CN106862782A - Method for repairing oil and gas pipeline without stopping transmission - Google Patents
Method for repairing oil and gas pipeline without stopping transmission Download PDFInfo
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- CN106862782A CN106862782A CN201510919327.3A CN201510919327A CN106862782A CN 106862782 A CN106862782 A CN 106862782A CN 201510919327 A CN201510919327 A CN 201510919327A CN 106862782 A CN106862782 A CN 106862782A
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- 238000000034 method Methods 0.000 title claims abstract description 109
- 230000005540 biological transmission Effects 0.000 title claims description 6
- 238000003466 welding Methods 0.000 claims abstract description 188
- 230000008569 process Effects 0.000 claims abstract description 72
- 230000008439 repair process Effects 0.000 claims abstract description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 30
- 238000001816 cooling Methods 0.000 claims description 5
- 239000012530 fluid Substances 0.000 claims description 3
- 238000003912 environmental pollution Methods 0.000 abstract description 4
- 239000007789 gas Substances 0.000 description 103
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 14
- 229910000831 Steel Inorganic materials 0.000 description 9
- 238000010276 construction Methods 0.000 description 9
- 239000010959 steel Substances 0.000 description 9
- 239000003345 natural gas Substances 0.000 description 7
- 230000008859 change Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 239000003209 petroleum derivative Substances 0.000 description 3
- 208000032544 Cicatrix Diseases 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 125000004108 n-butyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 231100000241 scar Toxicity 0.000 description 2
- 230000037387 scars Effects 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000010913 used oil Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K31/00—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups
- B23K31/02—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups relating to soldering or welding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K2101/00—Articles made by soldering, welding or cutting
- B23K2101/04—Tubular or hollow articles
- B23K2101/06—Tubes
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Pipe Accessories (AREA)
Abstract
The invention discloses a method for repairing an oil and gas pipeline without stopping transportation, and belongs to the technical field of oil and gas pipeline repair. The method for repairing the oil and gas pipeline comprises the following steps: step a, acquiring the wall thickness of a pipeline at a part needing to be repaired on an oil and gas pipeline; b, acquiring the actual pressure of the part needing to be repaired on the oil and gas pipeline; c, determining welding process parameters according to the wall thickness of the pipeline and the actual pressure, wherein the welding process parameters comprise the diameter of a welding rod, the output current of an electric welding machine and the electric welding time; and d, welding a pipeline cover on the outer surface of the part needing to be repaired on the oil and gas pipeline according to the welding process parameters. By adopting the method, the oil and gas pipeline can be repaired on the premise of not stopping transportation, the repairing efficiency is high, the labor intensity of constructors is low, and the environmental pollution is avoided.
Description
Technical Field
The invention relates to the technical field of oil and gas pipeline repair, in particular to a method for repairing an oil and gas pipeline without stopping transmission.
Background
The oil and gas pipeline can be partially corroded in the process of conveying the oil and gas for a long time, the corroded part can be leaked, the normal conveying of the oil and gas is seriously influenced, and potential safety hazards exist. Therefore, in order to ensure the normal transportation of oil and gas, the corroded part of the oil and gas pipeline needs to be repaired.
At present, a commonly used oil and gas pipeline repairing method welds a metal plate on the outer surface of a part of an oil and gas pipeline to be repaired. However, the pipe pressure is high in the process of conveying the oil and gas pipeline, the temperature of a welding pool is high, the pressure resistance is poor, the oil and gas pipeline is easy to break in the welding process, and the substance in the oil and gas pipeline rushes out to cause accidents. Therefore, before welding, the oil and gas pipelines need to be shut down, emptied after the pipeline pressure is reduced to zero, and then welded.
In the process of implementing the invention, the inventor finds that at least the following problems exist in the prior art: the existing method for repairing the oil and gas pipeline needs to stop the oil and gas pipeline and empty the oil and gas pipeline, the operation of the process is complex, the whole repairing time is prolonged, the working efficiency is low, and the labor intensity of constructors is increased. Meanwhile, long-time outage of oil and gas pipelines may cause safety accidents, for example, oil may be solidified after long-time outage. In addition, the petroleum and natural gas leaks to the surrounding environment in the process of emptying the oil and gas pipeline, so that the waste of the petroleum and natural gas and the environmental pollution are caused.
