CN113294603A

CN113294603A - Double-clamping sleeve pipeline joint and preparation method thereof

Info

Publication number: CN113294603A
Application number: CN202110573210.XA
Authority: CN
Inventors: 罗文军; 励行跟; 孙夫君; 励洁; 魏世军; 李征; 沈锴; 陈腾翔; 励勇
Original assignee: NINGBO TIANSHENG SEALING PACKING CO Ltd
Current assignee: CGN Engineering Co., Ltd; NINGBO TIANSHENG SEALING PACKING Co.,Ltd.
Priority date: 2021-05-25
Filing date: 2021-05-25
Publication date: 2021-08-24

Abstract

The invention discloses a double-clamping sleeve pipeline connector and a preparation method thereof. The preparation method comprises the following steps: the manufacturing of connector, the manufacturing of nut, the manufacturing of preceding cutting ferrule, the manufacturing of back cutting ferrule. The invention provides a specific structure of a nuclear-grade application double-clamping casing pipeline joint and a preparation method thereof, and reduces the use cost of the double-clamping casing pipeline joint.

Description

Double-clamping sleeve pipeline joint and preparation method thereof

Technical Field

The invention relates to the field of pipeline sealing, in particular to a double-clamping sleeve pipeline joint.

Background

The double-bayonet joint is an essential seal for the core instrumentation tubes as they penetrate the reactor pressure vessel head. The cutting ferrule joint belongs to a loop pressure boundary part, is in contact with a loop coolant, can be used for 60 years and ensures reliable sealing under high temperature, high pressure and high radiation. At present, the cutting ferrule connectors used at the pressure boundary of a primary loop of a domestic reactor comprise 30 thousands of Qinshan, CAP1000 and Hualongyi, products of American Vivialok company (Swagelok) are adopted, no substitute products exist at home, and the technology and purchase are limited considerably. Therefore, the development of the ferrule for sealing the core instrument penetration piece has great urgency and necessity.

Disclosure of Invention

The invention aims to provide a double-clamping-sleeve pipeline joint and a preparation method thereof aiming at the defects in the prior art.

In order to achieve the purpose, the invention adopts the following scheme:

a double-clamping sleeve pipeline joint comprises a screw cap, a front clamping sleeve, a rear clamping sleeve and a connecting body, wherein the screw cap is in threaded connection with the connecting body, and the rear clamping sleeve and the front clamping sleeve are arranged in a cavity formed by the screw cap and the connecting body; the front cutting sleeve is in a circular truncated cone shape and comprises a small end and a large end, the included angle A between the outer wall of the front cutting sleeve and the axis is 15-25 degrees, and the included angle B between the inner wall of the large end and the axis is 40-60 degrees; the section of the rear cutting ferrule is similar to a high-heeled shoe, the outer wall of the rear cutting ferrule comprises a front section, a middle section and a rear section, the end face of the front section is perpendicular to the axis, the end face of the rear section inclines forwards, and the included angle C between the end face of the rear section and the axis is 60-90 degrees, the included angle D between the front section of the outer wall and the axis is 30-40 degrees, the rear section of the outer wall is parallel to the axis, the middle section of the outer wall comprises three sections of outer walls sunken towards the axis, the included angle E between the first outer wall and the radial direction is 40-50 degrees, the included angle F between the second outer wall and the axis is 10-15 degrees, and the included angle G between the third outer wall and the radial direction is 35-45 degrees; the middle rear part of the inner wall of the rear ferrule inclines outwards, and the included angle H between the inclined plane and the axis is 6-10 degrees; the outer diameter of the connector is provided with an external thread matched with the internal thread of the screw cap, the inner wall of the connector matched with the front ferrule in the connector is an inner conical surface which inclines outwards, and the included angle I between the connector and the axis is 15-25 degrees.

Furthermore, the connector can be divided into a straight-through type, a bent-through type, a three-way type and a pipe cap according to the shape of the connector.

Further, the included angle a is 18 °.

Further, the angle B is 45 °.

Further, the angle C is 80 °.

Further, the included angle D is 37.5 °.

Further, the angle E is 45 °.

Further, the angle F is 11 °.

Further, the angle G is 38 °.

Further, the angle H is 8 °.

Further, the included angle I is 20.5 °.

