ceramic substrate covered with the copper foil in an oxygen-containing atmosphere to a temperature above the eutectic temperature of Cu and Cu.sub.2 O, but below the melting temperature of copper in a vacuum furnace at a pressure of not more than 1 mbar while maintaining a furnace atmosphere with a partial oxygen pressure between 0.001 and 0.1 mbar.

Abstract: A method of brazing heat exchanger cores in a cell inside which two heat exchangers are subjected to a gas flux flowing first through one heat exchanger in a first direction, then to a gas flux flowing through other heat exchanger in an opposite direction.

Abstract: A process for manufacturing a piston ring is disclosed wherein web-like first metal member which will form a base of a piston ring and web-like second metal member which will form a wear resistant layer of the piston ring are separately fed and joined together. The joined web is subject to curving to gradually decrease a radius of curvature.

Abstract: In a process for diffusion bonding of at least two metal workpieces of a reactive metal, particularly titanium, the improvement for expelling entrapped air from between surfaces of such workpieces prior to diffusion bonding, which comprises precoating the metal surfaces of the workpieces which are to be diffusion bonded with a substance capable of decomposing at a temperature above about 800.degree. F. and below the diffusion bonding temperature of the workpieces, e.g. of the order about 1300.degree. F., such substance being preferably polytetrafluoroethylene, to form an inert gas having a density greater than air, heating the workpieces to a temperature above about 800.degree. F. and causing decomposition or pyrolysis of such substance and forming an inert gas having a density greater than air, and flushing the inert gas together with the entrapped air out of contact with the surfaces of the workpieces, preferably by means of argon having a density greater than the pyrolysis products or the inert gas.

Abstract: Surfaces of copper or brass which are to be joined by tin/lead alloy soldering in a non-oxydizing atmosphere are first wetted by a treating liquid containing an organic solvent typified by ethyl alcohol; a polyhydric alcohol derivative typified by ethylene glycol; and an organic, halogen-containing activator typified by aniline hydrochloride. In the resulting soldered joint, the solder has spread acceptably well and little oxidation or wetting agent resident is formed.

Abstract: A first metal surface of a first article of metal, such as the metalization layer on a silicon semiconductor device, is bonded to an opposing or second metal surface of a second article of metal, such as a "structured copper" strain buffer, using an improved method of thermo-compression diffusion bonding that involves temperature control independent of compressional force control, whereby a superior bond is obtained.

Abstract: Beryllium to metal seals are produced by forming on a beryllium surface by cathode sputtering a first metal layer from a group of metals including tantalum, niobium, zirconium, hafnium, titanium or vanadium, an intermediate cathode sputtered layer of a refractory metal and outer layer of a readily brazable metal and soldering the readily brazable layer to another metallic body.

Abstract: A purge gas unit is provided for establishing an enclosed zone for purge gas within a tube or pipe having portions which are to be joined by welding at a predetermined location relative to the length of the tube or pipe. The purge unit includes at least one cone to be positioned on one side of the location where the welding is performed and a second cone positioned on the other side of the location. A purge gas supply tube is connected between the cones and has at least one opening therebetween through which purge gas is supplied to the weld zone in the pipe or tube between the cones. The gas supply tube extends through one of the cones beyond the weld zone defined between them and is connected to gas supply means.

Abstract: A pipe repair device has a tubular housing and an expandable seal. The tubular housing includes a central passageway extending along its longitudinal axis and opening on the opposite ends of the housing. A mechanism is provided at one end of the housing for attaching a conduit to the housing in fluid communication with the passageway. The expandable seals can comprise annular tubes of resilient material which are expanded to form a seal between the device and the pipe in which it is inserted by supplying fluid pressure to the tube interiors. A mechanism for supplying purge gas to the interior of the pipe adjacent the work area can be provided adjacent and downstream of the seals. When two seals are provided, an interstage volume is defined between the seals into which fluid may be conveyed and withdrawn.

Abstract: A system for preparing the abutting ends of pipe sections which are to be subsequently pressure welded together by the application of external heat to the joint and axial inward pressure on the respective pipe sections. The pipe ends are initially formed, or subsequently ground or cut so that the radially innermost portions of the ends are in contact with each other, and the radially outermost portions of the ends are slightly spaced from each other, preferably providing a radially outward diverging gap between the pipe ends.

