What are the applications of D-type pipes in the transportation industry
Source：
ridui.cn Release date： 2025-09-01
Information summary：In the transportation industry, D-type pipes (pipes with a cross-section of "D" shape, one side is flat and the other side is curved) are widely used in scenarios that require structural support, spatial adaptation, and functional integration due to their unique structural advantages - the flat side is easy to install stably, and the curved side combines strength and lightweight characteristics. T
In the transportation industry, D-type pipes (pipes with a cross-section of "D" shape, one side is flat and the other side is curved) are widely used in scenarios that require structural support, spatial adaptation, and functional integration due to their unique structural advantages - the flat side is easy to install stably, and the curved side combines strength and lightweight characteristics. The specific application areas are as follows:
1、 Automotive Industry: Core Requirements for Lightweight and Structural Adaptation
The automotive manufacturing industry has high requirements for the "lightweighting" and "space utilization" of components, and the structure of D-shaped pipes perfectly meets this demand, mainly used for:
1. Body structural components
As auxiliary support components of the vehicle body frame, such as door anti-collision reinforcement pipes, chassis side beam reinforcement sections, roof longitudinal beam support pipes, etc. The flat side can be directly welded or bolted to the body sheet metal and frame to avoid the risk of misalignment during the installation of curved pipes; The curved side can disperse the collision impact force, improve the local rigidity of the vehicle body, and save installation space more than circular pipes of the same strength (especially suitable for compact areas such as doors and chassis).
The battery pack frame of new energy vehicles: D-type tubes are commonly used as peripheral protective frames for battery packs. The flat side is attached to the battery pack shell, and the curved side faces outward, which can protect the battery pack from impact and reduce the frame's occupation of chassis space, adapting to the flat design of battery packs.
2. Exhaust system and cooling system
The exhaust branch pipes and intercooler connecting pipes of some car models will use D-shaped pipes: the flat side can be close to the engine cylinder block or vehicle body floor (reducing the impact of thermal radiation on surrounding components), and the curved side optimizes the airflow channel to reduce exhaust resistance; Meanwhile, the torsional strength of D-shaped pipes is superior to that of flat pipes, and they can adapt to the vibration environment during engine operation.
3. Interior and functional brackets
The side support tubes of the seat frame, the wiring harness fixing brackets under the center console, etc.: The flat side can be attached to the seat back and center console shell, making it easy to fix the seat adjustment mechanism or wiring harness buckle. The curved side enhances the load-bearing capacity of the brackets, avoiding the "uncomfortable feeling" when passengers come into contact.
2、 Rail Transit Industry: Key Applications of High Rigidity and Safety Protection
Rail transit (high-speed rail, subway, urban rail) has strict requirements for the "fatigue resistance" and "stability" of components, and D-pipes are mainly used for:
1. Vehicle structure and safety protection
The side wall columns and floor support beams of the train carriage: The flat side of the D-shaped pipe is welded to the inner wall and floor panel of the carriage, and the curved side faces towards the interior or exterior of the carriage. This can enhance the longitudinal/transverse rigidity of the carriage (resist lateral forces during track operation) and reduce the occupation of the interior space by the pipe material (especially suitable for narrow body carriages such as subways).
The protective frame of the equipment compartment at the bottom of the train: The frame surrounded by D-shaped pipes can protect key equipment such as traction converters and braking systems. The flat side is attached to the equipment compartment shell, and the curved side resists the impact of track debris and rainwater. At the same time, it is lighter than rectangular pipes and reduces the "unsprung mass" of the train.
2. Braking system and pipelines
The brake air ducts (transmitting compressed air) of some trains use D-shaped pipes: the flat side can be fixed on the support of the vehicle chassis to avoid the pipeline shaking during train operation; The inner wall of the curved side is smooth, reducing the resistance of compressed air flow and ensuring braking response speed (especially suitable for the "fast braking" requirements of high-speed trains).
3. Door and Connection System
Guide rails for train doors and windshield support pipes between carriages: The flat side of the D-shaped pipe can be equipped with rails and sealing strips, while the curved side enhances the wear resistance and support strength of the rails, making it suitable for frequent opening and closing of train doors; The windshield support pipe is fixed to the end face of the carriage through the flat side, enhancing the sealing of the carriage connection.
3、 Aerospace Industry: High Precision and Extreme Environment Adaptation
The aerospace industry has high requirements for the "strength to weight ratio" and "corrosion resistance" of pipes, and D-type pipes are mainly used for:
1. Aircraft fuselage and wing structure
The fuselage frame and wing leading edge support tubes of small general-purpose aircraft (such as helicopters and light fixed wing aircraft): The flat side of the D-shaped tube can be attached to the skin (reducing the gap between the skin and the tube, reducing flight resistance), and the curved side can bear aerodynamic loads. At the same time, it is easier to splice with other structural components (such as wing ribs and beams) than the circular tube, reducing the number of welding points and improving structural reliability.
Luggage rack support and seat rails in aircraft cabins: fixed flat side rails or luggage rack shells, with curved sides to enhance support strength, suitable for the needs of "lightweight+high load-bearing" in the cabin.
2. Ground transportation and launch assistance for spacecraft
Ground transfer support for satellites and rockets: D-shaped tubes serve as crossbeams or columns for the support, with flat sides attached to the transfer platform or spacecraft shell to avoid scratching precision equipment; The curved side enhances the anti bending ability of the bracket, adapting to the vibration and impact during ground transportation.
Auxiliary support tube for launch tower: Some of the climbing ladder handrails and equipment platform guardrails of the launch tower will use D-shaped tubes. The flat side is convenient for installing anti slip pads or fixing buckles, while the curved side enhances the grip comfort and corrosion resistance of the handrails (resisting the high temperature and high humidity environment of the launch site).
4、 Ship and Ocean Transport Industry: Weather Resistance and Space Adaptation
Ship transportation needs to cope with seawater corrosion and wind and wave impact, and the structural advantages of D-type pipes are reflected in:
1. Ship structure and deck equipment
Deck guardrails and cabin partition frames for small vessels (such as yachts and workboats): The flat side of the D-shaped pipe can fit the deck or cabin wall, making it easy to weld and fix, reducing the occupation of deck passage space by guardrails; The curved side is made of corrosion-resistant alloy (such as 316 stainless steel) to resist seawater corrosion and enhance the impact resistance of the guardrail (to adapt to wind and wave shaking).
Pipeline support for ship engine room: The flat side is fixed on the engine room wall or equipment base, and the curved side supports the fuel and cooling water pipes to avoid displacement of the pipelines due to ship shaking. At the same time, it is easier to fit with the pipeline buckle than circular pipes.
2. Ports and logistics transportation equipment
The auxiliary structures of gantry cranes and quay cranes in container terminals: D-shaped pipes serve as guide rods for lifting equipment and reinforcement pipes for supports. The flat side is attached to the lifting equipment shell or track, while the curved side enhances the structural strength to meet the "high-frequency, high load" requirements during container lifting; At the same time, the flat side facilitates the installation of wear-resistant bushings, extending their service life.
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