Buried or trenchless three-layer co-extrusion modified polypropylene power cable protection pipe

Abstract

The utility model discloses a buried or trenchless three-layer co-extrusion modified polypropylene power cable protection pipe, which consists of an outer pipe layer, a middle pipe layer and an inner pipe layer, and is characterized in that the outer pipe layer 1 and the inner pipe layer 3 are both of a flat-wall pipe structure, the middle pipe layer 2 is of a corrugated structure and comprises a convex annular cylinder 21 and a concave annular cylinder 22, and the convex annular cylinder 21 and the concave annular cylinder 22 are arranged on the outer pipe layer 1 and the inner pipe layer 3. The convex annular cylinders 21 and the concave annular cylinders 22 are alternately, circularly and continuously distributed; when horizontal directional drilling back-dragging is carried out, a pipe cap 4 is adopted to be connected with the buried or trenchless three-layer co-extrusion modified polypropylene power cable protection pipe through a pipe hoop 5, one end of a back-expanding head 6 is connected with the pipe cap 4, the other end of the back-expanding head 6 is connected with a drill rod 7, and a power head 8 is connected with the drill rod 7. And the back-expanding head 6 and the three-layer co-extrusion modified polypropylene power cable protection pipe are driven to perform reverse back-dragging movement at the same time until the three-layer co-extrusion modified polypropylene power cable protection pipe is dragged to a designated position, and pipeline laying construction is completed.

Description

Technical Field

[0001] The utility model relates to a pipe material for power cables, in particular to a three-layer co-extruded modified polypropylene power cable protection pipe for underground or trenchless use. Background Art

[0002] When the power cable protection pipe is constructed by horizontal directional drilling trenchless technology, there are problems that the pipe is not easy to deform, the tensile strength is not high, and it cannot be welded; when the plastic coated steel pipe is used, the compressive strength is high, but it is not easy to bend; when the polyvinyl chloride pipe is used, the deformation performance is good, but the bonding connection strength of the polyvinyl chloride adhesive is low, and the joint of the pulled pipe is easy to break. Therefore, a three-layer co-extruded modified polypropylene power cable protection pipe for underground or trenchless use is designed, which can be hot-melt welded and consists of an outer pipe layer, a middle pipe layer, and an inner pipe layer. The outer pipe layer is made of a material with excellent toughness, good low-temperature performance, high tensile elongation at break, easy to deform, and the bending radius can be less than or equal to 75 times the nominal diameter of the pipe; the middle pipe layer is made of a material with high tensile strength and elastic modulus, so its ring stiffness, ring segment thermal compression force, and tensile strength are higher than ordinary MPP, greater than 28MPa; the inner pipe layer is made of a material with good heat resistance, and the Vicat softening temperature is higher than 150℃; it can be suitable for trenchless construction of power cable protection pipes. Summary of the invention

[0003] The technical solution adopted by the utility model to solve its technical problems is to provide a three-layer co-extruded modified polypropylene power cable protection pipe for underground or trenchless use, which can be connected by hot-melt welding, wherein the inner layer and the outer layer are flat wall structures, the middle pipe layer is a corrugated structure, the outer pipe layer has excellent toughness, the middle pipe layer is tensile and compressive, and the inner pipe layer is heat-resistant, and is suitable for trenchless construction of power cable protection pipes.

[0004] The utility model is realized as follows: a three-layer co-extruded modified polypropylene power cable protection tube for underground or trenchless use, comprising an outer tube layer 1, a middle tube layer 2, and an inner tube layer 3;

[0005] The outer tube layer 1 and the inner tube layer 3 are both flat-wall tube structures, and the middle tube layer 2 is a corrugated structure, including a convex annular cylinder 21 and a concave annular cylinder 22, and the convex annular cylinder 21 and the concave annular cylinder 22 are alternately and continuously distributed;

[0006] The inner diameter of the outer tube layer 1 is the same as the outer diameter of the outer surface of the convex annular cylinder 21 of the middle tube layer 2, and they are coaxially hot-melted together; the outer diameter of the outer surface of the concave annular cylinder 22 of the middle tube layer 2 is the same as the outer diameter of the inner tube layer 3, and they are coaxially hot-melted together;

[0007] When the horizontal directional drilling is pulled back, the pipe cap 4 is connected with a three-layer co-extruded modified polypropylene power cable protection pipe for burial or trenchless use;

