A plastic-coated stainless steel corrugated pipe for gas

Abstract

The application provides a plastic-coated stainless steel corrugated pipe for gas, which comprises a stainless steel corrugated pipe, a gasket layer, a stiffness adjusting layer and a plastic coating layer arranged in sequence from inside to outside, the stiffness adjusting layer is composed of a plurality of axially distributed stiffness adjusting rings, each ring body is provided with a hinged part with a convex part and a movable groove on both sides, adjacent ring bodies are hinged to each other, the convex part can slide in the movable groove with gradually increasing depth by controlling the axial spacing between the ring bodies, when the ring bodies are away from each other, the convex part slides into a region with a larger groove depth, the ring bodies can freely move, a flexible section is formed, and the bending is convenient to install, when the ring bodies are close to each other, the convex part enters a region with a smaller groove depth and is tightly locked, a locking section is formed, the pipe body is effectively prevented from drooping or shaking, the continuous stress on the joint part is reduced, the local stiffness of the gas corrugated pipe is actively adjusted, the flexibility during installation and the structural stability during use are combined, and the application relates to the technical field of gas hoses.

Description

Technical Field

[0001] This invention relates to the field of gas hose technology, and more specifically to a plastic-coated stainless steel corrugated pipe for gas applications. Background Technology

[0002] Gas-specific stainless steel corrugated pipes are a type of metal hose that replaces traditional rubber hoses. Their core features lie in the corrosion resistance and high temperature resistance of stainless steel, as well as the pressure resistance and flexibility provided by the corrugated structure. A safe and reliable sealed connection is achieved through threaded interfaces.

[0003] The aforementioned stainless steel corrugated pipes also include flexible corrugated pipes with moderate hardness and ultra-flexible corrugated pipes with softer hardness. The ultra-flexible ones have a smaller bending radius and can be easily bent without effort. They are especially suitable for special scenarios that require complex wiring, bypassing obstacles, or connecting mobile gas equipment. Their extreme flexibility provides greater convenience and flexibility for installation, but all of them must be installed by professionals in accordance with regulations.

[0004] Flexible corrugated pipes are relatively rigid and can be bent manually, but require a certain amount of force and are not easily deformed after bending. Ultra-flexible pipes have a smaller bending radius and can be easily bent without much effort, making them particularly suitable for special scenarios requiring complex wiring, bypassing obstacles, or connecting mobile gas equipment. However, flexible corrugated pipes are difficult to install in narrow spaces, and forced bending is quite strenuous and may lead to stress concentration, affecting their lifespan. Ultra-flexible corrugated pipes are prone to sagging and swaying due to their own weight or external forces, which may generate continuous stress on the connectors. Therefore, there is an urgent need for a flexible, position-controllable stainless steel corrugated pipe specifically for gas applications. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings and deficiencies of the prior art by proposing a plastic-coated stainless steel corrugated pipe for gas combustion.

[0006] The present invention provides a plastic-coated stainless steel corrugated pipe for gas combustion, comprising a stainless steel corrugated pipe, a liner layer, a stiffness adjustment layer and a plastic coating layer arranged coaxially from the inside to the outside. The stiffness adjustment layer is composed of multiple stiffness adjustment rings distributed along the axial direction. Each stiffness adjustment ring includes a ring body and multiple hinge parts protruding from both ends of the ring body along the axial direction. The multiple hinge parts are evenly distributed along the circumferential direction, and there is a gap between two adjacent hinge parts along the circumferential direction. The hinge parts at both ends of the same ring body are staggered. One side wall of the hinge is provided with a protrusion at a position axially away from the ring body, and the other side wall is provided with a movable groove, and the depth of the movable groove gradually increases along the axial direction away from the ring body; Two adjacent rings are inserted into the axial gap of another ring through a hinge, and the protrusion is placed in the corresponding movable groove to achieve mutual hinge; By moving the relative parts of each ring, the protrusion slides in the movable groove, thereby adjusting the stiffness so that the bellows has a flexible section and a locking section. In the flexible section, the axial movement of each ring body is moved away from the other. The protrusion enters the side with a larger groove depth in the movable groove. The protrusion can move freely in the movable groove to reduce the stiffness of the bellows. In the locking section, the axial movement of each ring body brings them closer together, at least a portion of the protrusions enter the side of the movable groove with a smaller groove depth, the end face of the protrusion abuts against the end face of the movable groove, and the ring bodies interlock with each other to increase the rigidity of the bellows.

