CN107401655A

CN107401655A - Metal pipeline defect identification and welding-free maintenance method

Info

Publication number: CN107401655A
Application number: CN201610342273.3A
Authority: CN
Inventors: 梁爱国; 王庆林; 蒋华义; 王玉龙
Original assignee: Petrochina Co Ltd; Xian Shiyou University
Current assignee: Petrochina Co Ltd; Xian Shiyou University
Priority date: 2016-05-20
Filing date: 2016-05-20
Publication date: 2017-11-28
Anticipated expiration: 2036-05-20
Also published as: CN107401655B

Abstract

The invention provides a metal pipeline defect identification and welding-free maintenance method, wherein the method comprises the steps of establishing a damage data table, and establishing a functional relation between a damage working condition and safe construction pressure in the damage data table; detecting the damage condition of the pipeline through a detection device, and determining the safe construction pressure of the pipeline by inquiring a damage data table according to the damage condition determined after the detection of the detection device; selecting a matched sealing clamp according to the determined safe construction pressure and damage working condition; installing the sealing clamp at the damaged part of the pipeline, and forming a cavity between the sealing clamp and the outer wall of the pipeline; and injecting sealant into the cavity through the glue injection device so as to perform sealing maintenance on the damaged part of the pipeline, wherein the pressure generated by the sealant in the cavity is less than the safe construction pressure. The method effectively solves the problem that the pipeline cannot be repaired due to secondary damage of the injected sealant to the pipeline.

Description

Metal pipeline defect identification and welding-free maintenance method

Technical Field

The invention relates to the technical field of oil field pipeline damage and leakage maintenance, in particular to a metal pipeline defect identification and welding-free maintenance method.

Background

The pipeline maintenance method in the prior art usually needs to be stopped for maintenance and replacement, is difficult to maintain and long in time consumption, and is easy to cause safety accidents once a fire is started. The shutdown maintenance also causes additional economic loss due to production stoppage. Therefore, the pipeline damage caused by corrosion or scaling of the inner wall of the oil pipeline and the gas pipeline in the daily production and operation process of the oil field is usually maintained by adopting a fire-free injection type pressure sealing technology. The technology adopts a special sealing clamp, a new sealing structure is reconstructed on a leakage part, the leakage defect is quickly compensated, the medium leakage is prevented, the sealing purpose is realized, the temperature and pressure range of the applicable medium is wide, the plugging operation is simple and convenient, and the technology is widely popularized and applied at home and abroad.

When the injection type pressure sealing technology is applied, the internal pressure borne by the fixture is the resultant force of the system pressure leaked into the sealing cavity and the sealant extrusion force for completing sealing, and the pipeline can bear the combined action of the sealant extrusion force from the fixture glue injection groove and the pipeline body and the system pressure. The system pressure is acted on the pipeline by uniformly distributed loads, and the sealing extrusion force is injected into the sealing cavity through a plurality of injection holes. The whole process of sealant flowing, filling and compacting is carried out near each sealant injection hole, and the compression force represented by each sealant injection hole is different. If the external thrust of the injection agent is too great, or if it is not properly controlled, it will cause significant additional stress to the tubing, resulting in deformation or cracking of the tubing, causing irreparable damage. In addition, in the daily production and operation process of an oil field, the oil and gas metal pipeline is easy to cause corrosion or scaling of the inner wall and the outer wall of the pipeline due to long-time operation and delivery of high-temperature, high-pressure and highly corrosive fluid media, so that the phenomenon of thinning or punching of the pipe wall is generated, and a plurality of uncertain factors are brought to site construction.

Disclosure of Invention

The invention mainly aims to provide a metal pipeline defect identification and welding-free maintenance method, which aims to solve the problem that the pipeline cannot be repaired due to improper pressure control of injected sealant in the prior art.

In order to achieve the above object, according to one aspect of the present invention, there is provided a metal pipeline defect identifying and welding-free repair method, comprising: establishing a damage data table, and establishing a functional relation between a damage working condition and safe construction pressure in the damage data table; detecting the damage condition of the pipeline through a detection device, and determining the safe construction pressure of the pipeline by inquiring a damage data table according to the damage condition determined after the detection of the detection device; selecting a matched sealing clamp according to the determined safe construction pressure and damage working condition; installing the sealing clamp at the damaged part of the pipeline, and forming a cavity between the sealing clamp and the outer wall of the pipeline; and injecting sealant into the cavity through the glue injection device so as to perform sealing maintenance on the damaged part of the pipeline, wherein the pressure generated by the sealant in the cavity is less than the safe construction pressure.

Further, the damage working condition comprises the material type of the pipeline, the damage type of the pipeline and the distance between the damaged part and the glue injection groove of the sealing clamp; when the damage data table is established, fitting is carried out on the material type of the pipeline, the damage type of the pipeline and the distance between the damaged part and the glue injection groove of the sealing clamp so as to obtain safe construction pressure.

Further, the damage type includes a hole damage, and the safe construction pressure Psafe is obtained by the following formula:

Psafe＝157.05519-31.10771*ln(r+74.249)，

wherein the unit of the safe construction pressure Psafe is MPa, the damaged part of the pipeline is a porous structure, and r is the radius of the porous structure and the unit is mm.

Psafe＝247.00606-52.10033*ln(r+65.39911)，

Further, the damage type includes an axial fracture damage in an axial direction of the pipeline, and the safe construction pressure Psafe is obtained by the following formula:

Psafe＝25.55345-4.34022*ln(r-2.47777)，

wherein the unit of the safe construction pressure Psafe is MPa, and r is the damage length of the damaged part of the pipeline.

Further, the damage type includes a circumferential crack damage in a circumferential direction of the pipeline, and the safe construction pressure Psafe is obtained by the following formula:

Psafe＝23.80073-3.32896*ln(r-3.54268)，

Further, the temperature of the sealant when the sealant is injected into the cavity is T1, wherein T1 is more than 0 and less than or equal to 800 ℃.

Further, the using pressure of the sealant is P1, wherein P1 is less than or equal to 60 MPa.

Further, the temperature of the sealant before being injected into the cavity is T2, wherein the temperature is more than or equal to 90 ℃ and less than or equal to T2 and less than or equal to 120 ℃.

Further, the pressure of the sealant pushing device towards the cavity is P2, P3 is more than or equal to P2 is more than or equal to 70% of P4, and P3 is the rated pressure of the pipeline; p4 is safe construction pressure.

Further, the detection device comprises an ultrasonic flaw detector and an ultrasonic thickness gauge, when the thickness is less than or equal to 5mm, the ultrasonic flaw detector is used for detecting the pipeline, and when the thickness is less than 5mm, the ultrasonic thickness gauge is used for detecting the pipeline, wherein the thickness is the wall thickness of the pipeline.

Further, the sealing jig includes at least one of a flange jig, a single-groove ring jig, a double-groove jig, or a square box-shaped jig.

The technical scheme of the invention is applied, and the metal pipeline defect identification and welding-free maintenance method comprises the steps of establishing a damage data table, and establishing a functional relation between the damage working condition and the safe construction pressure in the damage data table. The damage working condition of the pipeline is detected through the detection device, and the safe construction pressure of the pipeline is determined by inquiring the damage data table according to the damage working condition determined after the detection of the detection device. And selecting a matched sealing clamp according to the determined safe construction pressure and damage working condition, installing the sealing clamp at the damage part of the pipeline, and forming a cavity between the sealing clamp and the outer wall of the pipeline. And injecting sealant into the cavity through the glue injection device so as to perform sealing maintenance on the damaged part of the pipeline, wherein the pressure generated by the sealant in the cavity is less than the safe construction pressure. The method effectively solves the problem that the pressure of the sealant is far greater than the safe construction pressure of the damaged pipeline due to blind injection of the sealant, so that the injected sealant further causes secondary damage to the pipeline, and the pipeline cannot be repaired.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 illustrates a flow diagram of an embodiment of a metal pipeline defect identification and weld-free repair method according to the present invention;

FIG. 2 illustrates a flow diagram of an embodiment of a leak site survey of a metal pipeline defect identification and weld-free repair method according to the present invention;

FIG. 3 shows a flow chart of an evaluation scheme of risk assessment software according to the present invention;

FIG. 4 illustrates a flow chart of a metal pipeline defect identification and weld-free repair method according to the present invention;

figure 5 shows a schematic structural view of a first sealing fixture according to the invention;

fig. 6 shows a schematic structural view from another perspective of the first sealing fixture according to the invention;

figure 7 shows a schematic structural view of a second sealing fixture according to the invention;

figure 8 shows a schematic structural view from another perspective of a second sealing fixture according to the present invention;

figure 9 shows a schematic structural view of a third sealing fixture according to the invention;

fig. 10 shows a schematic structural view from another perspective of a third sealing fixture according to the present invention;

figure 11 shows a schematic structural view of a fourth sealing fixture according to the invention;

FIG. 12 is a schematic view of a first embodiment of the present invention for sealing a damaged portion of a straight pipe section using a single groove sealing clamp;

FIG. 13 is a schematic diagram showing a second embodiment of sealing a straight pipe section flaw using a single groove sealing clamp according to the present invention;

FIG. 14 is a schematic diagram of a first embodiment of the present invention for sealing a damaged portion of a straight pipe section using a double groove sealing clamp; and

FIG. 15 is a schematic diagram of a second embodiment of the present invention for sealing a straight pipe section flaw using a double groove sealing clamp.

