RU2294475C1 - Method of working conical threaded pipe joint - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: method comprises applying paste made of a soft metal on the threaded surfaces of a pipe and/or a coupling to be joined. The paste is made of a zinc-containing composition, and threaded surface is preliminary heated by 45-200°C throughout the area.

EFFECT: enhanced reliability.

4 cl, 4 tbl, 6 ex

Description

The invention relates to the connection of structural elements and can be used in the manufacture of pipes with conical threaded connections for pumping corrosive and erosive media, mainly in the oil and oil refining industries, in the manufacture of drill, casing and tubing.

A known method of sealing a threaded pipe connection, which consists in applying a sealant to the thread, followed by screwing the pipes to be connected, the screwed ends of the pipes are magnetized before screwing, and magnetic material in the form of a powder or paste is concentrated as a sealant, which ends at the ends of the threads, after screwing the ends pipes are demagnetized [Copyright certificate SU No. 1622702, IPC 5 F 16 L 15/00, 1991].

The known method is time-consuming, and the magnetically active material as a sealant, as a rule, does not have the required ductility and hardness and does not provide the possibility of multiple screwing-unscrewing while maintaining the initial tightness of the threaded connection.

There is also a method of increasing the wear resistance of threaded joints operating in an aggressive environment, for example, when drilling oil and gas wells, which consists in wetting the surface of the threaded joint during rotation in a liquid technological medium based on water and glycerol with the inclusion of copper salts, after this treatment the surface of the threaded joint is additionally dried , varnish and a layer of a lubricating composition of 1-99% copper-containing powder or powder in a grease [patent RU No. 2214478, IPC 7 C 23 C 26/00, 2003, ].

A known method of labor and energy consumption, requires a large area of the industrial premises for its implementation.

There is also a method of producing a zinc-iron coating on the threaded sections of oil-grade pipes, which consists in galvanizing the surface of the pipe threaded joint by diffusion galvanizing, which is carried out in a container filled with a mixture of zinc powder and quartz sand [patent RU No. 2244094, IPC E 21 V 17/02, C 23 C 10/28, 2005].

The diffusion galvanizing method can be used only for processing small-sized products. To obtain a zinc coating using the known method is possible only on threaded joints of the couplings, while it is impossible to process the threaded surface of a pipe of large diameter. When connecting treated and untreated surfaces with each other, it is impossible to provide both corrosion resistance and tightness of the threaded joint as a whole.

There is also a method of sealing threaded joints by applying a viscous fluid lubricant to one mating surface before screwing up, and liquid glass-based coating containing aluminum powder in an amount of 20 wt.% Is applied to the second surface [USSR Author's Certificate No. 1239436, IPC F 16 J 15 / 00, 1986].

The disadvantages of this method include the fact that when it is implemented, one mating surface is treated with a composition based on liquid glass, containing, and the second, on a fat basis. When screwing together the elements to be connected, the threading screws of one threaded surface are embedded in the screws of the second surface, destroying the formed brittle layer of glass, the resulting fragments prevent the extrusion of viscous lubricant. Repeated screwing-unscrewing of a threaded connection requires cleaning of the threaded surface and its repeated processing, i.e. To ensure reliability during repeated make-up, additional processing of the threaded joint is required.

Closest to the proposed is a method of sealing conical connections of threaded pipe joints, which consists in the fact that the treatment is carried out by applying a sealing coating of soft metal, for example zinc, lead or tin, to the threaded surface of the connected parts before screwing, screwing is carried out by means of an electrometallizer, while the coating is applied to the thread hollows of the mating surfaces in the form of separate local formations, local distribution is ensured by using duktorov uniformly distributed along the length of troughs, screwing is performed using a lubricant casing [Copyright certificate USSR №901460, IPC E 21 B 17/08, F 16 L 15/00, 1982 g.].

Using the known method allows the processing of a threaded connection, ensuring tightness due to the uniform application of ductile metal. However, the method of applying metal requires special equipment and significant energy and labor costs.

The objective of the invention is to provide a method that provides both sealing and corrosion resistance of conical threaded pipe joints with improved wear resistance with minimal energy and labor.

This object is achieved in that the proposed method for processing conical threaded pipe joints involves the mechanical application on a pre-threaded threaded surface of the articulated surfaces of the pipe and / or the sleeve of the paste based on soft metal, while a highly filled zinc-containing composition is applied as a paste, which is applied to the preheated temperature 45-200 ° C threaded surface over its entire area and carry out knurling by conducting at least one cycle Chivanov-loosening pipe coupling.