[0007] Preferably, the locking section includes a straight section of the bellows and a curved section of the bellows; In the straight section of the bellows, the protrusion enters the side of the movable groove with a smaller groove depth, the pressure between the end face of the protrusion and the end face of the movable groove increases, and the rings jam against each other to increase the rigidity of the bellows. In the curved section of the bellows, the protrusion on the outer bend side enters the groove to a greater depth, while the protrusion on the inner bend side enters the groove to a lesser depth, in order to increase the rigidity of the bellows.

[0008] Preferably, the hinge is constructed as a toothed structure, the movable groove is constructed as a fan-shaped groove, and the width of the movable groove on the side closer to the ring is greater than that on the other side, so that the protrusion has a larger range of motion in the movable groove on the side closer to the ring.

[0009] Preferably, the active groove includes a first region and a second region that are continuously distributed, the second region being located on the side closer to the ring body, and the groove depth of the second region being less than the groove depth of the first region.

[0010] Preferably, the bottom surface of the first region is a plane, the bottom surface of the second region is an inclined plane, the first region and the second region are smoothly transitioned, and the protrusion is configured to slide within the first region and gradually lock and fix itself in the second region toward the ring body.

[0011] Preferably, when the protrusion is located at one end of the first region away from the ring body, the distance between two adjacent stiffness adjustment rings is the first ring distance L1; when the protrusion is located in the second region near the locked position of the ring body, the distance between two adjacent stiffness adjustment rings is the second ring distance L2.

[0012] Preferably, the stiffness adjustment ring comprises a metal ring or a plastic ring, and the minimum bending radius of the stiffness adjustment layer is greater than or equal to the minimum bending radius of the stainless steel bellows.

[0013] Preferably, the padding layer comprises a foam material layer or a plastic layer, and the thickness of the padding layer is less than the thickness of the plastic covering layer.

[0014] Preferably, the distance between any two adjacent rings is equal to the wave pitch of the stainless steel corrugated pipe.

[0015] Compared with the prior art, the advantages of the present invention are as follows: This invention provides a plastic-coated stainless steel corrugated pipe for gas applications, featuring a stiffness adjustment layer composed of multiple hinged stiffness adjustment rings. By changing the spacing between adjacent adjustment rings, the protrusions slide to different depths within the movable groove, thereby enabling flexible switching between a flexible section and a locking section of the pipe body. During installation, the adjustment rings can move freely, giving the pipe body the bendability of an ultra-flexible corrugated pipe. After installation, axial movement allows the protrusions to enter the shallow part of the groove and lock in place, forming a rigid section that prevents the pipe body from sagging or swaying, effectively reducing stress on the joints. This achieves active adjustment of the pipe body stiffness, combining excellent installation adaptability with operational stability. Attached Figure Description

[0016] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the hierarchical structure of a plastic-coated stainless steel corrugated pipe for gas combustion, as shown in an embodiment of the present invention. Figure 2 This is a schematic diagram of a partial cross-sectional structure of a plastic-coated stainless steel corrugated pipe for gas combustion, as shown in an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure in which the stiffness adjustment rings are hinged to each other on the outside of the stainless steel bellows, as shown in the embodiment of the present invention. Figure 4 This is a three-dimensional structural schematic diagram of the stiffness adjustment ring shown in an embodiment of the present invention; Figure 5 This is a three-dimensional structural schematic diagram of a half-section of the stiffness adjustment ring shown in an embodiment of the present invention; Figure 6 This is a schematic diagram of the distribution structure of the hinge portion on both sides of the ring body according to an embodiment of the present invention; Figure 7a This is a schematic diagram showing the positional relationship between the protrusions and the movable groove of the two stiffness adjustment rings under normal spacing, as shown in an embodiment of the present invention. Figure 7b This is a schematic diagram showing the positional relationship between the protrusions and the movable groove of the two stiffness adjustment rings at their maximum spacing, as illustrated in an embodiment of the present invention. Figure 7c This is a schematic diagram showing the positional relationship between the protrusions and the movable groove of the two stiffness adjustment rings at the minimum spacing, as shown in an embodiment of the present invention. Figure 8 This is a schematic diagram of the locking section and the flexible section in the straight pipe state of a plastic-coated stainless steel corrugated pipe for gas, as shown in an embodiment of the present invention. Figure 9 This is a schematic diagram of the locking section in the bent state of a plastic-coated stainless steel corrugated pipe for gas supply, as shown in an embodiment of the present invention.

