Self-floating rubber hoses are flexible pipes commonly used in fields such as water transportation of oil and water. They float on the water surface relying on their structural design (usually a foamed buoyancy layer). The reinforcement layer is the ‘skeleton’ of the hose body, serving as the core component that withstands various loads such as internal pressure, external pressure, tension, and bending. It directly determines the hose’s pressure-bearing capacity, tensile strength, and service life.

I. Importance of the Reinforcement Layer
The main functions of the reinforcement layer are:
1. Withstand internal pressure: Prevent excessive expansion or rupture of the hose under the pressure of the transported medium.
2. Withstand axial tension: Bear enormous tensile forces under dragging, connection, wave action, and tidal forces.
3. Resist flattening: Prevent the hose from being flattened under external water pressure, vacuum, or heavy object compression.
4. Provide torsional stiffness and bending stiffness: Maintain the basic shape of the hose while allowing flexible laying and recovery within permitted bending radii.

II. Structure and Materials of the Reinforcement Layer
The reinforcement layer of self-floating rubber hoses is typically not a single layer but a composite system composed of different materials and weaving angles. It is mainly divided into the following layers:
1. Internal Pressure Reinforcement Layer (or Skeleton Layer)
This is the primary layer for withstanding internal pressure.
• Materials: Usually high-strength synthetic fibers, most commonly:
◦ Polyester: Offers good dimensional stability and fatigue resistance, making it a common choice.
◦ Nylon: High strength and good toughness, but with slight strength loss in wet conditions.
◦ Aramid: Used for requirements of ultra-high strength and lightweight, but at a higher cost.
• Structure: Typically采用编织 or winding structure.
◦ Weaving Angle: This is a key parameter. According to grid theory, when the weaving angle of the reinforcing fibers is 54.7° (relative to the pipe axis), the hose will not experience length or diameter changes under internal pressure, reaching a balanced state. In actual production, adjustments are made based on specific operating conditions (such as prioritizing pressure resistance or tensile strength).
◦ Function: This layer mainly provides circumferential strength to resist radial expansion caused by internal pressure.

2. Tensile Reinforcement Layer
This is the primary layer for withstanding axial tension.
• Materials: Also uses high-strength synthetic fibers (polyester, nylon, aramid), but may be designed to merge with the internal pressure layer.
• Structure:
◦ If merged with the internal pressure layer, its weaving angle is less than 54.7° to provide stronger axial strength.
◦ For pipes with extremely high requirements, an independent tensile layer is set, usually采用 small-angle (close to 0°) winding or straight warp yarn structure, maximizing fiber strength to resist axial tension.

3. Compression Reinforcement Layer (or Flattening Prevention Layer)
For pipes needing to withstand significant external water pressure or vacuum, especially self-floating hoses used in deep water areas, this layer is required.
• Materials: Usually rigid materials such as steel wires or high-strength plastic spiral skeletons.
• Structure: Adopted spiral winding, embedding flat steel or round steel wires into the reinforcement layer to form a sturdy ‘spring’, preventing the hose from being flattened. This structural layer is typically located in the middle or outer part of the reinforcement layer.

III. Position of the Reinforcement Layer in the Overall Tube Wall Structure
The wall structure of a typical self-floating rubber hose, from inside to outside, is as follows:

1. Inner Rubber Layer: Resistant to medium corrosion and wear.

2. Inner Reinforcement Layer: Primarily for pressure-bearing and tensile strength, may consist of multiple layers made by weaving or winding synthetic fibers.

3. Buoyancy Layer: Usually closed-cell foam rubber or plastic (such as polyurethane foam), providing continuous buoyancy.

4. Pressure-Resistant Reinforcement Layer (if needed): Steel wire spiral skeleton.

5. Outer Reinforcement Layer: Provides additional protection and support.

6. Outer Rubber Layer: Weather-resistant, seawater-resistant, wear-resistant, and UV-resistant.
Note: The specific number of layers, sequence, and materials of the reinforcement layer will vary depending on the pipe’s design pressure, diameter, depth of use, and environmental conditions.
IV. Key Design Considerations
1. Balanced Design: Finding the optimal balance between internal pressure strength, axial tensile force, and bending fatigue performance. The braiding angle is a core parameter.
2. Adhesion Performance: Adhesion between reinforcement fibers and rubber is crucial. Fibers are typically treated with RFL impregnation to ensure strong chemical bonding with the rubber matrix, preventing delamination between layers.
3. Fatigue Life: Pipes undergo repeated bending under wave action, so the material and structure of the reinforcement layer must have excellent resistance to dynamic fatigue.
4. Weight and Buoyancy: Reinforcement layer materials (especially steel wires) increase pipe weight, which needs to be matched with the design of the buoyancy layer to ensure net buoyancy.
Summary
The reinforcement layer of a self-floating rubber hose is a complex and precise engineering structure. It is typically composed of high-strength synthetic fibers woven or wound at a specific angle to form a composite skeleton with both circumferential and axial strength. It may include sub-layers specifically responsible for pressure-bearing, tensile strength, and pressure flattening resistance. Understanding and optimizing the design of the reinforcement layer is key to manufacturing safe, reliable, and durable self-floating rubber hoses.

In simple terms, if we compare the rubber hose to the human body, the outer rubber layer is the skin, the buoyancy layer is the fat, and the reinforcement layer is the bones and muscles that provide support and movement.