Wherein the figures include the following reference numerals:

10. sealing the clamp; 11. injecting agent holes; 12. a threaded hole; 20. injecting glue groove; 30. a flange; 40. a bolt lug plate; 50. a three-way pipe; 60. bending the pipe; 70. a pipeline.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

As shown in fig. 1 to 4, according to a first embodiment of the present invention, a method for identifying defects of a metal pipeline and repairing the metal pipeline without welding is provided. The method comprises the steps of establishing a damage data table, and establishing a functional relation between a damage working condition and safe construction pressure in the damage data table. The damage working condition of the pipeline is detected through the detection device, and the safe construction pressure of the pipeline is determined by inquiring the damage data table according to the damage working condition determined after the detection of the detection device. And selecting a matched sealing clamp according to the determined safe construction pressure and damage working condition, installing the sealing clamp at the damage part of the pipeline, and forming a cavity between the sealing clamp and the outer wall of the pipeline. And injecting sealant into the cavity through the glue injection device so as to perform sealing maintenance on the damaged part of the pipeline, wherein the pressure generated by the sealant in the cavity is less than the safe construction pressure.

In the embodiment, the method effectively solves the problem that the pressure of the sealant is far greater than the safe construction pressure of the damaged pipeline due to blind injection of the sealant, so that the injected sealant further causes secondary damage to the pipeline, and the pipeline cannot be repaired. The sealing effect is not achieved because the pressure of the injected sealant is too small. According to the metal pipeline defect identification and welding-free maintenance method, the pressure of the injected sealant can be well controlled through the simulated safe construction pressure, so that the sealing effect of the injected sealant is proper, and the construction safety and success rate are effectively guaranteed.

Further, the damage working condition comprises the material type of the pipeline, the damage type of the pipeline and the distance between the damage position and the glue injection groove of the sealing clamp. When the damage data table is established, fitting is carried out on the material type of the pipeline, the damage type of the pipeline and the distance between the damaged part and the glue injection groove of the sealing clamp so as to obtain safe construction pressure. The method can quickly find the defects of thinning or leakage of pipelines such as oil and gas pipeline stations, refinery plants, long-distance pipelines and the like due to corrosion, accurately position the defect positions and quickly detect and identify the defects, and provides a set of welding-free pressurized maintenance and repair method to solve the problems of potential safety hazards and blindness deficiency in the prior maintenance technology. The method can better meet the field emergency requirement, ensure the success rate of sealing operation, safely and timely maintain the accident pipeline and ensure the safe production.

Wherein the safe construction pressure Psafe is obtained by the following formula:

Psafe＝157.05519-31.10771*ln(r+74.249)，

the unit of the safe construction pressure Psafe is MPa, the damage part of the pipeline is a porous structure, and r is the radius of the porous structure and the unit is mm. If the ratio of the pipe diameter D of the pipeline to the wall thickness of the pipeline is 168/5, the pipeline internal pressure P of the pipeline, namely the pipeline operating pressure, is 6.4MPa, and the damage type comprises hole damage, namely round hole perforation, the damage data table is woven into risk evaluation software, and the data of corresponding parameters are subjected to damage simulation through the risk evaluation software to measure the safe construction pressure of the pipeline under various working conditions, as shown in the following table 1, the error condition of the safe construction pressure simulated through the damage data and the safe construction pressure calculated through a safe construction pressure formula is shown.

TABLE 1

Radius of circular hole/mm	2.5	5	7.5	10	12.5	15	20
								Simulation result P/MPa	21.5	21.5	20	19	19	18	16
Formula calculation result P/MPa	22	21	20.1	19.1	18.2	17.3	15.6
								Error%	2.3	2.3	0.5	0.5	4.1	3.9	2.5

Table 1 shows that the error between the simulation result and the formula calculation result is small under different circular hole damage sizes, that is, the difference between the calculation structures of the simulation result and the formula calculation result is very small, and the accuracy of the safety construction pressure calculation is effectively improved by adopting the method.

As shown again in table 2, the defect form is still a round hole, and when the pipe diameter is 89mm, the wall thickness is 4mm, and the operating pressure is 1.6MPa, the safe construction pressure Psafe is obtained by the following formula:

Psafe＝247.00606-52.10033*ln(r+65.39911)，

the simulation results and the formula calculation results are shown in table 2:

TABLE 2

Radius of circular hole/mm	2.5	5	7.5	10	12.5	15	20
								Simulation result P/MPa	26	26	26	21	19	18.6	14.5
Formula calculation result P/MPa	27.2	25.4	23.5	21.8	20.1	18.4	15.3
								Error%	4.6	2.3	9.6	3.8	5.8	1.0	5.5

The defect form is axial crack, when the pipe diameter is 168mm, the wall thickness is 5mm, the operation pressure is 6.4MPa, the internal pressure P of the pipeline is 6.4MPa, and the safe construction pressure Psafe is obtained by the following formula:

Psafe＝25.55345-4.34022*ln(r-2.47777)，

wherein the unit of the safe construction pressure Psafe is MPa, and r is the damage length of the damaged part of the pipeline, namely the length of the crack.

The simulation results and the formula calculation results are shown in table 3:

crack length/mm	5	10	15	20	40	60	80
								Simulation result P/MPa	21.5	17	15	12	11	7	7
Formula calculation result P/MPa	21.5	16.8	14.6	13.1	9.8	8.0	6.7
								Error%	0	1.2	2.7	9.2	10.9	14.3	4.3

The defect form is circumferential crack damage along the circumferential direction of the pipeline, and when the pipe diameter is 377mm, the wall thickness is 8mm, and the operating pressure P is 1.6MPa, the safe construction pressure Psafe is obtained by the following formula:

Psafe＝23.80073-3.32896*ln(r-3.54268)，

The simulation results and the formula calculation results are shown in table 4:

TABLE 4

Crack length/mm	5	10	15	20	40	60	80
								Simulation result P/MPa	22.5	17.9	15.5	15	10.5	10.5	10
Formula calculation result P/MPa	22.5	17.6	15.7	14.5	11.8	10.4	9.4
								Error%	0	1.7	1.3	3.3	12.4	1.0	6.0

The metal pipeline defect positioning detection method is characterized in that a proper equipment and technology and a process scheme of manual identification and identification are selected according to the field condition, the position, the shape, the size and the type of a pipeline defect are identified and judged, basic data are provided for formulation of a maintenance and first-aid repair scheme, and blindness in a maintenance process is effectively avoided. The main detection technology comprises nondestructive detection and manual identification. The flow chart of the detection scheme is shown in fig. 2, and the specific operation steps are as follows:

step 1: and (4) surveying the leakage site, knowing and surveying the basic condition information of the oil and gas pipeline to be detected on the site, and preparing for formulating a detection scheme. Mainly comprises the following aspects:

1) history: historical corrosion detection conditions, repair conditions, line change and construction conditions and the like of the pipeline to be detected.

2) Pipeline layout: three-way, flange and bent pipe.

3) The specification of the pipeline is as follows: including pipe diameter, wall thickness, operating pressure, temperature, etc.

4) Pipeline anticorrosive coating: pitch, coal tar, epoxy powder, insulation layers, and the like. When the pipe body is covered with the insulating layer, the detected position needs to be processed, a certain detection space is reserved, and the detection space is usually not less than 0.5 m.

5) The pipeline supporting system comprises: simple support, annular clamp, welding support and the like.

6) Difficulty in approaching the detected position: when the support pipeline is detected, a ladder with a firm and stable structure is used, preferably two or more operators assist, and the operators are responsible for safety monitoring. When detecting a pipeline under a pit, a ladder is used, and when oil and water are more under the pit, rain shoes or oil-resistant water-repellent protective clothing are worn. When detecting high temperature pipeline, need measure the body temperature earlier, when the temperature was too high, need take special high temperature resistant gloves.

7) The ambient environment: the situation of dangerous sources existing around the detected position can affect the specific positions of equipment, instruments, platforms and buildings which are operated.

8) Expected defect types: and predicting the defect types, corrosion cracks, perforations, pitting corrosion, puncture and the like of the pipeline according to the leakage condition.