The mechanical application of the paste is carried out with a brush, roller or spray gun. The paste is a highly filled composition with a zinc content of at least 90 wt.% In the environment of the polymer binder. An ethyl silicate binder or any known binder that provides a highly filled zinc-containing composition with the desired fluidity can be used as a polymeric binder. The ethyl silicate binder is produced on an industrial scale according to TU 6-10-1468-79 or TU 2311-019-12288779-99 and is characterized by the following composition, wt.%: Ethyl silicate 11.5-12.7; polyvinyl butyral 5.5-7.7, phosphoric acid (73%) 0.15-0.45; ethyl alcohol 72.1-76.5; water is the rest. Fine zinc metal powder of PCVD grade or zinc powder of PCR-1 grade (zinc powder obtained by spraying zinc melt with inert gas) according to TU 0165-15-98 or PC-6 in accordance with GOST 12601 can be used as zinc. Zinc powders of these grades have high coefficient of polydispersity. The shape of the particles is diverse: there are spherical particles, there are particles of a scaly shape, there are particles of elongated, oblong shape.

The composition of a highly filled zinc powder composition in an ethyl silicate binder is commercially available and is known under the trade names "CEEC" and "CEEC MO" for use as anti-corrosion coatings for metal surfaces.

Zinc-filled paste is applied over the entire area of the heated surface of the thread in one layer. The temperature regime for new pipes can be provided directly during the threading process. For pipes and couplings, the threaded surface of which was formed long before processing, the temperature regime can be ensured by heating the machined threaded sections by any known methods. The applied paste is knurled by at least one make-unscrew cycle, for example, on a clutch loosening machine.

Soft metals such as zinc, copper, lead, tin and their alloys have long been known as materials used for the processing of threaded joints. Compositions using soft metals on a silicate, graphite and polymer base are also known as a sealing agent for threaded connections. In the sources of information known to us, we did not find data on highly filled zinc-containing compositions that could be applied mechanically on the machined surface and would provide a significant improvement in sealing properties, would preserve these properties for a long time under the conditions of numerous cycles of screwing-and-kneading of a threaded pair at work in an aggressive environment. It is known that oil pipes are subject to increased requirements due to the fact that threaded joints are affected not only by the oil-containing medium itself, but also by the pressure under which it is transported, as well as the abrasive effect of solid suspended particles that are present as impurities. It is also known that the processing of detachable threaded joints with greases does not, as a rule, provide the required sealing of the joint and uniformity of application over the threads. This is mainly due to the fluidity of such compositions, which, in turn, leads to extrusion of the applied paste when screwing and screwing the threaded pair and "pulling off" the paste from the treated surface without stretching it over the surface. Especially these phenomena are manifested in the processing of conical threaded joints. The use of a highly filled zinc-containing composition with a polymer binder provides uniform coating of the treated surface due to high adhesion and optimal fluidity, the temperature regime ensures the fixation of the applied paste layer on the thread without slipping with the formation of sagging, and at least one make-unscrew cycle provides grouting applied layer on the thread in accordance with the relief of the mating surface. The surface treated in this way provides high wear resistance of the threaded joint of oil assortment pipes, their corrosion resistance and tightness for a long time. All of the above indicators together provide high reliability of the threaded connection and maintainability at the place of operation.

The inventive method is implemented as follows.

An ethyl silicate binder in an amount of up to 10 wt.% Is introduced into the zinc powder of the PCR-1 or PC-6 or PCVD grades. Ethyl silicate binder is used in the following composition, wt.%:

ethyl silicate 11.5-12.7 polyvinyl butyral 5.5-7.7 phosphoric acid (73%) 0.15-0.45 ethanol 72.1-76.5 water rest

Ethyl silicate binder is available on an industrial scale, for example, according to TU 6-10-1468-79. The resulting composition is thoroughly mixed until a homogeneous paste is known under the trade name CEEC or CEEC MO.