Further, the inner diameters of the front clamping sleeve, the rear clamping sleeve and the connector are 2mm-50mm, and are preferably 12.7 mm; the outer diameter of the small end of the front cutting sleeve is 10mm-15mm, preferably 13.5mm, the inner diameter of the end face of the large end is 11.5mm-17mm, preferably 14.9mm, the outer diameter is 15mm-20mm, preferably 17.3mm, and the axial length of the front cutting sleeve is 5mm-10mm, preferably 7.3 mm; the outer diameter of the end face of the front section of the rear cutting sleeve is 11mm-14mm, preferably 13.3mm, the maximum outer diameter of the front section of the outer wall is 12mm-16mm, preferably 14.6mm, the outer diameter of the rear section of the outer wall is 14mm-17mm, preferably 15.6mm, and the axial length of the rear cutting sleeve is 2.5mm-5.5mm, preferably 3.8 mm; the inner diameter of the end face of the interface matched with the front ferrule in the connector is 12mm-18mm, preferably 15.6mm, the outer diameter is 15mm-19mm, preferably 17.4mm, and the inner diameter matched with the rear ferrule in the screw cap is 15mm-18mm, preferably 16 mm.

Furthermore, the tolerance of the inner diameters of the front clamping sleeve, the rear clamping sleeve, the connecting body and the nut is 0.095 mm-0.138 mm; the dimensional tolerances of the small end outer diameter, the large end face inner diameter, the large end face outer diameter and the axial length of the front cutting sleeve are all-0.05 mm, the dimensional tolerances of the front section end face outer diameter and the outer wall rear section outer diameter of the rear cutting sleeve are all-0.07 mm-0 mm, the dimensional tolerance of the maximum outer diameter of the front section of the outer wall is-0.1 mm-0 mm, and the dimensional tolerance of the axial length of the rear cutting sleeve is-0.05 mm; the tolerance of the inner diameter of the end face of the interface matched with the front cutting sleeve in the connector is 0 mm-0.07 mm, and the tolerance of the outer diameter is-0.1 mm-0 mm; the tolerance of the inner diameter of the screw cap matched with the rear cutting sleeve is-0.05 mm.

Further, the inner diameter of the nut comprises four parts, the first part is matched with the pipeline, the second part is matched with the rear clamping sleeve, the third part is matched with the front clamping sleeve, and the fourth part is matched with the connector.

Furthermore, in the inner diameter of the screw cap, the end surface of the second part and the rear end surface of the rear clamping sleeve have the same inclination angle.

Furthermore, the material of the screw cap, the front cutting ferrule, the rear cutting ferrule and the connecting body is 316 stainless steel or 316L stainless steel, and the strain hardening is 2-grade.

Furthermore, the surface of the internal thread of the screw cap is plated with silver, and the thickness of the silver plating layer is 0.05 mm-0.1 mm.

Further, the outer wall of the front cutting ferrule is carburized, the thickness of a carburized layer is 0.2mm-0.4mm, and the surface hardness is HV820-HV 840.

Further, the outer wall of the rear cutting ferrule is subjected to carburizing and nitriding treatment, the thickness of a carburized layer is 0.1mm-0.3mm, and the surface hardness is HV820-HV 840.

The application also provides a preparation method of the double-clamping sleeve pipeline joint, which comprises the following steps: manufacturing a connector, a screw cap, a front cutting sleeve and a rear cutting sleeve; in the manufacturing step of the front cutting ferrule, the machined front cutting ferrule is subjected to surface carburization, the thickness of a carburized layer is 0.2mm-0.4mm, the surface hardness is HV820-HV840, and in the manufacturing step of the rear cutting ferrule, the machined rear cutting ferrule is subjected to surface carburization and nitriding treatment, the thickness of a carburized layer is 0.1mm-0.3mm, and the surface hardness is HV820-HV 840.

Further, the manufacturing of the connector includes: blanking, turning an outer circle, drilling holes, turning the outer circle, milling a hexagon, finely turning threads and an inner cone, and inspecting.

Further, the manufacturing of the screw cap comprises: blanking, turning end surfaces and threads, milling an outer hexagon, finely turning an outer circle, plating silver on the surface of an inner thread, and inspecting, wherein the thickness of the silver plating layer is 0.05-0.1 mm.

Further, the manufacturing of the front ferrule includes: turning the outer circle and the end face, boring, chamfering, cutting, turning the end face, carburizing and inspecting.

Further, the manufacturing of the rear ferrule includes: turning the outer circle and the end face, boring, chamfering, cutting off, turning the inclined end face, nitriding, carburizing, oil quenching, tempering and inspecting.

