RU2524461C2 - Jointing of pipes with steam generator manifold - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and can be used for securing of heat exchange pipes in gas generator pipe-shape manifolds. First, manifold inner surface pipe ends are expanded, hydraulic expansion is performed within the manifold depth, front end expansion in zone adjoining the inner surface and mechanical beading of pipes in zone abutting on manifold outer surface. Note here that pipe front end expansion is executed by mechanical rolling by three-roll unit with drive shaft limited torque. Note also that hydraulic expansion is performed in one pass or two passes. Note that difference in diameters between rolling zones and hydraulic expansion section is maintained no t exceeding 0.75-1.0% of heat exchange pipe OD.

EFFECT: higher reliability, longer life.

3 cl, 1 dwg

Description

The invention relates to the processing of metals by pressure and can be used for flaring pipes in pipe sheets in the manufacture of critical components of heat exchange equipment mainly for nuclear power plants.

There are various ways to secure heat exchanger tubes:

a) with the help of roller mills, the power part of which contains tapered rollers (3 or 5 pieces) and a spindle, through the shank driven into rotation by a drive, often an electric one;

b) using hydraulic distribution, where the plastic deformation of the pipe section, located in the holes of the manifold or pipe grate, is carried out by compressed to high pressure fluid supplied into the chamber formed by two sealing rings or two groups of sealing rings located in the outer annular grooves of the probe and the inner pipe surface;

c) by means of press distribution, carried out by pressure of the material of the elastic sleeve, brought mechanically to a liquid state;

g) with the help of explosives, ensuring the pressure of the pipe against the wall of the hole.

A sufficiently productive and relatively inexpensive method of explosion distribution was not widely used due to the complexity and complexity of the subsequent cleaning of the inner surfaces of pipes from explosion products.

Press distribution is limitedly used due to the low resistance of the elastic element (sleeve) and the inaccurate arrangement of the end portion of the distribution zone.

There is a method of securing heat transfer tubes using tapered roller mills (RF patent No. 2360762 class B21D 39/10), where the torque on the spindle in the manufacture of the production connection, which determines the quality of manufacture of the fastener, is selected according to the test results of a control connection similar to the production one.

If lattices (collectors) with a sufficiently thick wall (over 100 mm) are used in the design of the heat exchanger, then, as experience has shown, a combination of different methods is usually used. Such a method, which is an analogue of the present invention, is described in the description of patent 2128098, cl. B21D 39/06.

By this method, the connection is carried out according to the following sequence of operations:

- preliminary distribution of pipe ends on the inner surface of the collector;

- welding of pipe ends with a grate (collector);

- hydraulic distribution in one or two transitions within the thickness of the tube grill;

- distribution of the front end in the area adjacent to the inner surface of the collector;

- mechanical rolling in the area of the rear end wall of the tube sheet, with the specified annular zone covering at least the entire transition section of the pipe at the end of the hydraulic distribution.

This method has found wide application in practice, however, it does not specify the method of front end distribution and the modes of hydraulic distribution and mechanical rolling, due to the properties of the materials used and which play a decisive role in ensuring reliable operation of the connection. A technique that allows one to estimate the final value of the hydraulic pressure is described in [Krips H., Podhorsky M. Hydraulisches Aufweiten - ein neus Verfahren zur Befestigungen fur Rohren. // VGB Kraftwerkstechnik. 56. 1976. No. 7. S.456-464]. There is also normative document OST 26-17-01-83 “Heat-exchange apparatuses and standard air-cooling apparatuses. Technical requirements for pipe expansion with torque limitation ”, by which it is possible to evaluate the parameters of the mechanical rolling mode using a roller tool. However, the exact range of the final values of the hydraulic transfer pressure and torque can only be established by fixing the pipes in the control sample after the necessary tests.