Step 2: determining a detection scheme, and determining the detection sequence, the detection method, the time arrangement, the safety protection facilities, the detection personnel, the safety responsibility supervision personnel and the like according to the information mastered by the survey, wherein:

1) the detection sequence is determined according to the actual situation on site, the normal operation of the pipeline is considered, the normal production is not delayed, and the detection flexibility and the program simplicity are combined.

2) The buried pipeline needs to be determined whether to be excavated or not according to the surveying condition, the detection times and the detection positions of pipelines around a leakage point are determined according to different anti-corrosion layers and different conveying media, and the ground pipeline can be directly detected.

And step 3: the instrument and equipment inspection and detection preparation mainly comprises:

1) the wall thickness of the pipeline is determined to be more than 5mm, and ultrasonic flaw detection is used. The thickness was 5mm or less, and the thickness was measured by an ultrasonic thickness meter. Before detection, the equipment is subjected to connection inspection, the equipment integrity is checked, the equipment is calibrated, the detection range is set, and the diameter and the wall thickness of the pipeline are marked. Selecting the detection position of the pipe section, measuring the temperature of the pipe body, processing the surface of the pipeline and the like.

2) The method can be used for manually identifying the exposed pipeline on the ground or the excavated pipeline which can be seen directly to see the pipeline defect, and measuring and determining the shape, the type and the size of the pipeline leakage defect.

And 4, step 4: carrying out detection, mainly comprising:

1) and detecting the pipeline body by using a portable ultrasonic flaw detector or an ultrasonic thickness gauge. Firstly, scanning is carried out, and the whole scanning is carried out on the area of the pipe section to be detected. When the defect reflection wave is found, the attenuator is adjusted to determine the area where the maximum reflection wave amplitude of the defect is located, so as to measure the plane position and the buried depth of the defect and record the position and the area where the wave amplitude is located.

2) For a pipeline section with a long buried distance, a proper position is required to be selected for excavation detection, and an anticorrosive coating of the pipeline section is stripped for detection; for pipelines with serious ultrasonic signal attenuation, such as wax crude oil, asphalt anti-corrosion layers or severely corroded pipe sections, the initial detection range can be properly shortened, and a close-spaced and multi-point measurement method is adopted to collect more detection data so as to facilitate analysis.

And 5: analyzing the detection result, analyzing the detection data and diagnosing the pipeline detection result. Marking the basic properties of the pipelines such as flanges, bent pipes, branch pipes, instruments and the like. Marking the buried position and the anticorrosive layer position, comparing and analyzing the detection data of different positions of the same pipe section and the data of the same position, superposing and analyzing, judging the circumferential positions of the defects and observing the defects, and classifying the severity of the defects.

Step 6: and rechecking, namely rechecking the result once or for many times to ensure the accuracy of the test result.

And carrying out verification and rechecking according to the defect diagnosis result. And after analyzing and comparing the detection results, rechecking and analyzing the pipe sections with suspicious defects, and comparing and analyzing the results with the previous detection results to determine the position of the pipe sections to be excavated. Determining the pipe section with the defect, marking the position of the defect, observing the corrosion condition of the pipe wall, and finely scanning the defect to determine the position, the property and the size of the defect by adopting other nondestructive detection means such as ultrasonic guided waves, magnetic powder, eddy current and the like according to different positions and conditions of the defect.

The metal pipeline defect risk evaluation scheme is characterized in that the stress and deformation conditions of the pipeline are simulated through software simulation in different defect forms (round holes, cracks, pits, fractures and the like) and in the defect sizes of the pipeline, the influence rules of different leakage defects on the pipeline damage are determined, risk analysis is conducted on the reasons of easy leakage and damage of the pipeline and the defect forms, risk evaluation analysis software is compiled, and a basis is provided for the formulation of a maintenance and first-aid repair scheme.

The programmed risk evaluation analysis software can analyze the pipeline defects detected on site, determine the influence of the pipeline defects on the normal operation of the pipeline, provide basis for the selection of tools, the size of safe construction pressure and the like in a maintenance and first-aid repair scheme, and facilitate the field use. The evaluation scheme flow chart is shown in fig. 3, and the specific operation steps are as follows:

step 1: analyzing the pipeline breakage reason and the defect form, comprising:

1) and (3) investigating and researching the specification parameters of the pipeline, problems existing in use, accident repair time, places, reasons, repair process technologies, relevant production, installation and maintenance standards and the like.

2) And analyzing and determining the reasons of easy leakage and breakage of the pipeline and the defect forms (round holes, cracks, pockmarks, fractures and the like) according to the investigation result.

Step 2: simulation of pipeline defects, comprising:

1) and testing relevant mechanical parameters of the pipeline.

2) And (3) establishing a mechanical model by using ANSYS software (or other mechanical analysis software) to simulate the stress and deformation conditions of the pipeline in different defect forms and defect sizes.

3) And determining the influence rule of different leakage defects on pipeline damage by combining the investigation and analysis results.

And step 3: and compiling risk evaluation software, performing risk analysis on the easily-leaked and damaged pipeline points, and compiling the risk evaluation software.

The welding-free pressurized maintenance first-aid repair scheme is a technical scheme that a corresponding pressurized sealing tool is used for welding-free pressurized sealing maintenance aiming at the pipeline defect condition and the defect risk evaluation result determined according to the pipeline defect positioning detection scheme, so that potential safety hazards or leakage points are eliminated, and the safe and normal operation of a pipeline is ensured. The method mainly comprises a tool selection scheme and a safe construction pressure determination scheme. The tool selection scheme is that proper sealing clamps and construction tools are processed and selected according to different defects of the pipeline and different influences on normal operation of the pipeline, and maintenance and first-aid repair are purposefully performed on the pipeline. The safe construction pressure determination scheme is characterized in that factory inspection, sealing performance test and safe construction pressure test are carried out on a sealing fixture (fixture for short) through a testing platform of the fixture, and software simulation (ANSYS and other mechanical analysis software) is combined to ensure the stability of the fixture in the construction process, determine the safe construction pressure of pressure sealing under the conditions of different defects and ensure the success rate of maintenance and repair schemes. The maintenance and first-aid repair scheme flow chart is shown in fig. 4, and the specific operation steps are as follows:

step 1: the selection of the sealing clamp determines the form of the used sealing clamp and the construction tool according to the different defect positions (such as flanges, straight pipe sections, elbows, tees and the like), defect shapes (such as longitudinal cracks, axial cracks, oblique cracks, point leakage, corrosion thinning and the like), defect sizes (such as crack lengths, leakage point sizes, corrosion degree of inner and outer walls of the pipeline and the like) and the different influences on the normal operation of the pipeline.

And a flange clamp is selected for the flange part defect. A single-groove annular fixture is generally selected for point leakage and single crack of the straight pipe section. The straight pipe section has leakage, cracks, corrosion, thinning and the like at multiple points, and a double-groove tubular clamp is generally selected. The leakage of the tee joint and the elbow is generally selected from a square box-shaped clamp. If the conditions that the overall reduction of the pipe wall is caused by overlong cracks, overlarge leakage points and overall corrosion of the inner wall and the outer wall of the pipeline, the overall strength of the pipeline is too low, the strength of the pipeline at the glue injection pressure point of the clamp is too low and the like are detected, the pipeline cannot be maintained by using the sealing clamp, and the pipeline needs to be replaced in a production stop manner.

Step 2: and (3) manufacturing and quality inspection of the sealing clamp, designing and processing the used clamp according to the corrosion requirement of the pipe conveying medium and the actual clamp requirement of field survey, and inspecting the quality of the sealing clamp by using a sealing clamp experiment platform. A schematic view of the clamp configuration is shown in fig. 5-15, wherein the sealing clamp 10 is placed on a pipeline 70 to seal it, as shown in fig. 5, wherein 30 is a flange, as shown in fig. 6, and wherein fig. 6 shows the bolt ear plate 40 on the sealing clamp 10. Fig. 7 shows a schematic view of the sealing jig 10 for sealing the tee 50, fig. 8 shows a schematic view of the sealant injection hole 11 of the sealing jig 10, fig. 9 shows a schematic view of the sealing jig 10 for sealing the elbow 60, wherein the sealing jig 10 is provided with a threaded hole 12, and fig. 12 to 15 show a schematic view of the sealant injection groove 20 of the sealing jig 10 for sealing the damage.