The resulting paste is applied to the machined threaded surface with a spatula, brush, roller or pneumatic spray in one layer. The layer thickness is 30-40 microns. Processing is carried out immediately after threading on pipes NKT-73 and / or couplings of category "K" until they cool or the surface of the cold pipes or couplings is heated to a temperature of 45-200 ° C. The applied layer is dried under natural conditions for 1.5-3 minutes. Knurling of the applied layer is carried out by screwing-unscrewing on a clutch loosening machine. The dynamics of wear of the threaded part of pipes and couplings was determined after every 5 cycles of screwing-unscrewing. The total number of screwing-unscrewing in one series of experiments was 30 times. The presence and wear of the threaded part was determined by screwing gauges into the sleeve and onto the threaded part of the NKT-73 pipes. Wear was judged by the interference determined by GOST 633-80 (change in the size of the depth of screwing gauges on the pipe NKT-73 and in the sleeve).

The invention is illustrated by examples of specific performance.

Example 1 (according to the invention)

The nipple parts of the pipes NKT-73 immediately after threading it are treated with a zinc-containing composition containing 91 wt.% Powder of the PCVD brand and ethyl silicate binder according to TU 6-10-1468-79 - the rest. The paste is obtained by mixing the components until a homogeneous paste is formed. The resulting paste is known in industry as an anti-corrosion compound under the trade name CEEC MO. The temperature of the threaded surface at the beginning of processing was 200 ° C. The paste was applied by brush in one layer. The paste was dried for 1.5 minutes. The sealing layer was knurled by screwing and unscrewing the “K” category coupling once by means of the UralNITI model 9959-263 coupling device No. 23 with a force of 1500 N · m. To conduct wear studies, a series of screwing-unscrewing was performed - 30 times. In order to determine the dynamics of wear, measurements of wear indicators were carried out after every 5 make-unscrews. The presence and size of wear was determined by screwing gauges into the sleeve and onto the threaded portion of the tubing. The results of wear tests are given in table 1.

Table 1. Object name The dynamics of the thread interference, mm Strength Closed /
Ampl.open kg Change
preload,% Ref Ref. with covered. St. 5 St. 10 St. 15 St. 20 St. 25 St. 30 St. Trumpet - 3.0 0,0 - 3.1 - 2.4 - 2.4 - 2.4 - 2.0 - 3.1 - 3.2 195/276 0.2 Coupling 4.7 - 4.6 4.6 4.2 4.2 4.2 4.6 4.3 195/276 0.3

Downhole tests to determine the performance and tightness of threaded joints were carried out in the conditions of the Bavlyneft oil and gas production department of the oil and gas industry. The length of the tubing string is 1250 m, the body of the pipe size 73 × 5.5. In the upper part of the column were installed 11 test pipes with couplings, the threaded parts of which were processed by the claimed method. Pressure testing of the 11 upper tubing was carried out with industrial water with a density of 1.0 g / cm ³ at a pressure of 15.0-17.0 MPa (150-170 atm) after every 4 hoisting operations (STR). The torque when making up the pipes was 1400 N · m. The threaded connections of the 10 upper pipes after 12 STR showed 100% tightness. The change in the tightness of the tested pipes was manifested after 30 STR, the tightness of the connection deteriorated by 3%.

Example 2 (according to the invention)

The processing of the threaded joint and testing was carried out as in Example 1. The paste was applied to the pipe thread at a surface temperature of 45 ° C, PCR-1 powder was used as zinc powder, and the drying time was 3 minutes. Tests for wear of threaded joints and their tightness during operation were carried out according to example 1. The results obtained are similar to the results obtained in example 1.

Example 3 (according to the invention)

The processing of the threaded joint and the tests were carried out as in Example 2. The paste was applied to the pipe thread and the coupling thread. Tests for wear of threaded joints and their tightness during operation were carried out according to example 1. The results obtained are similar to the results obtained in example 1.

Example 4 (according to the invention)

The processing of the threaded joint and the tests were carried out as in Example 2. The paste was applied to the thread of the coupling at a surface temperature of 45 ° C, PCVD grade powder was used as zinc powder, and the drying time was 3 minutes. Tests for wear of threaded joints and their tightness during operation were carried out according to example 1. The results obtained are similar to the results obtained in example 1.

The use of a highly filled zinc-containing paste for the inventive treatment of the threaded surfaces of pipes and / or couplings according to examples 1-4 led to an increase in the heating of the pipe-coupling pair during screwing and unscrewing. This indicates an increase in the contact area of rubbing surfaces and, therefore, an increase in the tightness of the thread. In addition, a certain change in the profile of the hollows and ridges of the thread is visually determined, which have a certain roundness, which is due to the filling of leaks in the thread during its plastic deformation. The change in the tightness of the threaded part of the coupling amounted to 0.3%, pipes - 0.2%.

