Prefabricated and decorated integrated light steel structure self-supporting integrated box-type exterior wall panel without thermal bridge

Abstract

This utility model belongs to the field of building industrialization technology, and specifically relates to an integrated, prefabricated, decorative, thermal bridge-free, lightweight steel structure self-supporting integrated box-type exterior wall panel. Its features include a lightweight steel frame, a set of Z-shaped keels set within the internal cavity of the lightweight steel frame, upper and lower integrated decorative cover plates covering the exterior of the lightweight steel frame, thermal insulation and sound insulation board I, thermal insulation and sound insulation board II, and a thermal bridge-free plastic-steel frame set along the edge of thermal insulation and sound insulation board I. This utility model forms a closed box body through a cold-formed steel frame and double-layer cover plates, with an integrated thermal insulation and sound insulation layer inside, achieving 100% factory prefabrication. This wall panel is suitable for automated robotic production and has advantages such as lightweight, high strength, energy saving, and rapid installation. It is applicable to prefabricated buildings, green and low-carbon buildings, civil buildings, and industrial buildings.

Description

Technical Field

[0001] This utility model belongs to the field of building industrialization technology, and in particular relates to an integrated box-type exterior wall panel with prefabricated and decorated non-thermal bridge light steel structure and self-supporting structure. Background Technology

[0002] Traditional cast-in-place concrete walls have long construction cycles, high energy consumption, and are difficult to integrate with insulation systems. Adding insulation later reduces floor height and increases construction complexity. While existing lightweight steel walls can reduce structural weight, they still have the following problems:

[0003] 1. Insufficient thermal and sound insulation performance: Traditional light steel walls are prone to forming thermal and acoustic bridges, affecting building energy efficiency and comfort.

[0004] 2. Difficulty in thermal insulation integration: Existing precast walls usually require on-site installation of thermal insulation, which is inefficient and difficult to control in terms of quality.

[0005] 3. Poor adaptability to intelligent manufacturing: Traditional wall structures are complex and difficult to automate, which restricts the efficiency of industrialized construction.

[0006] Chinese Patent, Patent No.: 2018218186600: Wall Structure of Light Steel Structure Prefabricated Buildings. This utility model's main structure is a light steel keel wall structure, integrating insulation and decorative panels, and can accommodate built-in water and electricity pipes. However, this technology uses a large number of screws and square tubular plates for fixing the light steel keel installation, resulting in a large number of screws, cumbersome connections, and difficulty in automated manufacturing. The frame uses a prefabricated cold-formed profile for prefabricated buildings, which is formed by setting 45° reverse chamfers at both ends and pre-drilled holes to assemble the frame with the panel corners. Due to the unique sheet metal characteristics of thin-walled cold-formed profiles, a process of orthogonal cutting of flat plates before forming is required, along with stress rebound characteristics, making it difficult to achieve a tight, gapless 45° chamfer assembly. Furthermore, the thermal bridging of the cold-formed profile frame is significantly detrimental to building insulation. Additionally, existing prefabricated wall full-fill insulation methods suffer from difficulties in pipeline pre-embedding and complex on-site construction. Summary of the Invention

[0007] The purpose of this utility model is to provide a modular, intelligently manufactured, assembled and decorated integrated light steel structure self-supporting box-type exterior wall panel without thermal bridges, realizing integrated prefabrication of structure and insulation, and meeting the needs of building industrialization.

[0008] The objective of this utility model is achieved through the following technical solution:

[0009] This utility model discloses an integrated, non-thermal bridge, lightweight steel structure self-supporting integrated box-type exterior wall panel, characterized in that it includes a lightweight steel frame, a set of Z-shaped keels disposed within the internal cavity of the lightweight steel frame, an upper integrated decorative cover covering the upper part of the lightweight steel frame, a lower integrated decorative cover covering the lower part of the lightweight steel frame, a thermal insulation and soundproofing board I disposed below the upper integrated decorative cover, a thermal insulation and soundproofing board II disposed above the lower integrated decorative cover, a thermal bridge-free plastic steel frame disposed along the edge of the thermal insulation and soundproofing board I, and a galvanized channel plate disposed at the bottom of the thermal insulation and soundproofing board I.

[0010] The light steel frame includes two parallel main frames and two parallel secondary frames, which are connected by connectors to form a rectangle.

