A system for producing chemicals, such as, ethylene or gasoline, at high temperature (above 1100 degrees C.) having a feedstock source. The system includes a chemical conversion portion connected with the feedstock source to receive feedstock and convert the feedstock to ethylene or gasoline. The conversion portion includes a coil array and a furnace that heats the feedstock to temperatures in excess of 1100 C. or 1200 C. or even 1250 C. or even 1300 C. or even 1400 C. A method for producing chemicals, such as ethylene or gasoline, at high temperature.

A refrigerant pipe is provided to be capable of preventing a change in a length by which the refrigerant pipe is inserted after the refrigerant pipe is inserted. The refrigerant pipe includes a heat-exchanger-side pipe having a pipe component insertion flare formed at an end portion of the heat-exchanger-side pipe and at least one protrusion formed on an inner peripheral portion of the pipe component insertion flare, and a pipe component having a smaller outer diameter than an inner diameter of the pipe component insertion flare. A height of the at least one protrusion is greater than a dimension of a clearance defined on the basis of a difference between the inner diameter of the pipe component insertion flare and the outer diameter of the pipe component. The pipe component is inserted into the pipe component insertion flare, and the pipe component has a groove formed by the at least one protrusion.

A joining structure includes: a first tube made of a first metal or alloy; a second tube made of a second metal or alloy different from the first metal or alloy; a coupling member having a cylindrical shape to provide therein a passage into which the first and second tubes are insertable, and having an opening on a side face thereof to penetrate into the passage; and a brazing material injected into the passage through the opening with an end face of the first tube and an end face of the second tube abutting on each other in the passage to braze the first tube, the second tube, and the coupling member. The second metal or alloy is more easily oxidizable than the first metal or alloy during brazing. An abutting position between the first and second tubes is deviated from the opening toward the second tube.

A joining structure includes: a first tube made of a first metal or alloy; a second tube made of a second metal or alloy different from the first metal or alloy; a coupling member having a cylindrical shape to provide therein a passage into which the first and second tubes are insertable, and having an opening on a side face thereof to penetrate into the passage; and a brazing material injected into the passage through the opening with an end face of the first tube and an end face of the second tube abutting on each other in the passage to braze the first tube, the second tube, and the coupling member. The second metal or alloy is more easily oxidizable than the first metal or alloy during brazing. An abutting position between the first and second tubes is deviated from the opening toward the second tube.

A brazing method connects an assembly made up of a pipe, a component provided with an opening, and a compensation element. The compensation element includes a support section and an insertion section that is arranged between an end of the pipe and the opening of the component. An inside diameter of the compensation element is smaller than a diameter of the opening in the component. The insertion section is inserted into the end of the pipe, and the support section is located between the pipe and the component and rests on the component at the edge of the opening. The compensation element, the pipe, and the component are heated, preferably inductively, in a region of the compensation element to a temperature above the melting temperature of brazing material that is present in the region of the brazing points.

A brazing method connects an assembly made up of a pipe, a component provided with an opening, and a compensation element. The compensation element includes a support section and an insertion section that is arranged between an end of the pipe and the opening of the component. An inside diameter of the compensation element is smaller than a diameter of the opening in the component. The insertion section is inserted into the end of the pipe, and the support section is located between the pipe and the component and rests on the component at the edge of the opening. The compensation element, the pipe, and the component are heated, preferably inductively, in a region of the compensation element to a temperature above the melting temperature of brazing material that is present in the region of the brazing points.

A heat transfer pipe has a flared portion having a shape of spherical zone with an inner diameter at the distal end being larger than an inner diameter at the proximal end. The flared portion is disposed with another pipe that is a target of coupling being disposed through the flared portion. The flared portion is coupled to the other pipe with a brazing material filling a gap between the other pipe and an inner wall of the flared portion.