The clamp is generally of a double-sided arc structure and is divided into an upper plate and a lower plate, the inner diameter of the arc surface of the clamp is the same as the outer diameter of a pipeline, the upper plate and the lower plate are connected through clamping lugs with bolts, two strip-shaped sealing grooves are formed in the joint, the joint surface of the upper plate and the lower plate can be sealed after sealant is injected, two annular glue injection grooves are formed in two sides of the clamp, and the pipeline and the clamp can be sealed after the sealant is injected. The upper and lower discs of the single-groove annular clamp are provided with grooves which are buckled to form an annular sealing cavity. The upper and lower discs of the double-groove tubular fixture are respectively provided with a strip-shaped glue injection groove, four mutually-connected sealing cavities are formed after buckling, namely two annular sealing cavities at two ends of the fixture and two strip-shaped sealing cavities at the joint surface of the upper and lower discs. The gap between the joint surfaces of the upper and lower discs of the fixture is less than 0.1 mm. The agent injection holes are uniformly arranged along the sealing cavity, and the distance between a straight line and an arc line between the two holes is smaller than 100 mm. The flange clamps are usually designed and processed according to the shape and size of the flange, and the square box-shaped clamps are determined according to the actual conditions of leakage parts such as a tee joint, an elbow and the like. The material of the sealing clamp is generally steel for a boiler pressure container according to the requirement of medium corrosivity; the wall thickness of the sealing jaws is determined by the nominal pressure of the pipeline.

For the defects that the corrosion area is large, the pitting corrosion is connected into sheets, the cracks are long, the area is large, and the like, but the defects are in a maintainable range, a lining protection sheet can be added into a clamp to seal under pressure, and the single-groove annular clamp needs to use the lining protection sheet. The protective lining is designed to prevent the sealant from entering the pipeline to contact with the pipe conveying medium or prevent the sealant from contacting with the pipe wall due to overlarge resistance when the single-groove clamp is used. The lining sheet (the wall thickness is generally 6mm) is manufactured according to the specification and the size of the annular groove of the fixture, the lining sheet is divided into an upper disc and a lower disc which are in staggered lap joint, the lining sheet is clamped on the annular groove to be filled, the edge can be processed into a sawtooth shape or a sharp edge according to actual needs, and the lining sheet is generally made of 45# steel according to the medium corrosivity requirement. After the fixture is manufactured and processed, the sealing fixture experiment platform is used for carrying out factory inspection, sealing performance test and safe construction pressure test on the fixture, and the safety and the stability of the fixture in the construction process are ensured.

Under the common condition, corresponding clamps are stored and inspected aiming at points which are easy to have defects and leak in oil field pipelines, so that the on-site emergency requirement is met.

And step 3: the determination of safe construction pressure comprises the following steps:

1) and testing the maximum elastic pressure which can be borne by the pipeline in the sealing agent injection process, namely the safe construction pressure by using the sealing clamp test platform to obtain the measurement results of the safe construction pressure under different pipeline parameters and defect forms.

2) And (4) performing simulation by using software (mechanics analysis software such as ANSYS) to determine the safe construction pressure under different conditions.

3) Comparing simulation and experimental results, optimizing and improving the simulation model to obtain a mechanical model according with actual conditions, further determining an empirical formula for calculating the safe construction pressure, and compiling safe construction pressure calculation software.

And 4, step 4: exempt from to weld and take pressure to press sealing operation includes:

1) selecting a non-curing sealant, wherein the use temperature is 0-800 ℃, the use pressure is less than 60MPa, and the sealant is heated to 90-120 ℃ before injection operation.

2) And (4) checking and confirming the defect condition of the pipe section in contact with the sealant before operation, and calculating and determining the safe construction pressure of the field condition through software.

3) And (4) carrying out pressurized sealing construction operation, wherein the glue injection pressure is controlled to be less than 70% of the safe construction pressure of the pipeline and not less than the rated pressure of the pipeline during operation.

And 5: and (4) after-treatment of construction, completely wrapping the sealing clamp by using a slip type plastic rubber sleeve after the construction is finished, attaching a certain mass of butter for corrosion prevention, and performing landfill recovery on the excavated pipe section.

The metal pipeline defect positioning detection scheme is a process scheme of selecting proper equipment, technology and manual identification and recognition by combining with the actual situation on site, the used nondestructive detection method has the characteristics of rapidness, accuracy and the like, is applied to the defect detection of in-service oil and gas pipelines, obtains the pipeline defect situation at the fastest speed by the minimum workload of underground pipeline excavation and anticorrosive coating stripping, and provides a detection basis for implementing pipeline under-pressure maintenance and ensuring the pipeline operation safety in the maintenance process.

The stress and deformation conditions of the pipeline are simulated by software simulation when different defect forms and defect sizes of the pipeline are different, and risk analysis is carried out on the reason that the pipeline is easy to leak and damage and the defect form. The programmed risk evaluation analysis software can analyze the pipeline defects detected on site, determine the influence of the pipeline defects on the normal operation of the pipeline, provide basis for the selection of the sealing clamp and the installation position, the magnitude of safe construction pressure and the like in the maintenance and repair scheme, and facilitate the definition of construction parameters.

The welding-free pressurized maintenance first-aid repair scheme is a technical scheme that a corresponding pressurized sealing tool is used for welding-free pressurized sealing maintenance according to the pipeline defect condition and the defect risk evaluation result determined by the pipeline defect positioning detection scheme, so that potential safety hazards or leakage points are eliminated, and normal operation of a pipeline is ensured. The scheme designs and processes or selects a proper sealing tool according to the actual situation on site, and performs welding-free maintenance and first-aid repair, and performs quality inspection on the used sealing tool before construction, so that the stability of the sealing tool in the construction process can be ensured. The determination of the safe construction pressure can ensure that the glue injection point can avoid the damage point of the pipeline, provide a safe construction pressure value, avoid the blindness of glue injection and effectively ensure the safety and the success rate of construction.

The method can quickly and accurately detect and identify the defects of the metal pipeline and implement the welding-free pressurized maintenance repair process method for the defect points, and can safely and effectively finish the pipeline repair of different pipe sections, different defects and different pressure grades. And each technical performance index of the repaired pipeline is not lower than that of the original pipeline design, so that the on-site emergency requirement is met, and the method has important significance for further development of pipeline damage leakage maintenance technology.

In the metal pipeline defect identification and welding-free maintenance method, the temperature of the sealant injected into the cavity is T1, wherein T1 is more than 0 and less than or equal to 800 ℃. The using pressure of the sealant is P1, wherein P1 is less than or equal to 60 MPa. The temperature of the sealant before being injected into the cavity is T2, wherein the temperature is more than or equal to 90 ℃ and less than or equal to T2 and less than or equal to 120 ℃.

The pressure of the glue injection device for pushing the sealant into the cavity is P2, P3 is more than or equal to P2 is more than or equal to 70% of P4, P3 is the rated pressure of the pipeline, and P4 is the safe construction pressure.

According to the second embodiment of the present invention, a seamless steel pipe having a pipe length of about 2.8km, an operating pressure of 3.4MPa, an outer diameter of 219mm and a wall thickness of 5mm, for example, for the inspection and maintenance of an aqueous crude oil pipeline in a transfer station, comprises:

1. and (3) positioning and detecting the defects of the pipelines:

step 1: and (4) surveying the site, and investigating the basic condition information of the pipe section to prepare for the detection scheme. The method mainly comprises the following steps:

1) history: the pipeline runs for more than 18 years, partial pipe sections are seriously corroded and scaled, pipe breakage and pipe leakage occur for a plurality of times, and the pipeline is repaired for more than 10 times in an accumulated way.

2) Pipeline layout: three-way, flange and bent pipe.

3) The specification of the pipeline is as follows: the diameter of the pipeline is phi 219mm, the wall thickness is 5mm, and the operating pressure is 3.4 MPa.

4) Pipeline anticorrosive coating: the insulation layer, the detected position does not need to be processed.

5) The pipeline supporting system comprises: and (5) simply supporting.

6) Difficulty in approaching the detected position: special high temperature resistant gloves are worn.

7) The ambient environment: there are no potential sources of danger around the detected location.

8) Expected defect types: corrosion cracks, perforations, and punctures.

Step 2: determining a detection scheme, determining the detection sequence, the detection method, the time arrangement, the safety protection facilities, the detection personnel, the safety responsibility supervision personnel and the like according to the information mastered by the survey, and comprising the following steps:

1) during detection, normal production is not delayed on the premise of actual field conditions.

2) The insulating layer is stripped, no leakage is generated around the leakage point, and the detection can be directly carried out.

And step 3: the instrument equipment examination and detection preparation comprises the following steps:

1) the pipe section had a wall thickness of 5mm and was inspected by ultrasonic. And finding thinned and problematic pipe sections, and measuring by using an ultrasonic thickness gauge.

2) The method comprises the steps of carrying out connection check on equipment, checking the integrity of the equipment, connecting the equipment, checking the integrity of a cable, whether the cable is fully charged or not and the like.

3) And calibrating the equipment, setting a detection range, and marking the diameter and the wall thickness of the pipeline.

4) Selecting a proper detection position, and avoiding larger reflection characteristics (such as flanges and the like) or placing the detection position in a detection blind area as much as possible;

5) the temperature of the tube body is measured.