Abstract: The invention relates to apparatus and a method for assembling a thermostatic type bellows unit of the type having a cup shaped bellows housing and disposed in spaced relation thereto a corrugated cup shaped diaphragm having a rigid annular flange. The assembling involves pressure welding the diaphragm flange to the housing. The apparatus includes a bottom electrode having a chamber for receiving and supporting the bellows unit and an upper electrode having a central projection which protrudes into the diaphragm and a surrounding collar for biasing the diaphragm flange into abutting engagement with the upper edge of the housing. A suction system including a passage in the electrode projection provides a partial vacuum for drawing the diaphragm into engagement with said upper electrode projection. The chamber is then flushed with a flushing medium.

Abstract: Disclosed is a welded side-seamed can formed by welding a can blank comprising a steel plate substrate having, formed thereon, a coating layer consisting of a metallic chromium layer and a chromium oxide layer formed on the metallic chromium layer, wherein the so-formed side seam has an exposed steel plate layer consisting of a compact and dense steel oxide formed mainly of magnetite, which has a thickness of 50 to 800 A, especially 50 to 400 A, and a coating of a resin or resinous composition consisting of carbonyl, hydroxyl, ether and epoxy groups at a concentration of 10 to 2000 millimoles per 100 g of the resin is formed on at least one surface portion of said side seam through said steel oxide layer.

Abstract: Method for making a tube for a cracking plant, by providing an inner tube, placing a reinforcement about said inner tube, said reinforcement having transverse openings or passages, placing an outer tube coaxially about said inner tube and said reinforcement, bonding together by pressure or fusion welding, said inner tube and said outer tube through said openings or passages in said reinforcement.

Abstract: An electrically conductive path through an insulating plate (10) is produced by forcing sheets of conductive material (13, 14) into contact through a hole (11) in the plate (10). The sheets (13, 14) are forced together with sufficient force to produce a cold weld junction, which is then plated with a conductive metal (102). Dies for producing the cold weld utilize metallic spheres (110), rods (188) or chemically etched projections (228). Shaped dies (268, 272) form a crimped joint without a cold weld, and offset dies (246, 250) produce a raised junction (252) for use as a mount for a planar component. In manufacturing a printed circuit board (160) the cold weld die (158) is produced with the same drill hole pattern as used to form the drill holes in the printed circuit board (160).

Abstract: Portable apparatus for welding by means of an oxy-gas flame, such as an oxy-acetylene or an oxy-petroleum gas flame or the like, comprises a device for supplying the gaseous fuel in gaseous form under pressure, a combustion oxygen generator and means for pressuring said combustion oxygen generator so as to make the oxygen available at a pressure compatible with the fuel delivery pressure, these means being realized by a connection between the oxygen generator and the fuel supply device.

Abstract: Disclosed is a method of welding a diaphragm to the housing sections of a diaphragm-controlled device. The diaphragm and housings are first clamped together to provide a component of force perpendicular to the areas or seat of the housing which hold the diaphragm. An electron beam directed at, above, and below the sandwich edge of the housing and diaphragm causes a weld to be formed in a portion of the seat. The clamping pressure and expansion of the liquified metal forces part of the metal out of the sandwiched area such that, upon cooling, the housings are brought together against the diaphragm in a secure and pressure-tight weld. In order to weld in a vacuum chamber, it is necessary to remove the gases in the chamber. Diaphragm devices are characterized by the housing having a cavity therein and the diaphragm dividing the cavity into two chambers. Gas evacuation and re-introduction must be controlled to avoid unwanted diaphragm distortion.

Abstract: A method which utilizes thermo-compression diffusion bonding to attach a metal foil to structured copper. The different rate of expansion of metal press members with temperature creates a force which squeezes the foil and copper together to achieve a bond when the press and the parts to be joined are heated to an elevated temperature. Because of the high pressure achieved by the press, diffusion bonding occurs at a low enough temperature to avoid problems associated with use of the liquid phase of any of the metals undergoing bonding.

Abstract: A method of brazing aluminum parts in an inert gas atmosphere is disclosed. The brazed filler metal is controlled to contain a ternary alloy of aluminum-silicon-magnesium and the base aluminum parts are controlled to contain a binary alloy of aluminum-magnesium. Magnesium in the base metal is controlled to 0.4-1.2% and in the filler metal it is controlled to 0.2-0.6%; in the filler metal only, silicon is controlled to 7-12%. The assembled base metal parts and filler metal are subjected to differential heating rates, one rate being limited to at least 50.degree. C./minute when the metal parts reach temperatures in the range of 400.degree.-550.degree. C., and a conventional rate when outside said temperature zone. As a result, three physical parameters are caused to occur simultaneously: initiation of porosity in oxide film on the metal parts, transport of magnesium to the oxide interface and reaction with the oxide, and initial melting of the filler metal as well as wettings of the oxide by the filler metal.

