RU2440196C2 - Method of applying one-layer coat on steel tube inner surface - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to application of liquid epoxy solutionless compositions on inner surfaces of tubes for constriction of whatever pipelines. Scraper is fed into tube at the rate of υ_B>L_mp/T_n. υ_B is scraper speed in travel from tube near end to its far end, m/min. L_mp is tube or tube section length whereon epoxy composition is applied, m. T_n is time interval between composition feed termination and beginning of its hardening, min. Said composition is applied at scraper out-of-tube speed υ_p=(0.05÷0.55)D_in·n_mp, where υ_p is scraper travel in applying epoxy composition on tube inner surface, m/min. D_in is tube inner diameter, m. n_mp is tube rotational speed, min^-1.

EFFECT: saving of epoxy composition, higher efficiency of application.

7 cl, 3 dwg, 3 tbl

Description

The invention relates to a process for applying liquid epoxy solvent-free compositions to the inner surfaces of pipes intended for the construction of pipelines for various purposes: high and low pressure pipelines, gas pipelines, oil pipelines.

A known method of coating the inner surface of a metal pipe (JP patent publ. No. 56056275 from 10/11/1979), in which the inner surface of the pipe is cleaned and heated, mounted on a platform with rollers and driven into rotation by drive rollers; the boom with the installed nozzle is pushed into the pipe, while moving through the nozzle epoxy material is applied and applied to the inner surface of the pipe. The uniform distribution of the epoxy material is ensured by its atomization in the form of a powder and deposition in an electrostatic field on the inner surface of a heated pipe.

Known quick-drying epoxy coating, applied without solvent in the form of a liquid two-component composition, which is resistant to oils, fuels, industrial wastewater, as well as impact and abrasion (http://www.tpaint.ru/amercoat/pdf/ph391pc.pdf) .

Amercoat 391RS epoxy coating has a volume ratio of two components: epoxy resin - 2 parts, hardener - 1 part, and is applied to the inner surface of the pipe by airless hot application at a temperature of 50-65 ° С under high pressure through a nozzle with a torch opening angle of 20 ° up to 60 °. The minimum pipe temperature for normal curing of the epoxy composition is 10 ° C. The period of time before polymerization begins after mixing the epoxy resin and hardener in the mixer located in front of the nozzle is 5 minutes. If the time interval between the cessation of the supply of components of the epoxy composition through the mixer and nozzle and its resumption is 5 minutes or more, then after the cessation of the supply of the epoxy composition for painting, the mixer and nozzle must be washed with a solvent.

Known installations for supplying two components of the epoxy composition (main component and hardener) through two hoses, mixing them in front of the nozzle and spraying through the nozzle with a torch opening angle of from 20 ° to 60 ° (http://www.wiwa.su).

A known method of applying an epoxy composition to the inner surface of a pipe of large diameter (patent KR publ. No. 100141653 B1 dated 05/30/1994) when it is rotated on a device with support and drive rollers and when moving the boom with a nozzle at its end, directed towards the inner surface of the pipe, through which a liquid epoxy composition is supplied and sprayed.

The method includes the following steps: cleaning the inner surface of the steel pipe with roughening 50-100 microns; installing the pipe on a support device with the possibility of rotation; heating the pipe to a temperature of 20-60 ° C; pipe rotation in one of the directions with a given angular velocity; the entry into the tube of the boom with two hoses leading two liquid components of the epoxy composition heated to a temperature of 50-65 ° C, a component mixer and a nozzle mounted on the end of the boom; applying a liquid epoxy composition to the inner surface of the pipe during its rotation and when moving the boom with the nozzle at a given speed, which provides a coating thickness of at least 300 microns for a given supply of the liquid composition; boom out of the pipe; removing coated pipes from the support device; installation of the next pipe on the support device.

The disadvantage of this method is that its description does not disclose the parameters of the rotational movement of the pipe and the translational movement of the boom, which ensures the distribution of the epoxy composition over the surface of the pipe and there is no data on the degree of unevenness of the thickness of the epoxy coating along the length of the pipe with a roughness of its cleaned surface of at least 50 μm .

