Method of assessment a rubber o-ring pipe connection

 

The invention relates to methods for the study of strength properties of materials o-rings pipe connections, for example, type “Socket” and can be used to determine the timing of replacement of sealing pipe joints. In the method of estimating the state of a rubber o-ring pipe connection at the first stage, the preparation of samples of a given geometric shape for measuring tensile strength, and elongation at break, hardness shore a, temperature limit of fragility. Then measure the physical and mechanical properties of the samples, compare them with the target values, the results of the error which is judged on the technical condition of the sealing rings, and excluded samples with indices do not match. Carry out the second stage, in which is placed the remaining samples in the oil and maintain them for at least 120 hours at a temperature of (702)°C. to Extract samples from oil thermostatic not less than 72 hours at a temperature of (702)°C, cooled to room temperature, determine the physical and mechanical properties. When the deviation while the s were prepared samples, for valid values accept the conditional tensile strength - frdof 9.4 MPa, elongation at breakrd111%, shore hardness A - 92,4Hd, a unit shore a,62,1, temperature limit fragility - thrdminus 24C. How accurately and comprehensively to determine the technical condition and performance properties of rubber o rings. 4 Il., table 4.

The invention relates to methods for the study of strength properties of materials o-rings pipe connection (for example, type “Socket”) and can be used to determine the timing of replacement seals joints pipe joints during operation collapsible pipelines (NRC), as well as manufacturing plants in the acceptance tests of the rings.

In recent years more and more urgent becomes the problem of the transport of oil and oil products in remote regions of the Far North, Siberia and the Far East. Use the cost of transportation ~ 5-7 $/t ($ - dollar USA)), increases the cost of oil, and in some cases makes its extraction unprofitable. The construction of the stationary pipeline systems during the pilot field development, usually associated with economic risk, with significant investment and it is not always technically and economically feasible.

As experience shows, widely used for solving the above-mentioned objectives, the NRC sets, providing the possibility of building highways with a length of 150 km, sealed in the range of excess pressures up to 8.0 MPa and at a vacuum of 500 mm of water. century, with flow up to 3000 t/day, the cost of transportation ~2 $/t, a payback period of capital investment 1 year.

The NRC sets include pipe connection Socket”, valves, mobile money transfer and accessories.

One of the problems in the field of efficient use of NRC to improve the technical level (functionality, reliability, efficiency, improvement of the system test and evaluation); reducing losses of petroleum products (reduction of accidental loss of oil products in different operating conditions, maintaining the quality of petroleum products); Popusoi), standing at the present time, is, in particular, the determination of technical condition of rubber o-rings, ensuring the integrity of the pipeline as a whole, as the most significant element pipe connection (type “Socket”). In one set of NRC (length 150 km) is operated at the same time ~ 30000 rings (the cost of the ring mark R 150 - 3-5 $/piece).

Rubber o-rings from the date of manufacture multiple times through different stages of the life cycle: storage, transportation, installation of the ring in the socket, the mounting of the NRC, crimping NRC, filling and pressure testing the NRC, pumping of oil by the NRC, emptying the NRC, the dismantling of the NRC, the dismantling of the rings of the bell, feeling a large complex mechanical deformation (bending, shear, compression, tension, raster, impact, abrasion, torsion) and physico-chemical effects of the pumped product and the external environment (swelling, leaching, solar radiation, temperature, ozone, oxygen, precipitation and so on).

Given the multiple cycles of impacts, the unevenness of their distribution, currently used planned maintenance system replacement rings NRC (average lifespan of 3 years "Leadership is peivate reliability and ecological safety of the NRC, and to assess the impact of petroleum products on the operational properties of the rings, performance, and suitability for further use in the connection, the “Bell” of the NRC during operation.

There is a method of assessment of technical condition of the sealing rings (TU 38 1051962-90 “Ring rubber o-field pipelines”), including the preparation of samples of a given geometric shape, definition of conditional tensile strength, and elongation at break, hardness shore a, temperature limit of the fragility of the samples prior to exposure to the oil and comparing that performance with a given value. Rejecting at least one of the indices from a given value of the ring are considered to be unhealthy.

