ANTI-HYDROGEN EMBRITTLEMENT WIRE REINFORCED COMPOSITE PIPE

Abstract

Method, devices, and systems for transporting high pressure hydrogen over long distance using anti-hydrogen embrittlement wire reinforced composite pipes are provided. In one aspect, an anti-hydrogen embrittlement wire reinforced composite pipe includes a plastic outer layer, a plastic inner layer, and a wire winding layer. The plastic inner layer is provided in the plastic outer layer, and materials of the plastic inner layer and the plastic outer layer are a thermoplastic material. The wire winding layer is provided between the plastic inner layer and the plastic outer layer and bonded with the plastic inner layer and the plastic outer layer by a hot melt adhesive. The wire winding layer is formed by a plurality of wires spirally wound in left rotation or right rotation.

Claims

1. A method comprising: arranging an anti-hydrogen embrittlement wire reinforced composite pipe between two containers that are separated with a long distance greater than a threshold distance; and transporting high pressure hydrogen over the long distance between the two containers using the anti-hydrogen embrittlement wire reinforced composite pipe, wherein the anti-hydrogen embrittlement wire reinforced composite pipe comprises a plastic outer layer, a plastic inner layer, and a wire winding layer, wherein the plastic inner layer is provided in the plastic outer layer, and materials of the plastic inner layer and the plastic outer layer comprise a thermoplastic material, and wherein the wire winding layer is provided between the plastic inner layer and the plastic outer layer and bonded with the plastic inner layer and the plastic outer layer by a hot melt adhesive, wherein the wire winding layer is formed by a plurality of wires spirally wound in left rotation or right rotation, wherein the wire winding layer is formed by at least two layers of wires interlaced and wound in opposite directions, and the wire winding layer has an even number of layers, and wherein a gap between adjacent wires of the plurality of wires is at least 1 mm, wherein the plurality of wires comprise a low carbon steel wire that has a carbon content of less than 0.25%, and wherein each of the at least two layers of wires comprises at least eight wires, wherein a material of the hot melt adhesive comprises modified high density polyethylene, and the hot melt adhesive completely wraps the plurality of wires through gaps between the plurality of wires, and wherein the anti-hydrogen embrittlement wire reinforced composite pipe has a burst pressure exceeding three times of a nominal pressure for hydrogen transportation, and the burst pressure of the anti-hydrogen embrittlement wire reinforced composite pipe is determined by formulas including: $p_B^z=\frac{{\mathrm{Nd}}^2\left({\sigma }_{\mathrm{bg}}{\cos }^2\alpha -{\sigma }_{\mathrm{bp}}\right)}{4r_i^2\cos \alpha }+{\sigma }_{\mathrm{bp}}\left(K^2-1\right)\mathrm{and}$ $p_B^{\theta }=\frac{{\mathrm{Nd}}^2\left({\sigma }_{\mathrm{bg}}{\sin }^2\alpha -{\sigma }_{\mathrm{bp}}\right)}{4r_i\left(r_i+r_o\right)\cos \alpha }+{\sigma }_{\mathrm{bp}}\left(K-1\right),$ where d represents a diameter of a wire of the plurality of wires, N represents a total number of wound wires, r.sub.i represents an inner radius of the anti-hydrogen embrittlement wire reinforced composite pipe, r.sub.o represents an outer radius of the anti-hydrogen embrittlement wire reinforced composite pipe, α represents an angle between a winding direction of the wire and an axial direction, K represents a factor (K=r.sub.i/r.sub.o), σ.sub.bg represents a strength limit of the wire, σ.sub.bp represents a calculated strength of polyethylene, p.sub.B.sup.z represents an annular burst pressure, p.sub.B.sup.θ represents an axial burst pressure, and the burst pressure is a minimum of the annular burst pressure and the axial burst pressure.

2. The method of claim 1, wherein the materials of the plastic inner layer and the plastic outer layer comprise high density polyethylene, and a density of the high density polyethylene is no less than 0.941 g/cm.sup.3.