The machining efficiency of tapered threaded joints was also evaluated by increasing the torque against the recommended RD by 36%. Under normal conditions, an excess of force leads either to a breakdown of the thread or to its deformation in the section 13-15 of the turn (the most loaded turns in the conical thread) or to additional wear of the thread. The study of the thread processed by the claimed method, in conditions of high torque did not lead to the above negative consequences.

The results of the tightness test of threaded connections according to examples 1-4 are shown in table 2.

Processing a conical threaded surface at a temperature below 45 ° C does not lead to the claimed result, because a "sliding" effect is manifested and the paste is pulled off the threaded surface when screwing-unscrewing without stretching it.

Processing at temperatures above 200 ° C is dangerous because may cause fire.

Example 5 (control)

Processing of threaded joints and testing was carried out according to example 2. As paste, standard graphite grease R-402 according to TU 301-04-020-92 was used, which was applied to the cold surface of the thread. The results of the wear tests are shown in table 3.

Table 3. Name
The facility The dynamics of the thread interference, mm Change in interference,% Ref. 5 St. 10 St. 15 St. 20 St. 25 St. Trumpet - 0.5 - 1.7 - 1.7 - 2.4 - 2.2 - 2.6 3,5 Coupling 3.3 4.7 3.9 3.8 3.6 4,5 2.0

The use of standard technology for tightening couplings using graphite lubricant at a torque of 1500 N · m after 25 screw-unscrewing leads to a change in the tightness of pipes NKT-73 to 2.1 mm and couplings to 1.2 mm, i.e. the change in the threaded part of pipes and couplings is 3.5% and 2.0%, respectively. On-site well tests of the performance and tightness of joints using standard graphite lubricant show the need for diagnostics and repair of pipes NKT-73 after 6-8 SPO.

Example 6 (control)

The processing of threaded joints and testing was carried out according to example 2. As a paste, Vympel grease with a zinc powder content of 30% was used, which was applied to the cold surface of the thread. The results of the wear tests are shown in table 4.

Table 4. Name
facility The dynamics of the thread interference, mm Change in interference,% Ref. 5 St. 10 St. 15 St. 20 St. 25 St. 30 St. Trumpet -2.4 -2.2 -2.2 -2.2 -4.0 -4.1 5,0 4.3 Coupling 6.1 4.8 4.4 4.3 4.2 4.0 4.1 3.3

As can be seen from the above data, the use of the proposed method allows to provide wear resistance of conical threaded joints, because after 30 screw-ups and unscrews, the change in tightness was 0.2-0.3%, and an increase in the make-up force by 36% (against the commonly applied torque) does not lead to thread breakage or deformation or other undesirable consequences. A comparative analysis of the wear resistance of a threaded joint treated by the inventive method with the wear resistance of a threaded joint treated with a standard lubricant allows us to conclude that the wear resistance of a threaded joint treated by the claimed method is 10-15 times higher.

Using the proposed method allows to increase by 2-2.5 times the working life of pipes in the well due to the high tightness of the threaded connection. The reliability of the claimed processing also provides the necessary hydraulic density of the pipe-coupling pair. In addition, the threaded connection processed by the claimed method is resistant to aggressive environments, is not subject to corrosion and is not washed out under the influence of petroleum products. The anticorrosive properties of the compound are provided by the well-known properties of highly filled zinc-containing compositions due to the known protective mechanisms of protection.

Thus, the conical threaded connections of the oil range processed by the claimed method, ensure the reliability of the pipe connection when working in aggressive environments due to the simultaneous increase in tightness, wear resistance and contribute to the preservation of these indicators at high forces and pressures.

Claims (4)

1. The method of processing conical threaded pipe joints, including the mechanical application of a paste based on soft metal on a pre-cut threaded surface of the articulated surfaces of the pipe and / or sleeve, characterized in that the paste is used highly filled zinc-containing composition, the paste is applied to preheated to a temperature of 45 -200 ° C threaded surface over its entire area with subsequent rolling of the paste on the articulated surfaces through at least one make-up cycle I-unscrewing the pipe with the coupling. 2. The method according to claim 1, characterized in that as a highly filled zinc-containing composition, a composition is used with a zinc content of at least 90 wt.% In a polymer binder medium. 3. The method according to claim 2, characterized in that an ethyl silicate binder is used as the polymer binder. 4. The method according to claim 1, characterized in that the mechanical application of the paste is carried out by brush, or roller, or spatula, or spray gun.