The disadvantage of this method is that all the physico-mechanical parameters are determined before contact with petroleum products that adequately characterizes the state of the rings only at the stage of acceptance testing (production), while the rubber sealing rings are products of multiple use and definition of these indicators before contact with petroleum products does not take into account the main types of impacts on the properties of resia and to determine the remaining lifetime in the operation.

The closest technical solution, taken as a prototype, is a method of assessment of technical condition of rubber products according to GOST 7338-90 Plate rubber and rubber. Technical conditions”, Moscow, Publishing house of standards, C. 7-11, 15-16, 19-20, which are preparing samples of a given geometric shape for measuring conditional tensile strength, and elongation at break, shore hardness, temperature limit fragility, then measure the physical and mechanical properties of the samples, compare them with the target values, the results of the error which is judged on the technical condition of the sealing rings, and excluded samples with indices do not match.

The disadvantage of the prototype is the definition of above to contact with oil, which does not allow to evaluate the technical condition of the seals and to determine their residual life during operation of the NRC.

The imperfection of methods of definition of indicators to assess the technical condition of the rubber sealing rings is the cause of reduced reliability and efficiency of the NRC.

The basis of the invention is Sonkovo status and performance properties of rubber sealing rings.

The technical result of the invention is to improve the reliability of the NRC, the validity of the results of the evaluation of the technical condition during the operation of rubber o-rings in the pipe connection with a simultaneous increase of ecological safety by reducing the risk of accidentally spilled petroleum products.

The technical result is achieved due to the fact that in the method of estimating the state of a rubber o-ring pipe connection, in which first stage, the preparation of samples of a given geometric shape for measuring conditional tensile strength, and elongation at break, hardness shore a, temperature limit fragility, then measure the physical and mechanical properties of the samples, compare them with the target values, the results of the error which is judged on the technical condition of the sealing rings, and excluded samples with indices do not match, wherein implementing the second stage, at which place the remaining samples in the oil and maintain them for at least 120 hours at a temperature of (70±2)°C, to extract samples from oil thermostatic not less chili and rejecting at least one of the indices of the maximum values are considered unhealthy, o-rings, of which were prepared samples, valid values accept the conditional tensile strength - frdof 9.4 MPa, elongation at breakrd111%, shore hardness A - 92,4Hd, a unit shore a,62,1), temperature limit fragility - thrdminus 24C.

In Fig.1 shows a pipe connection type “Socket”;

in Fig.2 - the sample in the form of bilateral blades (to determine the conditional tensile strength (fpand relative elongation at break (p));

in Fig.3 is a map of the placement of prefabricated pipeline Talakan-Vitim on the ground;

in Fig.4 is a diagram of the sampling sites the rubber sealing rings collapsible pipeline Talakan-Vitim (length of 111 km) to determine their technical condition.

Each segment is 37 km and contains ~ 4000 connections “Bell”. The sample is selected randomly from any connection site-specific, i.e. each ring has one shall be in the technique. Methods of estimating reliability parameters from experimental data. Ed. standards, 1990) with probability q=0.95 number of test objects, the number of samples of the rings should be at least 7 pieces from the site. When rejection of at least one sample of a particular sealing rings are wrong all the sealing rings of this section.

Connection type “Socket” consists of a tube 1, the end of which is curly and over which is placed the socket 2. The socket 2 has grooves and indentations, which posted microporous strip 3 and the sealing ring 4. Microporous strip 3 pojeta locking metal ring 5.

The samples represent a two-sided blade with a total length L, the width of the wide part, the length of the work area 1 and the width of the narrow part b.

Each of the identified parameters characterizes the physical condition of the sealing rings 4.

Thus, the relative strength of the fptensile characterized by extreme resistance to mechanical destruction.

Elongationpat break allows, directly or indirectly, to evaluate highly elastic and elastic properties of rubber when exposed to strain tensile, compression load, the combination of the elastic properties and the modulus of elasticity.

Temperature limit fragility thr indirectly characterizes the resistance of rubbers, operation rings NRC in different climatic zones.