3. The method of claim 1, wherein the plastic inner layer and the plastic outer layer have a same thickness.

4. The method of claim 3, wherein the plastic inner layer and the plastic outer layer have the thickness of at least 3 mm.

5. The method of claim 1, wherein the diameter of the wire is between 0.5 mm and 3 mm.

6. The method of claim 1, wherein the plurality of wires comprise an aluminized or copper-plated steel wire having an aluminum or copper-plated layer with a thickness more than 20 μm.

7. The method of claim 1, wherein the plurality of wires comprise a stainless steel wire having Ni with a content in a range of 10.00% to 14.00%, Cr with a content in a range of 16.00% to 19.00%, and Mo with a content in a range of 1.80% to 2.50%.

8. An anti-hydrogen embrittlement wire reinforced composite pipe, the composite pipe comprising: a plastic outer layer; a plastic inner layer; and a wire winding layer, wherein the plastic inner layer is provided in the plastic outer layer, and materials of the plastic inner layer and the plastic outer layer comprise a thermoplastic material, wherein the wire winding layer is provided between the plastic inner layer and the plastic outer layer and bonded with the plastic inner layer and the plastic outer layer by a hot melt adhesive, wherein the wire winding layer is formed by a plurality of wires spirally wound in left rotation or right rotation, wherein the wire winding layer is formed by at least two layers of wires interlaced and wound in opposite directions, and the wire winding layer has an even number of layers, and wherein a gap between adjacent wires of the plurality of wires is at least 1 mm, wherein a material of the hot melt adhesive is compatible with the thermoplastic material, and the hot melt adhesive completely wraps the plurality of wires through gaps between the plurality of wires, and wherein the composite pipe has a burst pressure exceeding three times of a nominal pressure for hydrogen transportation, and the burst pressure is determined by formulas including: $p_B^z=\frac{{\mathrm{Nd}}^2\left({\sigma }_{\mathrm{bg}}{\cos }^2\alpha -{\sigma }_{\mathrm{bp}}\right)}{4r_i^2\cos \alpha }+{\sigma }_{\mathrm{bp}}\left(K^2-1\right)\mathrm{and}$ $p_B^{\theta }=\frac{{\mathrm{Nd}}^2\left({\sigma }_{\mathrm{bg}}{\sin }^2\alpha -{\sigma }_{\mathrm{bp}}\right)}{4r_i\left(r_i+r_o\right)\cos \alpha }+{\sigma }_{\mathrm{bp}}\left(K-1\right),$ where d represents a diameter of a wire of the plurality of wires, N represents a total number of wound wires, r.sub.i represents an inner radius of the composite pipe, r.sub.o represents an outer radius of the composite pipe, α represents an angle between a winding direction of the wire and an axial direction, K represents a factor (K=r.sub.i/r.sub.o), σ.sub.bg represents a strength limit of the wire, σ.sub.bp represents a calculated strength of polyethylene, p.sub.B.sup.z represents an annular burst pressure, p.sub.B.sup.θ represents an axial burst pressure, and the burst pressure is a minimum of the annular burst pressure and the axial burst pressure.

9. The composite pipe of claim 8, wherein the materials of the plastic inner layer and the plastic outer layer comprise high density polyethylene, and a density of the high-density polyethylene is no less than 0.941 g/cm.sup.3.

10. The composite pipe of claim 9, wherein the material of the hot melt adhesive comprises modified high density polyethylene.

11. The composite pipe of claim 8, wherein the plastic inner layer and the plastic outer layer have a same thickness.

12. The composite pipe of claim 11, wherein the plastic inner layer and the plastic outer layer have the thickness of at least 3 mm.

13. The composite pipe of claim 8, wherein the diameter of the wire is between 0.5 mm and 3 mm.

14. The composite pipe of claim 8, wherein the plurality of wires comprise a low carbon steel wire that has a carbon content of less than 0.25%.