[0017] L, preset spacing; L1, first ring spacing; L2, second ring spacing; 10, stainless steel corrugated pipe; 20, padding layer; 30, stiffness adjustment ring; 300, gap; 31, ring body; 32, hinge; 320, movable groove; 3201, first area; 3202, second area; 321, protrusion; 40, plastic covering layer. Detailed Implementation

[0018] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0019] Both flexible and ultra-flexible corrugated pipes have certain drawbacks. The flexibility and rigidity of these two types of corrugated pipes are fixed and cannot be balanced. Flexible pipes sacrifice ease of installation in order to maintain their shape, making them difficult to use in complex cabinets. Ultra-flexible pipes are very easy to install, but their excessive flexibility makes it difficult for them to maintain ideal wiring on their own. They are prone to sagging and swaying due to their own weight or external forces, which may cause continuous stress on the connectors and affect the aesthetics.

[0020] Therefore, both types of corrugated pipes rely heavily on external pipe clamps to forcibly fix the lines, and their materials and structures do not have the ability to change stiffness.

[0021] like Figure 1 and Figure 2 As shown, the present invention provides a plastic-coated stainless steel corrugated pipe for gas, which aims to give the gas-specific stainless steel corrugated pipe variable stiffness to adapt to more complex installation environments. The pipe includes a stainless steel corrugated pipe 10, a liner layer 20, a stiffness adjustment layer and a plastic coating layer 40, which are concentrically distributed from the inside to the outside.

[0022] The stainless steel corrugated pipe 10 has a corrugation pitch of 2.0mm-4.0mm and a wall thickness of 0.25mm-0.40mm. The stainless steel corrugated pipe 10 is a standard ultra-flexible corrugated pipe. Therefore, the stainless steel corrugated pipe 10 has the flexibility of an ultra-flexible corrugated pipe and is relatively soft and easy to bend.

[0023] Because ultra-flexible corrugated pipes suffer from insufficient stress at joints due to factors such as pipe sagging and swaying, in order to compensate for the shortcomings of ultra-flexible pipes and combine some advantages of flexible pipes, the pipes are designed to have composite properties in their overall structure (i.e., they have the flexibility of ultra-flexible pipes and can also have the properties of rigid pipes in certain areas), so that the pipes as a whole can adapt to more complex installation environments.

[0024] By moving the relative parts 31, the protrusion 321 slides in the movable groove 320, thereby adjusting the stiffness so that the bellows has a flexible section and a locking section. In the flexible section, each ring 31 moves axially away from the other, and the protrusion 321 enters the side with a larger groove depth of the movable groove 320. The protrusion 321 can move freely in the movable groove 320 to reduce the stiffness of the bellows. Furthermore, in combination Figure 3 , Figure 4 , Figure 7a , Figure 7b and Figure 7c As shown, the stiffness adjustment layer includes multiple stiffness adjustment rings 30 that are distributed axially and hinged to each other. When the distance between any two adjacent stiffness adjustment rings 30 is a preset distance L (the stiffness adjustment rings 30 are covered by an outer plastic coating layer 40 at the preset distance L; to maintain the length between the stiffness adjustment rings 30 at the preset distance L under normal conditions, grooves can generally be pre-made on the outer wall of the stiffness adjustment rings 30; after the plastic coating layer 40 covers the outer layer of the stiffness adjustment rings 30, it forms an elastic ring on the pre-made groove, which can restrict the stiffness adjustment rings 30 to the preset position), the rings 31 can move freely, and the gas pipe as a whole is in a flexible state.

[0025] In the locking section, the rings 31 move axially closer together, and at least part of the protrusions 321 enter the side of the movable groove 320 with a smaller groove depth. The end face of the protrusion 321 abuts against the end face of the movable groove 320, and the rings 31 jam against each other to increase the rigidity of the bellows.