[0011] The aforementioned thermal insulation and sound insulation board I or thermal insulation and sound insulation board II both include a flanged inner lining board and an insulation board wrapped around the outside of this flanged inner lining board.

[0012] The feature is that the main frame or the secondary frame is respectively composed of U-shaped thin plate cold-formed profiles. These U-shaped thin plate cold-formed profiles include a U-shaped main body formed by cold bending four flanges and three web sections. The four flanges include two middle flanges and two outer flanges. The three web sections include a middle web section and two outer web sections disposed below both sides of the middle web section.

[0013] The two side edges of the intermediate web are respectively connected to one side edge of the two intermediate flanges, and the other side edge of each intermediate flange is connected to a side edge of an outer web. One side edge of each outer web is connected to an intermediate flange, and the other side edge is connected to an outer flange through a right-angle bend.

[0014] The intermediate flange and the outer flange are both located above the outer web.

[0015] The U-shaped thin sheet cold-formed profile of the main frame has a perforated flange at the connection of both ends of the middle web and above the middle web.

[0016] The two outer flanges of the U-shaped thin sheet cold-formed profile are provided with inward 180-degree hooks.

[0017] The hollow cavity keel is fixed to the two middle flanges on both sides of the concave thin plate cold-formed profile, which are folded inward at 90 degrees.

[0018] The upper integrated decorative cover plate covers the top of the light steel frame, and the lower integrated decorative cover plate is fixed to the bottom of the light steel frame, forming the bottom surface of the closed box.

[0019] The described thermal insulation board includes rock wool, phenolic board, aerogel or polyurethane foam.

[0020] The border of the non-thermal-bridge plastic-steel frame is filled with thermal insulation materials to form a thermal insulation shell.

[0021] Integrated water and electricity pipelines are arranged in the internal cavity of the light steel border frame, and quick interfaces are reserved at the ends of the pipelines.

[0022] Advantages of the utility model:

[0023] (1) The assembled and decorated integrated non-thermal-bridge light steel structure self-bearing integrated cassette exterior wall panel of the utility model is highly industrialized, fully prefabricated in the factory, has strong adaptability to intelligent manufacturing, adopts a standardized module design, is suitable for an automated production line, and robots can complete processes such as cutting, welding, and assembly, greatly improving production efficiency. The product is fully produced automatically on the production line, reducing on-site construction volume. The whole wall panel is prefabricated in the factory, and only hoisting and splicing are required on-site, shortening the construction period by more than 60% and reducing the dependence on labor.

[0024] (2) The assembled and decorated integrated non-thermal-bridge light steel structure self-bearing integrated cassette exterior wall panel of the utility model has a lightweight structure and high bearing capacity. It adopts a cold-formed steel border and optimizes the cross-section design. While reducing its own weight (40% lighter than concrete wall panels), it still has excellent bending and shear resistance.

[0025] The hanging connection of the channel-shaped parts and the hanging connection of the Great Wall steel bearing plates achieve convenient connection, cost savings, and improved assembly efficiency.

[0026] The hanging holes of the channel-shaped parts and the diamond-shaped hangers are jointly stamped. When the cassette panels are combined with each other, the cassette panels are connected to each other by the diamond-shaped hangers, and the cassette panels are made to achieve integral force transmission in the direction perpendicular to the concave main frame by the channel-shaped parts, realizing the integral force of multiple cassette floors or cassette roofs or cassette walls after installation.

[0027] The combination of the channel-shaped parts can also bear the external force from the inside and outside directions of the cassette panel. Thus, the external force is transmitted to the concave main frame by hanging the hook of the channel-shaped part on the long rectangular hole of the concave main frame. Furthermore, the concave main frame is connected to the single-hole by multiple groups of screws, and the external force is transmitted to the single-hole connector. The single-hole connector is connected to the steel column and steel beam by bolts, and the external force is transmitted to the beam and column.

[0028] (3) The assembled and decorated integrated non-thermal-bridge light steel structure self-bearing integrated cassette exterior wall panel of the utility model has excellent thermal insulation and sound insulation performance;

[0029] Flange lining and multi-layer thermal insulation structure: The lining board with a flange wraps rock wool or aerogel to form a continuous thermal insulation layer;

[0030] Sound insulation optimization: The composite structure can reduce impact noise and airborne sound transmission, with a sound insulation of ≥50dB, far exceeding that of ordinary concrete walls. The three-layer insulation (insulation cotton, static air layer, insulation cotton) is reliable, and the internal sound insulation cotton increases the sound insulation index.