The technical task of the invention is the creation of such a method of applying a single layer coating on the inner surface of a steel pipe, in which the specified thickness of the applied coating layer for one working movement of the boom with the nozzle will be at least 300 microns at a small additional cost of the epoxy composition associated with the deviation of the thickness of the coating layer from a given .

The technical problem is solved in the method of applying a single layer of epoxy coating on the inner surface of the steel pipe, including: cleaning the inner surface of the steel pipe with a roughening of 50-100 microns; installing the pipe on a support device with the possibility of rotation; heating the pipe to a temperature of 20-60 ° C; pipe rotation in one of the directions with a given angular velocity; the entry into the tube of the boom with two hoses leading two liquid components of the epoxy composition heated to a temperature of 50-65 ° C, a component mixer and a nozzle mounted on the end of the boom; applying a liquid epoxy composition to the inner surface of the pipe during its rotation and when the boom and nozzle are pulled out of the pipe at a given speed, which ensures a coating thickness of at least 300 microns at a given supply of the liquid epoxy composition and at a given rotational speed of the pipe; removal from the supporting device of the pipe coated with a coating on its inner surface; the installation of the next pipe on the support device, while introducing an arrow into the pipe at a speed

υ _B > L _mp / T _n ,

where υ _B is the speed of the boom from the near end of the pipe to the far, m / s;

L _mp - the length of the pipe or pipe section on which the epoxy coating is applied, m;

T _n - the period of time from the end of the filing of the liquid epoxy composition through the nozzle to the beginning of its polymerization (solidification), min;

- apply the epoxy composition at the speed of withdrawal of the boom from the pipe

_{υ p = (0,05 ÷ 0,55)} D · n _{mp corolla,}

where υ _p is the speed of the working movement of the boom when applying the epoxy composition to the inner surface of the pipe, m / min,

D _VN - inner diameter of the pipe, m,

n _mr. - pipe rotation frequency, min ^-1 ;

- removing the pipe coated with an internal epoxy coating, installing the next pipe on the support device and introducing the boom into the pipe from the near end to the far end is performed in a time less than the period from the cessation of supply of the epoxy composition through the nozzle to the beginning of its curing;

- the epoxy composition is applied to the inner surface of the pipe in the form of a coating having a thickening in the form of a spiral strip with a width

b = (0.03 ÷ 0.45) D _int

and step

s = (0.05 ÷ 0.55) D _int ,

where b and s are the width and pitch of the helical strip.

- the deviation of the thickness of the layer of the epoxy composition is within:

δ = ± (3% ÷ 5%) Δ _n ,

where δ is the deviation of the thickness of the layer of the epoxy composition on the inner surface of the pipe,

Δ _n is the nominal thickness of the epoxy coating layer on the inner surface of the pipe, microns;

- on the inner surface of the pipe is applied an epoxy solution-free two-component composition Amercoat 391 PC, consisting of the main component and hardener;

- the epoxy composition is applied to the inner surface of the spiral seam pipe with an outer surface diameter of 530-1420 mm and a length of 12.5 m with a weld seam rising no more than 0.3 mm above the inner surface;

- the epoxy composition is applied to the inner surface of the pipe with the diameter of the outer surface, selected from the range of 270-1420 mm, and a length of up to 12.5 m

EFFECT: applying to the inner surface of the pipe an epoxy coating of a given thickness of not less than 300 microns for one working movement of the boom with the nozzle with a small deviation of the thickness of the epoxy coating from its nominal value is achieved due to the following distinctive features of the method:

- introduce an arrow into the pipe at a speed

υ _B > L _mp / T _n ,

where υ _B is the speed of the boom from the near end of the pipe to the far, m / min;

L _mp - the length of the pipe or pipe section on which the epoxy coating is applied, m;

T _n - the period of time from the end of the filing of the liquid epoxy composition through the nozzle to the beginning of its polymerization (solidification), min;

- apply the epoxy composition at the speed of withdrawal of the boom from the pipe

