CN112728295A

CN112728295A - External anti-corrosion treatment method for underground pipeline

Info

Publication number: CN112728295A
Application number: CN202110011871.3A
Authority: CN
Inventors: 赵鹏龙; 李宝玲
Original assignee: China Eleventh Chemical Construction Co Ltd
Current assignee: China Eleventh Chemical Construction Co Ltd
Priority date: 2021-01-06
Filing date: 2021-01-06
Publication date: 2021-04-30

Abstract

The application relates to the technical field of underground pipeline construction, in particular to an underground pipeline external anti-corrosion treatment method. The method comprises the following steps: pretreating the surface of the pipeline; painting primer on the surface of the pipeline which is pretreated and has dry and dustless surface; winding an adhesive tape on the surface of the pipeline immediately after the primer is dried, wherein the temperature of the adhesive tape when being unwound is not lower than 5 ℃. According to the technical scheme provided by the invention, the defects of the primer on the surface of the pipeline can be reduced through the pretreatment process on the surface of the pipeline, and the problem that the adhesive tape is easy to bond and is not firm is solved through the restriction on the time for winding the adhesive tape and the environmental conditions, so that the external anticorrosion effect of the underground pipeline is improved.

Description

External anti-corrosion treatment method for underground pipeline

Technical Field

The application relates to the technical field of underground pipeline construction, in particular to an underground pipeline external anti-corrosion treatment method.

Background

When underground pipelines are laid, the surfaces of the pipelines need to be subjected to anticorrosion treatment, and the pipelines are usually subjected to anticorrosion by painting and taping.

At present, when the pipeline is subjected to corrosion prevention, a constructor usually simply paints and/or winds the surface of the pipeline with an adhesive tape, and the operation process is relatively random. In severe weather environments (such as sand wind weather, humid weather, cold weather and the like), the painted primer or the wound adhesive tape is easy to have the defects of primer falling off, bubbles in the primer, poor adhesive effect of the adhesive tape and the like, so that the problem of poor anticorrosion effect is caused.

Disclosure of Invention

The application aims to provide an underground pipeline external anti-corrosion treatment method which can improve the technical problem of poor surface anti-corrosion effect of the underground pipeline to a certain extent.

The technical scheme of the invention is realized as follows:

an underground pipeline external antiseptic treatment method comprises the following steps:

pretreating the surface of the pipeline;

painting primer on the surface of the pipeline which is pretreated and has dry and dustless surface;

winding an adhesive tape on the surface of the pipeline immediately after the primer is dried, wherein the temperature of the adhesive tape when being unwound is not lower than 5 ℃.

In a preferred embodiment of the present invention, the preprocessing includes: and removing attachments, rust and dust on the surface of the pipeline.

In a preferred technical scheme of the invention, the surface drying time of the primer is 3-5 min.

In a preferred technical scheme of the invention, the environmental temperature when the adhesive tape is wound on the surface of the pipeline is not lower than-5 ℃.

In a preferred embodiment of the present invention, the surface of the pipe is preheated to a temperature of 10 ℃ or higher.

In a preferred embodiment of the present invention, the time interval between the pretreatment of the surface of the pipe and the priming of the surface of the pipe is not more than 4 hours.

In a preferred embodiment of the present invention, the thickness of the thin film formed by the primer is not less than 30 μm.

In a preferred technical scheme of the invention, after the primer is dried, an adhesive tape is wound at the position of the welding seam of the pipeline to seal the welding seam.

In a preferred technical scheme of the invention, when the adhesive tape is wound, the joint of the two sections of adhesive tape is connected in an overlapping manner, and the overlapping length is not less than 100 mm.

In a preferred technical scheme of the invention, the surface of the part to be lapped at the tail end of the previous section of adhesive tape is coated with primer, and the starting end of the next section of adhesive tape is lapped after the surface is dried.

