SU1447636A1 - Method of repairing cast housing - Google Patents

Abstract

The invention relates to heat engineering and can be used to repair and restore resource cast casings. The purpose of the invention is to increase the reliability of the repair body and reduce labor costs. dl 9 8 The cracked zones are selected and cut for welding. In section 3, install a thin-walled insert T-shaped, bend its shelf 9 along the radius. The shelf 9 is mounted with a concave surface 11 to the bottom of the cutting 3, and between them a cavity 12 of oval cross section with a height of 0.1-0.3 cutting depth 3. The wall 13 of the insert must be made hollow. Brew cavities with a viscous metal between the wall 13 of the insert and the walls of the groove, leaving cavity 12 unattached. The insert is a compensator for internal stresses. Performing a thin-walled insert contributes to its elasticity. Cavity 12 is a trap for possible cracks. As a result of filling the cutting with this method, the level of residual stresses at the welding point decreases, which increases the reliability of the design. 1 hp f-ly, 10 ill. i (L us.d

Description

The invention relates to mechanical engineering, primarily power engineering, in particular, to methods for repairing cast turbine casings for a long time.

The purpose of the invention is to increase the reliability of the repaired case by reducing the level of residual stresses and reducing the labor costs,

FIG. I shows a section of a cast body with a fractured area; in fig. 2 - the same, butt-welded; in fig. 3 and 4 are sectional AAs in FIG. 2; in fig. 5 shows an embodiment of a welded insert; in fig. 6 and 7 - installation of an insert with a hollow wall; in fig. 8 - installation of the insert with an incompletely hollow wall; figure 9 - installation of the insert in a shallow sample; in fig. 10 is an embodiment of an integral pipe insert wall.

The repair of the molded case, on which there is a fractured zone 2, consists of the following. The removal of the defective metal section and the cutting 3 for welding are performed. An insert 45 is placed in section 3, which is welded to the walls 5. The insert 4 is installed so that its ends 6 are fixed (in the direction of the longitudinal axis of the insert) outside zone 2 in the intact metal of the housing 1. At the same time, the insert 4 additionally fulfills the function of the rib soda useful compressive stresses in zone 2.

The cavity 7 between the walls 5 and the joint 4 is filled with a viscous directional metal 8 (Fig. 3). The insert 4 is T-shaped with a shelf 9 bent along a radius not smaller than the radius 10 of notch 3. The concave surface 1t of the shelf 9 is fitted to the notch 3 so that a cavity 12 is formed between them. Wall 13 of the insert 4 can be made with Cavity 14 (Fig. 6 and 7). The wall 13 can be made hollow (FIG. 6 and 7) or part but hollow (FIG. 8).

The height of the cavity 12 should not be less than 0.1 of the depth of the groove. 3, since with a smaller height of this cavity, the increase in elasticity (decrease in the stiffness of the section) becomes insignificant and the cavity is ineffective. The height of the cavity 12 should not exceed 1/3 of the depth of the cut 3 of the condition. Provision of the necessary rigid

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ti (minimum) section, which, taking into account the composite compound containing high-strength elements

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inserts (Og l, jO, is not less than 0.9 of the original.

The power installation is repaired (capital, medium), the insulation is removed from the hull, opened up, cleaned up the formation of zones 2, revealed by their non-destructive control methods (SD, ultrasonic, electric potential method). Pneumatic hammer or electric arc gouging form a groove 3, polish the surface with a grinder, remove a layer of 3-4 mm. The insert 4 is installed from a metal identical to the metal of case 1. Thus, the fleet of turbine buildings is made mainly of steel 15H1F1ML. For it, it is advisable to insert the insert from high-quality steel 12H1MF or 15H1M1F, widely used at TPPs and having H 1.5-2.0 times higher than cast steel, plasticity and crack resistance characteristics. The insert 4 is welded to the walls 5 of the cutting 3 with austenitic or pearlitic electrodes. The latter option has the advantages that the use of special pearlitic electrodes with high plastic properties as welding materials makes it possible to avoid the embrittlement of the weld zone, which is characteristic (when using austenitic electrodes) for dissimilar welds that are operated at high more than 500 ° C) temperatures.

