Equipment for tapping in dangerous medium pipeline under pressure and using method

Abstract

The invention discloses equipment for tapping in a dangerous medium pipeline under pressure and a using method. The equipment comprises a main body bracket, transmission equipment and a tool bit assembly, the main body support is formed by fixedly connecting three positioning support columns, a top plate and a base, a motor in the transmission equipment is connected with a speed change gear box, the motor and the speed change gear box are fixed to the same bottom plate arranged at the lower end, the bottom plate is connected with the positioning support columns through sliding sleeves to achieve vertical sliding, and the bottom of the speed change gear box is connected with a bearing box at the lower end. The bearing box is connected with a shaft with a positioning drill bit, and the lower part of the shaft is connected with a bearing fixed on the base; a tool bit upper flange in the tool bit assembly is connected with a base flange through a bolt, and the tool bit upper flange is connected with a tool bit lower flange through a tool bit cavity; the safety, precision and efficiency of the pressure tapping operation of the dangerous medium pipeline and the adaptability to pipelines with different pipe diameters and materials are improved, and real-time monitoring and feedback functions are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline opening, and in particular to a device for opening a hole under pressure in a dangerous medium pipeline and a use method thereof. Background Art

[0002] In the petroleum and chemical industries, there are a large number of pipelines that transport dangerous media, such as flammable and explosive oil and gas, toxic and harmful chemical raw materials, etc. Traditional pipeline opening operations, if performed after the pipeline stops running and the medium is emptied, will affect the continuity of the entire production process and cause huge economic losses. However, pressurized opening operations face extremely high safety risks because dangerous media may leak under pressure, and there are the following shortcomings:

[0003] 1) The prior art does not provide a systematic sealing solution, and it is impossible to achieve a leak-free opening for toxic and flammable gas pipelines.

[0004] 2) The existing technology does not measure the drilling speed, and controls the rotation speed based on experience. When drilling holes in combustible and flammable gas pipelines, it is easy for the local temperature of the drill bit to be too high, causing combustion and explosion accidents.

[0005] 3) In the prior art, the drill bit and the shaft are manufactured in one piece, which cannot meet the requirement of replacing different types of drill bits according to different drilling conditions, and the scope of use is limited.

[0006] 4) In the existing technology, the drilling speed and depth are measured manually and lack quantitative standards.

[0007] In summary, the existing technology has many deficiencies in the pressurized opening of dangerous medium pipelines, and a new device and method of use are urgently needed to solve these problems. Summary of the invention

[0008] In view of the deficiencies in the prior art, the present invention discloses a device for opening a hole under pressure in a hazardous medium pipeline and a method for using the device to solve the problems raised in the above-mentioned background technology.

[0009] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a device for opening a hole under pressure in a dangerous medium pipeline, comprising a main body support, a transmission device and a cutter head assembly;

[0010] The main body bracket is composed of three positioning bracket columns fixedly connected to the top plate and the base, the top plate is located at the upper end of the base, and the top plate and the base are connected through three positioning bracket columns;

[0011] The transmission device includes a motor, a speed change gear box, a bearing box, a shaft and a bearing. The motor is connected to the speed change gear box on one side through a coupling provided at the output end, and the motor and the speed change gear box are fixed on the same bottom plate provided at the lower end. The bottom plate is connected to the positioning bracket column through a sliding sleeve to achieve up and down sliding. The bottom of the speed change gear box is connected to the bearing box at the lower end. The bearing box is connected to the shaft with a positioning drill bit, and the lower part of the shaft is connected to the bearing fixed on the base.

[0012] The upper flange of the cutter head in the cutter head assembly is connected to the base flange by bolts, and the cutter head is connected to the shaft by a key, and the key between the cutter head and the shaft is a flat key or a semicircular key; the lower end of the shaft is threadedly connected to a positioning drill bit, and the interior of the cutter head assembly is sealed and isolated from the shaft by a mechanical seal assembly to achieve effective sealing between the interior of the cutter head assembly and the shaft to prevent gas from escaping; the upper flange of the cutter head and the lower flange of the cutter head are connected by a cutter head cavity, and the cutter head is located inside the cutter head cavity.