Further, the specific processes of nitriding, carburizing, oil quenching and tempering of the rear ferrule comprise: heating to 650 deg.C in vacuum furnace, maintaining the temperature for 15-25min, heating to 950 deg.C, maintaining the temperature for 15-25min, introducing NH₃And N₂The flow rate is 8-15L/min, nitriding treatment is carried out for 20-40min, and the changing atmosphere is C introduction₂H₂+N₂Carburizing for 15-30min at flow rate of 8-15L/min, and introducing NH₃And N₂Nitriding at the flow rate of 8-15L/min for 15-30min under carburizing and nitriding pressure of 2000 Pa; then carrying out oil quenching, wherein in the oil quenching process, the rear sleeve is sleeved with oil and then stirred, the maximum stirring frequency is 50Hz, and the oil temperature is 60 ℃; the tempering process comprises the following steps: heating to 160 deg.C, maintaining the temperature for 120min, and air cooling to room temperature.

The double-clamping sleeve pipeline joint is mainly applied to nuclear safety related pressure boundary occasions of a nuclear power plant, in particular to occasions of small-caliber pressure pipeline connection, reactor core instrument penetrating piece sealing connection and the like.

Compared with the prior art, the invention has the advantages that: breaks through the monopoly of foreign technologies and realizes the localization of the ferrule pipe joint applied in nuclear grade. The beneficial effects brought by the method are as follows:

1. for the ferrule tube joint applied to nuclear grade, no domestic product can meet the requirement of nuclear grade application, and the application determines the specific size range and the specific manufacturing process of the double-ferrule tube joint on the basis of foreign products through continuous efforts.

2. On the basis that the material and the structure of the product meet the conditions, the heat treatment process parameters of the ferrule are continuously explored, the process parameters are continuously tried to be determined, so that the domestic product can have the same performance as the foreign product, a breakthrough result is obtained on the basis, a process parameter combination superior to the performance of the foreign product is unexpectedly obtained, and a solid foundation is laid for the localization of the ferrule pipe joint for nuclear-grade application.

Drawings

FIG. 1 is a schematic view of a joint assembly structure of a double-clamping sleeve pipeline

FIG. 2 is a schematic view of a front ferrule

FIG. 3 is a schematic view of a rear ferrule

FIG. 4 is a schematic view of a structure of a connecting body

FIG. 5 is a schematic view of a nut structure

FIG. 6 is a schematic view of a structure in which the connecting body is a through-hole

FIG. 7 is a schematic view of a structure in which the connecting body is a curved through

FIG. 8 is a schematic view of a tee joint

FIG. 9 is a schematic view of a structure in which the connecting body is a cap

FIG. 10 is a schematic representation of a linker

FIG. 11 is a drawing of a nut

Figure 12 is a drawing of a front ferrule

Figure 13 is a real object drawing of the rear ferrule

FIG. 14 shows the situation of the outer wall of the test sample tube being squeezed into the groove by the rear ferrule after the hydraulic test of foreign products

FIG. 15 shows the situation of the rear ferrule extruding into the outer wall of the test sample tube after the hydrostatic test in example 1

Reference numerals: 1. the nut, 2, the connector, 3, the preceding cutting ferrule, 4, the back cutting ferrule, 5, the pipeline, 6, the preceding cutting ferrule outer wall, 7, the main aspects inner wall, 8, the preceding cutting ferrule inner wall, 9, the main aspects terminal surface, 10, the tip terminal surface, 11, the anterior segment terminal surface, 12, the outer wall anterior segment, 13, the first section outer wall, 14, the second section outer wall, 15, the third section outer wall, 16, the outer wall back end, 17, the back end terminal surface, 18, the inner wall that is close to the back end terminal surface, 19, the inclined plane, 20, the back cutting ferrule inner wall front portion, 21, the interior conical surface, 22, the first portion, 23, the second part. 23. And a third section.

Detailed Description

According to the standard of nuclear grade ferrule connectors:

ASTM F1387-1999(R2012)Standard Specification for Performance of Piping and Tubing Mechanically Attached Fittings

RCC-E(2005)Design and Construction Rules for Electrical Equipment for Nuclear Islands(2005Edition)

RCC-M(2007)Design and Construction Rules for Mechanical Components of PWR Nuclear Islands(2007Edition)

the double-clamping casing pipeline joint meets the following test requirements:

1) air pressure test

Test medium: nitrogen or dry air, water (for immersion leak detection); test temperature: 25 +/-10 ℃; test pressure: 0.69MPa +/-0.04 MPa and 3.45MPa +/-0.17 MPa.

The test requirements are as follows: when the first-stage pressure is increased to 0.69MPa +/-0.04 MPa, the pressure is maintained for 5min (bubbles on the surface of the sample are allowed to fall off in 1 min), and no bubbles are obtained in the rest 4 min; if the pressure meets the requirement, the pressure is gradually increased to 3.45MPa +/-0.17 MPa, and the pressure is maintained for 5min without bubbles.