The invention has the beneficial effects that:

according to the technical scheme provided by the invention, the defects of the primer on the surface of the pipeline can be reduced through the pretreatment process on the surface of the pipeline, and the problem that the adhesive tape is easy to bond and is not firm is solved through the restriction on the time for winding the adhesive tape and the environmental conditions, so that the external anticorrosion effect of the underground pipeline is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a flow chart of a method for corrosion protection treatment of the exterior of an underground pipeline according to an embodiment of the present invention;

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or the orientations or positional relationships that the products of the present invention are conventionally placed in use, and are only used for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

Furthermore, the terms "horizontal", "vertical", "overhang" and the like do not imply that the components are required to be absolutely horizontal or overhang, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Some embodiments of the invention are described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.

The method for the anticorrosion treatment of the outside of the underground pipeline provided by the embodiment comprises the following steps:

s10: pretreating the surface of the pipeline;

s20: painting primer on the surface of the pipeline which is pretreated and has dry and dustless surface;

s30: winding an adhesive tape on the surface of the pipeline immediately after the primer is dried, wherein the temperature of the adhesive tape when being unwound is not lower than 5 ℃.

The individual steps are explained in further detail below.

In step S10, the pipe is generally made of steel, and therefore, the surface pretreatment should be performed as follows:

first, the surface of the steel pipe is cleaned of deposits such as slag, burrs, grease, and dirt. For pipelines overhauled by the anticorrosive coatings, the original anticorrosive coatings and residues are removed by using a proper method.

Secondly, rust on the surface of the pipeline is removed by adopting a mechanical or sand blasting projection rust removal method, the quality of the rust removal method reaches St3 grade or Sa2.5 grade specified in GB/T8923-1998-Steel surface before coating rust and rust removal grade, and the grade standard is shown in Table 1:

table 1: international mechanical surface treatment standard

After rust removal, the exposed defects on the surface of the steel pipe are treated, dust and abrasive materials attached to the surface are cleaned, and the surface of the steel pipe is kept dry. When the occurrence of the rust return or the surface contamination is caused, the surface pretreatment must be carried out again.

In step S20, the following requirements should be satisfied:

the time interval between the pretreatment of the pipeline surface and the painting of the primer is controlled within 4 hours, and the surface of the steel pipe is required to be dry and dustless. In the environment with large wind sand or large air humidity, the primer needs to be coated immediately after the surface of the pipeline is pretreated.

The primer should be stirred uniformly in the vessel. When the primer is thickened, a diluent is added and can be used after being diluted to a proper viscosity. The primer may be applied using a clean brush, roller, or some other mechanical method.

The primer coated on the steel pipe has no defects of missing coating, no air bubbles, clots, sagging and the like, and a uniform thin film is formed, wherein the thickness of the thin film is more than or equal to 30 microns. The weld of the pipe is carefully painted to prevent missing coating.

When the primer is used, attention should be paid to safety and splashing prevention, and the primer should be far away from a fire source. After the primer is used, the residual primer is poured back into the original iron container in time and the container is closed, so that the primer is prevented from volatilizing and wasting.

When manual painting is adopted, the usage amount of the primer is as follows: 6-8 m²Pipeline area per liter of primer, when mechanical spraying is adopted, the dosage of the primer is as follows: 8-10 m²Pipe area per liter of primer.

In step S30, the specific operation requirement is:

after the primer is dried (under the condition of normal temperature and natural air flow, generally 3-5 minutes are required), the adhesive tape can be wound. When the temperature is low or the groove is constructed, the surface drying time is prolonged to ensure the surface drying of the lower half part of the steel pipe.

The temperature of the adhesive tape needs to be above 5 ℃ when the adhesive tape is uncoiled, and the construction of the anticorrosive coating needs to be performed above-5 ℃. When the weather is cold, the environmental temperature is lower than 10 ℃ or the winding is just started, the adhesive layer of the adhesive tape is hard, in order to ensure that the adhesive tape has good bonding strength and remove water vapor on the surface of the steel pipe, a blast burner is preferably adopted to preheat the surface of the steel pipe (the head of each roll of the adhesive tape needs to be baked if necessary) so as to ensure the winding effect.