This approach is due to the fact that excessive pressure of the hydraulic distribution can cause increased residual stresses in the bridges between the pipes, and insufficient - gaps in the connection. Insufficient pressing of the pipe to the wall of the hole in the area of the rear end surface during mechanical rolling can cause crevice corrosion of the attachment point, and rolling will cause an excessive increase in the inner diameter of the pipe, i.e. transition step, or unacceptable peeling of pipes. An increase in the transition step between the hydraulic distribution section and the rolling zone increases the hydraulic losses in the pipes and reduces the efficiency heat exchanger, and peeling weakens the corrosion resistance of pipes.

The present invention solves the technical problem of improving the reliability of the attachment point of the heat exchange pipes in the steam generator manifold due to the correct choice of fixing modes.

The technical result, which is achieved in solving the problem, is to increase the service life of the pipe mount. Approximately marked increase may be 10%.

мм при ограничении крутящего момента величиной М_кр4=2,94-3,92 Нм, причем выступание рабочей конической поверхности ролика относительно наружной поверхности коллектора не должно превышать L_вр=6_-1 мм, а перепад диаметров внутренней поверхности трубы между зонами механического вальцевания и участком, на котором осуществляют гидравлическую раздачу, не должен быть больше 0,75…1% от наружного диаметра теплообменной трубы.The specified technical result is achieved by the fact that the connection of the pipes to the collector is a tube-shaped type of a known steam generator, including preliminary distribution of the ends of the pipes on the inner surface of the collector, pipe welding, hydraulic distribution within the thickness of the collector, the distribution of the front end in the area adjacent to the inner surface, and mechanical expansion in the area adjacent to the outer surface of the collector. In this case, the front end of the pipes is distributed by mechanical rolling with 3 roller rolling in the interval 0-6 ⁺¹ mm, calculated from the inner surface of the collector, with a torque limit on the drive shaft of M _cr1 = 2.2 ^+0.196 Nm, then hydraulic distribution mainly for 2 transitions in the interval 0 - N _gv , and N _gv = HI _min , where H is the collector wall thickness (sample length); I _min = 8 ... 12 mm, then using 3-roller rolling in the area adjacent to the inner surface of the collector, in the interval l _n = 0-15 _-1 mm, mechanical rolling is performed while the torque is limited to M _cr3 = 2.45 ^+0.196 Nm, then to remove the "pocket" in the area adjacent to the outer surface of the collector, mechanical rolling (rolling) is carried out using 3-roller rolling, starting at a depth $$L_{d\mathrm{about}\mathrm{at}}={133}_{-\mathrm{one}}^{+3}$$

mm with a torque limit of M _cr4 = 2.94-3.92 Nm, and the protrusion of the working conical surface of the roller relative to the outer surface of the collector should not exceed L _bp = 6 _-1 mm, and the difference in diameter of the inner surface of the pipe between the zones of mechanical rolling and the section where hydraulic distribution is carried out should not be more than 0.75 ... 1% of the outer diameter of the heat transfer pipe.

The specified technical result can also be achieved by the fact that the hydraulic distribution is carried out in 2 transitions, at the 1st transition of which the working medium with a pressure p ₁ = 196 ^{+ 9.8} MPa is ^brought into the chamber between the sealing elements of the probe and the pipe wall and kept for 1-5 seconds, and then to eliminate the "pocket" between the zone of mechanical rolling the front end and the beginning of the hydraulic pipes dispensing zone produce mechanical rolling of the roller 3 rolling of within the range of l _n = L + l _k = 0-15 _-1 mm with torque limitation moment

МПа и выдерживают в течение 3-5 сек.the value of M _kr2 = 1.96 ^+0.196 Nm, after which a probe is installed at the 2nd transition with the placement of sealing elements on the increased diameter of the probe, and a working medium with pressure is introduced into the chamber between the sealing elements on the probe and the wall of the hole $$p_2^{.}{343}^{+9.8}$$

MPa and incubated for 3-5 seconds.

There is another way to achieve this result, namely, that hydraulic distribution is performed in one transition, a probe is installed with sealing elements placed on its increased diameter, and a working medium with pressure p ₂ = is introduced into the chamber between the sealing elements on the probe and the pipe wall 343 ^{+ 9.8} MPa and incubated for 3-5 seconds.