[0031] The exterior of the wall is equipped with an insulated outer shell consisting of a plastic steel frame, rubber sealing strips, and insulation material, eliminating thermal bridging on the wall surface.

[0032] (4) The assembled and decorated integrated light steel structure self-supporting integrated box-type exterior wall panel of this utility model is green and low-carbon, conforms to the trend of sustainable development, reduces construction waste, has high precision in factory prefabrication, and has less material waste. Compared with cast-in-place concrete, it can reduce construction waste by 80%; steel, insulation materials, etc. can be disassembled and recycled, which meets the requirements of circular economy; modular design facilitates automobile transportation and long-distance container shipping.

[0033] (5) The integrated box-type exterior wall panel of this utility model, which is a self-supporting light steel structure without thermal bridge, is easy to construct and reduces the overall cost; it is quick to install: it adopts bolt connection or snap-on splicing, which eliminates the need for wet work and greatly shortens the construction cycle. It has self-supporting and force transmission functions (plate / frame / single hole connector / beam and column). The construction is simple and the beam and column nodes are simple because the single hole connector is used to connect the beam and column with bolts.

[0034] High degree of integration: Decoration, structure and pipeline are prefabricated in one piece, reducing on-site work by more than 30%. It has its own decorative function (panel decoration) and also has a sealing and waterproof function. The cavity formed by the wall panel can be used for wiring. At the same time, the equipment can automatically open and close the opening and closing holes on the inner and outer panels, and the inner and outer panels can be used directly as wall decoration.

[0035] Easy maintenance: The pipeline system can be quickly inspected and maintained through the access panel or external system, and the water, electricity and heating functions are highly integrated;

[0036] (6) The prefabricated and decorated integrated light steel structure self-supporting integrated box-type exterior wall panel of this utility model, through the innovative design of light steel box structure, integrated insulation and intelligent manufacturing, realizes the building industrialization goal of "factory prefabrication, rapid installation, energy saving and comfort", and is suitable for prefabricated buildings such as houses, apartments and hotels, with significant economic and social benefits. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of this utility model.

[0038] Figure 2 This is a sectional view of the box-type exterior wall panel of this utility model.

[0039] Figure 3 This is a cross-sectional view of the main frame of this utility model.

[0040] Figure 4 This is a cross-sectional view of the secondary frame of this utility model.

[0041] Figure 5 This is a top view and cross-sectional view of the box-type exterior wall panel and column joint of this utility model.

[0042] Figure 6 This is a view of the hook node of the zigzag keel and the light steel frame of the present invention. Detailed Implementation

[0043] The specific embodiments of this utility model are further described below with reference to the accompanying drawings.

[0044] like Figure 1-5 As shown, the present invention relates to an integrated, non-thermal bridge, lightweight steel structure self-supporting integrated box-type exterior wall panel, characterized in that it includes a lightweight steel frame, a set of Z-shaped keels 9 disposed within the internal cavity of the lightweight steel frame, an upper integrated decorative cover plate 10 covering the upper exterior of the lightweight steel frame, a lower integrated decorative cover plate 18 covering the lower exterior of the lightweight steel frame, a thermal insulation and soundproofing board I disposed below the upper integrated decorative cover plate 10, a thermal insulation and soundproofing board II disposed above the lower integrated decorative cover plate 18, a thermal bridge-free plastic steel frame 19 disposed along the edge of the thermal insulation and soundproofing board I, and a galvanized channel plate 20 disposed at the bottom of the thermal insulation and soundproofing board I.

[0045] The light steel frame includes two parallel main frames 12 and two parallel secondary frames 13. The two main frames 12 and the two secondary frames 13 are connected by connectors to form a rectangle.

[0046] The aforementioned thermal insulation and sound insulation board I or thermal insulation and sound insulation board II both include a flanged inner lining board 14 and an insulation board 11 wrapped around the outside of the flanged inner lining board 14.