_{υ p = (0,05 ÷ 0,55)} D · n _{mp corolla,}

where υ _p is the speed of the working movement of the boom when applying the epoxy composition to the inner surface of the pipe, m / min,

D _VN - inner diameter of the pipe, m,

n _mp . - pipe rotation frequency, min ^-1 ;

- removing the pipe coated with an internal epoxy coating, installing the next pipe on the support device and introducing the boom into the pipe from the near end to the far end is performed in a time less than the period from the cessation of supply of the epoxy composition through the nozzle to the beginning of its curing;

- the epoxy composition is applied to the inner surface of the pipe in the form of a coating having a thickening in the form of a spiral strip with a width

b = (0.03 ÷ 0.45) D _int

and step

s = (0.05 ÷ 0.55) D _int .

where b and s are the width and pitch of the helical strip;

- the deviation of the thickness of the layer of the epoxy composition is within:

δ = ± (3% ÷ 5%) Δ _n ,

where δ is the deviation of the thickness of the layer of the epoxy composition on the inner surface of the pipe,

Δ _n is the nominal thickness of the epoxy coating layer on the inner surface of the pipe, microns;

- on the inner surface of the pipe is applied an epoxy solution-free two-component composition Amercoat 391 PC, consisting of the main component and hardener;

- the epoxy composition is applied to the inner surface of the spiral seam pipe with an outer surface diameter of 530-1420 mm and a length of 12.5 m with a weld seam rising no more than 0.3 mm above the inner surface;

- the epoxy composition is applied to the inner surface of the pipe with the diameter of the outer surface, selected from the range of 270-1420 mm, and a length of up to 12.5 m

When the proposed method does not perform solvent cleaning of the mixer and nozzle during the coating time for the entire batch of pipes or during the work shift, as not only quickly enter the arrow with the nozzle into the pipe, but also the removal of the pipe with an internal epoxy coating, the installation of the next pipe on the support device and the introduction of the boom into the pipe from the near end to the far end is performed in a time shorter than the period from the cessation of the supply of the epoxy composition through the nozzle to the beginning of its curing.

Distinctive features or features equivalent to them are not found in the scientific, technical and patent information, which indicates that the invention meets the criterion of "novelty."

The above distinguishing features, ensuring the achievement of a technical effect, do not follow explicitly from the prior art, but are obtained as a result of experiments, studies and tests, therefore, the invention meets the criterion of "inventive step".

Figure 1 shows a longitudinal section of a pipe with a single layer of epoxy coating.

Figure 2 shows a diagram illustrating a method of applying a single layer coating on the inner surface of the pipe.

FIG. 3 shows a thickness chart of an Amercoat 391 PC epoxy coating within one pitch of a helical strip with an average thickening width in the form of a helical strip.

The method of applying a single layer coating 1 on the inner surface 2 of the steel pipe 3 (figure 1) includes

- cleaning the inner surface 2 of the steel pipe 3 with a roughness of 50-100 microns;

- installation of the pipe 3 on the supporting device 4 with the possibility of rotation;

- heating pipe 3 to a temperature of 20-60 ° C;

- rotation of the pipe 3 in one of the directions with a given angular velocity;

- the entry into the pipe 3 of the boom 5 with two hoses 6 and 7, leading two liquid components of the epoxy composition, heated to a temperature of 50-65 ° C, with a mixer component 8 and a nozzle 9 mounted on the end of the boom 5;

- applying a liquid epoxy two-component composition to the inner surface 2 of the pipe 3 during its rotation at a given speed at the output of the boom 5 with the nozzle 9 from the pipe at a given speed, which ensures a coating thickness at a given flow rate of the liquid epoxy composition and at a given speed of the pipe 3 1 not less than 300 microns;

- removal from the supporting device 4 of the pipe 3 with the coating 1;

- installation of the next pipe 3 on the supporting device 4,

while introducing arrow 5 into the pipe 3 at a speed

υ _B > L _mp / T _n ,

where υ _B is the speed of movement of the boom 5 from the proximal end 10 of the pipe 3 to the distal end 11, m / min;