[0008] The pipe cap 4 includes a bellows section 41, a chain 42, and a plugging cover 43. The plugging cover 43 is a hollow cone, the cone top 431 is connected to the chain 42, and the cone bottom 432 is connected to the bellows section 41;

[0009] The outer diameter of the bottom surface of the blocking cover 43 is consistent with the outer diameter of the outer tube layer 1, and the structure of the corrugated tube section 41 is consistent with the structure of the middle tube layer 2, that is, it includes a raised annular cylinder 21 and a recessed annular cylinder 22, and the raised annular cylinder 21 and the recessed annular cylinder 22 are alternately and continuously distributed;

[0010] The corrugated pipe section 41 of the pipe cap 4 is connected to the middle pipe layer 2 by a pipe hoop 5, and the outer diameter of the pipe hoop 5 is consistent with the outer diameter of the outer pipe layer 1;

[0011] When the horizontal directional drill is pulled back, the chain 42 is connected to the expansion head 6 of the horizontal directional drill, the expansion head 6 is connected to the drill rod 7, and the power head 8 drags the drill rod 7, and simultaneously drags the expansion head 6 and the three-layer co-extruded modified polypropylene power cable protection tube in the reverse direction until the three-layer co-extruded modified polypropylene power cable protection tube is dragged to the designated position, and the pipeline laying construction is completed;

[0012] The outer tube layer 1 is made of a material with excellent toughness; the middle tube layer 2 is made of a material with high tensile strength and elastic modulus; and the inner tube layer 3 is made of a material with good heat resistance.

[0013] The above-mentioned method for producing a three-layer co-extruded modified polypropylene power cable protection tube for underground or trenchless use comprises the following steps:

[0014] An outer tube layer 1, a middle tube layer 2 and an inner tube layer 3 are extruded separately by an extruder, and under the action of high temperature at a die, vacuum adsorption and cooling are performed to form a three-layer co-extruded modified polypropylene power cable protection tube for underground or trenchless use, which is a combination of the outer tube layer 1, the middle tube layer 2 and the inner tube layer 3.

[0015] The above-mentioned buried or trenchless three-layer co-extruded modified polypropylene power cable protection tube can be constructed by an underground construction method, the steps of which are:

[0016] Step 1: The bottom of the cable trench should be compacted to prevent settlement, and a 100-150mm C15 concrete cushion layer should be laid at the bottom of the trench and compacted and leveled;

[0017] Step 2: Before installation, arrange the lower half of the pipe sleepers in a row at a 2-meter interval at the bottom of the trench;

[0018] Step 3: First, place the first layer of pipes in the foundation pit, arrange them neatly, and connect them with pipe clamps; after laying the first layer, install the upper half of the pipe pillow, backfill with medium-coarse sand, tamp with water, and lay multiple layers according to this process; each time a layer of pipes is laid, the conduit is fixed with a pipe pillow;

[0019] Step 4: Seal the end with a pipe plug;

[0020] Step 5: Remove the port plug and insert the power cable.

[0021] The above-mentioned three-layer co-extruded modified polypropylene power cable protection tube for underground or trenchless use can be constructed by a horizontal directional drilling trenchless construction method, and the steps are as follows:

[0022] Step 1: Site layout

[0023] 1) Entrance pit work site: After the equipment is accepted upon arrival, it is placed in the entrance site. The equipment placement site must at least meet the requirements of the drilling rig placement position on the axis plus the length of the drill rod buried in the soil, the placement of surrounding auxiliary equipment and the channel required for the transportation of the drill rod, and easy access to water sources. A working pit needs to be dug on the axis of the equipment site. The size and depth of the working pit can be comprehensively considered based on factors such as the diameter and length of the pipeline and the soil layer;

[0024] 2) Exit pit work site: The exit pit work site must consider the exit pit excavation. The size and depth of the exit pit are also considered comprehensively based on factors such as the pipe diameter, length, soil layer, and whether mud can be discharged. In addition, it is also necessary to consider whether the pipeline welding site meets the requirements of the pipeline length. For short distances, only one welding is generally considered. When the length is too long, one docking can be considered if the soil layer conditions allow and the welding pipe site conditions are limited;

[0025] Step 2: Prepare the mud

[0026] Directional drilling should formulate a reasonable mud system according to different formation conditions, pipeline diameter and length, and select appropriate slurry-making materials to prepare mud. The mud viscosity should ensure the stability of the hole wall and be able to carry the drill cuttings to the surface. The key formula of the mud is to add bentonite, which has good impermeability and can improve the viscosity of the mud to prevent groundwater from seeping into the borehole;

