阅读说明：本技术 直埋蒸汽保温管道外套钢管在线防腐结构及其施工方法 (On-line anticorrosion structure of directly-buried steam heat-preservation pipeline outer sleeve steel pipe and construction method thereof ) 是由 刘领诚 于 2019-12-13 设计创作，主要内容包括：本发明公开了直埋蒸汽保温管道外套钢管在线防腐结构,涉及蒸汽管网技术领域,包括蒸汽管,蒸汽管周侧包裹设置有保温层,保温层上套设有钢套管,钢套管与保温层之间设置有空气层；钢套管上套设有外套管,外套管与钢套管之间填充有泡沫层。针对现有技术存在直埋蒸汽保温管钢制外套钢管腐蚀严重的问题,本发明利用泡沫层和外套管隔绝地下水对钢套管外表面的侵蚀,同时,由于设置了泡沫层,增加了钢套管外的热阻,从而提高钢套管内壁处的温度,有利于钢套管内壁处的水以气态的方式存在,从而减轻钢套管内壁的腐蚀,达到完美的防腐效果。(The invention discloses an online anticorrosion structure of a directly-buried steam heat-insulation pipeline outer sleeve steel pipe, and relates to the technical field of steam pipe networks, wherein the steam pipe comprises a steam pipe, a heat-insulation layer is wrapped around the steam pipe, a steel sleeve is sleeved on the heat-insulation layer, and an air layer is arranged between the steel sleeve and the heat-insulation layer; the steel sleeve is sleeved with an outer sleeve, and a foam layer is filled between the outer sleeve and the steel sleeve. Aiming at the problem of serious corrosion of the steel outer sleeve of the directly-buried steam insulation pipe in the prior art, the invention utilizes the foam layer and the outer sleeve to isolate the corrosion of underground water to the outer surface of the steel sleeve, and simultaneously, the foam layer is arranged to increase the thermal resistance outside the steel sleeve, thereby improving the temperature at the inner wall of the steel sleeve, being beneficial to the water at the inner wall of the steel sleeve to exist in a gaseous state, reducing the corrosion of the inner wall of the steel sleeve and achieving the perfect corrosion prevention effect.)

1. The on-line anti-corrosion structure for the outer sleeve steel pipe of the directly-buried steam heat-insulation pipeline comprises a steam pipe (6), and is characterized in that a heat-insulation layer (4) is wrapped around the steam pipe (6), a steel sleeve (5) is sleeved outside the heat-insulation layer (4), and an air layer (2) is arranged between the steel sleeve (5) and the heat-insulation layer (4);

the steel sleeve (5) is sleeved with an outer sleeve (1), and a foam layer (3) is filled between the outer sleeve (1) and the steel sleeve (5).

2. The on-line anticorrosion structure for the externally sleeved steel pipe of the directly-buried steam insulation pipeline as recited in claim 1, wherein the insulation layer (4) is a glass wool felt, and the foam layer (3) is rigid polyurethane foam.

3. The on-line anticorrosion structure for the externally sleeved steel pipe of the directly-buried steam insulation pipeline according to claim 1, wherein the material of the externally sleeved pipe (1) is high-density polyethylene.

4. The on-line anticorrosion structure of the directly-buried steam heat-preservation pipeline outer sleeve steel pipe according to claim 1, characterized in that a mounting seam (8) is formed in the side wall of the outer sleeve (1) along the axial direction of the outer sleeve, and a sealing strip (7) is fixed to the side wall of the outer sleeve (1) along the extending direction of the mounting seam (8).

5. The on-line anticorrosion structure of the externally sleeved steel pipe of the directly-buried steam heat-insulating pipeline as recited in claim 1, wherein the steel sleeve (5) is connected with a moisture exhaust pipe, and the moisture exhaust pipe is communicated with the air layer (2).

6. The on-line anticorrosion structure of the externally sleeved steel pipe of the directly-buried steam heat-preservation pipeline as recited in claim 1, wherein a heat-insulating cushion layer is pasted at a position with a higher temperature on the outer surface of the steel sleeve (5).

7. The on-line anticorrosion structure of the directly-buried steam heat-preservation pipeline outer sleeve steel pipe as recited in claim 6, wherein the heat insulation cushion layer is a nano aerogel felt with a thickness of 5 mm-20 mm.