In a more preferred embodiment, the weld of the pipe is reinforced by a narrow tape with a width of 30-50 mm, i.e. the narrow tape is covered on the weld and then compacted by hand or a wooden smoothing tool.

In winding the tape, the tape is spirally wound on the primed tube as required for the lap joint, using a suitable mechanical or manual tool. The adhesive tape should maintain a certain tension force, and the force is uniform, so that the adhesive tape layers are tightly connected. When the adhesive tape is wound, the width of the adhesive tape is strictly required according to the standard, because air bubbles are easily generated in a south with higher temperature and smaller temperature difference than in a moisture south. The side seams of the tape should be parallel and not twisted. The joint of the two sections of adhesive tapes is provided with an overlap part of more than 100 mm. If necessary, the surface of the end part of the previous section of adhesive tape is painted with primer or fully baked, and the starting end of the other section of adhesive tape is lapped after the surface is dried. The beginning and end of each section of adhesive tape should be tightly pressed by a smooth wooden tool so as not to be tilted.

The machine is a powerful measure for ensuring the winding quality of the adhesive tape, the hand-wound adhesive tape is difficult to achieve uniform surface quality and consistent tension, and the hand-wound adhesive tape can be used only when mechanical construction cannot be carried out under special conditions, but the adhesive tape with narrower width is used. The winding anti-corrosion adhesive tape can not be loosened sometimes and can be tightened sometimes to wind with uniform force as much as possible, the best effect can be achieved only by tensioning the adhesive tape during winding until the adhesive tape is wound when the adhesive tape is narrowed rapidly, otherwise, the adhesive tape can bulge after being exposed to the sun.

If the winding belt is prefabricated in a factory, cold winding or hot winding construction can be adopted, the pipe can be rotated (manually or electrically), and the winding equipment can also be rotated, and a welding reserved section of 150 mm and 200 mm is reserved at the pipe end.

After the adhesive tape is wound, the anti-corrosion layer of the pipeline is subjected to quality standard inspection. The quality of the anticorrosive coating meets the following requirements:

appearance: the pipeline is subjected to full-line visual inspection, the joint repairing and the wound repairing parts are inspected one by one in a prefabrication plant, the surface of the anticorrosive layer is smooth, the lap joint is uniform, no wrinkle exists, no permanent bubbles exist, and no damage exists. It should be noted that: when the weather is hot or the sunlight is sufficient, bubbles are often generated in the wound tape. Since the tape itself has a certain elasticity and self-repairing ability, these bubbles can disappear by itself, so this condition should not be regarded as a quality problem. If long-lasting bubbles are generated, they should be removed like wrinkles.

According to SY/T0414-2017 standard, the width of the adhesive tape used for fixing the pipe diameter is shown in the following table:

table 2: comparison table for pipe diameter and width of used adhesive tape

Pipe diameter/mm	Adhesive tape width/mm	Pipe diameter/mm	Adhesive tape width/mm
				25～100	50	350～600	100
100～300	75	650～1400	150

Because the steel pipe absorbs heat, and the black color of the anti-corrosion adhesive tape absorbs heat, the pipe body is forbidden to be exposed to the sun after being anti-corrosion, and the pipe body is placed in a cool and ventilated place for storage.

Thickness: the primer coated on the steel pipe has no defects of missing coating, no air bubbles, clots, sagging and the like, and a uniform thin film is formed. The film thickness should be greater than or equal to 30 microns. The weld joint should be carefully painted to prevent missing coating. When measuring, the instrument and equipment which are harmful to the anticorrosive coating are not suitable for use. The thickness of the adhesive tape has great influence on the anticorrosion quality, and the increase of the thickness of the adhesive tape can increase the anticorrosion capability.