15. The composite pipe of claim 8, wherein the plurality of wires comprise an aluminized or copper-plated steel wire having an aluminum or copper-plated layer with a thickness more than 20 μm.

16. The composite pipe of claim 8, wherein the plurality of wires comprise a stainless steel wire having Ni with a content in a range of 10.00% to 14.00%, Cr with a content in a range of 16.00% to 19.00%, and Mo with a content in a range of 1.80% to 2.50%.

17. The composite pipe of claim 8, wherein each of the at least two layers of wires comprises at least eight wires.

18. The composite pipe of claim 8, wherein the nominal pressure is 2 MPa.

19. A hydrogen pipe network system comprising: at least two containers that are separate with a long distance greater than a threshold distance; and at least one anti-hydrogen embrittlement wire reinforced composite pipe arranged between the at least two containers and configured to transport high pressure hydrogen between the at least two containers over the long distance, wherein each of the at least one anti-hydrogen embrittlement wire reinforced composite pipe comprises a plastic outer layer, a plastic inner layer, and a wire winding layer, wherein the plastic inner layer is provided in the plastic outer layer, and materials of the plastic inner layer and the plastic outer layer comprise a thermoplastic material, and wherein the wire winding layer is provided between the plastic inner layer and the plastic outer layer and bonded with the plastic inner layer and the plastic outer layer by a hot melt adhesive, wherein the wire winding layer is formed by a plurality of wires spirally wound in left rotation or right rotation, wherein the wire winding layer is formed by at least two layers of wires interlaced and wound in opposite directions, and the wire winding layer has an even number of layers, and wherein a gap between adjacent wires of the plurality of wires is at least 1 mm, wherein a material of the hot melt adhesive is compatible with the thermoplastic material, and the hot melt adhesive completely wraps the plurality of wires through gaps between the plurality of wires, and wherein the anti-hydrogen embrittlement wire reinforced composite pipe has a burst pressure exceeding three times of a nominal pressure for hydrogen transportation, and the burst pressure of the anti-hydrogen embrittlement wire reinforced composite pipe is determined by formulas including: $p_B^z=\frac{{\mathrm{Nd}}^2\left({\sigma }_{\mathrm{bg}}{\cos }^2\alpha -{\sigma }_{\mathrm{bp}}\right)}{4r_i^2\cos \alpha }+{\sigma }_{\mathrm{bp}}\left(K^2-1\right)\mathrm{and}$ $p_B^{\theta }=\frac{{\mathrm{Nd}}^2\left({\sigma }_{\mathrm{bg}}{\sin }^2\alpha -{\sigma }_{\mathrm{bp}}\right)}{4r_i\left(r_i+r_o\right)\cos \alpha }+{\sigma }_{\mathrm{bp}}\left(K-1\right),$ where d represents a diameter of a wire of the plurality of wires, N represents a total number of wound wires, r.sub.i represents an inner radius of the anti-hydrogen embrittlement wire reinforced composite pipe, r.sub.o represents an outer radius of the anti-hydrogen embrittlement wire reinforced composite pipe, α represents an angle between a winding direction of the wire and an axial direction, K represents a factor (K=r.sub.i/r.sub.o), σ.sub.bg represents a strength limit of the wire, σ.sub.bp represents a calculated strength of polyethylene, p.sub.B.sup.z represents an annular burst pressure, p.sub.B.sup.θ represents an axial burst pressure, and the burst pressure is a minimum of the annular burst pressure and the axial burst pressure.

20. The hydrogen pipe network system of claim 19, wherein the plurality of wires comprise a low carbon steel wire that has a carbon content of less than 0.25%, and wherein each of the at least two layers of wires comprises at least eight wires.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a schematic structural diagram illustrating an anti-hydrogen embrittlement wire reinforced composite pipe according to an embodiment of the present disclosure.

[0024] FIG. 2 is a schematic diagram illustrating a change in tensile strength of Q235 steel and 45 steel at different hydrogen concentrations.