L _mp - the length of the pipe 3 or pipe section 3, which is applied epoxy coating 1, m;

T _n is the period of time from the end of the filing of the liquid epoxy composition through the nozzle 9 to the beginning of its curing, min;

- apply the epoxy composition at a speed of withdrawal of the boom 5 from the pipe 3

_{υ p = (0,05 ÷ 0,55)} D · n _{mp corolla,}

where υ _p is the speed of the working movement of the boom 5 when applying the epoxy composition to the inner surface of 2 pipes 3, m / min,

D _VN - inner diameter of the pipe 3, m,

n _mr. - the frequency of rotation of the pipe 3, min ^-1 .

The removal of the pipe 3 with the internal epoxy coating 1 applied, the installation of the next pipe on the supporting device 4 and the introduction of the boom 5 into the pipe 3 from the proximal end 10 to the distal end 11 are carried out in a shorter time period from the cessation of the supply of the epoxy composition through the nozzle to the beginning of its curing .

The epoxy composition is applied to the inner surface 2 of the pipe 3 in the form of a coating 1 having a thickening in the form of a spiral strip 12 wide

b = (0.03 ÷ 0.45) D _int

and step

s = (0.05 ÷ 0.55) D _int ,

where b and s are the width and pitch of the helical strip 12.

The deviation of the thickness of the layer of the epoxy composition is within:

δ = ± (3% -5%) Δ _n ,

where δ is the deviation of the thickness of the layer of the epoxy composition on the inner surface 2 of the pipe 3,

Δ _n is the nominal thickness of the epoxy coating layer on the inner surface of the pipe, microns; with Δ _n = 400 μm δ = ± (12-20) μm (Figs. 3, 4).

On the inner surface 2 of the pipe 3 is applied an epoxy solution-free two-component composition Amercoat 391 PC, consisting of the main component and hardener.

The epoxy composition is applied to the inner surface of 2 pipes 3 up to 12.5 m long with an outer surface diameter of 270-1420 mm, as well as to the inner surface of 2 spiral seam 3 pipes with an outer surface diameter of 530-1420 mm and a length of 12.5 m with a weld rising above the inner surface by no more than 0.3 mm.

Achievement of the declared parameters of the method of applying an epoxy coating and the obtained technical effect are confirmed by the results of its implementation at LLC “Pipe insulation plant”.

In this method, with the help of a special installation, an Amercoat 391 PC two-component epoxy solution-free coating was applied to the inner surface of pipes ⌀273 × 5, ⌀325 × 7, ⌀530 × 10, ⌀820 × 12, ⌀1420 × 14. The coating on the inner surface of each pipe heated to a temperature of 10 ° -60 ° C was carried out during its rotation on a special installation with spraying through the nozzle the components of the epoxy composition connected in front of the nozzle heated to a temperature of 55-65 ° C. An arrow with a nozzle was introduced with a speed of 12-48 m / min into pipes with a diameter of 273 mm or more with automatic feeding and was withdrawn with a set speed of more than 0.5 m / min during coating on the inner surface of the pipe, which corresponds to items 1 and 2 claims

Measurements of coating thickness, pitch and strip width of the inner surface of pipes with a diameter of 263 mm or more were carried out directly in the pipe, as well as on samples cut from pipes with a length equal to 2-5 steps of the screw strip, and for pipes with an inner diameter of less than 263 mm - on cut samples. Other epoxy coating quality indicators determined during testing are shown in Table 3.

Tests showed that a coating having a width and pitch of a helical strip within the limits specified in paragraph 3 of the claims, as well as coating thickness and deviations from it, which are in the ranges of values given in claims 2, 3 of the claims, provide the necessary indicators the quality of the epoxy coating are shown in table 1. The technical effect achieved from the obtained parameters is shown in table 2. The width of the helical strip, less than 0.03 D _ext . (b <0.03 D _int , for s> 0.55 D _int ), it does not ensure the achievement of the properties indicated in table 3 in the region of the helical strip.