Adhesion (peel strength): this index is directly related to the quality of the corrosion protection layer. The water permeability is related to the adhesion between the tape and the pipe, so that the steel pipe should be ensured to have sufficient adhesion. In the national standard SY/T0414-2017, the peel strength is measured by the following method: and (3) cutting the adhesive tape layer with the width of 10 mm and the length of more than 100 mm by using a knife along the annular direction until the pipe body. Then pulling the tube wall by a spring balance at an angle of 90 degrees at a speed of not more than 300mm/min, and the peel strength should be more than 20N/cm, and the test should be carried out after 24 hours.

Or according to the test method of the 3kg copper weight suspension method in the American ASTM-1000 standard: an adhesive tape layer with the width of 5cm and the length of 10cm is cut on the vertical side surface of the anti-corrosion layer pipeline, a 3kg weight is hung at 180 degrees, the weight is qualified when the falling distance of the weight is less than 10cm within 10 minutes, the falling distances of the adhesive tapes are all less than 3cm within 10 minutes, and the detection is carried out at normal temperature (5-20 ℃), the humidity is less than 75 percent and the adhesive tapes are wound for 24 hours.

And (3) electric spark leakage detection: and in the prefabrication stage and on site, a direct current power supply electric spark leak detector is used for carrying out full-line detection on the pipeline, and repaired ports and repaired wounds are checked one by one. The moving speed of the leak detection probe is 0.3 m/s, and the probe is qualified as not sparking.

The index mainly controls defects caused during construction or some defects of the adhesive tape, so that 100% detection is required. The leak detection voltage for pinhole detection is to consider not only to detect small pinholes, but also to ensure that the coating is not broken down perfectly, and simultaneously to make the leak detection voltage value conform to the actual voltage grade of the used electric spark detector. During the leakage detection, the surface of the corrosion-resistant layer must be ensured to be dry, and the detection electrode is kept at least 13mm away from the end of the metal pipe or the bare metal leakage surface. The electric spark detection voltage of the polyethylene adhesive tape is not less than 3000 volts.

After the quality standard inspection is carried out on the anticorrosive coating of the pipeline, the method also can comprise the steps of repairing the damage:

after the anticorrosive pipeline is checked out of defects, the anticorrosive pipeline is marked and repaired in time. When repairing, the damaged part should be repaired, the loose burr part is removed, cleaned and coated with primer.

And for small-range pinhole defects, the same adhesive tape as the original pipe body anticorrosive coating is used for repairing by a patching method. When repairing, a piece of adhesive tape with the thickness of 100 multiplied by 100 mm is cut, a fillet is cut on the patch, and the patch is stuck to the repaired part after the primer is dried.

For larger exposed areas where the coating is damaged or leaking, the damaged coating is removed, the edges are trimmed and smoothed, and the damaged area is spirally wrapped with tape of appropriate width.

For lap widths that are not as specified, tape having a width of at least 100 mm should be used to spiral wrap the tape in the lap direction.

The patch and primer should extend at least 50 mm in each direction to the defect area and be tightly compacted using a wood smoothing tool so that it does not lift.

After the adhesive tape is wound, the method also comprises the steps of stacking and carrying the prefabricated anti-corrosion pipeline.

The stacking number of the anti-corrosion pipes is based on the principle that the anti-corrosion layer is not damaged, and the number of the stacking number is generally not more than three. Different types of finished pipes are stacked respectively, and soft materials such as paper boxes, sawdust and protective sleeves are padded between the anti-corrosion pipe layers and at the bottom of the anti-corrosion pipe layers so as to prevent the anti-corrosion layers from being damaged. When the wound anticorrosion pipes are stacked, waste anti-adhesion films or protective sleeves are wound at a plurality of positions where the middle and two ends of the pipes are located.

If the taped pipe is to be left in a factory or open trench for more than two weeks or when the weather is hot, the pipe may be covered with talc and kraft paper or other suitable temporary material. The storage time of the anti-corrosion pipeline in a leakage day is not longer than 3 months. The corrosion-resistant pipeline needs to avoid insolation above 20 ℃.