[0025] FIG. 3 is a schematic diagram illustrating a change in fracture toughness of 316 stainless steel and 304 stainless steel at different hydrogen concentrations.

[0026] Reference numerals are listed as follows: plastic outer layer 101; hot melt adhesive binder 102; plastic inner layer 103; and wire winding layer 104.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The present disclosure is described in further detail below in conjunction with the accompanying drawings.

[0028] As shown in FIG. 1, an embodiment of the present disclosure provides an anti-hydrogen embrittlement wire reinforced composite pipe including a plastic outer layer 101, a plastic inner layer 103, and a wire winding layer 104. The plastic inner layer 103 is provided in the plastic outer layer 101, and materials of the plastic inner layer 103 and the plastic outer layer 101 are a thermoplastic material. The anti-hydrogen embrittlement wire reinforced composite pipe can be arranged between at least two containers (e.g., hydrogen refueling stations, chemical plants, power stations, or any other hydrogen-demanding sectors) that are separated over a long distance (e.g., more than 5 km) and be configured to transport high pressure hydrogen over the long distance between the at least two containers.

[0029] Polyethylene (PE) pipes are widely used in municipal water supply and drainage and gas transport. The maximum working pressure of PE 100 high density polyethylene pipe for transporting city gas is 0.8 MPa and the density is usually no less than 0.941 g/cm.sup.3. The hydrogen pressure at an outlet of a hydrogen electrolyzer is usually above 2 MPa, thus the existing polyethylene pipes cannot meet the pressure requirements of the pipe for transporting hydrogen. Unlike metals, high-density polyethylene will not suffer from hydrogen embrittlement. The hydrogen absorbed by high-density polyethylene exists in the form of diatomic molecules and will not be separated as hydrogen does in metals. Therefore, the hydrogen embrittlement resistance of the high density polyethylene can be used for pipes for long-distance transport hydrogen. In an embodiment of the present disclosure, the high density polyethylene is selected as the base material of the plastic inner layer 103 and the plastic outer layer 101. Specifically, the hydrogen permeability of the high density polyethylene is 0.89×10.sup.−9 mol H.sub.2/m.Math.s.Math.MPa.

[0030] The strength of the pipe made of the high density polyethylene alone is not sufficient to meet the needs of the pipe for transporting hydrogen, thus, in the present disclosure, a wire is wrapped around the plastic inner layer 103 (as a plastic substrate) formed by the high density polyethylene to increase the strength of the pipe, and after wrapping the wire, the wire and the plastic substrate bear the pressure together, and thus the strength of the pipe is increased after wrapping the wire. Based on a similar principle, for the high-strength steel wire winding reinforced pipe and the wire mesh skeleton reinforced pipe, a reinforced layer is also provided in the thermoplastic inner layer, and through a reasonable pipe design, the high-strength steel wire winding reinforced pipe and the wire mesh skeleton reinforced pipe can bear a pressure of 6.3 MPa or more. In the present disclosure, the wire winding layer 104 is provided between the plastic inner layer 103 and the plastic outer layer 101.

[0031] In an embodiment, the plastic inner layer 103 and the plastic outer layer 101 have a same thickness, and the plastic inner layer 103 and the plastic outer layer 101 have the thickness of at least 3 mm to avoid possible instability in the operation of the composite pipe and to prevent excessive thermal effects on the pipe and the reinforcement layer caused by the temperature difference between the inner layer 103 and the outer layer 101 by ensuring the thickness of the plastic inner layer 103 and the plastic outer layer 101.