[0026] like Figure 8 and Figure 9 As shown, the locking section includes a straight section and a curved section of the bellows. In the straight section, the protrusion 321 enters the side of the movable groove 320 with a smaller groove depth, and the end face of the protrusion 321 abuts against the end face of the movable groove 320. The rings 31 interlock with each other to increase the rigidity of the bellows. In the curved section, the protrusion 321 on the outer bend side enters the side of the movable groove 320 with a larger groove depth, and the protrusion 321 on the inner bend side enters the side of the movable groove 320 with a smaller groove depth to increase the rigidity of the gas pipe.

[0027] The stiffness adjustment ring 30 can move relative to the stainless steel bellows 10 when it is bent. When the distance between two adjacent stiffness adjustment rings 30 in the radial direction is the first ring distance L1 on one side and the distance between the other side is the second ring distance L2, the stiffness adjustment rings 30 are relatively fixed. The stiffness adjustment rings 30 form a hard section on the outside of the stainless steel bellows 10, which is the bent section of the bellows. When the distance on both sides is L2, it is the straight section of the bellows.

[0028] By setting multiple interlocking stiffness adjustment rings 30 on the outer layer of the ultra-flexible stainless steel corrugated pipe 10 to form a stiffness adjustment layer, the stiffness adjustment rings 30 can be in a movable state that allows relative movement between them and in a fixed state that is locked together. When the stiffness adjustment rings 30 are in the movable state, the pipe as a whole can be bent at will, thus exhibiting the flexibility of an ultra-flexible pipe, which facilitates pipe laying. When the stiffness adjustment rings 30 are in the locked state, the pipe is in a rigid pipe state in that area. The rigid section can be set at the connection between the two ends of the pipe and the joint to avoid continuous stress on the joint. The rigid section can also be set at pipe clamps or where suspension is required, which can reduce the stress at the pipe clamps and the degree of freedom of the pipe, making the laid pipe have more stable performance.

[0029] In this way, the pipe material has both flexibility and rigidity. In its flexible state, it is easy to lay and install the pipe. After installation, the required sections can be bent or stretched to form rigid sections, making the pipe material more stable after installation. This will not generate continuous tensile stress on the joints and pipe clamps, effectively improving the sealing of the pipe connections and thus ensuring safety.

[0030] like Figure 1 , Figure 4 and Figure 5 As shown, the stiffness adjustment ring 30 includes a ring body 31 and hinge portions 32 arranged axially on both sides of the ring body 31. There is a gap 300 between two adjacent hinge portions 32 in the circumferential direction, and the hinge portions 32 at both ends of the ring body 31 are staggered.

[0031] Furthermore, in order to enable the circumferentially distributed hinge portions 32 to hinge with each other to restrict movement, one side of the hinge portion 32 is provided with a concave movable groove 320, and the other side is provided with a protruding protrusion 321. When the hinge portion 32 is in the gap 300, the protrusion 321 is in the movable groove 320. Multiple ring bodies 31 are inserted into the gap 300 in the axial direction through the hinge portion 32, and the protrusion 321 is placed in the corresponding movable groove, forming a structure that is hinged with each other.

[0032] Thus, when any two rings 31 are spliced ​​together in the axial direction, the hinge part 32 extends into the gap 300, so that the protrusion 321 on the hinge part 32 cooperates with the movable groove 320 on the adjacent hinge part 32, so that the protrusion 321 can only move within the movable groove 320, thereby realizing the mutual hinge between the rings 31 that can move within a certain range.

[0033] Furthermore, when the stiffness adjustment rings 30 are hinged together, in order to enable the pipe to obtain a larger bending angle and improve the overall flexibility of the pipe, the hinge part 32 is constructed as a toothed structure, and the movable groove 320 is constructed as a fan-shaped groove.

[0034] like Figure 6 As shown, the width of the movable groove 320 on the side closer to the ring 31 is greater than that on the other side, which allows the protrusion 321 to have a larger range of motion on the side closer to the ring 31 within the movable groove 320. This allows the protrusion 321 to have a larger range of motion in the radial direction, thereby increasing the included angle between the two rings 31. Compared to the linear movement of the protrusion 321 in the axial direction, this allows the pipe to obtain a larger bending angle.