The cavity 7 between the wall 5 and the insert 4 is filled with a viscous directional metal 8 according to the following technology. First, lining (1-2 layers) is performed on the free surface of the cut 3 and the insert 4, and then the cavities 7 are filled with a layer-by-layer surfacing of a viscous electrode metal. In order to effectively distribute the residual stresses, the filling of the cavities between the insert and the walls of the grooves is carried out, a sequence of 1-2 layers welding to the left and right of the insert.

The insert 4 is thin-walled T-shaped. Its shelf 9 is bent along a radius exceeding the minimum radius 10 in the zone of its bottom, and is set with a concave surface 11

3

the shelves 9 to the cutting 3, forming between them the internal saNTKHyryro cavity 12 of the oval cross section with a height of 0.1-0.3 cutting depth 3. The wall 13 of the insert 4 is made with cavity 14.

With a significant depth of cutting 3 exceeding 2/3 of the wall thickness of the housing 1, it is advisable to install the insert 4 with the wall 13 in the form of an oval (after rolling) solid pipe (16 11 mm) (Fig. 10), with a depth of cutting 3 from 2/3 to 1/3, - indicated in FIG. 6-8 varieties of inserts 4 based on the characteristics of the repaired area (complexity of the form, the degree of development of the resource) and the conditions of repair (availability of appropriate materials, technology). With a cutting depth of 3 less than 1/3 of the body wall thickness of 1 g of the effective insert shown in FIG. 9. At the same time, the thickness of its flange 9 is 0.08-0.1 N, and for large depths of cutting 0.05-0.08 N, where H is the thickness of the wall of the housing 1. The width of the wall 13 when it is out the surface of the housing should not exceed half the width of the cavity 7 to optimize the properties of the composite composite created.

As the cutting depth 3 increases, the danger of creating significant residual stresses increases and, as a result, repeated cracks (thermomechanical high-temperature loading - cyclic creep) due to an increase in the possible volume of the deposited metal increase.

With the proposed method, this danger is eliminated by increasing the elasticity of the repair zone of the housing 1 as a result of increasing the size of cavity 12 and inserting cavity 14. When (reducing the depth of cutting, when it is no more than 1/3 N, it is extremely simple and with minimal labor). 1 rata AND variant of the method (Fig, 9).

Example. Repair of a cast cylinder body of an average pressure turbine K-800-240 with a capacity of 800,000 kW. In the casing, the findings are revealed (during installation)

447636

Wrinkled zones in the flange to the body transitions and the steam inlet pipe into the body. The depth of the first cutting was 0.2 N, and the second was 0.7 N. The first repair was carried out in accordance with the variant in FIG. 9. As a shelf of the T-shaped insert, a section of pipe 76 And of the 10 or 12H1MF was used. The surfacing of the viscous metal was carried out by pearlitic electrodes without heat treatment. For the second cutting, the repair option presented in FIG. 8, In this case, the wall and the shelf of the insert are also made of sections of pipe 76 P HMF, gfivarkoy wall to shelf. The labor costs for repairing the hull have decreased compared to the known method by

20 one-third, the consumption of TML-4V electrodes (type E-09HM) decreased by 40%, and the repair time was reduced by 1.7 times (the preparation of insert elements is made in advance, and

25 their fit-in-place - during repair). .

Claims (2)

Invention Formula 30 A method for repairing a molded case, including removing defective metal sections, cutting for welding, placing an insert of metal identical to the case into cutting, fixing it with welding, filling the cutting with a viscous weld metal, characterized in that, in order to increase the reliability of the repaired case, reduction 40 levels of residual stresses and reduced labor costs, the insert is made thin-walled with a T-shaped cross-section, bend its shelf along a radius not less than the minimum radius from the bottom of the groove, the concave surface of the flange is set to the bottom of the groove; 35 50 welded cutting edges. 2. A method according to claim 1, characterized in that the T-shaped insert is made with a hollow wall. X V I y .l   7 77 one v FIG, g f3 ue.ff i 8 Faye. 7 Phases 9 Compiled by L.Nazarova Editor A.Ogar TehredL.Oliynyk Order 6790/17 Circulation 922 VNINPI State Committee for Inventions and Discoveries at i luii USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 i 14 15 8  I / l Phases. eight Faye. 0 Proofer I.Myska Single item