The method of connecting pipes with a thin tube sheet of a shell-and-tube heat exchanger

Abstract

The analysis of methods of fastening of pipes in a thin tube grid of shell and tube-type heat exchangers is carried out and the choice of joints of welded joints of pipes with deflection holes of thin pipe grating is substantiated. Calculated dimensions of holes, diameter drilling and the pitch of their placement on a pipe grid.

The optimal diameter of the drill holes for the trowel is 25 mm, which ensures that there are no cracks and burrs when the holes are ø38 mm. The technique of obtaining a qualitative butt joint of a pipe with a thin pipe grid of steel 12Х18Н10Т with the use of argon-arc welding with a non-melted electrode, without the addition of the automation of the welding process is worked out.

The basic scheme of installation and a welding torch for automatic welding of pipes with a broken openings in pipe grids is developed. For pipe connection of steel 12X18Н10Т with a wall thickness of 2 mm, the satisfactory formation of the seam is established at a welding current of 75-95 A, the voltage of the arc 18-19 V and welding speed 12,0-13,0 m / g, the consumption of argon is 10- 12 l / min

Properties of discharge and butt joints of tubes with a tubular lattice have been investigated, on the basis of which analysis it was established that: the maximum strength of the weld seam of a pipe with a thin tubular lattice is ensured when jointed and connected to the V-shaped bevel edges; in the zone of thermal impact of the butt weld compound an increase in grain is observed up to 9 points (against 11 points in the main steel of steel 12Х18Н10Т); a brittle brewing of the thickness of the metal and a satisfactory formation of the joints is provided when welding with a tungsten electrode that does not melt in two passages.

As a result of the carried out researches it is established the principle possibility of obtaining a qualitative butt weld joint of the pipe with annealing openings with argon arc welding with non-melted electrode, the use of which will improve the quality of welding and the ability to control welded joints, reduce the length of the pipe by 20 mm and, accordingly, metal thickness of shell and tube heat exchangers.