[0047] The main frame 12 or the secondary frame 13 is respectively composed of U-shaped thin plate cold-formed profiles. This U-shaped thin plate cold-formed profile includes a U-shaped main body formed by cold bending four flanges and three web sections. The four flanges include two middle flanges 3 and two outer flanges 4. The three web sections include a middle web 1 and two outer web sections 2 disposed on both sides below the middle web 1.

[0048] The two side edges of the intermediate web 1 are respectively connected to one side edge of the two intermediate flange plates 3, and the other side edge of each intermediate flange plate 3 is connected to one side edge of an outer web 2. One side edge of each outer web 2 is connected to an intermediate flange plate 3, and the other side edge is connected to an outer flange plate 4 through a right-angle bend 5.

[0049] The intermediate flange plate 3 and the outer flange plate 4 are both located above the outer web plate 2.

[0050] The U-shaped thin plate cold-formed profile of the main frame 12 has a perforated flange 8 at the connection of the two ends of the intermediate web 1 and above the intermediate web 1.

[0051] The two outer flanges 4 of the U-shaped thin sheet cold-formed profile are provided with inward 180-degree hooks 6.

[0052] The hollow zigzag keel 9 is fixed to the two middle flange plates 3 on both sides of the concave thin plate cold-formed profile, which are folded inward at 90 degrees.

[0053] The upper integrated decorative cover 10 covers the top of the light steel frame, and the lower integrated decorative cover 18 is fixed to the bottom of the light steel frame to form the bottom surface of the closed box.

[0054] The insulation board 11 includes rock wool, phenolic board, aerogel or polyurethane foam.

[0055] The frame of the non-thermal bridge plastic steel frame 19 is filled with thermal insulation material 21 to form an insulated outer shell.

[0056] The light steel frame has an internal cavity for integrated water and electricity pipelines, with quick-connect interfaces reserved at the ends of the pipelines.

[0057] When the exterior wall panel and the interior wall panel are joined, a decorative flashing structure is installed at the joint.

[0058] This utility model provides an integrated, non-thermal bridge-free, lightweight steel structure, self-supporting, box-type exterior wall panel with modular design, facilitating intelligent factory manufacturing and rapid on-site assembly. The specific structure includes:

[0059] 1. Light steel frame: A rectangular frame is formed by welding or bolting concave cold-formed profiles and corner structural installation parts to serve as the main load-bearing structure of the wall. The cross-sectional shape is optimized to improve bending stiffness. Single-hole connector 15 can be selected as the connector. The design of single-hole connector 15 allows for quick installation and wall laying with the square tube beam of the building's steel structure frame.

[0060] 2. Upper integrated decorative cover plate 10 and lower integrated decorative cover plate 18: forming the bottom surface of the closed box, which can be decorated with OSB board, fiber cement board, or thin steel plate with wallpaper, etc. Interior and exterior walls are not limited to color-coated steel sheets, galvanized sheets, steel strips, and aluminum sheets; other materials include decorative carbon crystal panels, decorative flooring, OSB boards, cement boards, magnesium crystal boards, calcium silicate boards, gypsum boards, etc.

[0061] 3. Functional layer structure: Thermal insulation and sound insulation layer: The thermal insulation and sound insulation layer located inside the decorative cover plate is made of rock wool, phenolic board, aerogel or polyurethane foam wrapped with a flanged inner lining plate 14 (such as galvanized steel plate or aluminum plate) to form a continuous thermal insulation and sound insulation barrier, reducing thermal bridge and sound bridge effects.

[0062] 4. Hollow enclosed cavity design: This provides sound and heat insulation while reducing the need for additional insulation and soundproofing materials. For higher sound insulation requirements, soundproofing cotton panels can be installed on one or both sides of the inner cavity.

[0063] 5. Hollow cavity rib 9: Fixed to the two middle flange plates 3 on both sides of the U-shaped thin plate cold-formed profile, which are folded inward at 90 degrees, to provide stable support.

[0064] 6. External insulation layer: A plastic steel heat insulation frame is installed on the outside of the heat insulation and sound insulation board I. The heat insulation frame is filled with heat insulation material 21 to form an insulation shell.

[0065] 7. Smart Manufacturing Adaptability

[0066] Standardized production: All components (frame, cover, insulation layer) are designed according to a uniform module, which facilitates automated cutting, welding and assembly.

[0067] Robot assembly: The use of robotic arms to automatically lay the insulation layer improves production precision.