6) The surface of the pipeline is cleaned, so that enough space is exposed around the pipe body, and the inspection is facilitated.

And 4, step 4: developing a test comprising:

1) firstly, the position of leakage and seepage is manually identified, and the shape, type and size of the leakage are measured and determined. The flange connection part is found to have the puncture through manual identification.

2) And (3) coating the coupling agent in the positions of the rest pipe sections to be detected, namely the range of the probe moving area, and detecting by adopting the probe of the ultrasonic detector. Scanning all the cross sections and two sides of the welding seam, performing sawtooth scanning, wherein the moving speed of the probe is not more than 150mm/s, the displacement of the probe along the welding seam direction should be overlapped by 15% every time, and parallel or oblique parallel scanning should be performed on two sides of the welding seam in order to detect transverse defects.

3) When the defect reflection wave is found, the attenuator is adjusted to determine the area where the maximum reflection wave amplitude of the defect is located, so as to measure the plane position and the buried depth of the defect and record the position and the area where the wave amplitude is located.

4) When the defect of wall thickness reduction such as corrosion reduction is found, further detection and confirmation are carried out by using an ultrasonic thickness gauge, and the position is recorded.

And 5: analyzing the detection result, comprising:

1) marking the known basic properties of the pipeline such as flanges, bent pipes, branch pipes, instruments and the like.

2) And marking the buried position and the anticorrosive layer position.

3) Comparing and analyzing detection data of different positions of the same pipe section and an analysis method such as superposition of data of the same position, judging the axial and circumferential positions of the defects and observing the defects, and classifying the severity of the defects; the analysis shows that the straight pipe of the pipe section has no leakage condition, and the flange joint has puncture.

Step 6: and (4) rechecking, namely rechecking and analyzing the detection result, and comparing and analyzing the result with the previous detection result.

And 7: and (5) obtaining a detection conclusion.

The method is used for testing and detecting the pipe section, and is ideal when the leakage exists at the flange connecting part and the corrosion conditions of other pipe sections are similar and the leakage detection is avoided.

2. And (3) carrying out risk analysis on the defects:

and risk analysis is carried out on the flange through the compiled risk evaluation software to obtain that: the puncture is small at the position, the corrosion conditions of the surrounding pipe sections are similar, and the internal pressure is not more than 22.5 MPa.

3. The method is characterized in that the pipe section defect is subjected to maintenance repair without welding and pressure, and the steps are as follows:

step 1: and selecting a sealing clamp, wherein the leakage point is positioned at the flange and is small-area leakage, selecting the flange clamp, and the structure of the clamp is shown in figure 5.

Step 2: and (3) manufacturing and quality inspection of the sealing clamp, selecting a flange clamp which is manufactured, processed and subjected to quality inspection from a clamp storage library, wherein the clamp is made of steel for a boiler pressure container and has the wall thickness of 15 mm. The glue injection holes are distributed in 8 holes, the groove depth of the glue injection groove is 10mm, and the gap between the joint surface of the clamp and the pipe section is less than 0.5 mm.

And step 3: and determining safe construction pressure, and calculating by using various basic parameters brought by the programmed safe construction pressure calculation software, wherein the theoretical safe construction pressure is 19.2MPa, the pressure of the pipeline in the agent injection process is not more than 22.5MPa, and the pressure of the agent injection is not more than 35 MPa.

And 4, step 4: the welding-free pressurized sealing operation is carried out by selecting a non-curing sealing injection agent, wherein the use temperature is 0-800 ℃, and the use pressure is less than 60 MPa. And (3) checking and confirming the defect condition of the flange contacting with the sealant, heating the sealant to 90-120 ℃ before use, injecting the sealant along the injection holes in sequence, controlling the injection pressure to be below 30MPa during operation, increasing the injection pressure to 35MPa after full injection, stopping injecting the sealant, and sealing the injection holes by bolts.

And 5: and (4) post-construction treatment, namely wrapping the sealing clamp by using a slip type plastic rubber sleeve after construction is finished, and attaching grease with certain mass inside for corrosion prevention.

According to the third embodiment of the invention, the detection and maintenance of the pipeline of the sewage discharge line of a certain united station, which take the spiral weld steel pipe with the length of 11500m, the operating pressure of 2.2MPa, the outer diameter of 325mm and the wall thickness of 5mm as an example, comprises the following steps:

1. the method for positioning and detecting the pipeline defects comprises the following steps:

1) history: the pipeline runs for about 23 years, partial pipe sections are seriously corroded and scaled, pipe breakage and pipe leakage occur for a plurality of times, and the accumulated repair is carried out for 11 times.

2) Pipeline layout: three-way, flange and bent pipe.

3) The specification of the pipeline is as follows: the diameter of the pipeline is 325mm, the wall thickness is 5mm, and the operating pressure is 2.2 MPa.

4) Difficulty in approaching the detected position: most of the pipe sections are buried underground, oil and water are more under a pit, and the ladder is needed to be used for wearing the oil-resistant and water-repellent protective clothing.

5) The ambient environment: there are no potential sources of danger around the detected location.

6) Expected defect types: corrosion cracking, perforation, pitting.

Step 2: and determining a detection scheme, and determining the detection sequence, the detection method, the time arrangement, the safety protection facilities, the detection personnel, the safety responsibility supervision personnel and the like according to the information mastered by the survey.

2) Whether the buried part of the pipe section is excavated is determined according to the situation; and after excavation, stripping the anticorrosive layer, and determining the detection times and detection position selection of the pipeline around the leakage point.

3) The detection method comprises the following steps: detecting signals of partial ground pipe sections are clear, detecting each section once to find suspicious problem pipe sections, and performing key investigation; most of the buried pipe sections determine the detection times and the detection positions of each section of the pipeline according to the conditions.

1) the wall thickness of the pipe section is 5mm, and ultrasonic flaw detection is used; and finding thinned and problematic pipe sections, and measuring by using an ultrasonic thickness gauge.

2) Performing connection inspection on the equipment to inspect the integrity of the equipment; connecting the equipment, checking the cable integrity, whether it is fully charged, etc.

4) And selecting a proper detection position to avoid large reflection features (such as flanges and the like) or place the detection position in a detection blind area as far as possible.

5) The temperature of the tube body is measured.

And 4, step 4: developing a test comprising:

1) firstly, manually identifying the positions where leakage and seepage occur, and measuring to determine the shape, type and size of the leakage; the artificial identification shows that a diagonal crack exists at a position 340km away from the entrance.

2) Coating a coupling agent on the positions of the rest pipe sections to be detected, namely within the range of the probe moving area, and detecting by adopting an ultrasonic detector probe; scanning all the cross sections and two sides of the welding seam, performing sawtooth scanning, wherein the moving speed of the probe is not more than 150mm/s, the displacement of the probe along the welding seam direction should be overlapped by 15% every time, and parallel or oblique parallel scanning should be performed on two sides of the welding seam in order to detect transverse defects.

And 5: analyzing the detection result, comprising:

2) And marking the buried position and the anticorrosive layer position.

3) Comparing and analyzing detection data of different positions of the same pipe section and an analysis method such as superposition of data of the same position, judging the axial and circumferential positions of the defects and observing the defects, and classifying the severity of the defects; analysis shows that the pipe section has one corrosion crack, the pipe wall around the crack is integrally thinned, and leakage occurs.

And 7: and (5) obtaining a detection conclusion.

The pipe section is tested and detected by the method, and is verified by means of excavation, anti-corrosion layer removal and the like, an inclined crack with the length of 17mm is found at a position 340km away from an inlet, the pipe wall around the crack is integrally thinned, and leakage occurs; the corrosion conditions of other pipe sections are similar, and the detection is not missed, so that the method is ideal.

2. And (3) carrying out risk analysis on the defects, and carrying out risk analysis on the pipe section through compiled risk evaluation software to obtain that: the crack is small, and the surrounding pipe wall is thinned, but the influence on the pressure bearing capacity of the pipeline is weak; the pressure bearing of the pipeline is not more than 20.1 MPa.

step 1: and (3) selecting a sealing clamp, wherein a corrosion leakage point is positioned on the straight pipe section and is far away from the flange, the elbow, the tee joint and the like, the corrosion form is an oblique crack, the length is small, and the straight pipe section single-groove annular clamp needs to be selected.

Step 2: manufacturing a sealing clamp and inspecting quality, wherein a single-groove annular clamp which is manufactured, processed and subjected to quality inspection is selected from a clamp storage library, the clamp is made of steel for a boiler pressure container, and the wall thickness of the clamp is 15 mm; the fixture is a double-arc-surface structure, the common single-groove annular fixture is provided with 6 holes for glue injection, the groove depth of the glue injection groove is 10mm, and the gap between the fixture and the joint surface of the pipe section is less than 0.5 mm. The lining protection slips are used, and the materials of the lining protection slips are 45# steel according to the requirement of corrosion resistance.