Disclosure of Invention
In order to solve the technical problem, the invention provides a method for repairing an oil and gas pipeline without stopping transportation.
Specifically, the method comprises the following technical scheme:
the method for repairing the oil and gas pipeline without stopping transmission comprises the following steps:
step a, acquiring the wall thickness of a pipeline at a part needing to be repaired on an oil and gas pipeline;
b, acquiring the actual pressure of the part needing to be repaired on the oil and gas pipeline;
c, determining welding process parameters according to the wall thickness of the pipeline and the actual pressure, wherein the welding process parameters comprise the diameter of a welding rod, the output current of an electric welding machine and the electric welding time;
and d, welding a pipeline cover on the outer surface of the part needing to be repaired on the oil and gas pipeline according to the welding process parameters.
Further, in the step c, when the wall thickness of the pipeline is less than or equal to 6mm, the diameter of the welding rod is 2.5 mm; when the wall thickness of the pipeline is more than 6mm, the diameter of the welding rod is 3.2 mm.
Further, the electric welding time in the step c is 6-8 s; and d, stopping welding every 6-8 s, and cooling the welding part.
Further, between step a and step b, also include: and adjusting the gathering and transportation pressure of the oil and gas pipeline to be within the pipeline pressure bearing range in the welding process according to the wall thickness of the pipeline.
Further, when the wall thickness of the pipeline is not less than 2.5mm and not more than 3mm, the pressure-bearing range of the pipeline in the welding process is not more than 0.6 MPa; when the wall thickness of the pipeline is more than 3mm and less than or equal to 4mm, the pressure-bearing range of the pipeline in the welding process is less than or equal to 1 MPa; when the wall thickness of the pipeline is more than 4mm and less than or equal to 5mm, the pressure-bearing range of the pipeline in the welding process is less than or equal to 2 MPa; when the wall thickness of the pipeline is more than 5mm and less than or equal to 6mm, the pressure-bearing range of the pipeline in the welding process is less than or equal to 3 MPa; when the wall thickness of the pipeline is more than 6mm and less than or equal to 7mm, the pressure-bearing range of the pipeline in the welding process is less than or equal to 4 MPa; when the wall thickness of the pipeline is larger than 7mm, the pressure-bearing range of the pipeline in the welding process is larger than 4 MPa.
Further, between step b and step c, also include: acquiring the water content of the fluid in the oil and gas pipeline; and c, determining the output current of the electric welding machine according to the wall thickness of the pipeline, the actual pressure and the water content.
Further, when the water content is less than or equal to 0.5%, the output current of the electric welding machine is 75A; when the water content is more than 0.5% and less than or equal to 10%, the output current of the electric welding machine is 75-90A; and when the water content is larger than 10%, the output current of the electric welding machine is 90A.
Further, in the step d, the welding times are 2; the first welding adopts 422 type welding rod; the second weld was performed using a 427 type electrode.
Furthermore, the pipeline cover comprises a cover body, an upper cover plate and side cover plates positioned at two ends of the cover body, the cover body and the upper cover plate are combined to form a hollow cylinder, and the inner diameter of the hollow cylinder is larger than the outer diameter of the oil-gas pipeline; the side cover plate comprises a first side cover plate and a second side cover plate, the first side cover plate and the second side cover plate are combined to form a circular ring, the inner diameter of the circular ring is matched with the outer diameter of the oil and gas pipeline, and the outer diameter of the circular ring is matched with the outer diameter of a hollow cylinder formed by combining the cover body and the upper cover plate.
Further, when a plugging valve is arranged at a part of the oil and gas pipeline needing to be repaired, an opening is formed in the cover body or the upper cover plate; the pipeline cover also comprises a plugging valve cover.