[0068] Digital management: By combining BIM technology, we can achieve full-process information management of wall surfaces from design and production to construction.

[0069] Preferred solution:

[0070] The frame of the U-shaped thin sheet cold-formed profile is made of galvanized carbon steel of Q235 or above with a thickness of 0.7mm-3.0mm.

[0071] The box is molded with a thickness of 150 mm - 300 mm, a width of 600 mm - 1220 mm, and a length of 250 mm - 12000 mm.

[0072] Wall panel integrated module manufacturing process:

[0073] 1. Packaging film: Brand-printed thin film packaging (to be removed on-site after installation).

[0074] 2. The inner surface is a 0.5mm thick color steel plate channel. This plate can be made of materials such as carbon crystal plate or honeycomb aluminum plate. Wallpaper can also be applied to this plate on-site or at the factory. Switch and socket holes are set on the plate surface according to the design.

[0075] 3. Black and white glue: The factory uses an automatic glue-applying machine to apply the glue.

[0076] 4. 50mm thick rock wool: cut into strips and laid out, with a density of over 150 kg, and the cotton fibers perpendicular to the board surface. The cotton fixing nails pass through the groove board and are fixed to the 30mm Z-shaped keel 9, and the spacing between the surfaces along the Z-shaped keel 9 should not exceed 400mm.

[0077] 5. Black and white glue: Apply glue manually.

[0078] 6. 0.25mm thick flanged inner lining plate 14: On the concave shoulder plane. Place an L-shaped ten-hole piece 17 at each of the four corners of the shoulder.

[0079] 7. One side concave shoulder inner zigzag keel 9: The spacing density of the 30mm zigzag keels 9 on one side is not greater than 1 meter. The inner plane of the keel is level with the concave shoulder. The 30mm zigzag keel 9 on one side is connected to the other 30mm zigzag keel 9 by a vertical keel 16 with a C-shaped cross section and a width of 28mm.

[0080] 8. Hollow layer: Water pipes and electrical wiring are installed in the middle, with integrated connectors through φ40 conduit openings.

[0081] 9. The spacing of the 30mm Z-shaped keel on the other side of the concave shoulder should not exceed 1 meter. The outer plane of the keel should be flush with the concave shoulder on the other side.

[0082] 10. 0.25mm thick galvanized channel plate flange inner lining plate 14: Place a 4mm thick L-shaped ten-hole piece 17 in each of the four corners of the channel plate. The material of this piece is Q355.

[0083] 11. Black and white glue: Glue is applied by an automatic glue-applying machine in the factory.

[0084] 12. 50mm thick rock wool: cut into strips and laid out, with a density of over 100 kg, and the cotton fibers perpendicular to the board surface. The cotton fixing nails pass through the galvanized channel plate and connect to the 30mm Z-shaped keel 9, with a spacing of no more than 400mm between nails on the 30mm Z-shaped keel 9.

[0085] 13. Black and white glue: Glue is applied by an automatic glue-applying machine in the factory.

[0086] 14. 0.6mm thick galvanized aluminum sheet as integrated decorative cover: Includes light holes, pre-drilled at the factory. Options include carbon crystal sheet, honeycomb aluminum sheet, or color-coated sheet with wall covering. Switch and socket holes are provided according to the design.

[0087] 15. Packaging film: Brand-printed film packaging is used.

[0088] 16. Concave frame: The four sides are made of concave-shaped thin plate cold-formed profile. The parameters and materials of the concave frame can be selected according to the preferred scheme based on the stress model.

[0089] 17. Connectors: The connectors are made of Q355 steel. Single-hole connectors 15 can be installed at the four corner shoulders outside the thin-walled steel frame as needed. The single-hole connectors 15 are connected to the concave frame, inner groove plate, and L-shaped ten-hole connectors 17 with 10 M5 or M6 screws.

[0090] 18. Thermal bridge-free frame 19: Located on the outer side of the concave frame, it is composed of two sections, A and B, of a plastic steel frame. Its cavity is filled with thermal insulation material 21 to form an insulated outer shell.

[0091] Wall construction and combined applications:

[0092] Diamond hook holes 7 can be provided on two adjacent frame sides. When the wall panels are spliced ​​together, the diamond hook holes 7 on the two adjacent frame sides are aligned with the hooks and inserted into the holes. Then, the wall panels are moved horizontally, and the hooks and holes form a tight hook structure, so that the adjacent frame sides of the two box-type wall panels fit tightly together and share the load. There will be no misalignment or loose gaps between the two box-type wall panels at the joint.