8. The construction method of the on-line anticorrosion structure of the directly-buried steam heat-preservation pipeline outer sleeve steel pipe is characterized by comprising the following steps of:

s1, removing the covering soil around the outer sleeve (1) covering the direct-buried steam heat-preservation pipe;

s2, splitting the high-density polyethylene sleeve along the axial direction to form a mounting seam (8), sleeving the high-density polyethylene sleeve on the steel sleeve (5) through the mounting seam (8), and fixing the sealing belt (7) at the mounting seam (8) through a hot melting method;

s3, coaxially fixing the high-density polyethylene sleeve and the steel sleeve (5) by adopting a bracket;

s4, pouring rigid polyurethane foam raw materials between the steel sleeve (5) and the high-density polyethylene sleeve, and performing foaming operation to form a polyurethane foam layer (3).

9. The construction method of the on-line anticorrosion structure of the directly-buried steam heat-preservation pipeline outer sleeve steel pipe as recited in claim 7, further comprising:

before the anticorrosion repairing operation, a thermal imager is used for detecting the surface temperature of the steel sleeve (5) in a normal working state;

and a heat insulation cushion layer is pasted on the part with higher surface temperature of the steel sleeve (5).

10. The construction method of the on-line anticorrosion structure of the directly-buried steam heat-preservation pipeline outer sleeve steel pipe as recited in claim 7, further comprising:

and after the anticorrosion repairing operation, detecting the surface temperature of the steel sleeve (5) in a normal working state.

Technical Field

The invention relates to the technical field of steam pipe networks, in particular to an online anticorrosion structure of a directly-buried steam heat-preservation pipeline outer sleeve steel pipe and a construction method thereof.

Background

The steam pipeline direct-buried laying technology has nearly thirty years of history in China. The basic structure form of the directly buried steam insulation pipe is that a steel outer sleeve is additionally arranged outside a steam steel pipe insulation layer. And performing corrosion prevention treatment on the outer surface of the outer sleeve steel pipe after rust removal. The outer side of the outer sleeved steel pipe is directly covered with soil. The corrosion prevention of the outer sleeved steel pipe is finished in a factory. No matter which anticorrosion method is used, the anticorrosion material is used as the main body of the outer sleeve steel pipe, and the anticorrosion is reliable. The heat preservation pipes are welded and butted on the engineering site. The interface between the tubes is called an interface. The corrosion prevention of the interface outer sleeve steel pipe is finished in an engineering field. The corrosion prevention of the interface is more due to the factors of operation conditions and operation environments. This is a worldwide problem.

The steam insulation pipe uses various insulation materials. The glass wool felt is a widely applied heat-insulating material, and is called a soft heat-insulating material. The glass wool felt is breathable and permeable, and the construction experience of the early direct-buried steam pipeline laying engineering is short. The situation that water enters the heat-insulating layer of the heat-insulating pipe in construction often occurs. Due to the aspect of the heat insulation structure, the inner surface of the steel pipe sleeved outside the soft heat insulation pipe cannot be protected from corrosion. The directly buried steam heat insulation pipeline is usually buried under the ground surface by 1-3 m. The soil has certain heat preservation performance. In winter in the north, soil layers in the field are frozen, the thickness of frozen soil layers is limited, and deeper soil layers are not frozen. This is very good evidence. Because the soil layer has the heat preservation effect, the temperature of the outer steel pipe of the steam heat preservation pipe is usually kept at about 50 ℃. When the heat-insulating material in the heat-insulating pipe becomes damp, soaks and falls off, the heat-insulating performance is reduced, and the temperature of the steel sleeve is still higher. For common steel, air, moisture and 50-90 ℃ temperature are sufficient conditions for corrosion. According to engineering investigation, the corrosion of the inner surface of the outer sleeve steel pipe of the direct-buried laying steam insulation pipe is more serious than that of the outer surface. After the steel pipe sleeved outside the heat preservation pipe is corroded and perforated, underground water enters the heat preservation pipe layer of the pipeline through holes formed by corrosion, the heat preservation of the pipeline is accelerated to deteriorate, and the heat loss of the pipe network is increased sharply until the pipe network is scrapped.

