Many export heavy trucks have completed ocean shipping, and as soon as the vehicles arrive at overseas ports, premature aging phenomena such as hardening, cracking, and decreased elasticity of water pipes, belts, sealing rubber rings, and chassis rubber bushings are found. Although it is a brand new vehicle that has not yet been put into high-intensity operation, the rubber parts have experienced wear and tear. Many customers may mistakenly believe that it is a quality problem with the parts themselves, but in fact, it is mostly accelerated aging caused by the special environment of ocean shipping. Understanding the damage mechanism of rubber components in the maritime environment, taking good measures for sea protection and post landing inspection can effectively delay the failure of rubber components and avoid faults such as leakage and abnormal noise when new cars land.
High concentration salt spray corrosion is the main cause of rubber damage in maritime transportation. The ocean air contains a large amount of salt, and the interior of the container is not completely isolated from external water vapor. Salt spray particles will penetrate into the cabinet with the air and adhere to the surface of rubber components. Salt has strong hygroscopic properties and will remain in rubber gaps, hose surfaces, and seal grooves for a long time, continuously eroding the rubber polymer structure and damaging its toughness. After long-term salt spray erosion, rubber will accelerate hardening, generate fine cracks on the surface, and the sealing performance will decrease accordingly. In the later stage of heavy load use, it is easy to cause hose cracking and sealing leakage.
The high temperature and high humidity enclosed environment inside the container exacerbates rubber oxidation. There is a large temperature difference between day and night during ocean voyages. Containers are exposed to sunlight during the day, causing a sharp increase in temperature inside the container. At night, they are cooled by seawater, resulting in the formation of a large amount of condensed water vapor inside the container. The alternating cycle of high temperature and high humidity prevents heat and moisture from dissipating in a sealed space, which accelerates the rubber oxidation reaction. Rubber is exposed to a humid and hot environment for a long time, causing rapid loss of internal plasticizers. The originally flexible rubber gradually becomes hard and brittle. Even when the vehicle is not in operation, static storage can cause aging, which is also an important reason for abnormal wear and tear of rubber parts in new sea freight cars.
The oil pollution and anti-corrosion agents attached to the sea transportation process cause secondary damage. Vehicles going out to sea will undergo chassis anti-corrosion spraying. If some wax and anti-corrosion oil agents are sprayed improperly, they may splash onto the surfaces of belts, hoses, and rubber seals, and the oil medium will cause rubber swelling. After rubber comes into contact with grease, the material will deteriorate, causing swelling, stickiness, and surface peeling, which will damage its original physical properties. At the same time, the chemical gases evaporated from other goods in the container will also react with the rubber, further accelerating the aging and damage of the components.
Maritime turbulence causes hidden stress damage to rubber components. The ship's hull continues to shake and bounce during sea navigation, and the entire vehicle repeatedly vibrates inside the cabinet. The rubber hoses, bushings, and shock-absorbing rubber pads continue to withstand static pulling and compression, resulting in invisible stress fatigue inside the rubber. Although there is no visible damage on the exterior, the internal structure has been damaged, and after being put into heavy-duty operation, it will quickly expose aging faults.
In response to the aging problem of rubber components caused by sea transportation, it is necessary to take good measures to protect the front and rear ends. During the stage of container loading and sea going, it is necessary to protect the rubber parts by covering them to avoid direct contact of anti-corrosion wax and oil stains on the rubber surface; After opening the box on the ground, promptly clean the salt spray residue on the surface of the rubber components, comprehensively inspect the condition of the belts, hoses, and various seals, and evaluate and replace the parts that have already hardened or developed micro cracks in advance. Through special inspections after landing, hidden dangers caused by sea transportation can be eliminated in advance, ensuring stable operation of vehicles in the later stage.