[0032] The plastic layers (the plastic inner layer 103 and the plastic outer layer 101) and the wire winding layer 104 of the composite pipe are bonded by a hot melt adhesive. Since the wire material and the high density polyethylene material of the base material are incompatible, the embodiment of the present disclosure uses the hot melt adhesive to bond the plastic layers 101, 103 and the wire winding layer 104, so that the wire and the high density polyethylene can bear the pressure together, and the advantages of both materials are fully utilized. The hot melt adhesive needs to have excellent bonding performance and barrier performance. A material of the hot melt adhesive can be compatible with a material of the plastic layers. In some examples, the hot melt adhesive can include modified high density polyethylene. The modified high density polyethylene can be obtained by modifying the high density polyethylene to have a sufficient interfacial bonding strength as a hot melt adhesive. In the present disclosure, the wire winding layer 104 is bonded to the plastic inner layer 103 and the plastic outer layer 104 by hot melt adhesive 102, and the wire winding layer 104 is formed by a plurality of wires spirally wound in left rotation or right rotation.

[0033] In an embodiment of the present disclosure, the wire winding layer 104 is further optimized, where the wire winding layer 104 is formed by at least two layers of wires interlaced and wound in opposite directions, and the wire winding layer 104 has an even number of layers. The interlacing and winding arrangement of the wire can optimize the stress distribution of the pipe when the pressure is applied to the pipe. A single wire winding layer or each of the at least two layers of wires in this embodiment has at least eight wires, and a gap between adjacent wires of the at least eight wires is at least 1 mm to ensure that the wires are evenly stressed and that the hot melt adhesive can completely wrap the wires through the gaps between the wires to ensure bonding.

[0034] As a pipe for transporting hydrogen, the transport medium is pure hydrogen, the pipe shall be resistant to hydrogen embrittlement. Hydrogen penetration to the inside of the pipe will occur during the transportation of hydrogen in the pipe, thus the wound wire in the present disclosure adopts the anti-hydrogen embrittlement steel wire to avoid the phenomenon of hydrogen embrittlement of the wire during the long-term use of the composite pipe and reduce the mechanical properties of the pipe. The hydrogen permeability of high density polyethylene is 0.89×10.sup.−9 mol H.sub.2/m.Math.s.Math.MPa, hydrogen may still slowly penetrate into the plastic base material of the composite pipe, and the metal material of the reinforced layer may be gradually affected by hydrogen corrosion in the long term accumulation of hydrogen transport of the pipe. The inventor found that the low carbon steel wire, the aluminum or copper-plated steel wire, the stainless steel wire has the ability to resist hydrogen embrittlement, and the high strength steel wire has a significant decrease in material mechanical properties after hydrogen corrosion occurs due to its high carbon content.

[0035] To this end, by comparing the mechanical properties of different anti-hydrogen embrittlement steel wire materials in hydrogen environment, the present disclosure finally selects three kinds of anti-hydrogen embrittlement steel wires including: (1) a low carbon steel wire, where the low carbon steel wire includes a carbon content of less than 0.25%; (2) an aluminized or copper-plated steel wire, where aluminum or copper is plated on the surface of ordinary high strength steel wire, and the thickness of the aluminized or copper-plated layer is more than 20 μm; (3) a stainless steel wire, where the content of metal elements is controlled in the steel, and the stainless steel wire includes Ni of 10.00% to 14.00%, Cr of 16.00% to 19.00%, and Mo of 1.80% to 2.50%. In addition, considering that the mechanical property of the anti-hydrogen embrittlement steel wire is weaker than that of the ordinary high strength steel wire, the diameter of the wire is between 0.5 mm and 3 mm to ensure the pressure bearing capacity of the wire, so as to avoid the strength failure of the wire.

[0036] FIG. 2 is a schematic diagram illustrating a change in tensile strength of Q235 steel (about 0.17%˜0.25% carbon) and 45 steel (about 0.45% carbon) at different hydrogen concentrations, and FIG. 2 shows that the tensile strength of both steels fluctuates as the hydrogen concentration increases. However, the comparison shows that with the increase of hydrogen concentration, the tensile strength of 45 steel fluctuates more, and the difference between the maximum value and the minimum value is 23 MPa, and the difference of Q235 steel is 15 MPa. In the above two steels, the carbon content of Q235 steel is lower, and the higher the carbon content is in the hydrogen environment, the more the mechanical properties of steel will decline, while the mechanical properties of low carbon steel will not decline significantly in the hydrogen environment. Therefore, the low carbon steel with carbon content less than 0.25% can be selected as the material for the anti-hydrogen embrittlement wire in the present disclosure.