2) Hydrostatic test

Test medium: water; test temperature: 25 +/-10 ℃; test pressure: 0.69MPa +/-0.04 MPa and 38.79MPa +/-1.29 MPa.

The test requirements are as follows: pressurizing to 0.69MPa +/-0.04 MPa at the first stage, and maintaining the pressure for 5min, wherein no leakage is required; the second-stage pressure is gradually increased to 38.79MPa +/-1.29 MPa at an average increasing rate not exceeding 172MPa/min, and the pressure is maintained for 5min without leakage.

3) Pulse test

Test medium: water; test temperature: 25 +/-10 ℃; test pressure: 34.39MPa +/-1.29 MPa and 5.17MPa +/-1.29 MPa.

The test requirements are as follows: before the test is started, during the test and after the test is finished, at least 50% of the detachable test pieces are used for repeated assembly test.

Pressurizing the test piece to 34.39MPa +/-1.29 MP, then reducing the pressure to 5.17 +/-1.29 MPa to be a pulse cycle, completing 106 cycle tests at the speed of not more than 75 cycles per minute, carrying out repeated assembly tests alternately when the pulse tests are carried out, and carrying out hydrostatic tests after the pulse tests. No leakage exists in the whole test process.

4) Bending fatigue test

Test medium: water; test temperature: 25 +/-10 ℃; test frequency: 3 Hz; rated pressure: 25.86 MPa; and (3) test period: 30000 Total cycles.

The test requirements are as follows: the reassembly test should be performed using at least 50% of the removable coupons. In the bending fatigue test, the maximum positive strain and the maximum negative strain should not exceed 2 percent, repeated assembly tests should be conducted alternately during the test, and a hydraulic test is conducted after the test. No leakage exists in the whole test process.

5) Tensile test

Test temperature: room temperature; stretching speed: 1.3 mm/min.

Minimum allowable tensile load: not less than (Kt) x (Ap) x (Sy), (Kt 1, Ap instrument tube actual cross-sectional area, Sy minimum specified instrument tube yield strength)

6) Hydraulic bursting test

Test temperature: 25 +/-10 ℃; test pressure: 103.44 MPa.

The test requirements are as follows: pressurizing to 103.44MPa at a pressurizing rate of no more than 127MPa/min, and maintaining for at least 1min without bursting or leakage.

7) Repeated assembly test

Test temperature: and (4) room temperature.

The test requirements are as follows: the test pieces were selected from the test pieces that passed the pulse test and the bending fatigue test, and the same amount of test pieces were selected from the test pieces that passed the above two tests. And simultaneously, ensuring that at least 50 percent of test pieces subjected to the two tests are subjected to repeated assembly tests.

Before testing, mounting, dismounting and reassembling were carried out 1 time, with the sealing surfaces being rotated manually by 60 to 90 ° before each assembly. At 25%, 50%, 75%, 100% of the pulse test and bending fatigue test cycles, the test was interrupted and disassembled and assembled 2 times again, respectively. And (4) the test piece has no leakage after the pulse test and the bending fatigue test are finished, and the test piece passes the test.

8) Rotational bending test

Test temperature: room temperature; test pressure: 3.45 MPa; bending moment: rm is more than or equal to multiplied by 35 percent (Rm pipe material tensile strength, MPa).

The test requirements are as follows: before the test, a gas pressure test and a water pressure test are carried out. And pressurizing the test piece by a static pressure of 3.45MPa after the bending moment is loaded according to requirements, and rotating the test piece at a speed of not less than 1750 revolutions per minute for at least 106 cycles. There should be no leakage during the test. And after the rotary bending test is finished, the hydraulic test is carried out, and no leakage exists.

9) Vibration test

Test temperature: room temperature; test pressure: 25.86 MPa; vibration conditions are as follows: MIL-STD-167 (type I: Environment).

The test requirements are as follows: before the test, a pneumatic test and a hydraulic test should be carried out. The vibration test was conducted in three fundamental directions (X, Y and Z), respectively, and after completion of the test in one direction, the test in the other direction was conducted, and after completion of the test, the hydrostatic test was conducted without leakage.

10) Thermal cycle test

Design temperature: 360 ℃; cold state temperature: room temperature; rated pressure: 25.86 MPa; and (3) heat preservation time: 120 min; cycle number: 3 times; test medium: high temperature oil.

And (4) acceptance requirements: no visible leakage should occur at the sample seal during the entire test.

