In port oil loading and unloading operations, the transfer of crude oil and refined oil products from ship to ship and from ship to shore requires large-diameter flexible pipelines to maintain reliable sealing in the dynamic working conditions connecting the terminal and the oil tanker. This type of hose not only needs to remain non swollen and non degradable under long-term immersion in oil, but also withstand continuous mechanical wear during dragging on the concrete floor of the dock and dynamic stretching caused by tidal fluctuations. The large-diameter wear-resistant rubber hose covered with oil resistant synthetic rubber is a systematic solution for this scenario - using an oil resistant inner rubber layer to construct an anti swelling barrier, using an oil resistant outer rubber layer to resist the oil pollution, sun exposure, and mechanical wear of the dock, and using a multi-layer composite reinforcement structure to carry the alternating working conditions of positive pressure transportation and negative pressure suction, becoming a "safe, durable, and reliable" flexible channel for oil loading and unloading docks.
1、 Oil resistant dual barrier: a synergistic anti swelling system between the inner and outer layers
The internal and external media environments faced by oil loading and unloading hoses are completely different - the inside of the hose contains crude oil, refined oil or liquid chemicals with different aromatic hydrocarbon contents, while the outside of the hose is the dock deck splashed with oil pollution and the coastal air containing salt spray. The core idea to address this differentiated corrosion threat is the dual oil resistant design inside and outside.
The inner rubber layer directly contacts the conveying medium, and its oil resistance determines the medium adaptability of the hose. For different oil loading and unloading needs, the inner layer material can be selected and graded. For conventional petroleum products such as gasoline, diesel, and crude oil, NBR (nitrile rubber) is the most widely used solution due to its polar nitrile structure's natural anti permeability ability to non-polar mineral oil; For oils or chemicals with high aromatic content (≥ 30%), they need to be upgraded to FKM (fluororubber) or special HNBR formulas with better oil resistance [citation: 6] [citation: 7].
As the first line of defense against the dock environment, the outer rubber layer adopts a special synthetic rubber formula that is resistant to oil, weather, and seawater [citation: 1] [citation: 7]. In the oil loading and unloading operations at the dock, the outer rubber layer not only faces chemical erosion from oil droplets, but also needs to deal with UV aging caused by deck sun exposure, corrosion from tidal salt spray, and mechanical wear caused by hose dragging and ship shaking. The outer layer of oil resistant synthetic rubber is made by adding anti ozone agents and anti ultraviolet absorbers, which enable the hose to maintain elasticity and prevent cracking even after long-term outdoor exposure [citation: 5].
2、 Structure and Size: Engineering Matching between Large Diameter and Large Diameter
The loading and unloading of oil products at the dock have clear engineering requirements for hose diameter and pressure bearing capacity. The inner diameter of large-diameter marine oil hose covers a wide range of 102mm to 2000mm, and the common working pressure ranges from 2-8MPa. The burst pressure is generally 3-4 times the working pressure [citation: 2] [citation: 6]. For negative pressure suction conditions that may occur during loading and unloading operations, large-diameter oil hoses are often equipped with built-in metal spiral wires as external support skeletons, which increase their negative pressure resistance to 0.7-0.9 bar [citation: 2] [citation: 7].
The reinforcement layer adopts a composite structure of high-strength synthetic fibers, polypropylene textiles, and galvanized steel wires, and achieves a synergistic bearing of "radial blast resistance+axial tensile resistance" through multi-layer winding [citation: 2]. Some high-end products adopt a lightweight design composed of stainless steel corrugated pipes and polymer materials, which significantly improves bending flexibility while maintaining pressure bearing capacity. The working temperature covers a wide range of -40 ° C to 120 ° C, enabling it to maintain consistent performance in cold winter start-up and tropical dock high temperature exposure environments, which is an important technical foundation for all-weather operation of the dock throughout the year [citation: 6] [citation: 7].
3、 Dock adaptation: anti-static, flange connection and safety regulations
Oil loading and unloading belong to high-risk operations, and electrostatic discharge design is a mandatory requirement for safety access. The product must pass ATEX explosion-proof certification and anti-static testing to ensure that static charges can be safely introduced into the ground during high-speed oil flow and friction, fundamentally eliminating the risk of fire and explosion caused by spark discharge [citation: 4] [citation: 6]. For the loading and unloading of low-temperature liquid chemicals such as LNG and LPG, additional adaptation requirements for extremely low temperatures need to be met. Emergency release devices (ERCs) should be installed at the joints to automatically disconnect the ship from the pipeline in case of emergencies and prevent the expansion of leakage accidents [citation: 9].
In terms of end connections, large-diameter oil hoses are usually equipped with integral carbon steel flanges or plug-in joints, with flange specifications matching ANSI 150 #/300 # standards. The sealing surface adopts RF (protruding surface) form to ensure the reliability of the connection under high-pressure output of the dock oil pump [citation: 6]. The large-diameter flange connection enables the installation and replacement of a single hose to be completed in a shorter period of time, significantly reducing the time required for ship berthing operations. During installation, it is necessary to plan the pipeline route in advance to avoid exceeding the bending radius limit of the hose (usually 15-20 times the pipe diameter) and causing damage to the reinforcement layer. In daily inspections, special attention should be paid to whether the outer adhesive layer swells or cracks due to oil immersion, whether the flange joint bolts are loose or corroded, and whether the electrostatic grounding system is well connected.
In summary, the large-diameter wear-resistant rubber hose covered with oil resistant synthetic rubber perfectly meets the systematic requirements of "oil resistance, wear resistance, and anti-static" for port oil loading and unloading, with its NBR/FKM graded inner lining for oil resistance barrier, oil resistant and weather resistant outer rubber for dock environmental protection, and composite reinforced structure and anti-static certification for safety assurance. From gasoline and diesel to liquid chemicals, from extreme cold of -40 ℃ to high temperature of 120 ℃, from ship shore flange connection to explosion-proof emergency detachment, the design of each layer of oil resistant rubber and each galvanized steel wire is aimed at the same goal: to provide reliable guarantees for safe and efficient fluid transportation without swelling, leakage, and failure at the oil loading and unloading dock.