The application of the invention is shown in figure 1, which shows the steps of fastening pipes in a tube-shaped collector of a water-water steam generator of the PGV type and the parameters checked.

и до полного устранения кольцевых зазоров между концами труб 2 и стенками отверстий в коллекторе 1 (фиг.1,а) механическим вальцеванием 3-х роликовым инструментом при ограничении крутящего момента величиной М_кр1=2,2^+0,196 Нм. После этого выполняют кольцевую сварку 3 с использованием известных устройств, например сварочной головки АГ-10-18. В последнем случае повышается качество соединения и отпадает необходимость промежуточной обработки отверстий соединения для выполнения последующих операций. Фрагмент узла соединения после завершения этих операций показан на фиг.1,а. После завершения последней операции появляется переходная зона L_пз от d_тр.вн до $$d_{тр.вн}^{,}$$

.As with the implementation of known technologies, in this method, the ends of the prepared pipes 2 are introduced into the holes of the collectors 1 with a wall thickness H, preferably above 100 mm, and the ends of the pipes are installed flush or with some protrusion relative to the inner surface of the collector. Then carry out the distribution of the front (input) end of all pipes 2 in a limited area of length L = 6 ⁺¹ mm from d _tr.vn to $$d_{tR.\mathrm{at}n}^{,}$$

and to completely eliminate the annular gaps between the ends of the pipes 2 and the walls of the holes in the manifold 1 (Fig. 1, a) by mechanical rolling with a 3-roller tool while limiting the torque to M _cr1 = 2.2 ^+0.196 Nm. After that, ring welding 3 is performed using known devices, for example, the welding head AG-10-18. In the latter case, the quality of the connection increases and there is no need for intermediate processing of the holes of the connection to perform subsequent operations. A fragment of the connection node after completion of these operations is shown in figure 1, a. After the last operation is completed, a transition zone L _pz from d _tr.vn to $$d_{tR.\mathrm{at}n}^{,}$$

.

The next step in the manufacture of the connection of the pipes 2 to the collector 1 is to distribute the pipe 2 within the wall thickness of the collector 1.

More appropriate, this stage of hydraulic distribution of the pipe 2 within the wall thickness of the collector 1 is carried out as follows. To do this (see Fig. 1, b), a probe 4 is inserted into the pipe 2 with an outer diameter of the sealing rings 5 under the dimension d _trv , while both rings are placed in the pipe 2 within the thickness of the pipe 1 board, but the ring lying closer to the inner surface of the collector, is located beyond the transition zone L _pz after the distribution of the inlet section L of the pipe 2, and the ring lying closer to the outer surface of the collector is located at a distance from the inner surface of the collector Н _Гв = HI _min , where H is the thickness of the collector wall (length sample); I _min = 8 ... 12 mm. Through channel 6 of probe 4, a working medium is fed into the annular gap between the sealing elements 5 and pipe 2, its pressure is raised to the required value to ensure distribution and the required time t = 1 ... 5 sec is maintained at the distribution pressure. In this case, there should be no plastic deformation of the jumpers between the holes in the collector. Then the pressure of the medium is released, the medium is sucked out of the annular gap and the probe 4 is removed from the pipe 2. Then, to reduce the diameter difference in the depth interval l _n = L + l _k = 0-15 _-1 mm, mechanical rolling is performed with a 3-roller tool the limitation of the torque value of M _kr2 = 1.96 ^+0.196 Nm. Then the 2nd transition is performed, when probe 4 is installed in the pipe, where usually the sealing elements are placed on bores with an increased diameter, and a working medium with a pressure of p ₂ = 343 ^{+ 9.8} MPa is ^introduced into the chamber between the sealing elements 5 and pipe 2 aged there for 3-5 seconds.

A fragment of the connection node after the considered step is shown in figure 1, c.

In the "pockets" formed after the hydraulic distribution operation (Fig. 1, c) with lengths l _k and l _min , stagnant zones may occur that accelerate the process of electrochemical corrosion. As the studies showed, it is advisable to eliminate them by treating these areas with roller rolling.