[0027] Step 3: Guided Drilling

[0028] After the equipment is fixed, the drill bit drives the drill rod to rotate and move forward according to the set angle under the action of the power head, and under the control of the navigator, drills according to the depth and length required by the construction, and penetrates the ground after reaching the designated location. The incident and exit angles should be between 4° and 20°;

[0029] Step 4: Expand the hole

[0030] After the navigation is completed, remove the navigation drill bit, install and fix the expansion head and drill pipe, pull the power head back, and pull the drill pipe with the expansion head back in the opposite direction to expand the pipe diameter. Generally, the hole diameter increases by 100mm each time the back is pulled. If the soil layer is very good, you can consider skipping the expansion step;

[0031] Step 5: Pipe welding

[0032] Welding machine status adjustment → pipe preparation → pipe alignment check → preheating → heating and melting → pressurized docking → pressure-maintaining cooling;

[0033] Step 6: Pipeline Pullback

[0034] After the pre-expanded hole diameter reaches 1.2-1.5 times the diameter of the pull-back pipe and the hole is cleaned, the pipe is fixed on the transfer case behind the expander head while the expander head is pulled back. The power head drags the drill rod, and the expander head and the pipe are pulled back in the opposite direction at the same time until the pipe is dragged to the designated position, completing the pipeline laying construction.

[0035] The utility model discloses a three-layer co-extruded modified polypropylene power cable protection tube for underground or trenchless use, which has the following advantages:

[0036] 1. A three-layer co-extruded modified polypropylene power cable protection pipe for underground or trenchless use, which can be hot-melt welded and is suitable for trenchless construction or underground construction of power cable protection pipes;

[0037] 2. It consists of an outer tube layer, a middle tube layer and an inner tube layer. The outer tube layer is made of materials with excellent toughness, good low-temperature performance, high tensile elongation at break, easy deformation, and a bending radius that is less than or equal to 75 times the nominal diameter of the pipe; the middle tube layer is made of materials with high tensile strength and elastic modulus, so its ring stiffness, ring segment thermal compression force, and tensile strength are higher than ordinary MPP, greater than 28MPa; the inner tube layer is made of materials with good heat resistance, and the Vicat softening temperature is higher than 150°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is an axial cross-sectional view of a three-layer co-extruded modified polypropylene power cable protection tube for underground or trenchless use of the utility model, wherein 1 is an outer tube layer, 2 is a middle tube layer, and 3 is an inner tube layer;

[0039] Figure 2 It is an axial cross-sectional view of the pipe cap 4 of the utility model, wherein 41 is a bellows section, 42 is a chain, and 43 is a blocking cover;

[0040] Figure 3 This is an axial cross-sectional view of the connection between a three-layer co-extruded modified polypropylene power cable protection tube for underground or trenchless use and a tube cap 4 of the utility model;

[0041] Figure 4 The utility model is a structural schematic diagram of a three-layer co-extruded modified polypropylene power cable protection tube for underground or trenchless use, which is connected to a pipe cap 4 through a pipe clamp 5, one end of a back-expanding head 6 is connected to the pipe cap 4, and the other end of the back-expanding head 6 is connected to a drill rod 7, and a power head 8 drags the drill rod 7, carrying the back-expanding head 6 and the three-layer co-extruded modified polypropylene power cable protection tube. DETAILED DESCRIPTION

[0042] The present invention is described in detail below with reference to specific embodiments and accompanying drawings:

[0043] As attached Figure 1 As shown, a three-layer co-extruded modified polypropylene power cable protection tube for underground or trenchless use comprises an outer tube layer 1, a middle tube layer 2, and an inner tube layer 3;

[0044] The outer tube layer 1 and the inner tube layer 3 are both flat-wall tube structures, and the middle tube layer 2 is a corrugated structure, including a convex annular cylinder 21 and a concave annular cylinder 22, and the convex annular cylinder 21 and the concave annular cylinder 22 are alternately and continuously distributed;

[0045] The inner diameter of the outer tube layer 1 is the same as the outer diameter of the outer surface of the convex annular cylinder 21 of the middle tube layer 2, and they are coaxially hot-melted together; the outer diameter of the outer surface of the concave annular cylinder 22 of the middle tube layer 2 is the same as the outer diameter of the inner tube layer 3, and they are coaxially hot-melted together;

[0046] When the horizontal directional drilling is pulled back, the pipe cap 4 is connected with a three-layer co-extruded modified polypropylene power cable protection pipe for burial or trenchless use.