When the anticorrosive pipeline is loaded, unloaded, carried and hoisted, a wide nylon belt or a special hoisting tool is adopted, and the hoisting tool damaging the anticorrosive coating cannot be used. And a reasonable hoisting method is adopted, and light hoisting is performed. Strictly forbidding damaging the anticorrosive coating, strictly forbidding directly sleeving the iron hoist chain on the anticorrosive coating for hoisting, strictly forbidding operating methods which are harmful to the anticorrosive coating, such as throwing, colliding, impacting, dragging and the like. Corresponding protective measures are taken to prevent the anticorrosive coating from being damaged during transportation.

When the pipes are arranged beside the groove, soft objects such as cartons are placed on all the skid supports to protect the anti-corrosion pipes.

When the anti-corrosion pipeline is buried, the following requirements are met:

before the pipeline is placed in a ditch, the open-air storage time of the buried anticorrosive pipeline is not longer than 3 months, and reliable protective measures are taken.

The depth and width of the pipeline are required to meet the requirements of relevant design and construction specifications.

The cleaning, ditch laying, backfilling and hoisting of the pipe ditch meet the corresponding construction acceptance standard, and measures must be taken to protect the anticorrosive coating from being damaged. The pipe ditch must not have bricks, stones or other hard objects. The bottom of the pipe ditch is preferably covered with fine soil or fine sand of 300 mm. The pipeline is carefully operated when being put into the ditch, so that the pipeline is prevented from impacting the ditch wall. After the pipeline is ditched, fine soil and fine sand are backfilled until the top of the pipeline is more than 100 mm. During the backfilling process, it is ensured that there are no stones or other materials that may damage or penetrate deeply into the erosion resistant layer. In areas where there is hard backfill, some suitable material should be used for protection.

100% electric spark leakage detection is carried out before the pipeline is put into a ditch.

The pipeline should be subjected to appearance inspection after being put into the ditch. And the detection after the pipeline is backfilled is executed according to corresponding standards and pipeline construction acceptance specifications.

After the anticorrosive pipe is checked out of defects, the anticorrosive pipe should be marked and repaired in time.

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. An underground pipeline external antiseptic treatment method is characterized by comprising the following steps:

pretreating the surface of the pipeline;

2. The underground pipeline external preservation treatment method according to claim 1, wherein the pretreatment comprises: and removing attachments, rust and dust on the surface of the pipeline.

3. The method for anticorrosion treatment of the outside of an underground pipeline according to claim 1, wherein the surface drying time of the primer is 3 to 5 min.

4. The method for the anticorrosion treatment of the outside of an underground pipeline according to claim 1, wherein the ambient temperature when the adhesive tape is wound on the surface of the pipeline is not lower than-5 ℃.

5. The method for corrosion prevention treatment of the outside of an underground pipeline according to claim 4, wherein the surface of the pipeline is preheated to a temperature of 10 ℃ or higher.

6. The method of claim 1, wherein the time interval between the pretreatment of the pipe surface and the priming of the pipe surface is not more than 4 hours.

7. The method for anticorrosion treatment of the outside of an underground pipe according to claim 1, wherein the primer forms a thin film having a thickness of not less than 30 μm.

8. The method for anticorrosion treatment of the outside of an underground pipeline according to claim 1, wherein after the primer is dried, an adhesive tape is wound on the position of the welding seam of the pipeline to seal the welding seam.

9. The method for anticorrosion treatment of the outside of an underground pipeline according to claim 1, wherein when the adhesive tape is wound, the joint of the two sections of the adhesive tape is connected in an overlapping manner, and the overlapping length is not less than 100 mm.

10. The method of claim 9, wherein the primer is applied to the surface of the portion to be overlapped at the end of the previous segment of tape, and the initial end of the subsequent segment of tape is overlapped after the primer is dried.