The technical scheme provided by the embodiment of the invention has the beneficial effects that:
in the method for repairing the oil and gas pipeline provided by the embodiment of the invention, welding process parameters such as the diameter of a welding rod, the output power of an electric welding machine, the electric welding time and the like are determined according to the wall thickness and the actual pressure of a part to be repaired on the oil and gas pipeline, so that the welding process parameters are matched with the wall thickness and the pipeline pressure of the pipeline, the welding part of the oil and gas pipeline can bear the change of conditions such as temperature, pressure and the like in the welding process, and the safety accident caused by the rupture of the oil and gas pipeline in the welding process. By adopting the oil and gas pipeline repairing method provided by the embodiment of the invention, the oil and gas pipeline does not need to be shut down, the repairing operation is greatly simplified, the working efficiency is improved, the normal transportation of the petroleum and the natural gas is not influenced, and the environmental pollution is avoided. Compared with the existing method for repairing the oil and gas pipeline under the condition of stopping transportation, the method for repairing the oil and gas pipeline without stopping transportation provided by the embodiment of the invention can reduce the switching flow time of about 1.5 hours and can avoid emptying the oil and gas pipeline for 2-3 hours.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic flow chart of a method for repairing an oil and gas pipeline without stopping transportation provided in example 1;
FIG. 2 is a schematic flow chart of a method for repairing an oil and gas pipeline without stopping transportation according to embodiment 2;
FIG. 3 is a schematic view showing the connection of the pipe cover and the oil and gas pipeline in embodiment 2;
FIG. 4 is a schematic view showing the structure of an "inverted T-shaped" pipe cover according to example 2;
fig. 5 is an exploded view of the "inverted t" duct cover of embodiment 2, in which: 5a is a structural schematic diagram of a first side cover plate, 5b is a structural schematic diagram of an upper cover plate, 5c is a structural schematic diagram of a second side cover plate, and 5d is a structural schematic diagram of a cover body;
FIG. 6 is a schematic view of the structure of a "n-butyl" duct cover in example 2;
FIG. 7 is a schematic view of a "side-T" type tunnel cover according to example 2;
fig. 8 is a schematic structural view of a pipe cover in a line shape in embodiment 2.
The reference numerals denote:
1. a duct cover; 101. a cover body; 102. a second side cover plate; 103. a first side cover plate;
104. an upper cover plate; 105. plugging the valve cover;
2. an oil and gas pipeline;
3. drainage short circuit;
4. and (4) plugging the valve.
Detailed Description
In order to make the technical solutions and advantages of the present invention clearer, the following will describe embodiments of the present invention in further detail with reference to the accompanying drawings.
Example 1
The embodiment provides a method for repairing an oil and gas pipeline without stopping transportation, and referring to fig. 1, the method for repairing the oil and gas pipeline by transportation comprises the following steps:
step 101, acquiring the wall thickness of a pipeline at a part needing to be repaired on an oil and gas pipeline;
102, acquiring the actual pressure of a part needing to be repaired on an oil and gas pipeline;
103, determining welding process parameters according to the wall thickness of the pipeline and the actual pressure, wherein the welding process parameters comprise the diameter of a welding rod, the output current of an electric welding machine and the electric welding time;
and 104, welding a pipeline cover on the outer surface of the part needing to be repaired on the oil and gas pipeline according to the welding process parameters.
In the oil and gas pipeline repairing method provided by the embodiment, welding process parameters such as the diameter of a welding rod, the output power of an electric welding machine, the electric welding time and the like are determined according to the wall thickness and the actual pressure of a part to be repaired on an oil and gas pipeline, so that the welding process parameters are matched with the wall thickness and the pipeline pressure of the pipeline, the welding part of the oil and gas pipeline can bear the change of conditions such as temperature and pressure in the welding process, and the safety accident caused by the rupture of the oil and gas pipeline in the welding process is prevented. By adopting the oil and gas pipeline repairing method provided by the embodiment of the invention, the oil and gas pipeline does not need to be shut down, the repairing operation is greatly simplified, the working efficiency is improved, the normal transportation of the petroleum and the natural gas is not influenced, and the environmental pollution is avoided.