Example 1

In order to meet the test requirements and enable the domestic double-clamping sleeve joint to meet the nuclear-grade use requirements, the applicant determines the specific size range of the double-clamping sleeve pipeline joint on the basis of foreign product patent disclosures by continuously exploring, thereby providing the double-clamping sleeve pipeline joint:

as shown in fig. 1, a double-ferrule pipeline connector comprises a nut 1, a front ferrule 3, a rear ferrule 4 and a connector 2, wherein the nut 1 is in threaded connection with the connector 2, and the rear ferrule 4 and the front ferrule 3 are arranged in a cavity formed by the nut 1 and the connector 2; the pipeline 5 is connected by a double-clamping sleeve pipeline joint. The sealing principle is as follows: the front ferrule 3 is pushed into the connector 2 and the body 5 to form the main seal, while the rear ferrule 4 is hinged inwardly to form a strong grip on the body 5. The geometry of the rear ferrule 4 helps to create an advanced engineering hinge-ferrule action that translates axial movement into radial squeezing action on the tube body, requiring only a small assembly torque in operation. The inner diameters of the front cutting ferrule 3, the rear cutting ferrule 4 and the connecting body 2 are 12.7 mm.

As shown in fig. 2, the front cutting ferrule 3 is in a circular truncated cone shape and comprises a small end and a large end, an included angle a between the outer wall 6 of the front cutting ferrule and the axis is 18 degrees, an included angle B between the inner wall 7 of the large end and the axis is 45 degrees, the inner wall 8 of the front cutting ferrule is parallel to the axis, the end face 9 of the large end is perpendicular to the axis, and the end face 10 of the small end is perpendicular to the axis; as shown in the physical representation of the front ferrule in fig. 12.

As shown in fig. 3, the section of the rear ferrule 4 is similar to a high-heeled shoe, the outer wall of the rear ferrule comprises a front section, a middle section and a rear section, the end surface 11 of the front section is perpendicular to the axis, the end surface 17 of the rear section is inclined forwards and forms an angle of 80 degrees with the axis, the angle D between the front section 12 of the outer wall and the axis is 37.5 degrees, the rear section 16 of the outer wall is parallel to the axis, the middle section of the outer wall comprises three sections of outer walls which are sunken towards the axis, the angle E between the outer wall 13 of the first section and the radial direction is 45 degrees, the angle F between the outer wall 14 of the second section and the axis is 11 degrees, and the angle G between the outer wall 15 of the third section and the radial direction is 38 degrees; the front part 20 of the inner wall of the rear cutting sleeve is parallel to the axis, the middle rear part of the inner wall of the rear cutting sleeve inclines outwards, and the included angle H between the inclined surface 19 and the axis is 8 degrees; the inner wall 18 close to the rear end face 17 is parallel to the axis; as shown in the pictorial view of the rear ferrule of fig. 13.

The external diameter of the connector 2 is provided with an external thread matched with the internal thread of the nut, as shown in fig. 4, the inner wall of the connector 2 matched with the front ferrule 3 is an inner conical surface 21 which inclines outwards and has an included angle I of 20.5 degrees with the axis. FIG. 10 shows a schematic representation of the linker.

As shown in fig. 5, the internal diameter of the nut 1 comprises three parts, a first part 22 for mating with the tubing, a second part 23 for mating with the rear ferrule, and a third part 24 for mating with the connector. The end face of the second portion 23 of the nut inner diameter has the same inclination angle as the rear end face 17 of the rear ferrule 4. Such as the physical representation of the nut shown in figure 11.

Wherein, the tolerance of the inner diameters of the front cutting sleeve 3, the rear cutting sleeve 4, the connector 2 and the nut 1 is 0.095 mm-0.138 mm; the dimensional tolerances of the small end outer diameter, the large end face inner diameter, the large end face outer diameter and the axial length of the front cutting sleeve 3 are all-0.05 mm, the dimensional tolerances of the front section end face outer diameter and the outer wall rear section outer diameter of the rear cutting sleeve 4 are all-0.07 mm-0 mm, the dimensional tolerance of the maximum outer diameter of the front section of the outer wall is-0.1 mm-0 mm, and the dimensional tolerance of the axial length of the rear cutting sleeve 4 is-0.05 mm; the tolerance of the inner diameter of the end face of the interface matched with the front cutting sleeve 3 in the connector 2 is 0 mm-0.07 mm, and the tolerance of the outer diameter is-0.1 mm-0 mm; the tolerance of the inner diameter of the screw cap1 matched with the rear cutting ferrule 4 is-0.05 mm.

The preparation method of the double-clamping sleeve pipeline joint comprises the following steps:

manufacturing a connecting body: blanking, turning an outer circle, drilling holes, turning the outer circle, milling a hexagon, finely turning threads and an inner cone, and inspecting.