At a time from the end of the filing of the epoxy composition through the nozzle to the beginning of its curing, not exceeding 5 minutes, due to the high speed of the boom entering the pipe, the need to clean the mixer and nozzle from the epoxy composition is excluded, since the epoxy composition does not have time to cure before coating the next pipe.

table 2 No. PF 1-6 restrictions on coverage Technical Effect Provided by Parameter Limitations
coverings one. b = (0.03-0.45) · D _int Provides minimum consumption of epoxy composition while meeting all the requirements for the coating 2. s = (0,05-0,55) · D _ext Provides high quality coating, has little effect on the flow of fluid in the pipe 3. Δ _in ^max -Δ _c ^min ≤70 μm No peeling during testing, dielectric continuity, transient resistance in accordance with the requirements of technical conditions four. δ = ± 20 μm 5. Amercoat 391 PC In terms of quality, it provides the coating parameters declared in PF 1-3, including on the inner surface of pipes according to PF 4, 5

Claims (7)

1. The method of applying a single-layer coating on the inner surface of the steel pipe, including: cleaning the inner surface of the steel pipe with roughening 50-100 microns; installing the pipe on a support device with the possibility of rotation; heating the pipe to a temperature of 20-60 ° C; pipe rotation in one of the directions with a given angular velocity; the entry into the tube of the boom with two hoses leading two liquid components of the epoxy composition heated to a temperature of 50-65 ° C, a component mixer and a nozzle mounted on the end of the boom; applying a liquid epoxy two-component composition to the inner surface of the pipe during its rotation in the process of withdrawing the boom with the nozzle from the pipe at a given speed, which ensures a coating thickness of at least 300 microns for a given supply of liquid epoxy composition and for a given rotational speed of the pipe; removing coated pipes from the support device; installing the next pipe on a support device, characterized in that the arrow is introduced into the pipe at a speed
υ _B > L _mp / T _n ,
where υ _In - the speed of movement of the boom from the near end of the pipe to the far, m / min;
L _mp - the length of the pipe or pipe section on which the epoxy coating is applied, m;
T _n - the period of time from the end of the filing of the liquid epoxy composition through the nozzle to the beginning of its curing, min;
- apply the epoxy composition at the speed of withdrawal of the boom from the pipe
υ _p = (0.05 ÷ 0.55) D _int · n _mp ,
where υ _p is the speed of the working movement of the boom when applying the epoxy composition to the inner surface of the pipe, m / min;
D _int - inner diameter of the pipe, m;
n _mp - pipe rotation frequency, min ^-1 . 2. The method according to claim 1, characterized in that the removal of the pipe coated with an internal epoxy coating, the installation of the next pipe on the support device and the introduction of the boom into the pipe from the near end to the far end is performed in a time less than the period of time from the termination of the filing of the epoxy composition through nozzle before it begins to cure. 3. The method according to claim 1, characterized in that the epoxy composition is applied to the inner surface of the pipe in the form of a coating having a thickening in the form of a spiral strip with a width
b = (0.03 ÷ 0.45) D _int ,
and step
s = (0.05 ÷ 0.55) D _int ,
where b and s are the width and pitch of the helical strip. 4. The method according to claim 3, characterized in that the deviation of the thickness of the layer of the epoxy composition is within
δ = ± (3% ÷ 5%) Δ _n ,
where δ is the deviation of the thickness of the layer of the epoxy composition on the inner surface of the pipe;
Δ _n is the nominal thickness of the epoxy coating layer on the inner surface of the pipe, microns. 5. The method according to claims 1 to 4, characterized in that on the inner surface of the pipe is applied an epoxy solution-free two-component composition Amercoat 391 PC, consisting of a main component and a hardener. 6. The method according to claims 1 to 4, characterized in that the epoxy composition is applied to the inner surface of the spiral seam pipe with a diameter of the outer surface of 530-1420 mm and a length of up to 12.5 m with a weld seam rising above the inner surface by no more than 0, 3 mm. 7. The method according to claims 1 to 4, characterized in that the epoxy composition is applied to the inner surface of the pipe with a diameter of the outer surface, selected from a range of 270-1420 mm, and a length of up to 12.5 m

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