Example 2
The embodiment provides a method for repairing an oil and gas pipeline without stopping transportation, and welding process parameters such as the diameter of a welding rod, the output power of an electric welding machine, the electric welding time and the like are matched with the wall thickness of the pipeline and the pressure of the pipeline, so that the welding part of the oil and gas pipeline can bear the change of conditions such as temperature, pressure and the like in the welding process, the oil and gas pipeline is prevented from being broken in the welding process, and the oil and gas pipeline is repaired on the premise of not stopping transportation. Referring to fig. 2, the method of repairing an oil and gas pipeline includes the steps of:
step 201, construction preparation.
Firstly, in a standard construction operation pit, cleaning a part needing to be repaired on an oil and gas pipeline, and removing a heat preservation layer and an anticorrosive layer on the surface of the part. And then selecting a proper pipeline cover 1, drawing lines on possible welding positions on the surfaces of the pipeline cover 1 and the oil and gas pipeline 2 in the subsequent welding process, and if scars exist on the drawn lines, polishing the scars.
Referring to fig. 3 to 8, the duct cover 1 adopted in the present embodiment mainly includes an "inverted t-shaped" duct cover (fig. 4), an "n-shaped" duct cover (fig. 6), a "side t-shaped" duct cover (fig. 7), and a "straight" duct cover (fig. 8). The 'inverted T-shaped' pipeline cover, the 'n-shaped' pipeline cover and the 'side T-shaped' pipeline cover are suitable for repairing an oil and gas pipeline which is provided with a drainage short circuit 3 and a plugging valve 4 near a part needing to be repaired, and each pipeline cover comprises a cover body 101, an upper cover plate 104, side cover plates positioned at two ends of the cover body 101 and a plugging valve cover 105. The cover body 101 and the upper cover plate 104 are combined to form a hollow cylinder, and the inner diameter of the formed hollow cylinder is larger than the outer diameter of the oil-gas pipeline 2. The side cover plate comprises a first side cover plate 103 and a second side cover plate 102, the first side cover plate 103 and the second side cover plate 102 are combined to form a circular ring, the inner diameter of the circular ring is matched with the outer diameter of the oil and gas pipeline 2, and the outer diameter of the circular ring is matched with the outer diameter of a hollow cylinder formed by combining the cover body 101 and the upper cover plate 104. When the oil and gas pipeline is repaired, the first side cover plate 103 and the second side cover plate 102 are welded with the oil and gas pipeline, so that the pipeline cover 1 is integrally welded to the part of the oil and gas pipeline needing to be repaired.
The n-butyl pipeline cover is characterized in that an opening hole inverted T-shaped pipeline cover is arranged on the upper cover plate 104, an opening hole is formed in the bottom of the cover body 101, a side T-shaped pipeline cover is formed in the side face of the cover body 101, a proper pipeline cover 1 is selected according to the positions of the drainage short circuit 3 and the plugging valve 4 on the oil and gas pipeline, the drainage short circuit 3 and the plugging valve 4 extend out of the opening hole, and the plugging valve cover 105 is sleeved outside the drainage short circuit 3 and the plugging valve 4 and is welded and fixed with the upper cover plate 104.
The 'straight-line-shaped' pipeline cover is suitable for repairing an oil and gas pipeline which is not provided with a drainage short circuit 3 and a plugging valve 4 and is close to a part needing to be repaired, and comprises a cover body 101, an upper cover plate 104 and side cover plates positioned at two ends of the cover body 101, wherein each side cover plate comprises a first side cover plate 103 and a second side cover plate 102. The connection mode of the straight-line-shaped pipeline cover and the oil-gas pipeline is the same as that of the inverted T-shaped pipeline cover, the n-butyl-shaped pipeline cover and the side T-shaped pipeline cover.
The duct cover 1 described above can be prefabricated in advance. And welding blind plates at two ends of the steel pipe to obtain the prefabricated pipe cover. In a construction site, the prefabricated pipeline cover is cut into a cover body 101, a first side cover plate 103, a second side cover plate 102 and an upper cover plate 104 according to actual conditions, and the cover body, the first side cover plate 103, the second side cover plate 102 and the upper cover plate 104 are connected with an oil and gas pipeline and then welded into a whole. And for repairing the oil and gas pipeline provided with the drainage short circuit 3 and the plugging valve 4, holes are opened at corresponding positions.