Manufacturing the screw cap: blanking, turning end faces and threads, milling outer hexagons, finely turning outer circles, plating silver on the surfaces of the inner threads, and inspecting, wherein the thickness of the silver plating layer is 0.08 mm.

Manufacturing a front ferrule: turning the outer circle and the end face, boring, chamfering, cutting, turning the end face, carburizing and inspecting. The outer wall of the front cutting sleeve is carburized, the thickness of a carburized layer is 0.3mm, and the surface hardness is HV 830.

Manufacturing a rear ferrule: turning the outer circle and the end face, boring, chamfering, cutting off, turning the inclined end face, and performing surface treatment: heating in a vacuum furnaceHeating to 650 deg.C and maintaining for 20min, heating to 950 deg.C and maintaining for 20min, introducing NH₃And N₂The flow rate is 10L/min, nitriding treatment is carried out for 30min, and the replacement atmosphere is C₂H₂+N₂The flow rate is 10L/min, carburization is carried out for 20min, and then the atmosphere is changed to NH₃And N₂Nitriding at the flow rate of 10L/min for 20min, wherein the pressure of carburizing and nitriding is 2000 Pa; then carrying out oil quenching, wherein in the oil quenching process, the rear sleeve is sleeved with oil and then stirred, the maximum stirring frequency is 50Hz, and the oil temperature is 60 ℃; tempering: heating to 160 ℃, preserving heat for 120min, and cooling to room temperature; and (6) checking. The outer wall of the rear cutting ferrule is carburized and nitrided, the thickness of a carburized layer is 0.2mm, and the surface hardness is HV 830.

Wherein, the connector can be a straight-through (figure 6), a bent-through (figure 7), a tee (figure 8) and a pipe cap (figure 9).

The results of the tests are shown in table 1 when the connectors are straight, bent, three-way and pipe caps, and it can be seen from table 1 that the double-clamp pipe joints can pass the tests and meet the requirements of nuclear-grade application.

TABLE 1 statistical table of test items of double-clamp casing pipeline joint

In the research and development process of double-chuck pipeline connector, the inventor finds that the difficulty of the specific size determination process of each part in the pipeline connector is very large, the size tolerance fit among the parts is also very important, through continuous test and exploration, the size and tolerance of each part which can be matched with the performance of the front chuck sleeve, the rear chuck sleeve and the nut after surface treatment are finally determined, and the excellent sealing effect of the double-chuck pipeline connector can be exerted.

In addition, in the research and development process of the surface treatment process of the clamping sleeve, the surface treatment process of the rear clamping sleeve is important for the sealing performance of the double-clamping-sleeve pipeline joint, the surface hardness of the rear clamping sleeve of foreign products is as high as HV832, the coordination of the thickness of a permeable layer and the surface hardness is realized, and the sufficient toughness of the clamping sleeve is guaranteed, so that the key factor for solving the standard-reaching problem of the joint is provided, the required surface hardness is difficult to achieve if the thickness of the permeable layer is too small, the toughness of the clamping sleeve is reduced while the surface hardness is achieved if the thickness of the permeable layer is too large, the clamping sleeve is not enough in toughness, the clamping sleeve is extremely easy to break in a hydraulic test and cannot pass the test, and the inventor of the application finds out reasonable surface treatment process parameters of the rear clamping sleeve finally, the requirement of the main sealing effect of the front clamping sleeve on the toughness is not high, and on the basis that the surface hardness of the front clamping sleeve is met, the influence of the toughness of the rear clamping sleeve on the hinge-clamping effect determines whether the whole tightness can be kept in the hydraulic test Seal the effect, according to the processing technology parameter in this application, can realize reaching sufficient surface hardness under the prerequisite that the rear cutting ferrule oozing layer thickness is thinner, satisfy the hydrostatic test requirement. Furthermore, the inventor finds that when the thickness of the penetrating layer of the rear ferrule is 0.2mm and the surface hardness is HV830, the sealing performance of the hydraulic test of foreign products with the surface hardness of HV832 can be achieved, which is unexpected by the inventor, and particularly shown in Table 2, the test basis is as follows: the initial pressure applied was 10% of the rated pressure and the assembled samples were tested to determine if no fluid leakage was maintained at the pipe or ferrule and pipe joint. If no leakage occurs, the second step gradually increases the sample pressure to 150% of the rated pressure of the pipe or ferrule fitting (at a nuclear power rated pressure of 25MPa, the service pressure is 37.5MPa), and this increased pressure tests the ability of the sample to maintain a seal.