[0013] Preferably, a ladder is provided on the side of the main support, and the ladder of the main support is provided with anti-slip patterns to facilitate personnel to climb safely to perform equipment maintenance.

[0014] Preferably, the speed display meter of the speed change gear box is a digital speed display meter, which accurately displays the rotation speed in the speed change gear box. The speed display meter on the speed change gear box shows a sudden increase in speed or a sudden increase in progress speed, thereby judging whether the positioning drill has drilled through the pipeline.

[0015] Preferably, in the cutter head assembly, the cutter head upper flange, the cutter head cavity and the cutter head lower flange are connected by welding.

[0016] Preferably, exhaust and pressure relief valves and pressure gauges are installed on both sides of the cutter head cavity, and the exhaust and pressure relief valves on the cutter head cavity are automatically controlled valves, which automatically open for exhaust and pressure relief when the internal pressure of the cutter head assembly reaches a set pressure value.

[0017] Preferably, a cut and fallen pipe recovery device is provided at the lower end of the positioning drill bit, and the cut and fallen pipe recovery device consists of a compression spring, a rotating pin and a rotating shaft assembly. The upper end of the compression spring is connected to the positioning drill bit, and the lower end of the compression spring is connected to the rotating pin shaft. When the positioning drill bit penetrates the pipe, the compression spring pushes the rotating pin from a vertical position to a horizontal position to hang upside down on the inner wall of the pipe, ensuring that after the cutter head completes cutting the pipe, the cut pipe fragments are recovered to prevent them from falling into the inside of the pipe and being unable to be removed; the rotating pin is made of high-strength alloy steel to ensure its strength when hanging upside down on the inner wall of the pipe.

[0018] Preferably, in the cut and fallen pipe recovery device, the elastic coefficient of the compression spring is greater than the thrust for moving the rotating pin to a horizontal position.

[0019] The present invention also provides a method for using a device for opening a hole under pressure in a dangerous medium pipeline, comprising the following steps:

[0020] S1. Surface treatment: After determining the opening point, clean the pipeline and avoid areas with welds and severe corrosion;

[0021] S2, short circuit welding:

[0022] 1) Pipe fitting installation: Install the flange short-circuit directly above the pipeline, and grind the pipes and flange short-circuit with straight welds and spiral welds to make the fitting gap no greater than 2 mm;

[0023] 2) Pipe fitting pairing: The distance difference between the two ends of the flange short-joint flange and the pipe top along the pipeline axis direction is not greater than 1 mm, the non-intersection degree between the flange short-joint flange axis and the pipeline axis at the location is not greater than 1.5 mm, and the flange short-joint flange plane is horizontal in the annular direction of the pipe;

[0024] 3) Pipe fitting welding pressure measurement: When the pipeline is welded under pressure, the operating pressure is lower than the maximum pressure allowed for pipeline welding under pressure. The maximum pressure P allowed for pipeline welding under pressure is calculated according to the formula:

[0025]

[0026] In the calculation formula, P is the pressure allowed for pressure welding of the pipeline, in MPa; ￡s is the minimum yield limit of the pipe, in MPa; T is the actual wall thickness of the pipeline at the welding point, in mm; C is the wall thickness correction value caused by welding, in mm and is taken as 2.8mm according to the specification; D is the outer diameter of the pipeline, in mm; F ​​is the safety factor, which is 0.6 for crude oil and refined oil pipelines and 0.5 for natural gas and coal gas pipelines;

[0027] 4) Welding material selection: match according to the pipe base material;

[0028] 5) Weld seam treatment: After the pipe is welded, observe the weld seam. If there are any incomplete weld seams, grind them and re-weld them to ensure the welding quality is qualified;

[0029] S3. Install the valve: After the weld is tested and qualified, the inner hole of the valve is concentric with the inner hole of the short-circuit flange, and the eccentricity does not exceed 1 mm. When the valve and the opening are short-circuited, a flange gasket is added in the middle, and the bolts are tightened symmetrically to ensure that the valve can be opened and closed flexibly;

[0030] S4. Install the hole tapping machine: Install the hole tapping machine with the valve closed, and connect the nitrogen pipeline to the exhaust pressure relief valve;

[0031] S5, opening under pressure:

[0032] 1) Pressure test and leak detection: After installing the valve and the tapping machine, open the valve, pressurize the valve, flange short circuit and the tapping machine as a whole to the same pressure as the pressure in the pipeline (depending on the medium, the slight positive pressure is 0.03-0.05MPa) and test the pressure to check whether the flange surface and weld are leaking. After passing the test, proceed with the tapping operation;

[0033] 2) Drilling operation: Feed the drilling cutter slowly during drilling operation, record the feed scale when it contacts the steel pipe, start drilling, use fast turn and slow feed mode, adjust the cutter head speed according to the speed display instrument on the speed change gear box, observe the feed scale while drilling, and strictly control the feed amount when approaching the through hole. When the speed display instrument on the speed change gear box shows that the speed suddenly increases or the progress speed suddenly increases, it means that the positioning drill has drilled through the pipe. At this time, slow down the drill speed and stop the operation when further confirming that the feed is unobstructed;

[0034] S6. Dismantle the hole opening machine:

[0035] 1) Pressure release: When the cutter head retreats to the initial position, close the valve on the pipeline, close the exhaust pressure relief valve, remove the nitrogen charging pipeline, and then open the exhaust pressure relief valve to release the pressure in the cutter head cavity to normal pressure;

[0036] 2) Dismantling and cleaning: dismantle the hole-opening machine, clean the iron chips in the barrel knife and the cut pipe skin arc plate, lift the hole-opening machine out of the working area for loading, and remove the hole-opening tools and materials in the working area.

[0037] Preferably, when selecting welding materials in the short-circuit welding step, a Φ2.5 electrode is used for the first welding, the current is controlled at 80-90A, the arc voltage is controlled between 22-25V, and each weld of about 30mm in length needs to wait for the parent material to cool before continuing welding; a Φ3.2 electrode is used for the second welding, the welding current is controlled between 100-120A, and the welding voltage is controlled between 25-27V.

[0038] Preferably, when the pressure is released in the step of removing the hole opener, if there is residual pressure in the cutter head cavity, the pipeline valve is closed, the exhaust pressure relief valve is closed, and the exhaust pressure relief valve is opened to release the pressure until the pressure in the cutter head cavity is released to normal pressure.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. The present invention improves the safety, accuracy, efficiency and adaptability of pressurized hole opening operations for hazardous medium pipelines to pipelines of different diameters and materials, and has real-time monitoring and feedback functions.

[0041] 2. In the present invention, a series of operations such as surface treatment to avoid dangerous parts, precise short-circuit welding installation requirements, concentricity and sealing requirements for valve installation, safe operation when installing the hole-opening machine, and pressure control when opening holes under pressure and removing the hole-opening machine can effectively prevent the leakage of dangerous media and avoid safety accidents such as explosion, fire, environmental pollution and casualties caused by media leakage.

[0042] 3. In the present invention, surface treatment helps to accurately determine the hole opening position, various precise requirements in short-circuit welding ensure the compatibility of the short-circuit and the pipeline, the concentricity of the valve installation ensures the accuracy of subsequent operations, and precise operations during the pressurized hole opening process ensure the hole opening quality, such as pressure testing, leak detection, and tool feed control during the hole opening operation. These measures together improve the accuracy of the entire pressurized hole opening operation.

[0043] 4. In the present invention, clear steps and parameter settings standardize the operation process, such as electrode specifications, current, voltage and welding length control during welding of welding materials, pressure relief operation, etc. At the same time, operations such as cleaning the work area and tidying up equipment and tools help to improve the efficiency of the next operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0045] In the attached picture:

[0046] Figure 1 It is a schematic diagram of the structure of the device for opening a hole in the present invention;

[0047] Figure 2 It is a structural schematic diagram of a cut and fallen pipeline recovery device of the present invention;

[0048] Figure 3 It is a structural schematic diagram of the rotating shaft assembly of the present invention;