The pipe material of the steel pipe for prefabricating the pipe cover 1 can adopt 20# steel, and can adopt 20# boiler steel if high strength is needed. The diameter of the steel pipe may be one to two orders of magnitude thicker than the diameter of the oil and gas pipeline 2. The common diameter sequence of the steel tube is as follows:etc.; for example, when the oil and gas pipeline 2 isThe pipe of (2) can be selectedOrTo pre-form the pipe cover 1. The wall thickness of the steel pipe can be selected according to the design pressure bearing of the oil and gas pipeline. The lengths of the steel pipes include, but are not limited to, 500mm, 750mmm and 1000mm to meet the requirements of different repair areas. The plugging valve cover 105 can be selectedThe 20# pipe is prefabricated independently, and the drainage short joint 3 and the plugging valve 4 are sleeved during construction and then butt-welded with the pipeline cover 1.
Step 202, obtaining the wall thickness of a pipeline at a part needing to be repaired on the oil and gas pipeline.
Because the pipeline wall thickness needs to be obtained under the condition of not stopping transportation, a small-sized wall thickness measuring instrument based on the ultrasonic measurement principle can be adopted to obtain the pipeline wall thickness of the part needing to be repaired on the oil and gas pipeline. The small wall thickness measuring instrument is controlled by a micro processor, and can quickly measure the thickness of the pipeline arm without damage and preparation; the device consists of a transmitting circuit, a receiving circuit, a high-frequency oscillator, a counting gate, a counter, a central processing unit, a keyboard, a display and the like; the working principle is as follows: ultrasonic pulses transmitted by the probe reach an object to be measured and are transmitted in the object, the ultrasonic pulses are reflected and received when reaching a material interface, and the wall thickness of the oil and gas pipeline is determined by accurately measuring the transmission time of the ultrasonic waves in the material.
And step 203, regulating the gathering and transportation pressure of the oil and gas pipeline to be within the pressure bearing range of the pipeline in the welding process according to the wall thickness of the pipeline obtained in the step 202.
Different pipe wall thicknesses can withstand different pressure ranges during the welding process. In order to ensure the safety of subsequent welding operation, the gathering and transportation pressure of the oil-gas pipeline can be adjusted to the pipeline pressure-bearing range in the welding process, so that the oil-gas pipeline is in a low-pressure transportation mode. The corresponding relationship between different pipeline wall thicknesses and pressure bearing ranges thereof is as follows:
when the wall thickness of the pipeline is more than or equal to 2.5mm and less than or equal to 3mm, the pressure-bearing range of the pipeline in the welding process is less than or equal to 0.6 MPa;
when the wall thickness of the pipeline is more than 3mm and less than or equal to 4mm, the pressure-bearing range of the pipeline in the welding process is less than or equal to 1 MPa;
when the wall thickness of the pipeline is more than 4mm and less than or equal to 5mm, the pressure-bearing range of the pipeline in the welding process is less than or equal to 2 MPa;
when the wall thickness of the pipeline is more than 5mm and less than or equal to 6mm, the pressure-bearing range of the pipeline in the welding process is less than or equal to 3 MPa;
when the wall thickness of the pipeline is more than 6mm and less than or equal to 7mm, the pressure-bearing range of the pipeline in the welding process is less than or equal to 4 MPa;
when the wall thickness of the pipeline is larger than 7mm, the pressure-bearing range of the pipeline in the welding process is larger than 4 MPa.
For example, the gathering and transportation pressure of the oil and gas pipeline should be adjusted to 0.6MPa or less when the wall thickness of the pipeline is 3mm, 1MPa or less when the wall thickness of the pipeline is 3.5mm, 2MPa or less when the wall thickness of the pipeline is 4.5mm, 3MPa or less when the wall thickness of the pipeline is 6mm, and 4MPa or less when the wall thickness of the pipeline is 7 mm.