[0093] The box-type wall panel connects to the pre-drilled holes (or connecting plates or tapping holes) on the load-bearing structural columns or steel beams of the building through the single-hole connector 15 connected at the four corners of the concave frame, enabling quick bolt installation. The installation is simple and the wall structure after installation is safe and reliable.

Claims

1. A self-supporting integrated box-type exterior wall panel with prefabricated and decorative features, characterized in that: The system includes a light steel frame, a set of Z-shaped keels disposed within the internal cavity of the light steel frame, an upper integrated decorative cover covering the upper part of the light steel frame, a lower integrated decorative cover covering the lower part of the light steel frame, a thermal insulation and soundproofing board I disposed below the upper integrated decorative cover, a thermal insulation and soundproofing board II disposed above the lower integrated decorative cover, a thermal bridge-free PVC frame disposed along the edge of the thermal insulation and soundproofing board I, and a galvanized channel plate disposed at the bottom of the thermal insulation and soundproofing board I. The light steel frame includes two parallel main frames and two parallel secondary frames, which are connected by connectors to form a rectangle. The aforementioned thermal insulation and sound insulation board I or thermal insulation and sound insulation board II both include a flanged inner lining board and an insulation board wrapped around the outside of this flanged inner lining board.

2. The integrated, non-thermal bridge, lightweight steel structure, self-supporting, box-type exterior wall panel with prefabricated decoration as described in claim 1, characterized in that: The feature is that the main frame or the secondary frame is respectively composed of U-shaped thin plate cold-formed profiles. These U-shaped thin plate cold-formed profiles include a U-shaped main body formed by cold bending four flanges and three web sections. The four flanges include two middle flanges and two outer flanges. The three web sections include a middle web section and two outer web sections disposed below both sides of the middle web section. The two side edges of the intermediate web are respectively connected to one side edge of the two intermediate flanges, and the other side edge of each intermediate flange is connected to a side edge of an outer web. One side edge of each outer web is connected to an intermediate flange, and the other side edge is connected to an outer flange through a right-angle bend. The intermediate flange and the outer flange are both located above the outer web.

3. The integrated, non-thermal bridge, lightweight steel structure, self-supporting, box-type exterior wall panel with prefabricated decoration as described in claim 2, is characterized in that... The U-shaped thin sheet cold-formed profile of the main frame has a perforated flange at the connection of both ends of the middle web and above the middle web.

4. The integrated, non-thermal bridge, lightweight steel structure, self-supporting, box-type exterior wall panel with prefabricated decoration as described in claim 2, is characterized in that... The two outer flanges of the U-shaped thin sheet cold-formed profile are provided with inward 180-degree hooks.

5. The integrated, non-thermal bridge, lightweight steel structure self-supporting box-type exterior wall panel with prefabricated decoration as described in claim 2, characterized in that, The hollow cavity keel is fixed to the two middle flanges on both sides of the concave thin plate cold-formed profile, which are folded inward at 90 degrees.

6. The integrated, non-thermal bridge, lightweight steel structure self-supporting box-type exterior wall panel with prefabricated decoration as described in claim 2, characterized in that, The upper integrated decorative cover plate covers the top of the light steel frame, and the lower integrated decorative cover plate is fixed to the bottom of the light steel frame, forming the bottom surface of the closed box.

7. The integrated, non-thermal bridge, lightweight steel structure self-supporting box-type exterior wall panel with prefabricated decoration as described in claim 1, characterized in that, The insulation board includes rock wool, phenolic board, aerogel, or polyurethane foam.

8. The integrated, non-thermal bridge, lightweight steel structure self-supporting box-type exterior wall panel with prefabricated decoration as described in claim 1, characterized in that, The frame of the non-thermal bridge plastic steel frame is filled with thermal insulation material to form an insulated outer shell.

9. The integrated, non-thermal bridge, lightweight steel structure self-supporting box-type exterior wall panel with prefabricated decoration as described in claim 1, characterized in that, The light steel frame has an internal cavity for integrated water and electricity pipelines, with quick-connect interfaces reserved at the ends of the pipelines.

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