[0049] Numbers in the figure: 1. Motor; 2. Speed ​​change gear box; 3. Bearing box; 4. Shaft; 5. Bearing; 6. Top plate; 7. Base; 8. Bolt; 9. Upper flange of cutter head; 10. Mechanical seal assembly; 11. Key; 12. Positioning drill bit; 13. Pressure gauge; 14. Cutter head cavity; 15. Exhaust and pressure relief valve; 16. Lower flange of cutter head; 17. Cutter head; 20. Ladder; 21. Rotating pin; 22. Compression spring; 23. Positioning bracket column; 24. Cutting and falling pipe recovery device; 25. Rotating shaft assembly. DETAILED DESCRIPTION

[0050] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0051] Example: Figure 1-Figure 3 As shown, a device for opening a hole under pressure in a dangerous medium pipeline comprises a main body support, a transmission device and a cutter head assembly;

[0052] Furthermore, the main support is composed of three positioning support columns 23 fixedly connected to the top plate 6 and the base 7, the top plate 6 is located at the upper end of the base 7, and the top plate 6 and the base 7 are connected through the three positioning support columns 23, and a ladder 20 is provided on the side of the main support, and the ladder 20 of the main support is provided with anti-slip patterns, which is convenient for personnel to climb safely to perform equipment maintenance;

[0053] Furthermore, the transmission device includes a motor 1, a speed change gear box 2, a bearing box 3, a shaft 4 and a bearing 5. The motor 1 is connected to the speed change gear box 2 on one side through a coupling provided at the output end, and the motor 1 and the speed change gear box 2 are fixed on the same bottom plate provided at the lower end, and the bottom plate is connected to the positioning bracket column 23 through a sliding sleeve to achieve up and down sliding. The bottom of the speed change gear box 2 is connected to the bearing box 3 at the lower end, and the bearing box 3 is connected to the shaft 4 with the positioning drill bit 12. The lower part of the shaft 4 is connected to the bearing 5 fixed on the base 7. The speed display meter of the speed change gear box 2 is a digital speed display meter, which accurately displays the rotation speed in the speed change gear box 2. The speed display meter on the speed change gear box 2 shows that the speed suddenly increases or the progress speed suddenly increases, so as to judge whether the positioning drill bit 12 has drilled through the pipeline;

[0054] Furthermore, the upper flange 9 of the cutter head in the cutter head assembly is connected to the flange of the base 7 by bolts 8, and the cutter head 17 is connected to the shaft by a key 11, and the key 11 between the cutter head 17 and the shaft 4 is a flat key or a semicircular key; the lower end of the shaft 4 is threadedly connected to the positioning drill bit 12, and the interior of the cutter head assembly is sealed and isolated from the shaft 4 by a mechanical seal assembly 10 to achieve effective sealing between the interior of the cutter head assembly and the shaft 4 to prevent gas from escaping; the upper flange 9 of the cutter head and the lower flange 16 of the cutter head are connected by a cutter head cavity 14, and the cutter head is located inside the cutter head cavity 14. In the cutter head assembly, the upper flange 9 of the cutter head, the cutter head cavity 14 and the lower flange 16 of the cutter head are connected by welding; exhaust pressure relief valves 15 and pressure gauges 13 are respectively installed on both sides of the cutter head cavity 14, and the exhaust pressure relief valves 15 on the cutter head cavity 14 are automatic control valves, which automatically open for exhaust pressure relief when the internal pressure of the cutter head assembly reaches the set pressure value.

[0055] Among them, Figure 2 and Figure 3As shown, a cut and fallen pipe recovery device 24 is provided at the lower end of the positioning drill bit 12, and the cut and fallen pipe recovery device 24 is composed of a clamping spring 22, a rotating pin 21 and a rotating shaft assembly 25. The upper end of the clamping spring 22 is connected to the positioning drill bit 12, and the lower end of the clamping spring 22 is connected to the axis of the rotating pin 21. When the positioning drill bit 12 penetrates the pipe, the clamping spring 22 pushes the rotating pin 21 from a vertical position to a horizontal position to hang upside down on the inner wall of the pipe, ensuring that after the cutter head completes cutting the pipe, the cut pipe fragments are recovered to prevent them from falling into the pipe and being unable to be taken out; the rotating pin 21 is made of high-strength alloy steel to ensure the strength when hanging upside down on the inner wall of the pipe. In the cut and fallen pipe recovery device 24, the elastic coefficient of the clamping spring 22 is greater than the thrust to move the rotating pin 21 to the horizontal position.

