RU2316405C2 - Tube in tube wall fastening method - Google Patents

Abstract

FIELD: power machine engineering, possibly manufacture of heat exchange apparatuses.

SUBSTANCE: method comprises steps of placing tube having annular shoulder on outer surface in flanged opening of tube wall till tube resting upon inner surface of said opening; forming surface of shoulder and inner surface of opening in such a way that to provide their matched joining; fixing tube against possible movement and fastening it in opening of tube wall due to performing zone-to-zone deformation of tube and flanging opening by means of pressure pad. Shoulder on outer surface of tube may be in the form of tore-like zigzag or fixed ring.

EFFECT: improved manufacturability of method, enhanced operational reliability and fluid-tightness of formed joint.

3 cl, 4 dwg

Description

The invention relates to methods for securing pipes in the openings of the tube sheets and can be used, for example, in the manufacture of heat exchangers.

The simplest is the fastening of pipes in tube sheets (boards) by means of flaring, but the experience of operating heat exchangers, in particular regenerators, has shown in some cases malfunctioning of rolling joints, leading to loss of tightness.

In some cases, rolling joints are replaced by welded and soldered ones. (V.N. Zemzin, L.D. Frenkel. Welded constructions of steam and gas turbines, M., State Scientific and Technical Institute of Mechanical Engineering, 1962), but the connection of pipes with a tube sheet by welding is not applicable when they are placed on the tube sheet or pipe before welding thermally unstable elements (TNE) like strain gauges, etc.

Closest to the proposed solution is a method of fixing pipes in a tube sheet according to the patent of the Russian Federation No. 2078636, B21D 39/06 (publ. 05/10/1997), in which a pipe with ring protrusions in the form of a trapezoid is installed in the hole of the tube sheet having ring grooves on the outer surface, fix the pipe, and then fix the pipe in the tube sheet due to the application of compressive forces from the inner surface of the pipe.

The disadvantages of this method include the impossibility of its use when fastening pipes in thin-walled tube sheets due to their inevitable deformation, as well as the need for mandatory execution of annular grooves in the tube sheets, which is also unacceptable when using thin-walled pipe sheets.

The whole invention is to improve the manufacturability of the method of fixing pipes in the tube sheet with a simultaneous increase in the reliability and tightness of the obtained connection, especially in conditions of a sharp temperature drop and when using thin-walled tube sheets.

This goal is achieved by the fact that in the proposed method, an annular ledge is made on the outer surface of the pipe, then the pipe is installed in the flanged hole of the pipe lattice, the pipe is fixed from possible movement and its subsequent fixation in the pipe lattice hole by applying compressive force. The pipe is installed in the hole of the tube sheet until it stops according to the performed mutually agreed mates on the annular ledge of the pipe and the inner surface of the flanged hole. Fix the pipe by the zone deformation of the pipe and the flanged hole with a press washer. The step on the outer surface of the pipe is in the form of a ridge of a toroidal shape or in the form of a fixed ring.

Distinctive features of the proposed method with their influence on the technical result are:

- the implementation of mutually agreed pairing on the annular ledge of the pipe and the inner surface of the flanged hole allows you to provide a minimum gap between the connected surfaces, to prevent leakage of the sealant and to ensure its complete hardening over the entire surface, and this in turn leads to increased strength and tightness of the connection when performing this method ;

- the use of a press washer when securing the pipe in the tube sheet provides an overlap connection, which is more technologically advanced and does not limit the use of TNE;

- the presence of an annular ledge on the outer surface of the pipe makes it possible to apply force to the tube sheet along the axis of the pipe (by pressing a press washer) without deformation of the thin-walled tube plate; in the case of using pipes of small diameters, due to the increased complexity of manufacturing an annular ledge by plastic deformation methods, it is performed in the form of a fixed ring on the outer surface of the pipe.

The proposed method is illustrated by drawings, where Figures 1 and 2 show the connection of the pipe and tube sheet, respectively, before assembly and after the implementation of this method, while on the outer surface of the pipe there is a ledge in the form of a ridge of a toroidal shape, Figures 3 and 4 show this connection respectively, before assembly and after the implementation of the method when performing the step in the form of a fixed ring.

The method is as follows.

Preliminarily, on the outer surface of the pipe 1, a plastic step 2, for example, rolling, performs an annular ledge 2 in the form of a ridge of a toroidal shape - Fig. 1, and in the case of using pipes of small diameter on the outer surface of the pipe 1, a ledge 2 is made in the form of a fixed ring - Fig. 3. On the tube sheet 3 perform a hole with flanging. On the annular ledge 2 of the pipe 1 and the inner surface of the flanged holes perform mutually agreed mates (of the same radius R). Then install the pipe 1 in the hole of the tube sheet until it stops in the annular ledge 2 with the simultaneous application of sealant in the gaps between the connected surfaces. The fastening of the pipe in the hole of the tube sheet is carried out by the zone deformation of the pipe 1 and the flanged hole using the press washer 4 - Fig.2, 4.

The proposed method of fixing pipes in the holes of the tube sheet was tested in the manufacture of a recuperative heat exchanger consisting of copper pipes with a diameter of 8 mm and a wall thickness of 1 mm, a brass tube plate with a thickness of 1.5 mm and steel press washers.

Checked two options. In the first case, on the outer surface of a copper pipe with a diameter of 8 mm and a thickness of 1 mm, an annular ledge was rolled out in the form of a ridge of a toroidal shape, and flanged holes were made on a brass tube sheet. The mutually agreed mates at the contact point of the ledge and the flanged hole are made with radii equal to 3 mm, in the second embodiment, a ring acting as a ledge was installed on the outer surface of the pipe and fixed with an anaerobic sealant Anaterm-112, the mates were also made with a radius of 3 mm.

Then, according to the first and second options, the pipe was installed in the hole of the tube sheet all the way into the annular ledge, at the same time filling the gaps between the connected surfaces of the tube, the ring ledge and the tube sheet with Anaterm-112 sealant, and the press washer was pressed into the flange.

Testing of the proposed technical solution confirmed the increase in the manufacturability of the method of fixing pipes in the tube sheet while increasing the strength and tightness of the connection obtained by implementing this method.

Claims (3)

1. A method of securing pipes in a tube sheet, including performing an annular ledge on the outer surface of the pipe, installing the pipe in a flanged hole of the tube sheet, fixing the pipe from possible movement and then securing it in the hole of the tube sheet by applying compressive force, characterized in that the pipe is installed into the flanged hole of the tube sheet until the stop of the ledge of the pipe into the inner surface of the flanged hole, which are made with the formation of a mutually agreed pair, and pipe fastening is carried out by means of zone deformation of the pipe and flanging of the hole using a press washer. 2. The method according to claim 1, characterized in that the annular ledge on the outer surface of the pipe is made in the form of a ridge of a toroidal shape. 3. The method according to claim 1, characterized in that the annular ledge on the outer surface of the pipe is made in the form of a fixed ring.

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