It should be noted that, in the actual construction process, the step 203 may not be performed, that is, the subsequent welding step is performed in the full-pressure conveying mode, but there is a safety risk in this way, and in order to ensure the construction safety, the subsequent welding step is preferably performed in a low-pressure state.
And 204, acquiring the actual pressure of the part needing to be repaired on the oil and gas pipeline.
In the process of petroleum and natural gas transportation, the actual pressures of different parts of an oil-gas pipeline are different, so that the actual pressure of the part needing to be repaired on the oil-gas pipeline needs to be obtained. The pressure gauge can be temporarily installed at the position needing to be repaired on the oil and gas pipeline to obtain the actual pressure.
And step 205, acquiring the water content of the fluid in the oil and gas pipeline.
Because the water content of the oil or natural gas conveyed in the oil and gas pipeline can also influence the subsequent welding, the welding process parameters can be considered to be matched with the water content of the oil or natural gas. For the oil and gas pipeline provided with the drainage short circuit 3 and the plugging valve 4, the water content of the oil or gas can be measured by collecting an oil or gas sample from the drainage short circuit 3.
And step 206, determining welding process parameters including the diameter of the welding rod, the output current of the electric welding machine and the electric welding time according to the wall thickness of the pipeline obtained in the step 202, the actual pressure obtained in the step 204 and the water content obtained in the step 205.
Wherein,
the corresponding relation between the wall thickness of the pipeline and the diameter of the welding rod is as follows:
when the wall thickness of the pipeline is less than or equal to 6mm, the diameter of the used welding rod 65 is 2.5 mm;
when the wall thickness of the pipeline is more than 6mm, the diameter of the welding rod is 3.2 mm.
When the diameter of the welding rod is small, the resistance is low and the current is high when the diameter of the welding rod is large.
The corresponding relation among the wall thickness of the pipeline, the actual pressure and the output current of the electric welding machine (bottom welding, namely the first welding):
when the wall thickness of the pipeline is more than or equal to 2.5mm and less than or equal to 3mm and the actual pressure of the pipeline in the welding process is less than or equal to 0.6MPa, the electric welding machine outputs current: 60A to 65A;
when the wall thickness of the pipeline is more than 3mm and less than or equal to 4mm and the actual pressure of the pipeline in the welding process is less than or equal to 1MPa, the output current of the electric welding machine is 65A;
when the wall thickness of the pipeline is more than 4mm and less than or equal to 5mm and the actual pressure of the pipeline in the welding process is less than or equal to 2MPa, the output current of the electric welding machine is 70A;
when the wall thickness of the pipeline is more than 5mm and less than or equal to 6mm and the actual pressure of the pipeline in the welding process is less than or equal to 3MPa, the output current of the electric welding machine is 75A;
when the wall thickness of the pipeline is more than 6mm and less than or equal to 7mm and the actual pressure of the pipeline in the welding process is less than or equal to 4MPa, the output current of the electric welding machine is 80A;
when the wall thickness of the pipeline is more than 7mm and the actual pressure of the pipeline is more than 4MPa in the welding process, the output current of the electric welding machine is 90A.
The corresponding relation between the water content and the output current of the electric welding machine is (bottom welding, namely the first welding):
when the water content is less than or equal to 0.5%, the output current of the electric welding machine is 75A;
when the water content is more than 0.5% and less than or equal to 10%, the output current of the electric welding machine is 75-90A;
when the water content is more than 10%, the output current of the electric welding machine is 90A.
The higher the water content is, the larger the output current of the electric welding machine is. The water has the function of reducing the temperature, so that when the water content is higher, the temperature of the molten pool cannot be overhigh even if higher current is adopted.
When the output current of the electric welding machine determined by the wall thickness of the pipeline and the actual pressure is inconsistent with the output current of the electric welding machine determined by the water content, a smaller current is selected to ensure the safety in the welding process. For example, when the wall thickness of the pipeline is more than 4mm and less than or equal to 5mm, the actual pressure of the pipeline in the welding process is less than or equal to 2MPa, and the water content is more than 10%, the output current of the electric welding machine is 70A; when the wall thickness of the pipeline is more than 7mm, the actual pressure of the pipeline is more than 4MPa in the welding process, and the water content is less than or equal to 0.5%, the output current of the electric welding machine is 75A.