[0035] like Figure 6 , Figure 7a , Figure 7b and Figure 7c As shown, the active groove 320 includes a first region 3201 and a second region 3202 that are continuously distributed. The second region 3202 is located on the side close to the ring body 31, and the groove depth of the second region 3202 is less than the groove depth of the first region 3201.

[0036] Furthermore, the bottom surface of the first region 3201 is flat, and the bottom surface of the second region 3202 is inclined. The first region 3201 and the second region 3202 are smoothly transitioned. The protrusion 321 is configured to slide within the first region 3201 and gradually lock and fix itself in the second region 3202 towards the ring body 31.

[0037] Thus, when the protrusion 321 moves within the first region 3201, the entire pipe is in a flexible state that can be bent at will. When the protrusion 321 moves to the second region 3202 and gradually approaches the ring 31, the stiffness adjustment ring 30 can be changed from a movable state to a mutually locked state. At this time, the pipe is in a rigid section in this region, making the region more stable after the pipe is installed.

[0038] In some embodiments, such as Figure 7b and Figure 7cAs shown, when the protrusion 321 is located at the end of the first region 3201 away from the ring 31, the distance between two adjacent stiffness adjustment rings 30 is the first ring distance L1. When the protrusion 321 is located in the second region 3202 near the jammed position of the ring 31, the distance between two adjacent stiffness adjustment rings 30 is the second ring distance L2. Generally, the length of the first ring distance L1 is greater than the axial length of the ring 31, while the length of the second ring distance L2 is less than the axial length of the ring 31, so that the two adjacent rings 31 can have a certain angle when bent and jammed. In addition, after the distance between the rings 31 is stretched, the pipe can also form a rigid section in this region. In this rigid case, it can also be selected according to the requirements.

[0039] In a preferred embodiment, the distance between any two adjacent rings 31 is equal to the corrugation pitch of the stainless steel corrugated pipe 10. The stiffness adjustment ring 30 includes a metal ring or a plastic ring. The minimum bending radius of the stiffness adjustment layer is greater than or equal to the minimum bending radius of the stainless steel corrugated pipe 10. The stiffness adjustment ring 30 can not only form local hard sections to improve the stability of the pipe after installation, but the interconnection between the stiffness adjustment rings 30 can also improve the compressive and tensile properties of the pipe, ensuring the safety of the gas-specific stainless steel corrugated pipe. In order to give the ring 31 a certain elastic recovery ability, a plastic ring is generally used.

[0040] In some embodiments, the padding layer 20 includes a foam material layer or a plastic layer. The thickness of the padding layer 20 is less than the thickness of the plastic covering layer 40. The padding layer 20, located between the stiffness adjustment ring 30 and the stainless steel bellows 10, can prevent the stiffness adjustment ring 30 from rubbing against the stainless steel bellows 10, thus providing protection.

[0041] In conjunction with the above embodiments, the stiffness adjustment rings 30 form a stiffness adjustment layer by hinged connections, allowing the pipe to move relatively during bending and maintain flexibility. When the spacing on the bending side changes to a jammed state or is directly stretched to a jammed state, the stiffness adjustment rings 30 become relatively fixed, forming a rigid section, thereby achieving variability in pipe stiffness. This allows the pipe to maintain its shape stably after installation, reducing continuous stress at joints and pipe clamps, improving durability and safety. At the same time, the outer side of the stainless steel corrugated pipe 10 has compressive and tensile strength, protecting the inner stainless steel corrugated pipe 10.