Steam supply, like water supply and power supply, cannot be interrupted for a long time. However, the direct-buried steam pipe network renovation cannot be completed in hours or days. For the serious situation facing the corrosion perforation of the outer sleeve steel pipe, the on-site corrosion prevention and updating of the outer sleeve steel pipe are the most practical and feasible method.

In the conventional method for corrosion prevention of steel pipes, rust removal, decontamination and drying are required on the surfaces of the steel pipes. However, in the on-line pipe network, it is very difficult to operate the rust removal, decontamination and drying of the outer surface of the steel sleeve, not to say, the inner surface of the outer sleeve steel pipe which is seriously corroded meets the requirements.

Disclosure of Invention

Aiming at the problem of serious corrosion of the steel outer sleeve steel pipe of the directly-buried steam heat-preservation pipe in the prior art, the invention aims to provide the online corrosion prevention structure of the steel outer sleeve steel pipe of the directly-buried steam heat-preservation pipe and the construction method thereof, and the online corrosion prevention structure has the advantages of simple structure, convenience in operation and capability of effectively preventing the steel sleeve from being continuously corroded.

In order to achieve the purpose, the invention provides the following technical scheme:

the direct-buried steam heat-insulation pipeline outer sleeve steel pipe online anticorrosion structure comprises a steam pipe, wherein a heat-insulation layer wraps the periphery of the steam pipe, a steel sleeve is sleeved outside the heat-insulation layer, and an air layer is arranged between the steel sleeve and the heat-insulation layer;

the steel sleeve is sleeved with an outer sleeve, and a foam layer is filled between the outer sleeve and the steel sleeve.

Through above-mentioned technical scheme, in anti-corrosion structure, foam blanket and outer tube cover are located on the steel casing, and isolated groundwater is to the erosion of steel casing surface, simultaneously, owing to set up the foam blanket, the foam blanket has good heat preservation and heat-proof quality, has increased the thermal resistance outside the steel casing, then when the normal transportation process of hot steam, the temperature of steel casing inner wall department will rise, reaches more than one hundred degrees centigrade, and the water of steel casing inner wall department exists with gaseous state's mode, and the inner wall of steel casing is difficult for receiving the corruption, to sum up, can reach perfect anticorrosive effect.

Furthermore, the heat-insulating layer is made of glass wool felt, and the foam layer is made of hard polyurethane foam.

Through the technical scheme, the glass wool felt is low in price and easy to obtain. The heat preservation effect is excellent; the rigid polyurethane foam has the advantages of air impermeability and water impermeability, and is favorable for forming a good thermal resistance medium.

Furthermore, the outer sleeve is made of high-density polyethylene.

Through the technical scheme, the high-density polyethylene has the advantages of corrosion resistance, air impermeability and water impermeability, and is beneficial to forming an isolation medium on the outer layer of the foam layer, so that the corrosion resistance protection of the steel sleeve is further enhanced.

Furthermore, the outer sleeve lateral wall has seted up the installation seam along its axial, the outer sleeve lateral wall is followed the installation seam extending direction is fixed with the sealing area.

Through the technical scheme, the installation seam is arranged, so that the outer sleeve can be conveniently installed on the steel sleeve in the line; the sealing belt is used for closing the installation seam after the outer sleeve is installed.

Furthermore, a moisture discharge pipe is connected to the steel sleeve and communicated with the air layer.

Through above-mentioned technical scheme, the intraformational water of air is heated the vaporization back, is discharged by arranging the damp pipe, effectively avoids moisture deposit in the air bed.

Furthermore, a heat insulation cushion layer is pasted on the position with higher temperature on the outer surface of the steel sleeve.

Through above-mentioned technical scheme, steel casing receives the corruption back, and the cotton attenuation of partial position glass, thermal insulation performance weakens, and the temperature of this department will be higher than normal position, through attached high-efficient thermal-insulated bed course, avoids overheated temperature to transmit to the foam blanket.

Furthermore, the heat insulation cushion layer is a nano aerogel felt with the thickness of 5 mm-20 mm.

Through the technical scheme, the nano aerogel felt has the advantages of softness, easiness in cutting, low density, inorganic fire resistance, overall hydrophobicity, greenness and environmental friendliness.