The electric welding time means that after welding for a certain time, the welding is stopped, and the water is sprayed to cool the welding part, especially the bottom welding line directly contacted with the oil gas pipeline 2 and the pipeline cover 1 is regularly sprayed with water to cool. The welding time can be determined according to the temperature change in the molten pool. For the working conditions with a 422 gauge electrode of 2.5mm diameter and 20# steel for the oil and gas pipeline, the welding time can be determined with reference to table 1.
TABLE 1 correspondence of welding time to bath temperature
As can be seen from the data in Table 1, the arc striking time is required to be below 8s, the electric welding time is controlled to be 6-8 s, namely, the welding is stopped for cooling by water spraying every 6-8 s of welding, so that the safety of the welding operation is ensured.
In order to ensure the strength and quality of the weld, 2 welds were performed. The first welding is based on the 422 type welding rod, the second welding is based on the 427 type welding rod, the 422 type welding rod has the characteristic of relatively low melting point, and the welding strength is relatively low. In order to make up for the deficiency of the first welding, the 427 type welding rod for the second welding has a relatively high melting point and a relatively high welding strength. The two times of welding are mutually matched to effectively prevent the phenomenon of weld bead crack.
And step 207, welding a pipeline cover on the outer surface of the part needing to be repaired on the oil and gas pipeline according to the welding process parameters determined in the step 206.
In the process of welding the pipeline cover 1, the first side cover plate 103 and the second side cover plate 102 are welded to the oil and gas pipeline 2, then the first side cover plate 103 and the second side cover plate 102 are welded, then the cover body 101 and the second side cover plate 102 are welded, the upper cover plate 104 and the first side cover plate 103 are welded, and for the pipeline cover 1 provided with the plugging valve cover 105, the plugging valve cover 105 and the upper cover plate 104 or the cover body 101 are welded in a butt welding mode to complete the repair of the oil and gas pipeline 2. In the welding process, the color and the welding touch of a welding pool are accurately grasped, so that the welding is firm, the repair is ensured not to leak, and the balance point of the operation is grasped; the theory of electric welding molten pool is familiar with, and the phase change rule of the temperature of the molten pool is mastered to ensure that the strength, rigidity, stiffness and elastic modulus of the welding spot area of the pipeline reach the standard. For electric welding in direct contact with the oil and gas pipeline 2, for example, welding between the first side cover plate 103 and the second side cover plate 102 and the oil and gas pipeline 2, the welding is required to be stopped for 6-8 seconds every time the welding is stopped, and water is sprayed for cooling; for electric welding which is not in direct contact with the oil and gas pipeline 2, such as welding between each part of the pipeline cover 1, measures of spot welding, limited-time stop welding and water spray cooling can be omitted, but general specifications of electric welding are required to be followed. After the repair is completed, the gathering and transportation pressure is adjusted back to the normal gathering and transportation pressure.
In conclusion, the oil and gas pipeline repairing method provided by the embodiment solves the problems that the traditional pipeline repairing method after pipeline stopping is frequent in operation of the pipeline stopping and switching process, frequent in operation of the furnace stopping and switching process, frequent in operation of the emptying and switching process, large in oil falling and oil receiving workload, polluted in construction periphery, long in repairing construction time, high in construction cost, high in labor intensity of constructors and the like. Compared with the existing method for repairing the oil and gas pipeline under the condition of stopping transportation, the method for repairing the oil and gas pipeline without stopping transportation provided by the embodiment can reduce the switching flow time of about 1.5 hours, can avoid emptying the oil and gas pipeline for 2-3 hours, obviously improves the oil and gas pipeline repairing efficiency, reduces the labor intensity of constructors, and does not pollute the environment.