[0056] The present invention also provides a method for using a device for opening a hole under pressure in a dangerous medium pipeline, comprising the following steps:

[0057] S1. Surface treatment: After determining the opening point, clean the pipeline and avoid areas with welds and severe corrosion;

[0058] S2, short circuit welding:

[0059] 1) Pipe fitting installation: Install the flange short-circuit directly above the pipeline, and grind the pipes and flange short-circuit with straight welds and spiral welds to make the fitting gap no greater than 2 mm;

[0060] 2) Pipe fitting pairing: The distance difference between the two ends of the flange short-joint flange and the pipe top along the pipeline axis direction is not greater than 1 mm, the non-intersection degree between the flange short-joint flange axis and the pipeline axis at the location is not greater than 1.5 mm, and the flange short-joint flange plane is horizontal in the annular direction of the pipe;

[0061] 3) Pipe fitting welding pressure measurement: When the pipeline is welded under pressure, the operating pressure is lower than the maximum pressure allowed for pipeline welding under pressure. The maximum pressure P allowed for pipeline welding under pressure is calculated according to the formula:

[0062]

[0063] In the calculation formula, P is the pressure allowed for pressure welding of the pipeline, in MPa; ￡s is the minimum yield limit of the pipe, in MPa; T is the actual wall thickness of the pipeline at the welding point, in mm; C is the wall thickness correction value caused by welding, in mm and is taken as 2.8mm according to the specification; D is the outer diameter of the pipeline, in mm; F ​​is the safety factor, which is 0.6 for crude oil and refined oil pipelines and 0.5 for natural gas and coal gas pipelines;

[0064] 4) Selection of welding materials: Match according to the base material of the pipeline; pay special attention to intermittent welding during welding; use Φ2.5 welding rod for the first welding, control the current at 80-90A, and control the arc voltage at 22-25V. For each weld of about 30mm in length, wait for the base material to cool before continuing welding; use Φ3.2 welding rod for the second welding, control the welding current at 100-120A, and control the welding voltage at 25-27V.

[0065] 5) Weld seam treatment: After the pipe is welded, observe the weld seam. If there are any incomplete weld seams, grind them and re-weld them to ensure the welding quality is qualified;

[0066] S3. Install the valve: After the weld is tested and qualified, the inner hole of the valve is concentric with the inner hole of the short-circuit flange, and the eccentricity does not exceed 1 mm. When the valve and the opening are short-circuited, a flange gasket is added in the middle, and the bolts are tightened symmetrically to ensure that the valve can be opened and closed flexibly;

[0067] S4. Install the hole tapping machine: install the hole tapping machine with the valve closed, and connect the nitrogen pipeline to the exhaust pressure relief valve 15;

[0068] S5, opening under pressure:

[0069] 1) Pressure test and leak detection: After installing the valve and the tapping machine, open the valve, pressurize the valve, flange short circuit and the tapping machine as a whole to the same pressure as the pressure in the pipeline (depending on the medium, the slight positive pressure is 0.03-0.05MPa) and test the pressure to check whether the flange surface and weld are leaking. After passing the test, proceed with the tapping operation;

[0070] 2) Drilling operation: feed the drilling cutter slowly during drilling operation, record the feed scale when it contacts the steel pipe, start drilling, use fast turn and slow feed mode, adjust the cutter head speed according to the speed display instrument on the speed change gear box 2, observe the feed scale while drilling, and strictly control the feed amount when approaching the through hole. When the speed display instrument on the speed change gear box 2 shows that the speed suddenly increases or the progress speed suddenly increases, it means that the positioning drill bit 12 has drilled through the pipe. At this time, slow down the drill bit speed, and stop the operation when further confirming that the feed is unobstructed;

[0071] S6. Dismantle the hole opening machine:

[0072] 1) Pressure release: After the cutter head retreats to the initial position, the valve on the pipeline is closed, the exhaust pressure relief valve 15 is closed, the nitrogen charging pipeline is removed, and then the exhaust pressure relief valve 15 is opened to release the pressure in the cutter head cavity 14 to normal pressure; during the pressure release in the step of removing the hole tapping machine, if there is residual pressure in the cutter head cavity 14, the pipeline valve is closed, the exhaust pressure relief valve 15 is closed, and the exhaust pressure relief valve 15 is opened to release the pressure until the pressure in the cutter head cavity 14 is released to normal pressure;

[0073] 2) Dismantling and cleaning: dismantle the hole-opening machine, clean the iron chips in the barrel knife and the cut pipe skin arc plate, lift the hole-opening machine out of the working area for loading, and remove the hole-opening tools and materials in the working area.