The construction method of the on-line anticorrosion structure of the outer sleeve steel pipe of the directly-buried steam heat-preservation pipeline comprises the following steps:

s1, removing the covering soil around the outer sleeve of the direct-buried steam heat-preservation pipe;

s2, splitting the high-density polyethylene sleeve along the axial direction to form a mounting seam, sleeving the high-density polyethylene sleeve on the steel sleeve through the mounting seam, and fixing the sealing belt at the mounting seam by a hot melting method;

s3, coaxially fixing the high-density polyethylene sleeve and the steel sleeve by adopting a bracket;

s4, pouring rigid polyurethane foam raw materials between the steel sleeve and the high-density polyethylene sleeve, and performing foaming operation to form a polyurethane foam layer.

Through above-mentioned technical scheme, in anticorrosive structure, foam blanket and outer tube cover are located on the steel casing, dual protection, and isolated groundwater is to the erosion of steel casing surface, and simultaneously, owing to set up the foam blanket, the foam blanket has good heat preservation and heat-proof quality, has increased the thermal resistance outside the steel casing, then when the normal transportation process of steam, the temperature of steel casing inner wall department will rise, reaches more than one hundred degrees centigrade, and the water of steel casing inner wall department exists with the mode of gaseous state, and the inner wall of steel casing is difficult for receiving the corruption, to sum up, can reach perfect anticorrosive effect.

Further, the method also comprises the following steps: before the anticorrosion repairing operation, detecting the surface temperature of the steel sleeve in a normal working state by using a thermal imager; and (3) pasting a heat insulation cushion layer on the part with higher temperature on the surface of the steel sleeve.

Through above-mentioned technical scheme, original insulating tube heat preservation layer is impaired back, and local thermal insulation performance weakens, and the temperature of this department will be higher than normal position, through attached thermal-insulated bed course, avoids overheated temperature to transmit to the foam blanket.

Further, the method also comprises the following steps:

and after the anticorrosion repairing operation, detecting the surface temperature of the steel sleeve in a normal working state.

Through above-mentioned technical scheme, ensure that the temperature of steel casing department is higher than one hundred degrees centigrade under the normal operating condition, moisture in the air zone is in the gaseous state.

Compared with the prior art, the invention has the beneficial effects that:

(1) the foam layer and the outer sleeve are sleeved on the steel sleeve, so that corrosion resistance can be realized from the inner side and the outer side of the steel sleeve at the same time, and the corrosion resistance of the steel sleeve after corrosion resistance repair is greatly improved;

(2) furthermore, the moisture exhaust pipe is communicated with the air layer, so that moisture in the air layer is conveniently exhausted in a gaseous state, and the moisture is prevented from being accumulated in the air layer;

(3) furthermore, the heat insulation cushion layer is attached to the steel sleeve, so that the partially weakened heat insulation performance of the steel sleeve is compensated, the foam layer is protected, and the steel sleeve is prevented from bearing overhigh temperature.

Drawings

Fig. 1 is a schematic diagram of the structure in the present embodiment.

Reference numerals: 1. an outer sleeve; 2. an air layer; 3. a foam layer; 4. a heat-insulating layer; 5. steel casing; 6. a steam pipe; 7. a sealing tape; 8. and (6) installing a seam.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

On-line anticorrosion structure of direct-burried steam insulation pipeline overcoat steel pipe, as shown in fig. 1, including steam pipe 6, 6 week side parcels of steam pipe are provided with heat preservation 4, heat preservation 4 is the cotton felt of glass usually, the cotton felt of glass has and keeps warm effectually, the quality is light, the advantage of low price, coaxial cover is equipped with steel sleeve 5 on the heat preservation 4, be provided with air bed 2 between steel sleeve 5 and the heat preservation 4, the cover is equipped with outer tube 1 on the steel sleeve 5, the 1 material of outer tube is high density polyethylene, it has foam blanket 3 to fill between outer tube 1 and the steel sleeve 5, foam blanket 3 is the rigid polyurethane foam.

Firstly, the high-density polyethylene outer sleeve 1 is not easy to corrode, is not air-permeable and water-impermeable, and is widely used as a shell of a cold and hot water direct-buried heat preservation pipe in the prior art. Thus, the concern that ground water may contact and corrode the outer surface of the outer jacket tube 1 is eliminated.