To remove the “pocket” closest to the inner surface of the collector, a _roll with rollers 7 placed in a relatively short casing 8 so that they overlap the zone is introduced into the expanded section of the pipe 2 to a depth of l _n = L + l _k = 0-15 _-1 mm length l _to (figure 1, g). After this, the rotation of the spindle 9 of the rolling formed "pocket" is removed. The magnitude of the torque should be M _kr3 = 2.45 ^+0.196 Nm.

мм, а выступание рабочей конической поверхности роликов не должно превышать L_вр=6_-1 мм.In removing the distal length l _min «pocket» rolling of relatively long body 10 is introduced into the tube 2 so that the rollers 11 overlap the "pocket" (Figure 1, d). In this case, rolling begins at a depth $$L_{d\mathrm{about}\mathrm{at}}={133}_{-\mathrm{one}}^{+3}$$

mm, and the protrusion of the working conical surface of the rollers should not exceed L _BP = 6 _-1 mm.

In both cases, the difference in diameters between the zones of mechanical rolling and the area where plastic deformation was carried out by a working medium compressed to high pressure can be kept no more than 0.75 ... 1% of the outer diameter of the heat exchanger pipe to reduce hydraulic losses. In mechanical rolling operations, it must be taken into account that in the case of rolling with an odd number of rollers other than z _{ii, the} torque must be increased by z _ii / 3 times.

Claims (3)

1. The method of connecting pipes to the collector of a tube-shaped steam generator, characterized in that
The ends of the pipes are introduced into the holes of the collector, the front end of the pipes is distributed until the annular gaps between the ends of the pipes and the walls of the holes are completely eliminated by mechanical rolling with 3-roller rolling in the interval 0-6 ⁺¹ mm, calculated from the inner surface of the collector, with a torque limit of drive shaft with a value of M _cr1 = 2.2 ^+0.196 Nm,
after that, hydraulic distribution is performed in the interval 0-N _gv , and N _gv = N-I _min , where N is the collector wall thickness, I _min = 8 ... 12 mm,
then using 3-roller rolling in the area adjacent to the inner surface of the collector, in the interval l _n = 0-15 _-1 mm, mechanical rolling is performed while the torque is limited to M _cr3 = 2.45 ^+0.196 Nm,
further, to remove the "pocket" in the area adjacent to the outer surface of the collector, mechanical rolling is performed using 3-roller rolling, which begins at a depth

mm with a torque limit of M _cr4 = 2.94-3.92 Nm, and the protrusion of the working conical surface of the roller relative to the outer surface of the collector should not exceed L _BP = 6 _-1 mm,
in this case, the difference in the diameters of the inner surface of the pipe between the zones of mechanical rolling and the section where hydraulic distribution is carried out should not exceed 0.75 ... 1% of the outer diameter of the pipe. 2. The method according to claim 1, characterized in that that hydraulic distribution is carried out in 2 transitions, at the 1st transition of which a probe with sealing elements is introduced into the pipe, a working medium with pressure p is fed into the annular gap between the sealing elements and the pipe_one= 196^+9.8 MPa and held for 1-5 seconds, then the pressure of the working medium is dropped, the probe is removed, and then, to eliminate the "pocket" between the zone of mechanical rolling of the front end of the pipes and the beginning of the zone of hydraulic distribution, mechanical rolling is performed with 3-roller rolling in the interval l_n= L + l_k= 0-15_-one mm with torque limit M_kr2= 1.96^+0.196 Nm, a probe with sealing elements is installed at the 2nd transition, a working medium with pressure p is fed into the annular gap between the sealing elements and the pipe₂= 343^+9.8 MPa and incubated for 3-5 seconds.   3. The method according to claim 1, characterized in that that perform hydraulic distribution in one transition, install a probe with sealing elements, in the annular gap between the sealing elements and the pipe serves a working medium with a pressure p₂= 343^+9.8 MPa and incubated for 3-5 seconds.

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