[0074] Finally, it should be noted that the above description is only a preferred example of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A device for opening a hole under pressure in a dangerous medium pipeline, characterized by: It includes a main body support, a transmission device and a cutter head assembly; The main body bracket is composed of three positioning bracket columns fixedly connected to the top plate and the base, the top plate is located at the upper end of the base, and the top plate and the base are connected through three positioning bracket columns; The transmission device includes a motor, a speed change gear box, a bearing box, a shaft and a bearing. The motor is connected to the speed change gear box on one side through a coupling provided at the output end, and the motor and the speed change gear box are fixed on the same bottom plate provided at the lower end. The bottom plate is connected to the positioning bracket column through a sliding sleeve to achieve up and down sliding. The bottom of the speed change gear box is connected to the bearing box at the lower end. The bearing box is connected to the shaft with a positioning drill bit, and the lower part of the shaft is connected to the bearing fixed on the base. The upper flange of the cutter head in the cutter head assembly is connected to the base flange by bolts, and the cutter head is connected to the shaft by a key; the lower end of the shaft is threadedly connected to a positioning drill bit, the interior of the cutter head assembly is sealed and isolated from the shaft by a mechanical seal assembly, the upper flange of the cutter head and the lower flange of the cutter head are connected by a cutter head cavity, and the cutter head is located inside the cutter head cavity.

2. The device for opening a hole under pressure in a dangerous medium pipeline according to claim 1, characterized in that: A ladder is arranged on the side of the main frame, and anti-slip patterns are arranged on the ladder of the main frame.

3. The device for opening a hole under pressure in a dangerous medium pipeline according to claim 1, characterized in that: The speed display meter of the speed change gear box is a digital speed display meter, which accurately displays the rotation speed in the speed change gear box. The speed display meter on the speed change gear box shows a sudden increase in speed or a sudden increase in progress speed, thereby judging whether the positioning drill has drilled through the pipeline.

4. The device for opening a hole under pressure in a dangerous medium pipeline according to claim 1, characterized in that: In the cutter head assembly, the cutter head upper flange, the cutter head cavity and the cutter head lower flange are connected by welding.

5. The device for opening a hole under pressure in a dangerous medium pipeline according to claim 1, characterized in that: An exhaust pressure relief valve and a pressure gauge are installed on both sides of the cutter head cavity respectively. The exhaust pressure relief valve on the cutter head cavity is an automatic control valve, which automatically opens for exhaust pressure relief when the internal pressure of the cutter head assembly reaches a set pressure value.

6. The device for opening a hole under pressure in a dangerous medium pipeline according to claim 1, characterized in that: A cut and fallen pipe recovery device is provided at the lower end of the positioning drill bit, and the cut and fallen pipe recovery device is composed of a compression spring, a rotating pin and a rotating shaft assembly. The upper end of the compression spring is connected to the positioning drill bit, and the lower end of the compression spring is connected to the rotating pin shaft. When the positioning drill bit penetrates the pipe, the compression spring pushes the rotating pin from a vertical position to a horizontal position to hang upside down on the inner wall of the pipe, ensuring that after the cutter head completes cutting the pipe, the cut pipe fragments are recovered.

7. The device for opening a hole under pressure in a dangerous medium pipeline according to claim 6, characterized in that: In the cut and dropped pipe recovery device, the elastic coefficient of the compression spring is greater than the thrust for moving the rotating pin to a horizontal position.