Secondly, the foam layer 3 formed by the rigid polyurethane foam is airtight and waterproof, and the foam layer 3 is firmly bonded with the surface of the steel sleeve 5 and the inner surface of the outer sleeve 1, so that the surface of the steel sleeve 5 is more reliably waterproof.

Thirdly, the foam layer 3 forms an additional heat insulation layer 4, so that the heat resistance is increased, and then the temperature of the steel sleeve 5 is increased. The temperature of the steel sleeve 5 is kept between 100 ℃ and 120 ℃ by designing the thickness of the interlayer of the steel sleeve and the plastic sleeve, and the heat-insulation interlayer between the steel sleeve 5 and the steam steel pipe is pressureless, so that moisture can not exist at the temperature of more than 100 ℃, and the inner surface of the steel sleeve 5 can be kept dry for a long time without continuous corrosion. Therefore, the problem of corrosion of the inner surface of the steel pipe of the outer sleeve of the insulating pipe is also thoroughly solved.

The steel sleeve 5 is connected with a moisture discharge pipe which is communicated with the air layer 2, and moisture at the steel sleeve 5 is discharged from the moisture discharge pipe after being heated to 100-120 ℃, so that the interior of the steel sleeve 5 can be kept dry.

The side wall of the outer sleeve 1 is provided with a mounting seam 8 along the axial direction, and the side wall of the outer sleeve 1 is fixed with a sealing belt 7 along the extending direction of the mounting seam 8. The outer sleeve 1 is not convenient to be sleeved and installed from the end part of the steam pipe 6, the installation seam 8 is arranged on the outer sleeve 1, the outer sleeve 1 is sleeved on the steam pipe 6 through the installation seam 8, the steam pipe 6 does not need to be detached, and therefore the online corrosion updating efficiency is greatly improved.

The heat preservation layer of the online steam heat preservation pipe can be damaged and lost locally, the temperature of the outer sleeved steel pipe at the locally damaged position is higher than the temperature of a normal position, the heat insulation cushion layer is pasted at the higher position of the temperature of the outer surface of the steel sleeve 5 and is a nano aerogel felt with the thickness of 5 mm-20 mm, so that the local heat preservation performance of the steel sleeve 5 is compensated, the temperature of the steel sleeve 5 is reduced to be transmitted to the foam layer 3, and the foam heat preservation layer is protected.

The construction method of the on-line anticorrosion structure of the outer sleeve steel pipe of the directly-buried steam heat-preservation pipeline comprises the following steps:

s1, removing the covering soil around the outer sleeve 1 covering the direct-buried steam heat-preservation pipe;

and (3) detecting the surface temperature of the steel sleeve 5 in an online working state by using a thermal imager, and attaching a thermal insulation cushion layer to the part with higher temperature on the surface of the steel sleeve 5 so as to reduce the heat radiation heat flow intensity of the corroded part of the steel sleeve 5.

S2, splitting the high-density polyethylene sleeve along the axial direction to form a mounting seam 8, pulling the high-density polyethylene sleeve from the mounting seam 8, sleeving the high-density polyethylene sleeve on the steel sleeve 5 by using the mounting seam 8, fixing a sealing strip 7 at the mounting seam 8 by a hot melting method, wherein the sealing strip 7 is made of the same material as or matched with the high-density polyethylene sleeve, the hot melting method adopts electric hot melting, and the electric hot melting device is the prior art.

And S3, coaxially erecting and fixing the high-density polyethylene sleeve and the steel sleeve 5 by adopting a bracket.

S4, pouring rigid polyurethane foam raw material between the steel sleeve 5 and the high-density polyethylene sleeve, and performing foaming operation to form the polyurethane foam layer 3. The foam raw materials flowing in the foaming process are subjected to chemical reaction to form internal pressure, so that the foam is filled in all spaces of the interlayer, the outer surface of the steel sleeve 5 is completely covered, and the connection effect of the foam layer 3 is enhanced.

After the anticorrosion repairing operation, the surface temperature of the steel sleeve 5 in a normal working state is detected, the thickness of the foam layer 3 and the thermal resistance thereof are ensured to be enough, and the temperature of the steel sleeve 5 is more than 100 ℃.