And step 3: determining safe construction pressure, and using the programmed safe construction pressure calculation software to bring various basic parameters into calculation to obtain: the theoretical safe construction pressure is 19.3 MPa; the pressure of the pipeline in the agent injection process is not more than 20.1MPa, and the pressure of the agent injection process is not more than 35 MPa.

And 4, step 4: the welding-free pressurized sealing operation is carried out by selecting a non-curing sealing injection agent, wherein the use temperature is 0-800 ℃, and the use pressure is less than 60 MPa. And (3) checking and confirming the defect condition of the pipe section in contact with the sealant, heating the sealant to 90-120 ℃ before use, injecting the sealant along the injection holes in sequence, controlling the injection pressure to be below 30MPa during operation, increasing the injection pressure to 35MPa after full injection, stopping injecting the sealant, and sealing the injection holes by using bolts.

And 5: and (4) after construction, completely wrapping the sealing clamp by using a slip type plastic rubber sleeve after construction is finished, and attaching a certain mass of butter for corrosion prevention.

According to the fourth embodiment of the invention, the detection and maintenance of the crude oil long-distance pipeline are taken as examples of seamless steel pipes with the length of about 20km, the operating pressure of 6.4MPa, the outer diameter of 168mm and the wall thickness of 5 mm.

1. And (3) positioning and detecting the defects of the pipelines: the method comprises the following steps:

1) history: the pipeline operates for more than 10 years, the corrosion and scaling phenomena of partial pipe sections are serious, pipe breakage and pipe leakage occur for a plurality of times, large-area pollution is caused, and the accumulated repair is carried out for 21 times.

2) Pipeline layout: three-way, flange and bent pipe.

3) The specification of the pipeline is as follows: the diameter of the pipeline is phi 168mm, the wall thickness is 5mm, the operating pressure is 6.4Mpa, the inlet temperature is 35 ℃, and the outlet temperature is 60 ℃.

4) Pipeline anticorrosive coating: an insulating layer; the detected position needs to be processed, and a detection space of 0.8 m is reserved.

5) The pipeline supporting system comprises: and (5) simply supporting.

8) Expected defect types: corrosion cracking, perforation, pitting.

5) The temperature of the tube body is measured.

And 4, step 4: developing a test comprising:

1) firstly, manually identifying the positions where leakage and seepage occur, and measuring to determine the shape, type and size of the leakage; and manually identifying that one corrosion perforation leaks at a position 10.7km away from the terminal point, and the rest pipe sections have no leakage.

And 5: analyzing the detection result, comprising:

2) And marking the buried position and the anticorrosive layer position.

3) Comparing and analyzing detection data of different positions of the same pipe section and an analysis method such as superposition of data of the same position, judging the axial and circumferential positions of the defects and observing the defects, and classifying the severity of the defects; the analysis shows that the pipe section has a corrosion perforation with the diameter of 2.5mm, scaling is formed around the pipe section, but no corrosion thinning occurs.

And 7: the detection conclusion is obtained, the pipe section is tested and detected by the method, and the means of excavation, anti-corrosion layer removal and the like are used for verification, so that the corrosion perforation hole with the diameter of 2.5mm is found at the position 10.7km away from the outlet, the corrosion conditions of the other pipe sections are all similar, and the pipe section is free from corrosion thinning and leakage detection, and is ideal.

2. And (3) carrying out risk analysis on the defects, and carrying out risk analysis on the pipe section through compiled risk evaluation software to obtain that: the corrosion perforation with the diameter of 2.5mm has small leakage, the corrosion conditions of the surrounding pipe sections are similar, the pipe sections are thinned without corrosion, and the internal pressure of the pipeline is not more than 22.8 MPa.

step 1: and (3) selecting a sealing clamp, wherein a corrosion leakage point is positioned on the straight pipe section and is far away from the flange, the elbow, the tee joint and the like, the corrosion mode is pitting corrosion, the leakage area is small, and the straight pipe section single-groove annular clamp needs to be selected.

Step 2: and (3) manufacturing and quality inspection of the sealing clamp, selecting a single-groove annular clamp which is manufactured, processed and subjected to quality inspection from a clamp storage library, wherein the clamp is made of steel for a boiler pressure container and has the wall thickness of 15 mm. The fixture is a double-arc-surface structure, the common single-groove annular fixture is provided with 6 holes for glue injection, the groove depth of the glue injection groove is 10mm, and the gap between the fixture and the joint surface of the pipe section is less than 0.5 mm. And a lining protective slip is attached.

And step 3: determining safe construction pressure, and using the programmed safe construction pressure calculation software to bring various basic parameters into calculation to obtain: the theoretical safe construction pressure is 23.9 MPa; the pressure of the pipeline in the agent injection process is not more than 22.8MPa, and the pressure of the agent injection process is not more than 35 MPa.

And 5: and (4) after-treatment of construction, completely wrapping the sealing clamp by using a slip type plastic rubber sleeve after the construction is finished, and internally attaching butter for corrosion prevention.

According to the fifth embodiment of the invention, taking the spiral weld steel pipe with the pipe length of 2784m, the operating pressure of 1.8MPa, the outer diameter of 219mm and the wall thickness of 7mm as an example, the detection and maintenance of the oily sewage treatment pipeline comprise:

1) history: the pipeline runs for about 5 years, partial pipe sections are seriously corroded and scaled, pipe breakage and pipe leakage occur for a plurality of times, and the accumulated repair is carried out for 12 times.

2) Pipeline layout: three-way, flange and bent pipe.

3) The specification of the pipeline is as follows: the diameter of the pipeline is phi 219mm, the wall thickness is 7mm, the operating pressure is 1.8Mpa, the station-entering temperature is 48 ℃, and the station-exiting temperature is 35 ℃.

4) Pipeline anticorrosive coating: an asphalt layer; the detected position needs to be processed, and a detection space of 0.7 m is reserved.

5) Difficulty in approaching the detected position: most of the pipe sections are buried underground, oil and water are more under a pit, and the ladder is needed to be used for wearing the oil-resistant and water-repellent protective clothing.

6) The ambient environment: there are no potential sources of danger around the detected location.

7) Expected defect types: corrosion cracking, perforation, pitting.

Step 2: determining a detection scheme, determining the detection sequence, the detection method, the time arrangement, the safety protection facilities, the detection personnel, the safety responsibility supervision personnel and the like according to the information mastered by the survey, and mainly comprising the following steps:

2) Whether the buried part of the pipe section is excavated is determined according to the situation; and after excavation, stripping an asphalt layer, and determining the detection times and detection position selection of the pipeline around the leakage point.

1) the wall thickness of the pipe section is 7mm, and ultrasonic flaw detection is used; and finding thinned and problematic pipe sections, and measuring by using an ultrasonic thickness gauge.

5) The temperature of the tube body is measured.

And 4, step 4: developing a test comprising:

1) firstly, manually identifying the positions where leakage and seepage occur, and measuring to determine the shape, type and size of the leakage; and manually identifying that a plurality of leakage points exist at one position of the pipe section, and leakage occurs.

And 5: analyzing the detection result, comprising:

2) And marking the buried position and the anticorrosive layer position.

3) And comparing and analyzing the detection data of different positions of the same pipe section and the data of the same position, superposing and other analysis methods, judging the axial and circumferential positions of the defects and observing the defects, and classifying the severity of the defects. Analysis shows that the pipe section is provided with a corrosion perforation with a larger area, the pipe wall of the part is integrally thinned, two 11mm long-axis cracks almost in a parallel state are arranged at a distance of 6mm, a plurality of corrosion perforations with the diameter of about 2mm are arranged around the cracks, and leakage occurs; the defect as a whole forms a substantially circular area of 18mm diameter.

And 7: the conclusion is that the pipe section is tested and detected by the method, and is verified by means of excavation, anti-corrosion layer removal and the like, a corrosion defect with a large area is found at a position 1203m away from an inlet, the pipe wall of the position is integrally thinned, two 11mm long-axis cracks almost in a parallel state are formed, the distance is 6mm, a plurality of corrosion through holes with the diameter of about 2mm are formed around the cracks, and leakage occurs; the whole defect approximately forms a circular area with the diameter of 18mm, the corrosion conditions of other pipe sections are similar, and the defect is free from missing detection and is ideal.

2. And (3) carrying out risk analysis on the defects, and carrying out risk analysis on the pipe section through compiled risk evaluation software to obtain that: the pipe section has more leakage points, the pipe wall is integrally thinned, and the pressure bearing capacity of the pipeline is weaker; the pressure of the pipeline is less than 18.5 MPa.

step 1: the selection of the sealing clamp, wherein a corrosion leakage point is positioned on the straight pipe section and is far away from the flange, the elbow, the tee joint and the like, the corrosion area is large, the pipe wall is integrally thinned, cracks and pitting corrosion exist, and the straight pipe section double-groove tubular clamp is required to be selected.