TABLE 2 comparison of hydrostatic test results

Test conditions	Shiweiroc sample	This application
			Torque (Nm)	50	60
Nut displacement (mm)	1.0	1.1
			Pressure (MPa)	37.5	37.5
Sealing performance	Without leakage	Without leakage
			Tensile properties	Without slippage	Without slippage
Residual Torque (Nm)	35	45
			Test time	2020.06.15	2020.08.15

As can be seen from table 2, when the dual ferrule tube-to-tube joint in embodiment 1 of the present application is used for testing, the thickness of the rear ferrule penetration layer is 0.2mm, the surface hardness is HV830, the thickness of the rear ferrule penetration layer of the shiviaroc sample is 0.2mm, and the surface hardness is HV832, after the hydraulic test, the displacement amount and the torque variation of the nut are also equivalent to those of the foreign product under the condition that the sealing performance of the example 1 is ensured to be the same as that of the foreign product, as shown in fig. 13 and 14, after the pressure test is performed on the dual ferrule tube-to-tube joint in embodiment 1, the extrusion grooving condition of the rear ferrule on the outer wall of the test sample tube is equivalent to that of the foreign product, which not only solves the problem that the dual ferrule tube-to-tube joint in the country meets the standard, but also reduces the requirement on the rear surface hardness, and reduces the manufacturing cost.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention. Furthermore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the description of the present invention, reference to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A double-clamping sleeve pipeline joint comprises a screw cap, a front clamping sleeve, a rear clamping sleeve and a connecting body, wherein the screw cap is in threaded connection with the connecting body, and the rear clamping sleeve and the front clamping sleeve are arranged in a cavity formed by the screw cap and the connecting body; the method is characterized in that: the front cutting sleeve is in a circular truncated cone shape and comprises a small end and a large end, the included angle A between the outer wall of the front cutting sleeve and the axis is 15-25 degrees, and the included angle B between the inner wall of the large end and the axis is 40-60 degrees; the section of the rear cutting ferrule is similar to a high-heeled shoe, the outer wall of the rear cutting ferrule comprises a front section, a middle section and a rear section, the end face of the front section is perpendicular to the axis, the end face of the rear section inclines forwards, and the included angle C between the end face of the rear section and the axis is 60-90 degrees, the included angle D between the front section of the outer wall and the axis is 30-40 degrees, the rear section of the outer wall is parallel to the axis, the middle section of the outer wall comprises three sections of outer walls sunken towards the axis, the included angle E between the first outer wall and the radial direction is 40-50 degrees, the included angle F between the second outer wall and the axis is 10-15 degrees, and the included angle G between the third outer wall and the radial direction is 35-45 degrees; the middle rear part of the inner wall of the rear ferrule inclines outwards, and the included angle H between the inclined plane and the axis is 6-10 degrees; the outer diameter of the connector is provided with an external thread matched with the internal thread of the screw cap, the inner wall of the connector matched with the front ferrule in the connector is an inner conical surface which inclines outwards, and the included angle I between the connector and the axis is 15-25 degrees.

2. The double-ferrule line connector of claim 1, wherein: the connector can be divided into a straight-through type, a bent-through type, a three-way type and a pipe cap according to the shape of the connector.

3. The double-ferrule line connector of claim 1, wherein: preferably, angle a is 18 °, angle B is 45 °, angle C is 80 °, angle D is 37.5 °, angle E is 45 °, angle F is 11 °, angle G is 38 °, angle H is 8 °, and angle I is 20.5 °.

4. The double-ferrule line connector of claim 1, wherein: the inner diameters of the front cutting sleeve, the rear cutting sleeve and the connector are 2mm-50mm, and preferably 12.7 mm; the outer diameter of the small end of the front cutting sleeve is 10mm-15mm, preferably 13.5mm, the inner diameter of the end face of the large end is 11.5mm-17mm, preferably 14.9mm, the outer diameter is 15mm-20mm, preferably 17.3mm, and the axial length of the front cutting sleeve is 5mm-10mm, preferably 7.3 mm; the outer diameter of the end face of the front section of the rear cutting sleeve is 11mm-14mm, preferably 13.3mm, the maximum outer diameter of the front section of the outer wall is 12mm-16mm, preferably 14.6mm, the outer diameter of the rear section of the outer wall is 14mm-17mm, preferably 15.6mm, and the axial length of the rear cutting sleeve is 2.5mm-5.5mm, preferably 3.8 mm; the inner diameter of the end face of the interface matched with the front ferrule in the connector is 12mm-18mm, preferably 15.6mm, the outer diameter is 15mm-19mm, preferably 17.4mm, and the inner diameter matched with the rear ferrule in the screw cap is 15mm-18mm, preferably 16 mm.