8. A method for using a device for opening a hole under pressure in a dangerous medium pipeline, characterized in that: The following steps are involved: S1. Surface treatment: After determining the opening point, clean the pipeline and avoid areas with welds and severe corrosion; S2, short circuit welding: 1) Pipe fitting installation: Install the flange short-circuit directly above the pipeline, and grind the pipes and flange short-circuit with straight welds and spiral welds to make the fitting gap no greater than 2 mm; 2) Pipe fitting pairing: The distance between the two ends of the flange short-joint flange and the pipe top along the pipeline axis is not greater than 1 mm, the non-intersection degree between the flange short-joint flange axis and the pipeline axis at the location is not greater than 1.5 mm, and the flange short-joint flange plane is horizontal in the annular direction of the pipe; 3) Pipe fitting welding pressure measurement: When the pipeline is welded under pressure, the operating pressure is lower than the maximum pressure allowed for pipeline welding under pressure. The maximum pressure P allowed for pipeline welding under pressure is calculated according to the formula: In the calculation formula, P is the pressure allowed for pressure welding of the pipeline, in MPa; ￡s is the minimum yield limit of the pipe, in MPa; T is the actual wall thickness of the pipeline at the welding point, in mm; C is the wall thickness correction value caused by welding, in mm and is taken as 2.8mm according to the specification; D is the outer diameter of the pipeline, in mm; F ​​is the safety factor, which is 0.6 for crude oil and refined oil pipelines and 0.5 for natural gas and coal gas pipelines; 4) Welding material selection: match according to the pipe base material; 5) Weld seam treatment: After the pipe is welded, observe the weld seam. If there are any incomplete weld seams, grind them and re-weld them to ensure the welding quality is qualified; S3. Install the valve: After the weld is tested and qualified, the inner hole of the valve is concentric with the inner hole of the short-circuit flange, and the eccentricity does not exceed 1 mm. When the valve and the opening are short-circuited, a flange gasket is added in the middle, and the bolts are tightened symmetrically to ensure that the valve can be opened and closed flexibly; S4. Install the hole tapping machine: Install the hole tapping machine with the valve closed, and connect the nitrogen pipeline to the exhaust pressure relief valve; S5, opening under pressure: 1) Pressure test and leak detection: After installing the valve and the tapping machine, open the valve, pressurize the valve, flange short-circuit and tapping machine as a whole to the same pressure as the pressure in the pipeline and test the pressure, check whether the flange surface and weld are leaking, and perform the tapping operation after passing the test; 2) Drilling operation: Feed the drilling cutter slowly during drilling operation, record the feed scale when it contacts the steel pipe, start drilling, use fast turn and slow feed mode, adjust the cutter head speed according to the speed display instrument on the speed change gear box, observe the feed scale while drilling, and strictly control the feed amount when approaching the through hole. When the speed display instrument on the speed change gear box shows that the speed suddenly increases or the progress speed suddenly increases, it means that the positioning drill has drilled through the pipe. At this time, slow down the drill speed and stop the operation when further confirming that the feed is unobstructed; S6. Dismantle the hole opening machine: 1) Pressure release: When the cutter head retreats to the initial position, close the valve on the pipeline, close the exhaust pressure relief valve, remove the nitrogen charging pipeline, and then open the exhaust pressure relief valve to release the pressure in the cutter head cavity to normal pressure; 2) Dismantling and cleaning: dismantle the hole-opening machine, clean the iron chips in the barrel knife and the cut pipe skin arc plate, lift the hole-opening machine out of the working area for loading, and remove the hole-opening tools and materials in the working area.

9. The method for using the device for opening a hole under pressure in a dangerous medium pipeline according to claim 8, characterized in that: When selecting welding materials in the short-circuit welding step, a Φ2.5 electrode is used for the first welding, the current is controlled at 80-90A, the arc voltage is controlled between 22-25V, and each weld of about 30mm in length needs to wait for the parent material to cool before continuing welding; a Φ3.2 electrode is used for the second welding, the welding current is controlled between 100-120A, and the welding voltage is controlled between 25-27V.

10. The method for using the device for opening a hole under pressure in a dangerous medium pipeline according to claim 8, characterized in that: During the pressure release in the step of removing the hole opener, if there is residual pressure in the cutter head cavity, repeatedly close the pipeline valve, close the exhaust pressure relief valve, and open the exhaust pressure relief valve to release the pressure until the pressure in the cutter head cavity is released to normal pressure.

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