The first embodiment is as follows: the specification of the direct-buried steam insulating pipe is phi 219x 6/phi 530x 8. The steam temperature of 240 ℃ requires the corrosion prevention and repair of the outer sleeve steel pipe.

Through thermal calculation, the soil heat conductivity coefficient is equal to 1.5W/m ℃ according to the soil temperature of 20 ℃, and the heat dissipation strength q of the original heat preservation pipe is equal to 102W/m ℃. The surface of the steel sleeve 5 is approximately equal to 46 ℃. The average surface temperature of the directly buried pipe sleeve is measured to be 60 ℃. The heat dissipation strength q of the heat preservation pipe is calculated to be increased by about 54% to about 155W/m.

Now select phi 655x10 high density polyethylene casing. The plastic sleeve is split axially. The longitudinal opening of the plastic sleeve is separated in the circumferential direction, and the plastic sleeve is sleeved outside the steel pipe sleeved outside the direct-buried steam pipe 6. The opening of the sleeve is then reclosed by hot-melt (commercially available molding equipment). Then, four groups of positioning brackets are embedded into the interlayer, so that the plastic sleeve and the steel pipe are kept concentric. Then the two ends of the plastic sleeve are closed. And injecting polyurethane foaming raw materials into the interlayer. And after the foam is hardened, removing the two end sealing plates. And (5) filling the injection port, and finishing the plastic-foam composite anticorrosion repairing work.

In this case, after the plastic-foam layer is added, the surface temperature of the original steel outer sleeve 1 is raised from 60 ℃ to 120 ℃. The inner surface of the steel casing 5 will evaporate if there is water. Inside-out corrosion no longer occurs.

Meanwhile, the thermal resistance of the heat-insulating pipe is increased due to the addition of the outer foam layer 3, and the heat radiation strength q of the pipeline is reduced from 155W/m to 98W/m. The heat loss is reduced by 37 percent compared with the current heat loss. The heat preservation effect of the steam heat preservation pipe at the initial stage is basically recovered.

Example two: the method of the embodiment is different from the method of the first embodiment in that: the direct-buried steam pipe 6 has the specification phi 630x 8/phi 1220x 12. The steam temperature is designed to be 280 ℃, the inner surface of the outer sleeve steel pipe is corroded, and the problem of corrosion prevention of the outer sleeve steel pipe needs to be solved.

A plastic pipe with the specification of phi 1380x16 is taken, and is sleeved outside a phi 1220 steel sleeve 5 after being split. The steam heat-preservation pipe of the embodiment has uneven aging of the original heat-preservation layer 4. The difference of the surface temperature of the steel jacket is obvious, and the distribution is not uniform. In order to adapt to the high temperature condition of the local surface, before the high-density polyethylene sleeve is sleeved, the surface temperature of the steam insulation sleeve is detected by using a thermal imager, and a nanometer aerogel felt with the thickness of 10 mm-20 mm is pasted on the part with the obviously ultrahigh local surface temperature.

In this example, a high temperature resistant material of 165 ℃ was used as the polyurethane foam material. The other steps are the same as in example one. After being covered by the plastic-foam anti-corrosion insulating layer 4, the temperature of the steel sleeve of the steam insulating pipe in the embodiment is increased to 128.2 ℃ (average). The heat dissipation intensity of the pipeline is recovered to the initial state of the construction of the heat preservation pipe.

In summary, the following steps:

when the steel sleeve is used, the foam layer and the outer sleeve are sleeved on the steel sleeve, so that corrosion resistance can be realized from the inner side and the outer side of the steel sleeve at the same time, and the corrosion resistance of the steel sleeve after corrosion resistance repair is greatly improved; the moisture exhaust pipe is communicated with the air layer, so that the moisture in the air layer is conveniently exhausted in a gaseous state, and the moisture is prevented from being accumulated in the air layer; the heat insulation cushion layer is attached to the steel sleeve, so that the heat insulation performance of the local part of the steel sleeve is compensated, the foam layer is protected, and the steel sleeve is prevented from bearing overhigh temperature.

The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the invention are covered by the protection scope of the invention.