Step 2: manufacturing and quality inspection of a sealing clamp, selecting a double-groove type clamp which is manufactured, processed and subjected to quality inspection from a clamp storage library, wherein the clamp is made of steel for a boiler pressure container and has the wall thickness of 15 mm; the fixture is a double-cambered surface structure, the common double-groove tubular fixture adopts 8-hole type glue injection holes for the annular sealing cavities, 6-hole type glue injection holes for the strip-shaped sealing cavities, the groove depth of the glue injection groove is 10mm, the width of the glue injection groove is 20mm, and the gap between the fixture and the joint surface of the pipe section is less than 0.5 mm.

Because the corrosion area at the position is large, the crack is long and a plurality of pitting corrosion exists, but in the maintainable range, the clamp is required to be lined with a protective slip for sealing under pressure. Manufacturing lining slips according to the specification and the size of the annular groove of the clamping apparatus, wherein the wall thickness is 6mm, the outer diameter is 220mm, the lining slips are overlapped in a staggered way by an upper disc and a lower disc, and the lining slips are clamped on the annular groove to be filled; the lining protection slip material is 45# steel according to the corrosion resistance requirement.

And step 3: determining safe construction pressure, and using the programmed safe construction pressure calculation software to bring various basic parameters into calculation to obtain: the theoretical safe construction pressure is 16.3 MPa; the pressure of the pipeline in the agent injection process is not more than 18.5MPa, and the pressure of the agent injection process is not more than 35 MPa.

And 4, step 4: the welding-free pressurized sealing operation is carried out, a non-curing sealing injection agent is selected, the use temperature is 0-800 ℃, and the use pressure is less than 60 MPa; and (3) checking and confirming the defect condition of the pipe section in contact with the sealant, heating the sealant to 90-120 ℃ before use, injecting the sealant along the injection holes in sequence, controlling the injection pressure to be below 30MPa during operation, increasing the injection pressure to 35MPa after full injection, stopping injecting the sealant, and sealing the injection holes by using bolts.

And 5: and (4) after-treatment of construction, completely wrapping the sealing clamp by using a slip type plastic rubber sleeve after the construction is finished, and attaching grease with certain mass inside for corrosion prevention.

According to the sixth embodiment of the present invention, taking the seamless steel pipe with the length of 800m, the operating pressure of 1.7MPa, the outer diameter of 377mm and the wall thickness of 6mm as an example, the detection and maintenance of a section of soft water pipeline of a gathering and transportation pipe network of a certain infusion and transportation combined station comprises:

1) history: the pipeline runs for about 4 years, the whole running condition is good, and the accumulated repair is carried out for 1 time.

2) Pipeline layout: three-way, flange and bent pipe.

3) The specification of the pipeline is as follows: the diameter of the pipeline is phi 377mm, the wall thickness is 6mm, and the operating pressure is 1.7 Mpa.

4) Difficulty in approaching the detected position: the pipe section is a ground pipe section and is exposed outside.

6) Expected defect types: corrosion cracks, perforations, and punctures.

Step 2: determining a detection scheme, determining the detection sequence, the detection method, the time arrangement, the safety protection facilities, the detection personnel, the safety responsibility supervision personnel and the like according to the information grasped by the survey, and comprising the following steps:

3) The detection method comprises the following steps: and (3) detecting partial ground pipe sections with clear detection signals, detecting each section once, finding suspicious problem pipe sections, and performing key investigation. And (3) determining the detection times and detection positions of each section of pipeline according to the conditions of part of buried pipeline sections.

1) the wall thickness of the pipe section is 6mm, and ultrasonic flaw detection is used; and finding thinned and problematic pipe sections, and measuring by using an ultrasonic thickness gauge.

5) The temperature of the tube body is measured.

And 4, step 4: developing a test comprising:

1) firstly, manually identifying the positions where leakage and seepage occur, and measuring to determine the shape, type and size of the leakage; and (5) manually identifying that a three-way joint 9m away from the terminal has a puncture, and the rest pipe sections have no leakage.

And 5: analyzing the detection result, comprising:

2) And marking the buried position and the anticorrosive layer position.

3) And comparing and analyzing the detection data of different positions of the same pipe section and the data of the same position, superposing and other analysis methods, judging the axial and circumferential positions of the defects and observing the defects, and classifying the severity of the defects. Analysis shows that the tee joint 9m away from the terminal point has a leak, the diameter of the leak point is about 3mm, and the overall condition of the rest pipe sections is good.

And 7: the detection conclusion is obtained, the pipe section is tested by the method, and the leakage is found out when the tee joint 9m away from the end point is punctured, the diameter of the leaking point is about 13mm, and the leakage occurs; the other pipe sections have good conditions and no detection leakage, and are more ideal.

2. And (3) carrying out risk analysis on the defects, and carrying out risk analysis on the pipe section through compiled risk evaluation software to obtain that: the leakage point at the tee joint is 3mm, the leakage point is small, and the influence on the pressure bearing capacity of the pipeline is weak; the pressure bearing of the pipeline is not more than 16.7 MPa.

step 1: and (3) selecting a sealing clamp, wherein a leakage point is positioned at the tee joint, the corrosion mode is a round hole, the diameter is 13mm, and a square box-shaped clamp needs to be selected.

Step 2: and (3) manufacturing and quality inspection of the sealing clamp, selecting a square box-shaped clamp which is manufactured, processed and subjected to quality inspection from a clamp storage library, wherein the clamp is made of steel for a boiler pressure container and has the wall thickness of 15 mm. The glue injection holes are distributed in 6 holes, the groove depth of the glue injection groove is 10mm, and the gap between the joint surface of the clamp and the bent pipe is less than 0.5 mm.

And step 3: determining safe construction pressure, and using the programmed safe construction pressure calculation software to bring various basic parameters into calculation to obtain: the theoretical safe construction pressure is 15.3 MPa; the pressure of the pipeline in the agent injection process is not more than 16.7MPa, and the pressure of the agent injection process is not more than 35 MPa.

According to the seventh embodiment of the invention, the detection and maintenance of the oil collecting main line of a certain well area by taking a seamless steel pipe with the length of 1467m, the operating pressure of 0.4MPa, the outer diameter of 219mm and the wall thickness of 5mm as an example comprises the following steps:

1. and (3) positioning and detecting the defects of the pipelines:

1) history: the pipeline runs for about 16 years, pipe breakage and pipe leakage caused by internal and external corrosion occur for several times, and the pipeline is repaired 8 times accumulatively.

2) Pipeline layout: three-way, flange and bent pipe.

3) The specification of the pipeline is as follows: the diameter of the pipeline is phi 219mm, the wall thickness is 5mm, and the operating pressure is 0.4 MPa.

4) Difficulty in approaching the detected position: the pipe section is a buried pipe section, and an oil-resistant and water-repellent protective clothing needs to be worn by means of a ladder.

6) Expected defect types: corrosion cracks, perforations, and punctures.

5) The temperature of the tube body is measured.

And 4, step 4: developing a test comprising:

1) firstly, manually identifying the positions where leakage and seepage occur, and measuring to determine the shape, type and size of the leakage; the manual identification shows that the elbow part 328m away from the starting point has a puncture, and the rest pipe sections have no leakage.

And 5: analyzing the detection result, comprising:

2) And marking the buried position and the anticorrosive layer position.

3) Comparing and analyzing detection data of different positions of the same pipe section and an analysis method such as superposition of data of the same position, judging the axial and circumferential positions of the defects and observing the defects, and classifying the severity of the defects; analysis shows that the elbow part which is 328m away from the starting point has a leak, the diameter of the leak point is about 4mm, and the overall condition of the rest pipe sections is good.

And 7: the detection conclusion is obtained, the pipe section is tested by the method, and the pipe section is verified by means of excavation, anti-corrosion layer removal and the like, and the leakage is found at the position of the elbow 328m away from the starting point, wherein the diameter of the leakage point is about 4mm, and the leakage occurs; the other pipe sections have good conditions and no detection leakage, and are more ideal.

2. And (3) carrying out risk analysis on the defects, and carrying out risk analysis on the pipe section through compiled risk evaluation software to obtain that: the leakage point at the elbow is 4mm, the leakage point is small, and the influence on the pressure bearing capacity of the pipeline is weak; the pressure bearing of the pipeline is not more than 21.1 MPa.

step 1: and (3) selecting a sealing clamp, wherein a leakage point is positioned at the elbow, the corrosion form is a round hole, the diameter is 4mm, and a square box-shaped clamp needs to be selected.