[0042] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A plastic-coated stainless steel corrugated pipe for use in gas applications, characterized in that, It includes a stainless steel corrugated pipe (10) arranged coaxially from the inside to the outside, a liner (20), a stiffness adjustment layer and a plastic covering layer (40); The stiffness adjustment layer is composed of multiple stiffness adjustment rings (30) distributed along the axial direction. Each stiffness adjustment ring (30) includes a ring body (31) and multiple hinge parts (32) protruding from both ends of the ring body (31) along the axial direction. The multiple hinge parts (32) are evenly distributed along the circumference. There is a gap (300) between two adjacent hinge parts (32) along the circumferential direction. The hinge parts (32) at both ends of the same ring body (31) are staggered. The hinge part (32) has a circumferentially protruding protrusion (321) on one side wall at a position axially away from the ring body (31), and a movable groove (320) on the other side wall, and the movable groove (320) is provided with a gradually increasing depth along the direction axially away from the ring body (31). Two adjacent ring bodies (31) are inserted into the gap (300) of another ring body (31) through a hinge (32), and the protrusion (321) is placed in the corresponding movable groove (320) to achieve mutual hinge; By moving relative to each of the rings (31), the protrusion (321) slides in the movable groove (320), thereby adjusting the stiffness so that the bellows has a flexible section and a locking section; In the flexible section, each of the rings (31) moves axially away, and the protrusion (321) enters the side with a larger groove depth of the movable groove (320). The protrusion (321) can move freely in the movable groove (320) to reduce the stiffness of the bellows. In the locking section, the axial movement of each of the rings (31) brings them closer together, at least a portion of the protrusions (321) enter the side of the movable groove (320) with a smaller groove depth, the end face of the protrusion (321) abuts against the end face of the movable groove (320), and the rings (31) jam against each other to increase the stiffness of the bellows.

2. The plastic-coated stainless steel corrugated pipe for gas supply according to claim 1, characterized in that, The locking section includes a straight section of the bellows and a curved section of the bellows; In the straight section of the bellows, the protrusion (321) enters the side of the movable groove (320) with a smaller groove depth, the pressure between the end face of the protrusion (321) and the end face of the movable groove (320) increases, and the rings (31) jam against each other to increase the rigidity of the bellows. In the curved section of the corrugated pipe, the protrusion (321) on the outer curved side enters the side of the movable groove (320) with a larger groove depth, and the protrusion (321) on the inner curved side enters the side of the movable groove (320) with a smaller groove depth, so as to increase the rigidity of the corrugated pipe.

3. A plastic-coated stainless steel corrugated pipe for gas combustion according to claim 1, characterized in that, The hinge (32) is constructed as a toothed structure, the movable groove (320) is constructed as a fan-shaped groove, and the width of the movable groove (320) on the side closer to the ring (31) is greater than that on the other side, so that the protrusion (321) has a larger range of motion in the movable groove (320) on the side closer to the ring (31).

4. A plastic-coated stainless steel corrugated pipe for gas combustion according to claim 1, characterized in that, The active groove (320) includes a first region (3201) and a second region (3202) that are continuously distributed. The second region (3202) is located on the side close to the ring (31), and the groove depth of the second region (3202) is less than the groove depth of the first region (3201).

5. A plastic-coated stainless steel corrugated pipe for gas combustion according to claim 4, characterized in that, The bottom surface of the first region (3201) is flat, and the bottom surface of the second region (3202) is inclined. The first region (3201) and the second region (3202) are smoothly transitioned. The protrusion (321) is configured to slide within the first region (3201) and gradually lock and fix itself in the second region (3202) towards the ring (31).

6. A plastic-coated stainless steel corrugated pipe for gas combustion according to claim 5, characterized in that, When the protrusion (321) is located at one end of the first region (3201) away from the ring body (31), the distance between two adjacent stiffness adjustment rings (30) is the first ring distance (L1). When the protrusion (321) is located in the second region (3202) near the ring body (31) in a stuck position, the distance between two adjacent stiffness adjustment rings (30) is the second ring distance (L2).

7. A plastic-coated stainless steel corrugated pipe for gas combustion according to claim 1, characterized in that, The stiffness adjustment ring (30) includes a metal ring or a plastic ring, and the minimum bending radius of the stiffness adjustment layer is greater than or equal to the minimum bending radius of the stainless steel bellows (10).

8. A plastic-coated stainless steel corrugated pipe for gas combustion according to claim 1, characterized in that, The padding layer (20) includes a foam material layer or a plastic layer, and the thickness of the padding layer (20) is less than the thickness of the plastic covering layer (40).

9. A plastic-coated stainless steel corrugated pipe for gas combustion according to claim 2, characterized in that, The distance between any two adjacent rings (31) is equal to the wave pitch of the stainless steel bellows (10).

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