The authors experimentally obtained valid (frd,rdNd, Thrd) the numerical values of physical and mechanical properties after exposure to oil and its subsequent evaporation. Determined that the strength, deformation and low-temperature properties of rubber are significantly changed after exposure to petroleum products and depend on the sort of product, time and temperature of contact. Thus, when the temperature of contact with oil (70±2)°With the change of physico-mechanical characteristics of rubber occurs during the first 3-5 days (72-120 h), with further contact changing parameters practically do not occur. When the temperature of contact with petroleum products (20±2)°C observed similar patterns and decrease the same as if 70C. However, the period of decline is slower during the first 5-15 days (120-360 h) contact (table 1). Thus, studies have shown that the time of contact the Oia (not less than 72 hours) at a temperature of (70±2)°C molasses that when conducting research it was found that the evaporation of the oil from the sample when the temperature (and hence the change of parameters) occurs mainly during the first 72 h (table 2). At the same temperature 70With no structural changes in the rubber ring. At a temperature of 50With the evaporation of petroleum products is much slower, which increases the test time. At temperatures above 70Simultaneously with the evaporation of the oil is aging rubber samples.

Studies have shown rings that were in operation, the range of operating state is within the valid values equal to: frd, MPa,9,4;rd, %,111; 92,4Hd, a unit shore a,62,1; thrd,With,minus 24.

Thus, the method of assessment of technical condition of the rubber o-ring pipe connection (type “Socket”) is that the rejection of the sealing rings selected to the ring, presented at test, for measuring conditional tensile strength, and elongation at break, hardness shore a, temperature limit fragility, the measurement of these physical-mechanical indicators, comparing them with predetermined in THE values and the rejection of samples, the performance of which does not meet specified (on THE 38 1051962-90).

In the second stage, the remaining sample is placed in the oil and incubated for at least 120 hours at a temperature of (70±2)°C, after extraction of the oil samples thermostatic not less than 72 hours at a temperature of (70±2)°C, then cooled to room temperature, and then determine the same physical and mechanical properties, and if the deviation of at least one of the indicators of the allowed values (these values are obtained experimentally) rings, of which the prepared samples is considered unhealthy.

The method is implemented as follows.

To determine the technical condition of rings of 7 units selected from each plot directly from compounds of the pipeline in accordance with the scheme of placement of sampling sites shown in Fig.4.

Samples for the determination of physical-mechanical indicators are manufactured with standards in the method of determining the index (cutting blanks of the desired thickness is produced from rings, and cutting samples from them is shancevym knife, the shape and size of which is determined by the configuration of the sample and measured by indicator):

conditional tensile strength and elongation at break according to GOST 270-75 “rubber. The method of determining uprugoopticheskii tensile property” is determined on samples in the form of bilateral shoulder blades, the form of which is shown in Fig.2, a total length L=115 mm, width of widest part=(25±1,0) mm, length of the work area 1=(25±0,5) mm and a width of narrowest part b=(6,00,4) mm the Essence of the method consists in stretching the sample at a constant speed until the gap and measuring the strength and elongation of the sample at the moment of rupture;

hardness shore a according to GOST 263-75 “rubber. Method for determination of hardness shore” is defined on the plate with parallel planes. The essence of the method consists in measuring the resistance of the sample to dive into it indenter;

temperature limit fragility according to GOST 7912-74 “rubber. Method of determining the temperature limit of fragility” is determined on samples in the form of strips with a width (6,0±0,5) mm and a length of 25 mm, the Essence of the method consists in determining the highest temperature at which a cantilever and klelw physico-mechanical properties of the samples and comparing them with predetermined (by THE 38 1051962-90), rejected defective samples, physical and mechanical properties which do not match, and, accordingly, the ring, from which the prepared samples. The remaining samples, suitable for show, put in oil heated to a temperature of (70±2)°C and at this temperature was kept for 120 hours

After extraction of the oil samples thermostatic 72 hours at a temperature of (70±2)°C, after temperature control them cool to room temperature, then determine the values of the same physico-mechanical characteristics of known methods and compared with the allowable values obtained experimentally: frd, MPa,9,4;rd, %,111; 92,4Hd, a unit shore a,62,1; thrd,With,minus 24.

