The present invention relates to an absorption chiller which comprises an evaporator, an absorber, a regenerator and a condenser and has an absorbing solution and a refrigerant circulating. A heat transfer pipe, which is provided on one or more of the evaporator, absorber, regenerator and condenser, is comprised, and a ductile stainless steel pipe, which has 1% or less of delta ferrite matrix structure on the basis of the grain size area, is applied to the heat-transfer pipe. Therefore, copper-level flexibility can be obtained in comparison with an existing stainless steel pipe.

A process for the continuous production of thin-walled, radially closed hollow profiles which are composed of nonferrous metals and have a small cross section comprises supply of a flat strip of the nonferrous metal to a forming apparatus (212) at a first supply speed. The thickness of the strip corresponds to the wall thickness of the hollow profile. The forming apparatus (212) is configured for continuous forming of the flat strip supplied into a shape corresponding to the hollow profile. After forming, two opposite edges of the flat strip rest flush against one another in a contact region. A welding apparatus (216) continuously welds the edges which rest flush against one another by means of a laser which emits light having a wavelength of less than 600 nm. The laser heats a point in a welding region which has a diameter which is less than 20% of the cross-sectional dimension of the hollow profile. The welded hollow profile is taken off from the welding region and taken up in an uptake device (226).

The present invention discloses a welding system, particular a welding system using an inert gas in order to provide an oxide free fusion zone, where the object to be welded has a first side and a second side, said first and second sides being opposite sides of the object to be welded, where the system comprises: a first wagon, in use suitable to be arranged on a first side of the object to be welded, where said wagon comprises means for remaining on the surface of the object to be welded, and being able to travel on the surface of the object to be welded, where a first welding device is arranged in connection to or on said wagon; a slave wagon, in use suitable to be arranged on a second side of the object to be welded, where said slave wagon comprises a tub, said tub having an upper rim adapted to the contour of the object to be welded, and where further a gas inlet is provided such that a suitable gas may be introduced into the tub, and where the slave wagon comprises means such that in use the rim of the tub on the slave wagon may remain proximate the second side of the object to be welded, and where means are provided for moving the slave wagon such that the tub is superposed the fusion zone on the object to be welded.

A method of preparing a pipe-section for welding to another pipe-section to form a pipeline comprising a plurality of said pipe-sections, the method comprising at least the steps of: (i) providing a pipe-section having first and second pipe-ends; (ii) defining a first portion L1 of the longitudinal length of the pipe-section from the first pipe-end being in the range 3% to 40% of the overall length of the pipe-section; (iii) defining a second portion L2 of the longitudinal length of the pipe-section from the end of the first portion L1 towards the second pipe-end; (iv) heating at least the first portion L1 to at least a first temperature T1 of at least 500 C. for at least 2 minutes; (v) maintaining a second temperature T2 of the second portion L2 during step (iv) below the first temperature T1. The invention is able to reduce the strain capacity during reel-laying of a pipeline formed from a plurality of pipe sections formed by the invention.

A method for producing a steel material for line pipes which has a tensile strength of 570 MPa or more, a compressive strength of 440 MPa or more, and a thickness of 30 mm or more, the method including heating a steel having a specific composition to a temperature of 1000 C. to 1200 C.; performing hot rolling such that a cumulative rolling reduction ratio in a non-recrystallization temperature range is 60% or more, a cumulative rolling reduction ratio in a temperature range of (a rolling finish temperature +20 C.) or less is 50% or more, and a rolling finish temperature is the Ar.sub.3 transformation point or more and 790 C. or less; and subsequently performing accelerated cooling from a cooling start temperature of the Ar.sub.3 transformation point or more, at a cooling rate of 10 C./s or more, until the temperature of a surface of a steel plate reaches 300 C. to 500 C.

A method for producing a steel material for line pipes including heating a steel having a specific composition to a temperature of 1000 C. to 1200 C.; performing hot rolling such that a cumulative rolling reduction ratio in a non-recrystallization temperature range is 60% or more, a cumulative rolling reduction ratio in a temperature range of (a rolling finish temperature +20 C.) or less is 50% or more, and a rolling finish temperature is the Ar.sub.3 transformation point or more and 790 C. or less; subsequently performing accelerated cooling from a temperature of the Ar.sub.3 transformation point or more, at a cooling rate of 10 C./s or more, to a cooling stop temperature of 200 C. to 450 C.; and then performing reheating such that the temperature of a surface of the steel plate is 350 C. to 550 C. and the temperature of the center of the steel plate is less than 550 C.

A preferable aspect of the present invention provides: an ultra-high-strength hot-rolled steel sheet containing, by weight, one or two of 0.40-0.60% of C, 0.7-1.5% of Mn, 0.3% or less (excluding 0%) of Si, 0.03% or less (including 0%) of P, 0.004% or less (including 0%) of S, 0.04% or less (excluding 0%) of Al, 0.3% or less (excluding 0%) of Cr, 0.3% or less (excluding 0%) of Mo, 0.9-1.5% of Ni, and 0.9-1.5% of Cu, 1.1% or more of Cu+Ni, 0.04% or less (excluding 0%) of Ti, 0.005% or less (excluding 0%) of B, 0.006% or less (excluding 0%) of N, and the balance Fe and other impurities, the alloy elements satisfying relational formulas 1 and 2 below, wherein a microstructure of the hot-rolled steel sheet comprises, by volume, 7% or more of ferrite and 93% or less of perlite; a steel pipe and a member each using the same; and manufacturing methods therefor. [Relational formula 1] (Mn/Si) #3 (weight ratio) [Relational formula 2] (Ni/Si) #1 (weight ratio)

Double magnetic coupling for two welding heads that work parallel and independent at the front and at the back, (N) and (S), in paramagnetic and diamagnetic materials.

For producing a welded ring, a band of a length corresponding to the circumference of the ring is bent into a ring and its two ends are welded together. The band ends to be welded together have an offset in the circumferential direction of the ring, the offset lying in the plane of the band. The welding is performed from both lateral edges of the ring, from the outside to the inside up to the offset. Welding having an overall improved welding quality and a higher tensile strength is thus obtained.

The present invention relates to steel pipe excellent in toughness of the weld metal part at a low temperature obtained by submerged arc welding in the longitudinal direction from both the inside and outside surfaces having strengths of the X60 to X70 class. The steel pipe of the present invention is a pipe having weld zones welded in a longitudinal direction at an inside surface and outside surface, wherein the tensile strength of the base metal is 480 to 620 MPa, the weld metal has a predetermined composition of constituents, when % X expresses a content of an element X in the weld metal, Pcm defined by Pcm=% C+% Si/30+(% Mn+% Cu+% Cr)/20+% Ni/60+% Mo/15+% V/10+5% B is 0.2% or less, Ceq defined by Ceq=% C+% Mn/6+(% Cr+% Mo+% V)/5+(% Ni+% Cu)/15 is 0.35 to 0.45%, defined by =(1.5(% O0.89% Al)+3.4% N% Ti)1000 is 20 to 40, and % Al/% O is 0.3 to 0.8.