[0037] In another embodiment, the anti-hydrogen embrittlement wire is made of aluminized or copper-plated steel wire, specifically, aluminum or copper is plated on the surface of ordinary high strength steel wire, and the thickness of the aluminized or copper-plated layer is more than 20 μm. By testing the mechanical properties of aluminized or copper-plated steel wire in a hydrogen environment, the result shows that the aluminized or copper-plated steel wire is virtually unaffected by hydrogen corrosion. The principle is that the aluminized or copper-plated layer can form a protection layer on the steel wire to isolate the hydrogen from penetrating into the steel wire, and thus the aluminized or copper-plated high strength steel wire can be selected as the anti-hydrogen embrittlement wire in the present disclosure. Further, the thickness of the aluminized or copper-plated layer is more than 20 μm to ensure the protective effect of the plating on the steel wire.

[0038] FIG. 3 is a schematic diagram illustrating a change of J-integral for 316 stainless steel and 304 stainless steel at different hydrogen concentrations, and the J-integral is used to characterize the fracture toughness of the material. FIG. 3 shows that the fracture toughness of two steels decreases with increasing the hydrogen concentration, but comparing the two steels, it can be found that the toughness of 304 stainless steel decreases more drastically in the hydrogen environment, while the fracture toughness of 316 stainless steel decreases less. Further, based on the researches by the inventor, hydrogen has an effect on the toughness of stainless steel, and by controlling the content of metal elements in stainless steel, the effect of hydrogen on the mechanical properties of steel can be reduced. For example, the nickel content of stainless steel affects the martensite content of the steel and thus affects the hydrogen embrittlement resistance of the steel. Therefore, the anti-hydrogen embrittlement wire in the present disclosure can be selected from the stainless steel wire with controlled metal content, where Ni content is from 10.00% to 14.00%, Cr content is from 16.00% to 19.00%, and Mo content is from 1.80% to 2.50%.

[0039] The application of the anti-hydrogen embrittlement wire reinforced composite pipe of the present disclosure is further described in detail below in conjunction with the actual production and operation scenarios of the pipe for transporting hydrogen.

Embodiment I

[0040] The anti-hydrogen embrittlement wire reinforced composite pipe provided by the present disclosure can be used to construct a long-distance and large-scale hydrogen transmission pipeline system. According to the relevant parameters of the embodiment of the present disclosure, the design dimensions of the composite pipe are obtained as follows. The nominal diameter of the composite pipe is 355 mm, the thickness of the plastic inner layer is 10 mm, the thickness of the plastic outer layer is 10 mm, the high-density polyethylene material of PE100 is used as the base material, and its calculated strength is 25 MPa, and a material of the wire is selected from the aluminized high strength steel wire with a diameter of 1.5 mm, and its lower limit of tensile strength is 1850 MPa. There are four wire winding layers, each of the four wire winding layers has 160 wires, and the angle for winding wire is 30°. The predicted annular burst pressure and axial burst pressure of the composite pipe are calculated by the force balance method. The burst pressure calculation formula can be determined by the following formulas:

[00002]$p_B^z=\frac{{\mathrm{Nd}}^2\left({\sigma }_{\mathrm{bg}}{\cos }^2\alpha -{\sigma }_{\mathrm{bp}}\right)}{4r_i^2\cos \alpha }+{\sigma }_{\mathrm{bp}}\left(K^2-1\right),\mathrm{and}$$p_B^{\theta }=\frac{{\mathrm{Nd}}^2\left({\sigma }_{\mathrm{bg}}{\sin }^2\alpha -{\sigma }_{\mathrm{bp}}\right)}{4r_i\left(r_i+r_o\right)\cos \alpha }+{\sigma }_{\mathrm{bp}}\left(K-1\right),$

where d represents a diameter of the wire, N represents a total number of wound wires, r.sub.i represents an inner radius of the composite pipe, r.sub.o represents an outer radius of the composite pipe, α represents an angle between a winding direction of the wire and an axial direction, K represents a factor (K=r.sub.i/r.sub.o), σ.sub.bg represents a strength limit of the wire, and σ.sub.bp represents a calculated strength of polyethylene. The annular burst pressure of the composite pipe p.sub.B.sup.z is calculated to be 30.44 MPa, and the axial burst pressure p.sub.B.sup.θ is calculated to be 6.78 MPa. The burst pressure is a minimum of the annular burst pressure and the axial burst pressure, and thus the burst pressure of the composite pipe is 6.78 MPa.

[0041] The designed service life of the composite pipe is more than 50 years, and the life of the composite pipe cannot be obtained through experimental testing by conventional means, and thus the load distribution of the composite pipe in service can be analyzed to establish the evaluation index of the long-term performance of the composite pipe. During the service process of the composite pipe, the wire reinforcement layer mainly bears the pressure, and the base material will gradually relax with the increase of use time. Therefore, the composite pipe of the present disclosure needs to have a long-term performance prediction method matching its structure. According to the long-term performance analysis of existing composite pipe, a relationship between the long-term performance of the composite pipe of the present disclosure and the short-term test burst pressure can be established, thus the burst pressure of the composite pipe of the present disclosure needs to be more than 3 times of the nominal pressure. If the composite pipe of the present disclosure meets the relationship, the composite pipe has sufficient long-term mechanical performance and can serve for more than 50 years.

[0042] The burst pressure of the composite pipe in the embodiment is 6.78 MPa, which is more than three times of the nominal pressure of 2 MPa. Therefore, the composite pipe of the embodiment can meet the demand of long-term hydrogen transport, can replace the metal pipe with the same design requirements, and can undertake the long-term hydrogen transport.

Embodiment II

[0043] The present disclosure can be used to construct an urban hydrogen pipe network system, and the following composite pipe is designed for an urban hydrogen pipe network according to the relevant parameters of the present disclosure. The nominal pressure of the pipe for transporting hydrogen is 2 MPa, and the nominal diameter is a diameter of the typical urban gas pipe, e.g., 160 mm. The relevant dimensions of the designed composite pipe are as follows. The thickness of the plastic inner layer is 10 mm, the thickness of the plastic outer layer is 10 mm, the high-density polyethylene material of PE100 is used as the base material, and its calculated strength is 25 MPa. The material of the wire is low carbon steel wire with a diameter of 1 mm, and its lower limit of tensile strength is 780 MPa. The wire winding layers are formed by two layers of wires interlacing and winding, each of the wire winding layers has 36 wires, and a winding angle is 20°. The annular burst pressure and the axial burst pressure of the composite pipe are calculated by the same force balance method as in the embodiment I. The annular burst pressure of the composite pipe p.sub.B.sup.z is calculated to be 17.17 MPa, and the axial burst pressure p.sub.B.sup.θ is calculated to be 6.39 MPa. The burst pressure is a minimum of the annular burst pressure and the axial burst pressure, thus the burst pressure of the composite pipe is 6.39 MPa. which is more than 3 times of the nominal pressure (2 MPa). Therefore, it is considered that the pipe designed by the present can be used to lay the urban hydrogen pipe network system.

[0044] It should be noted that the above described are only preferred embodiments of the present disclosure and are not intended to limit the present disclosure. Despite the detailed description of the present disclosure with reference to the above-mentioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions in the above-mentioned embodiments or to make equivalent substitutions for some of the technical features thereof. Any modification, equivalent substitution, improvement, etc. made within the spirit and principles of the present disclosure shall be included in the scope of the present disclosure.