The above description is only for facilitating the understanding of the technical solutions of the present invention by those skilled in the art, and is not intended to limit the present invention. 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 (10)
1. A method for repairing an oil and gas pipeline without stopping transmission is characterized by comprising the following steps:
step a, acquiring the wall thickness of a pipeline at a part needing to be repaired on an oil and gas pipeline;
b, acquiring the actual pressure of the part needing to be repaired on the oil and gas pipeline;
c, determining welding process parameters according to the wall thickness of the pipeline and the actual pressure, wherein the welding process parameters comprise the diameter of a welding rod, the output current of an electric welding machine and the electric welding time;
and d, welding a pipeline cover on the outer surface of the part needing to be repaired on the oil and gas pipeline according to the welding process parameters.
2. The method of repairing an oil and gas pipeline of claim 1, wherein in step c,
when the wall thickness of the pipeline is less than or equal to 6mm, the diameter of the welding rod is 2.5 mm;
when the wall thickness of the pipeline is more than 6mm, the diameter of the welding rod is 3.2 mm.
3. The method for repairing an oil and gas pipeline according to claim 1, wherein the electric welding time in step c is 6-8 s; and d, stopping welding every 6-8 s, and cooling the welding part.
4. The method of repairing an oil and gas pipeline of claim 1, further comprising between step a and step b:
and adjusting the gathering and transportation pressure of the oil and gas pipeline to be within the pipeline pressure bearing range in the welding process according to the wall thickness of the pipeline.
5. The method of repairing an oil and gas pipeline of claim 4,
when the wall thickness of the pipeline is not less than 2.5mm and not more than 3mm, the pressure-bearing range of the pipeline in the welding process is not more than 0.6 MPa;
when the wall thickness of the pipeline is more than 3mm and less than or equal to 4mm, the pressure-bearing range of the pipeline in the welding process is less than or equal to 1 MPa;
when the wall thickness of the pipeline is more than 4mm and less than or equal to 5mm, the pressure-bearing range of the pipeline in the welding process is less than or equal to 2 MPa;
when the wall thickness of the pipeline is more than 5mm and less than or equal to 6mm, the pressure-bearing range of the pipeline in the welding process is less than or equal to 3 MPa;
when the wall thickness of the pipeline is more than 6mm and less than or equal to 7mm, the pressure-bearing range of the pipeline in the welding process is less than or equal to 4 MPa;
when the wall thickness of the pipeline is larger than 7mm, the pressure-bearing range of the pipeline in the welding process is larger than 4 MPa.
6. The method of repairing an oil and gas pipeline of claim 1, further comprising between steps b and c:
acquiring the water content of the fluid in the oil and gas pipeline;
and c, determining the output current of the electric welding machine according to the wall thickness of the pipeline, the actual pressure and the water content.
7. The method of repairing an oil and gas pipeline of claim 6,
when the water content is less than or equal to 0.5%, the output current of the electric welding machine is 75A;
when the water content is more than 0.5% and less than or equal to 10%, the output current of the electric welding machine is 75-90A;
and when the water content is larger than 10%, the output current of the electric welding machine is 90A.
8. The method of repairing an oil and gas pipeline of claim 1, wherein in step d, the number of welds is 2; the first welding adopts 422 type welding rod; the second weld was performed using a 427 type electrode.
9. The method of repairing an oil and gas pipeline of claim 1, wherein the pipeline cover comprises a cover body, an upper cover plate and side cover plates at both ends of the cover body, the cover body and the upper cover plate are involuted to form a hollow cylinder, and the inner diameter of the hollow cylinder is larger than the outer diameter of the oil and gas pipeline;
the side cover plate comprises a first side cover plate and a second side cover plate, the first side cover plate and the second side cover plate are combined to form a circular ring, the inner diameter of the circular ring is matched with the outer diameter of the oil and gas pipeline, and the outer diameter of the circular ring is matched with the outer diameter of a hollow cylinder formed by combining the cover body and the upper cover plate.
10. The method of repairing an oil and gas pipeline of claim 9, wherein when a block valve is installed at a portion of the oil and gas pipeline requiring repair, an opening is provided in the cover body or the upper cover plate; the pipeline cover also comprises a plugging valve cover.
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| CN106862782B (en) | 2019-03-15 |
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