[0047] As attached Figure 2 As shown, the pipe cap 4 includes a bellows section 41 , a chain 42 , and a blocking cover 43 . The blocking cover 43 is a hollow cone, wherein the cone top 431 is connected to the chain 42 , and the cone bottom 432 is connected to the bellows section 41 .

[0048] As attached Figure 3 As shown, the outer diameter of the bottom surface of the blocking cover 43 is consistent with the outer diameter of the outer tube layer 1, and the structure of the corrugated tube section 41 is consistent with the structure of the middle tube layer 2, that is, it includes a raised annular cylinder 21 and a recessed annular cylinder 22, and the raised annular cylinder 21 and the recessed annular cylinder 22 are alternately and continuously distributed;

[0049] The corrugated pipe section 41 of the pipe cap 4 is connected to the middle pipe layer 2 by a pipe hoop 5 , and the outer diameter of the pipe hoop 5 is consistent with the outer diameter of the outer pipe layer 1 .

[0050] like Figure 4 As shown, when the horizontal directional drill is pulled back, the chain 42 is connected to the expansion head 6 of the horizontal directional drill, the expansion head 6 is connected to the drill rod 7, and the power head 8 drags the drill rod 7, carrying the expansion head 6 and the three-layer co-extruded modified polypropylene power cable protection tube to perform reverse pulling movement at the same time, until the three-layer co-extruded modified polypropylene power cable protection tube is dragged to the designated position, and the pipeline laying construction is completed.

Claims

1. A three-layer co-extruded modified polypropylene power cable protection tube for underground or trenchless use, characterized in that: It comprises an outer tube layer (1), a middle tube layer (2), and an inner tube layer (3); The outer tube layer (1) and the inner tube layer (3) are both flat-wall tube structures, and the middle tube layer (2) is a corrugated structure, comprising a convex annular cylinder (21) and a concave annular cylinder (22), and the convex annular cylinder (21) and the concave annular cylinder (22) are alternately and cyclically distributed continuously; The inner diameter of the outer tube layer (1) is the same as the outer diameter of the outer surface of the convex annular cylinder (21) of the middle tube layer (2), and they are coaxially heat-fused together; the outer diameter of the outer surface of the concave annular cylinder (22) of the middle tube layer (2) is the same as the outer diameter of the inner tube layer (3), and they are coaxially heat-fused together; When the horizontal directional drilling is pulled back, the pipe cap (4) is connected to a three-layer co-extruded modified polypropylene power cable protection pipe for burying or trenchless use.

2. The three-layer co-extruded modified polypropylene power cable protection tube for underground or trenchless use according to claim 1, characterized in that: The pipe cap (4) comprises a bellows section (41), a chain (42), and a blocking cover (43); the blocking cover (43) is a hollow cone, the top of the cone (431) is connected to the chain (42), and the bottom of the cone (432) is connected to the bellows section (41); The outer diameter of the bottom surface of the blocking cover (43) is consistent with the outer diameter of the outer tube layer (1), and the structure of the corrugated tube section (41) is consistent with the structure of the middle tube layer (2), that is, it includes a raised annular cylinder (21) and a recessed annular cylinder (22), and the raised annular cylinder (21) and the recessed annular cylinder (22) are alternately and continuously distributed in a cycle; The corrugated pipe section (41) of the pipe cap (4) is connected to the middle pipe layer (2) by means of a pipe hoop (5), and the outer diameter of the pipe hoop (5) is consistent with the outer diameter of the outer pipe layer (1); When the horizontal directional drill is towed back, the chain (42) is connected to the expansion head (6) of the horizontal directional drill, the expansion head (6) is connected to the drill rod (7), and the power head (8) drags the drill rod (7), carrying the expansion head (6) and the three-layer co-extruded modified polypropylene power cable protection tube.

3. The three-layer co-extruded modified polypropylene power cable protection tube for underground or trenchless use according to claim 1, characterized in that: The material of the outer tube layer (1) is excellent in toughness; the middle tube layer (2) is made of a material with high tensile strength and elastic modulus; and the inner tube layer (3) is made of a material with good heat resistance.

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