The proposed method of assessment of technical condition has been tested in 1996-2002 year, during the operation of the NRC Talakan-Vitim in the Republic of Sakha (Yakutia) state Conservatory “Sakhaneftegas”. Annually selected batch of o-rings, preparing samples and investigated the technical condition of the rings (the results ispy is ebouaney, given THAT (table 3).

In the second phase of testing, the samples were kept in oil, thermostatically and cooled to room temperature, and then was determined by the same physical and mechanical properties, as in the first stage (the results are presented in table 4). Samples No. 3 and 5 do not meet the allowable values, obtained experimentally, therefore, ring, selected from section 1 shall be deemed inoperative and must be replaced.

Using the claimed method, the authors were able to precisely determine the technical condition of the sealing rings, which ensured reliable operation NRC Talakan-Vitim for 6 years. For the entire period of operation, the NRC had no accidents and malfunctions associated with the spill and pollution.

Thus, the method of assessment a rubber o-ring pipe connection (type “Socket”) was adequate to assess the health and remaining life of the NRC, during operation to increase its reliability, environmental safety, and efficiency.

The invention can be used to determine the technical condition for newly manufactured rings (new), and former or finding opustenie (acceptance) values of physico-mechanical characteristics (frd,rdNd, Thrd).

Sources of information

1. Manual of field pipelines. - M.: Voenizdat, 1968, S. 322.

2. THE 38 1051962-90. Ring rubber o-field pipelines. DF, VNIMI, 1990, S. 2-3.

3. GOST 7338-90. Plate rubber and rubber. Technical conditions. - M.: Publishing House.standards, 1990, S. 7-11, 15-16, 19-20 (prototype).

4. RD 50-690-89. Methodical instructions. Reliability in engineering. Methods of estimating reliability parameters from experimental data. - M.: Publishing House. standards, 1990, S. 15-16.

5. GOST 269-66. The rubber. General requirements for physical and mechanical tests. - M.: Publishing House.standards, 1983, S. 1-2.

6. GOST 270-75. The rubber. The method of determining uprugoopticheskii tensile property. - M.: Publishing House.standards, 1980, S. 1-2.

7. GOST 263-75. The rubber. Method for the determination of shore hardness. - M.: Publishing House. standards, 1975, S. 1-2.

8. GOST 7912-74. The rubber. Method of determining the temperature limit of fragility. - M.: Publishing House. standards, 1974, S. 1.

Claims

Method of assessment the rubber platitudinously forms for measuring tensile strength, relative elongation at break, hardness shore a, temperature limit fragility, then measure the physical and mechanical properties of the samples, compare them with the target values, the results of the error which is judged on the technical condition of the sealing rings, and excluded samples with indices do not match, wherein implementing the second stage, in which is placed the remaining samples in the oil and maintain them for at least 120 hours at a temperature of (70±2)With, to extract samples from oil thermostatic not less than 72 hours at a temperature of (70±2)C, cooled to room temperature, determine the physical and mechanical properties and rejecting at least one of the indices of the maximum values are considered unhealthy, o-rings, of which there were prepared samples, valid values accept the conditional tensile strength frdof 9.4 MPa, elongation at breakrd111%, shore a hardness And 92,4Hd< minus 24C.

 

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FIELD: automatical aids for sampling liquids.

SUBSTANCE: system for sampling and delivering filtrate has filter submerged into tested medium and connected with collecting tank and vacuum pressure source which is connected with top hole of collecting tank by means of pneumatic pipe. System has sample receiving tank connected with collecting tank and control unit which has first output to be connected with vacuum pressure source. Collecting tank has two separated chambers - washing chamber and dispatching chamber. Lower hole of washing chamber has to be lower hole of collecting tank and side hole of dispatching chamber has to be side hole of collecting tank. Floating valve is installed inside washing chamber to shut off lower and top holes. Filter is connected with lower hole of collecting tank through sampling pipe. Side hole of collecting tank is connected with lower hole of tank for receiving samples through sampling pipe. Flow-type sensor and check valve are installed inside transportation pipe. Output of flow-type sensor is connected with input of control unit; second output of control unit is connected with control input of analyzer.

EFFECT: improved precision of measurement of sample ion composition; prolonged service life of filter.

1 cl, 1 dwg

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