SU908498A1 - Method of lining metallic tubes (its versions) - Google Patents

Description

(54) METHOD OF FUTTERING METAL PIPES (ITS BAP1-IAHT)

. FIELD OF THE INVENTION The invention relates to foundry production 3 integrity

centrifugal casting technology j and can be used in the manufacture of wear-resistant elements of pipelines operating under abrasive-corrosive effects.

A known method of lining metal parts of a pipeline, in which metal pipes are preheated to a temperature of 500-700 ° Cs, is installed vertically and filled with silicate melt, which forms a lining layer on the inner surface due to cooling and crystallization. Having obtained the required thickness of the hardened lining layer, the excess melt is drunk 1.

There is a method of manufacturing two-layer metal slag pipes by forming from a melt

tal of the shell, into which, immediately after the metal is poured, a melt of the ci-sheeted material is poured, which forms a lining layer, after which it is Sf 1

cooling the finished pipe 21,

A method is also known that the center of the sioro xnjTbHj is predominantly cast iron Hbix pipes, which consists in breaking the heat up to 280-480 ° C and applying a thermal insulation coating based on expanded perlite with a porosity of 70-85 and 4 on the inner surface of the mold.

The closest to the proposed by the achieved result is a method that includes applying a lining layer in a rotating metal pipe, extracting and subsequent heat treatment of BX

However, this method does not ensure reliable fixing of the lining (petrurgical) layer in

the metal pipe due to the different coefficients of thermal expansion of the petrurgic layer and the metal. As a result, a gap is formed between the lining layer and the metal pipe. This leads to the displacement of the lining layer relative to the metal pipe, the misalignment of the lining and metal layers of a two-layer pipe, destruction and loss of the lining layer due to mechanical effects. All of this has a negative effect on the quality of the produced products and significantly reduces the percentage of output of the manufactured and suitable products.

The purpose of the invention is to increase the reliability of fixing the lining layer in a metal pipe, increasing the quality and reliability of the annual

products with

The goal is achieved

the fact that in the method involving applying a lining layer in a rotating metal pipe, exposure and subsequent heat treatment before pouring: a lining layer on the inner surface of the metal pipe is applied a layer of filling 0.5-2 mm thick containing crushed perlite in the amount of 20-90% and mineral filler in the amount of a fraction of 0.2-1 nm.

Chopped perlite fractions of 0.2 mm are used as a shipment.

A petrurgic melt of a given composition is poured in a centrifugal way into a metal pipe installed horizontally on the rollers of a centrifugal machine, or mounted in an active support, or inserted directly into the mold of a centrifugal machine.

Before pouring the petroleum melt, a backfill layer consisting of pure perlite or containing perlite and mineral filler, or perlite, mineral filler and selenium scale is applied to the inner surface of the metal pipe. The composition of the filling is chosen depending on the / temperature and the composition of the inlet; p of the melt diameter and length of the manufactured pipes;

The amount of applied backfill is calculated from the conditions for the formation on the inner surface of a metal pipe of a layer thickness, 5-2 mm. Depending on the size (diameter length) of metal futures. the pipes calculate the mass (volume) of the applied perlite-containing coating TIN- Pre-calculated for each specific size, the mass (volume) of the perlite-containing coating of a given composition is filled into a special groove with a slot along the entire length, which is inserted inside the metal pipe during its rotation. The chute is inverted, backfilling through the slot is poured out and evenly distributed over the entire inner surface of the pipe under the action of centrifugal forces. Then, the chute is removed and a petroleum smelt with a temperature of 12801320 Co is poured into the inner shell. When pouring the melt and interacting with perlite, the main technical property of perlite, the ability to swell with

5 high temperatures. The breed softens, and the water containing it turns into steam, swelling the softened mass of the material 3-10 times. The increase in the volume of the layer of perlite

0 3-10 times leads to filling the gap formed between the footerO4HbiM layer and the metal shell as a result of the difference of their coefficients of thermal expansion

- and thereby ensures its wedging effect, which contributes to reliable fixation of the lining layer in the metal pipe, as well as its strict centering,

j preventing the lining layer from slipping and falling out during transport and installation into pipelines. All this makes it possible to obtain high-quality products that work reliably under abrasive-corrosive conditions.