5. The double-ferrule line connector of claim 1, wherein: the inner diameter tolerance of the front cutting sleeve, the rear cutting sleeve, the connector and the nut is 0.095 mm-0.138 mm; the dimensional tolerances of the small end outer diameter, the large end face inner diameter, the large end face outer diameter and the axial length of the front cutting sleeve are all-0.05 mm, the dimensional tolerances of the front section end face outer diameter and the outer wall rear section outer diameter of the rear cutting sleeve are all-0.07 mm-0 mm, the dimensional tolerance of the maximum outer diameter of the front section of the outer wall is-0.1 mm-0 mm, and the dimensional tolerance of the axial length of the rear cutting sleeve is-0.05 mm; the tolerance of the inner diameter of the end face of the interface matched with the front cutting sleeve in the connector is 0 mm-0.07 mm, and the tolerance of the outer diameter is-0.1 mm-0 mm; the tolerance of the inner diameter of the screw cap matched with the rear cutting sleeve is-0.05 mm.

6. The double-ferrule line connector of claim 1, wherein: the nut internal diameter includes four bibliographic categories, and the first portion matches with the pipeline, and the second portion matches with back cutting ferrule, and the third portion matches with preceding cutting ferrule, and the fourth portion matches with the connector, preferably, in the nut internal diameter, the terminal surface of second portion has the same inclination with the rear end face of back cutting ferrule.

7. The double-ferrule line connector of claim 1, wherein: the screw cap, the front cutting sleeve, the rear cutting sleeve and the connector are made of 316 stainless steel or 316L stainless steel, the strain hardening is 2-grade, preferably, the surface of the inner thread of the screw cap is plated with silver, the thickness of the plated silver layer is 0.05 mm-0.1 mm, preferably, the outer wall of the front cutting sleeve is subjected to carburizing treatment, the thickness of a carburized layer is 0.2mm-0.4mm, the surface hardness is HV820-HV840, preferably, the outer wall of the rear cutting sleeve is subjected to carburizing and nitriding treatment, the thickness of the carburized layer is 0.1mm-0.3mm, and the surface hardness is HV820-HV 840.

8. The method of making a double cassette line joint as claimed in any one of claims 1 to 7, wherein: the method comprises the following steps: manufacturing a connector, a screw cap, a front cutting sleeve and a rear cutting sleeve; in the manufacturing step of the front cutting ferrule, the machined front cutting ferrule is subjected to surface carburization, the thickness of a carburized layer is 0.2mm-0.6mm, the surface hardness is HV820-HV840, and in the manufacturing step of the rear cutting ferrule, the machined rear cutting ferrule is subjected to surface carburization, nitriding and tempering, the thickness of a carburized layer is 0.1mm-0.3mm, and the surface hardness is HV820-HV 840.

9. The method as set forth in claim 8, wherein: the manufacturing of the connector includes: blanking, turning an outer circle, drilling holes, turning the outer circle, milling a hexagon, finely turning threads and an inner cone, and inspecting;

preferably, the manufacturing of the screw cap comprises: blanking, turning end surfaces and threads, milling outer hexagons, finely turning outer circles, plating silver on the surfaces of the inner threads, and inspecting, wherein the thickness of the silver plating layer is 0.05-0.1 mm;

preferably, the manufacturing of the front ferrule comprises: turning the outer circle and the end face, boring, chamfering, cutting off, turning the end face, carburizing and inspecting;

preferably, the manufacturing of the rear ferrule comprises: turning the outer circle and the end face, boring, chamfering, cutting off, turning the inclined end face, nitriding, carburizing, oil quenching, tempering and inspecting.

10. The method as set forth in claim 9, wherein: the specific processes of nitriding, carburizing, oil quenching and tempering of the rear ferrule comprise: heating to 650 deg.C in vacuum furnace, maintaining the temperature for 15-25min, heating to 950 deg.C, maintaining the temperature for 15-25min, introducing NH₃And N₂The flow rate is 8-15L/min, nitriding treatment is carried out for 20-40min, and the changing atmosphere is C introduction₂H₂+N₂Carburizing for 15-30min at flow rate of 8-15L/min, and introducing NH₃And N₂Nitriding at the flow rate of 8-15L/min for 15-30min under carburizing and nitriding pressure of 2000 Pa; then carrying out oil quenching, wherein in the oil quenching process, the rear sleeve is sleeved with oil and then stirred, the maximum stirring frequency is 50Hz, and the oil temperature is 60 ℃; the tempering process comprises the following steps: heating to 160 deg.C, maintaining the temperature for 120min, and air cooling to room temperature.