And step 3: determining safe construction pressure, and using the programmed safe construction pressure calculation software to bring various basic parameters into calculation to obtain: the theoretical safe construction pressure is 19.8 MPa; the pressure of the pipeline in the agent injection process is not more than 21.1MPa, and the pressure of the agent injection process is not more than 35 MPa.

According to the eighth embodiment of the invention, the seamless steel pipe with the pipe length of 2.4km, the operating pressure of 2.5MPa, the external diameter of 219mm and the wall thickness of 7mm, the oil outlet line detection and maintenance of the oil transfer station are taken as examples, and the method comprises the following steps:

step 1: and surveying the basic condition information of the pipe section to prepare for the detection scheme. The method mainly comprises the following steps:

1) history: the pipeline runs for about 14 years, the corrosion and scaling phenomena of the pipeline are serious, and the pipeline is broken and leaked for many times, so that large-area oil leakage is caused, and the pipeline is repaired for 32 times in an accumulated way.

2) Pipeline layout: three-way, flange and bent pipe.

3) The specification of the pipeline is as follows: the diameter of the pipeline is phi 219mm, the wall thickness is 7mm, the operating pressure is 2.5Mpa, the station-entering temperature is 40 ℃, and the station-exiting temperature is 58 ℃.

4) Pipeline anticorrosive coating: an asphalt layer; the detected position needs to be processed, and a detection space of 0.6 m is reserved.

5) Difficulty in approaching the detected position: special high temperature resistant gloves are worn.

7) Expected defect types: corrosion cracking, perforation, pitting.

Step 2: determining a detection scheme comprising:

according to the information grasped by the survey, the detection sequence, the detection method, the time arrangement, the safety protection facilities, the detection personnel, the safety responsibility supervision personnel and the like are determined.

3) The detection method comprises the following steps: and (3) detecting partial ground pipe sections with clear detection signals, detecting each section once, finding suspicious problem pipe sections, and performing key investigation. Most of the buried pipe sections determine the detection times and the detection positions of each section of the pipeline according to the conditions.

5) The temperature of the tube body is measured.

And 4, step 4: developing a test comprising:

1) firstly, manually identifying the positions where leakage and seepage occur, and measuring to determine the shape, type and size of the leakage; manually identifying that a large-area oil leakage exists at the position 721m away from the terminal point, and the rest pipe sections have no leakage.

And 5: analyzing the detection result, comprising:

2) And marking the buried position and the anticorrosive layer position.

3) And comparing and analyzing the detection data of different positions of the same pipe section and the data of the same position, superposing and other analysis methods, judging the axial and circumferential positions of the defects and observing the defects, and classifying the severity of the defects. Analysis shows that the pipe section is provided with a corrosion perforation with a larger area, the pipe wall of the part is integrally thinned, 2 inclined seams are arranged around the pipe section, the lengths of the inclined seams are 55mm and 70mm respectively, an axial crack is 65mm, a plurality of corrosion perforations with the diameter of about 6mm are arranged around the crack, and leakage occurs.

And 7: the detection conclusion is obtained, the pipe section is tested by the method, and the method of excavation, anticorrosion layer removal and the like is used for verifying, so that a corrosion perforation hole with a large area is found at a position 721m away from the terminal point, the pipe wall of the position is integrally thinned, 2 oblique seams are arranged around the corrosion perforation hole, the lengths of the corrosion perforation hole are respectively 55mm and 70mm, an axial crack and 65mm, a plurality of corrosion perforation holes with the diameters of about 6mm are arranged around the crack, leakage occurs, and the whole defect approximately forms a circular area with the diameter of 100 mm. The corrosion conditions of other pipe sections are similar, and the detection is not missed, so that the method is ideal.

2. And (3) carrying out risk analysis on the defects, and carrying out risk analysis on the pipe section through compiled risk evaluation software to obtain that: the leakage point of the pipe section is more, the pipe wall is integrally thinned, the pressure bearing capacity of the pipeline is very weak, and the pipeline is recommended to be replaced after production is stopped.

step 1: the selection of the sealing clamp, the corrosion leakage point is positioned on the straight pipe section and is far away from the flange, the elbow, the tee joint and the like, the pipe wall is integrally thinned, cracks and pitting corrosion exist, the corrosion area is large, the sealing clamp cannot be used for maintenance, and the pipeline is replaced in a production halt mode.

And step 3: determining safe construction pressure, and using the programmed safe construction pressure calculation software to bring various basic parameters into calculation to obtain: the theoretical safe construction pressure is 8.2 MPa; the pressure of the pipeline in the agent injection process is not more than 10.5MPa, and the pressure of the agent injection process is not more than 18 MPa.

And 4, step 4: and (5) maintenance suggestion that the corrosion area at the position is large, the pipe wall is integrally thinned, large cracks and pitting corrosion exist, the maintainability range is exceeded, and the pipeline is suggested to be stopped and replaced.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A metal pipeline defect identification and welding-free maintenance method, characterized in that, comprising:

Establish a damage data table, and establish a functional relationship between damage conditions and safe construction pressure in the damage data table;

Detecting the damage condition of the pipeline through a detection device, and determining the safe construction pressure of the pipeline by querying the damage data table according to the damage condition determined after detection by the detection device;

Select a suitable sealing fixture according to the determined safe construction pressure and the damage condition; install the sealing fixture on the damaged part of the pipeline, and make the sealing fixture and the pipeline A cavity is formed between the outer walls of the

A sealant is injected into the cavity by a glue injection device to seal and repair the damaged part of the pipeline, and the pressure generated by the sealant in the cavity is lower than the safe construction pressure.

2. The metal pipeline defect identification and welding-free maintenance method according to claim 1, wherein the damage condition includes the material type of the pipeline, the damage type of the pipeline, and the relationship between the damage and the The distance between the glue injection grooves of the sealing fixture; when establishing the damage data table, the material type of the pipeline, the damage type of the pipeline and the damage and the glue injection groove of the sealing fixture The distance between them is fitted to obtain the safe construction pressure.

3. The metal pipeline defect identification and welding-free maintenance method according to claim 2, wherein the damage type includes hole damage, and the safe construction pressure Psafe is obtained by the following formula:

Psafe=157.05519-31.10771*ln(r+74.249),

in,

The unit of the safe construction pressure Psafe is MPa,

The damaged part of the pipeline is a hole-like structure, r is the radius of the hole-like structure, and the unit is mm.

4. The metal pipeline defect identification and welding-free maintenance method according to claim 2, wherein the damage type includes hole damage, and the safe construction pressure Psafe is obtained by the following formula:

Psafe=247.00606-52.10033*ln(r+65.39911),

in,

The unit of the safe construction pressure Psafe is MPa,

5. The metal pipeline defect identification and welding-free maintenance method according to claim 2, wherein the damage type includes axial crack damage along the axial direction of the pipeline, and the safe construction pressure Psafe passes the following The formula is obtained:

Psafe=25.55345-4.34022*ln(r-2.47777),

in,

The unit of the safe construction pressure Psafe is MPa,

r is the damaged length of the damaged part of the pipeline.

6. The metal pipeline defect identification and welding-free maintenance method according to claim 2, wherein the damage type includes circumferential crack damage along the circumferential direction of the pipeline, and the safe construction pressure Psafe passes the following The formula is obtained:

Psafe=23.80073-3.32896*ln(r-3.54268),

in,

The unit of the safe construction pressure Psafe is MPa,

r is the damaged length of the damaged part of the pipeline.

7. The metal pipeline defect identification and welding-free maintenance method according to claim 1, characterized in that the temperature when the sealant is injected into the cavity is T1, wherein 0<T1≤800°C.

8 . The metal pipeline defect identification and welding-free maintenance method according to claim 1 , wherein the sealant is used at a pressure of P1 , wherein P1 ≤ 60 MPa.

9. The metal pipeline defect identification and welding-free maintenance method according to claim 1, wherein the temperature before the sealant is injected into the cavity is T2, wherein 90°C≤T2≤120°C.

10. The metal pipeline defect identification and welding-free maintenance method according to claim 1, characterized in that the pressure of the sealant pushed by the glue injection device into the cavity is P2, and P3≤P2≤ 70% P4,

in,

P3 is the rated pressure of the pipeline;

P4 is the safe construction pressure.

11. The metal pipeline defect identification and welding-free maintenance method according to claim 1, wherein the detection device includes an ultrasonic flaw detector and an ultrasonic thickness gauge, and when 5mm≤δ, the ultrasonic flaw detector is used to detect The pipeline is inspected, and when δ<5mm, the ultrasonic thickness gauge is used to inspect the pipeline, wherein, the δ is the wall thickness of the pipeline.

12. The metal pipeline defect identification and welding-free maintenance method according to claim 1, wherein the sealing fixture includes a flange fixture, a single-groove ring fixture, a double-groove fixture or a square box-shaped fixture at least one of the