An example. During testing of the metal method, metal shells (pipes) with a thickness of 3 mm and a diameter of 320 mm are inserted into the chill mold of the centrifugal mashina. After installing the shell (pipe), a layer of perlite is applied to its inner surface during rotation using a special gutter. When turning the trough, perlite enters the pipe and is evenly distributed over the entire surface. The layer of applied perlite is varied to determine non-optimal optimal parameters (Table I) Thus, with a layer less than 0.5 mm, a sufficient volume of the expanded layer of perlite is not provided to fill the gap between the metal and the lining layer, which does not provide the necessary adhesion of the lining layer to the metal pipe. When applied to the inner surface of a metal pipe, a layer of perlt thick over 2 mm does not ensure heating of the entire thickness of the perlite layer, which leads to swelling of only a part of the layer of perlite, As a result, the remaining part of the perlite layer, not subjected to expansion, falls off, which does not provide the necessary adhesion of the lining layer to the metal pipe. When maintaining the required thickness of the perlite layer within 0.52 mm, the required parameters are provided. The lining (petroleum) of the melt is 1280-1320. The mold in the mold is carried out for 4-6 minutes. After holding the machine, it is stopped, the front cover is opened, and the metal pipe with a lining layer is pushed out to the receiving liter. After unloading, the product is placed in a chamber furnace to undergo heat treatment according to the mode adopted in the stone industry. During the heat treatment at 850–950 s, perlite particles that have not warmed up sufficiently in contact with the molten melt swell. The quality of the pipes obtained a good degree of adhesion of the lining layer and the metal pipe allows unhindered transport of the fabricated products and their installation without fear of falling out of the lining layer. Example 2. When testing the proposed method, rolled steel pipes with a diameter of 250 mm, a wall thickness of 10 mm and a length of 2 m are used. The pipes are installed on the rollers of a centrifugal machine, a layer of perlite is applied and the petrolurgic melt is filled at 1300-1320 ° C. The thickness of the applied perlite layer is varied in the same way as Example 1. The results are compared. B6 After aging for b min, metal pipes with a lining layer are placed in a tunnel kiln to undergo a heat treatment process. Table 1 Results of testing the method of lining metal pipes with petroleum material using pearlite backfill Characteristics Thickness of perlite backfill, mm of finished product Offset and fallout lining layer Reliable fixing of the lining layer in a metal pipe. Similar results are obtained when using a mixture consisting of minutes of perlite and mineral filler in various ratios at optimum layer thickness backfill. The expediency of introducing a mineral filler in the amount of 10-80% by volume is due to the fact that 4to with proper heating of perlite to the temperature of expansion, its volume increases by 5-10 ra, i.e. with a content of 20 vol.% feather; a sufficient propping action is achieved to ensure reliable fixation of the lining layer in a metal pipe. With increasing {-1ii temperature of the molten melt poured, the amount of mineral filler is increased to the maximum limit, since the degree of heating of the backfill depends on the temperature gradient between the melt and the backfill.

TabLg, 2 shows the results of the method of lining metal pipes with petro-magnetic melt using perlite-containing zaschka containing mineral filler. When less than 20% perlite is contained in the backfill, the wedging action during the expansion is insufficient and the lining layer is displaced92

85

1.5

78

22

70 50 35 20 iO

thirty

50 65 80 90

93

The use of iron scale in the backfill causes the need to increase the thermal conductivity of the backfill, improve the heating of the perlite particles and provide more favorable conditions for its expansion. When heated to high temperature, (d) the scale can be reduced to form with silicates (mineral filler and perlite) eutectics with improved adhesive properties on

ets in a metal cover. When the content of the filler is less than 10, both% get the same effect as with a normal perlite filling. Part of the perlite does not swell and plays the role of a filler, i.e. not used for the intended purpose. When reducing the thickness of the layer of backfill, the amount of mineral napolintel increased

Zasshka badly swollen, loss of lining layer

The backfill has bulged enough; the lining layer is shifted

The lining layer is securely fixed in the metal pipe

The same

Part of the perlite does not swell, the lining layer is securely fixed

Much of the perlite does not swell

relation to both the metal pipe and the lining layer. This allows for a more reliable fixing of the lining layer in a metal pipe. As a result of a series of experiments, it was determined that the optimum amount of iron oxide in the backfill is 10-20 vol.% (Table 3). When the scale content is less than 10%, the effect is not observed compared to conventional mineral filler.

990849810

and with an increase in the amount of dross in the output and in an increase of more than 20%, there is no further reliability of fixing the lining effect in improving the quality of the produced layer.

The results of testing the method of lining metal pipes with a petrological material using perlite, mineral filler and iron oxide filling

46

50

1,3

50 50

1.8

42 40 1.7

1.2

50

38

27

50

50 50

25 20

Table

The lining layer is fixed. Vtortsov swelling perlite insufficient

Also

The lining layer is fixed. Perlite swelling at the ends is good, tight fit to the metal pipe of the backfill layer

The stitching layer is tightly textured and adheres well to metal and lining material.

The backfill layer is compacted, monolith at the ends, good adhesion to metal and petrurgic material

The lining layer is securely fastened. No further effect was found.

Also

Claims (5)

Scale partially unreacted with filler and perlite Metal pipes with a lining layer of hardened petrurgical melt obtained by the proposed method (cast stone has a good presentation and high quality of the finished product. Metal pipes of various diameters and lengths can be obtained with stone casting. The fabricator made by the proposed method had a good commercial appearance, high quality due to the reliable fixation of the lining layer in metal A high pipe, a high percentage of the yield of useful products is 90-9. Invention 1, Method for lining metal pipes, mainly with petroleum material, which involves applying a lining layer to a rotatable metal pipe, holding and subsequent heat treatment, about 10 h and and so that, in order to increase the reliability of fixing the lining layer in the metal pipe, to increase the quality and reliability of the finished product, before pouring the lining layer, the inner surface of the metal pipe is applied ypki 0.5-2 mm thick containing crushed perlite in an amount of 20-90% and a mineral filler in an amount of 10-80% fraction 0.2-1 mm. 2. A method of lining metal pipes, mainly by a petroleum material, comprising applying a lining layer to a rotatable metal pipe, holding and subsequent heat treatment, which, in order to increase the reliability of fixing the lining layer in the metal pipe, increases the quality and reliability of the finished product crushed perlite fraction of 0.2 mm is applied by pouring the lining layer onto the inner surface of the metal pipe. Sources of information taken into account during the examination 1. USSR author's certificate No. 257237, - cl. F 16 L 57/00, 1966. 2 o Copyright Certificate of the USSR No. 468701. cl. B 22 D 13/06, 1973. 3. GOST 10832-64. 4. USSR author's certificate 549244, cl. B 22 D 13/00, 1975 5.Lipovsky I.E. and Dorofeev V.A. again petrurgii. M., Metallurgists, 972. with. 186.