Abstract: Water filled cavities are dried by replacing the water with a first liquid which is miscible with water and this is then replaced by a second liquid which is miscible with the first and which has a high vapor pressure. The second liquid is then replaced by a gas. The invention is particularly useful for removing water from between members which are to be explosively welded together underwater so as to improve the quality of the welded joint obtained.

Abstract: Plates of a plate heat exchanger, defining between them a space adapted to be traversed by a heat-exchange fluid, are held together and are soldered in a chamber in which the plates are heated by passing a heating fluid, generally an inert gas, directly through the passages between the plates.

Abstract: A method of brazing a stainless steel with a stainless steel or another metal wherein, in brazing the stainless steel with a stainless steel or another metal, the stainless steel side of both opposed jointing parts is plated with copper, then a copper base-tin alloy of a melting point of 850.degree. to 1081.degree. C. is used as a brazing material and said brazing material is heated together with the jointing parts to a temperature lower than the melting point of copper in a nonoxidizing gas atmosphere such that the brazing material may be melted at said temperature.The brazed stainless steels are cooled by being quickly passed through a temperature range of 850.degree. to 600.degree. C. The bonding force of the resulting stainless steels is much higher than heretofore obtained.

Abstract: Metal/ceramic abradable seals of the type used in jet aircraft are improved by maintaining a temperature differential between the metal/ceramic composite and the cooler substrate during cooling from the brazing temperature.

Abstract: A TIG pipe welding method which employs two sets of machine guide surfaces on the pipe ends. First radially inner guide surfaces cooperate with a sensor coupled to the welding torch to continuously monitor the arc gap between the welding electrode and the weld puddle as the welding electrode moves around the circumference of the pipe. The second set of radially outer surfaces cooperate with a welding carriage to guide the carriage and welding modules around the pipe joint. The carriage is constructed to provide a sealed welding chamber surrounding the electrode. An additional flow of shielding gas is provided around the torch electrode of a TIG or hot wire TIG welding module to augment the normal gas shield.

Abstract: An aluminum-silicon base brazing alloy contains between 4 and 20 percent by weight of silicon and between 0.0001 and 1.0 percent by weight, preferably between 0.005 and 0.1 percent by weight, of at least one of the elements sodium, potassium and lithium. Optionally, the brazing alloy may further include between 0.01 and 10 percent by weight, preferably between 0.05 and 2 percent by weight, of at least one of the elements bismuth, strontium, barium and antimony as well as between 0.00001 and 1.0 percent by weight, preferably between 0.0002 and 0.1 percent by weight, of beryllium. The remainder of the alloy consists essentially of aluminum and impurities conditioned by production of the brazing alloy. The alloy is used for the fluxless brazing of aluminum-containing articles in substantially non-oxidizing atmospheres.

Abstract: The present invention provides a method for rendering the environment about a container containing vapors of a combustible liquid relatively safe for blacksmithing operations by introducing an oxygen-depleted gas into the container and removing the oxygen-depleted gas and the vapors of the combustible liquid from the container to displace oxygen from the container and reduce the hazard of explosion.

Abstract: A method of fluxless brazing of aluminum parts is disclosed. Gaseous species, such as O.sub.2 and H.sub.2 O, which inhibit wetting are controlled by rapid heating (at least 100.degree. C./min) through a critical temperature range (such as 400.degree.-590.degree. C.) during heat-up to brazing temperatures. The formation of porosity through the oxide film and the collection of a promoter and wetting agent at the interface with the oxide film will thus occur simultaneously precluding disruption of wetting action by gaseous O.sub.2 or H.sub.2 O. Wicking of the wetting agent through the film porosity in the critical temperature range will then take place because of the limited time available for the reaction of gaseous O.sub.2 and H.sub.2 O with the film to form a duplex oxide. Heating may be carried out in a vacuum of 10.sup.-3 Torr or less or in an inert atmosphere with pulsed heating, provided the critical heating rate is observed in said critical temperature range.

Abstract: Plates of a plate heat exchanger, defining between them a space adapted to be traversed by a heat-exchange fluid, are held together and are soldered in a chamber in which the plates are heated by passing a heating fluid, generally an inert gas, through the passages between the plates. The apparatus comprises means for heating and cooling the fluid and a temperature-monitoring device connected to the heating means for controlling the latter. Preferably the heating fluid circulation path includes a drying station.