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large size viton o ring seal
O Ring

large size viton o ring seal

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  • large size viton o ring seal
  • large size viton o ring seal
  • large size viton o ring seal

Description

Large size O-rings refer to toroidal seals with significantly larger dimensions than standard industrial O-rings, typically used in heavy-duty applications requiring robust sealing for large diameters, high pressures, or extreme environments. Below are key details about their characteristics, applications, and considerations:

Key Dimensions and Standards

  • Cross-Sectional Diameter (CSD):

    • Ranges from 6 mm to 25 mm+ (standard industrial O-rings usually max at ~5 mm).

    • Larger CSDs provide greater compression and sealing capacity for high-pressure systems.

  • Inner Diameter (ID):

    • Can exceed 1 meter (e.g., 1.5m, 3m, or custom sizes for pipelines, tanks, or industrial equipment).

  • Standards:

    • May follow modified versions of AS568 or ISO 3601, but many are custom-manufactured due to non-standard sizes.

    • Often specified by OEMs (original equipment manufacturers) for unique applications.

Materials and Construction

  • Common Materials:

    • EPDM: Resistant to weather, steam, and mild chemicals (suitable for water treatment or marine applications).

    • Fluorocarbon (FKM/Viton): High-temperature (up to ~200°C) and chemical resistance (ideal for oil, fuel, or industrial fluids).

    • Nitrile (NBR): Cost-effective for oil-based systems but limited in extreme temperatures.

    • Silicone: Wide temperature range (-60°C to +200°C) for food-grade or medical applications.

    • Buna-N: A type of NBR used in general industrial sealing.

  • Reinforcements:

    • Wire or Fabric Insertions: Added for structural support in high-pressure applications (e.g., preventing extrusion in pipelines).

    • PTFE Coatings: Reduce friction and improve chemical resistance for dynamic seals.

Applications

Large O-rings are critical in industries requiring heavy-duty sealing for oversized components:


  1. Oil and Gas:

    • Seals for pipelines, valves, pumps, and storage tanks (e.g., subsea equipment, refineries).

    • High-pressure applications (e.g., 100 bar+ in hydraulic fracturing).

  2. Marine and Offshore:

    • Sealing for shipboard pipelines, hatches, submarine components, and underwater structures.

    • Resistance to saltwater, UV exposure, and extreme pressure (deep-sea applications).

  3. Water and Wastewater Treatment:

    • Seals for large pumps, filters, valves, and storage tanks (chlorine, wastewater, or chemical resistance required).

  4. Power Generation:

    • Steam turbines, boilers, and cooling systems (high-temperature/pressure environments).

    • Nuclear reactors (specialized materials for radiation resistance).

  5. Heavy Machinery and Industrial Equipment:

    • Hydraulic cylinders in construction equipment (e.g., excavators, cranes).

    • Large-scale industrial presses, mixers, or reactors.

  6. Aerospace and Defense:

    • Seals for aircraft fuel tanks, missile systems, or heavy military machinery.

Design and Installation Challenges

  1. Manufacturing Complexity:

    • Large O-rings are often custom-molded due to non-standard sizes, requiring specialized tooling.

    • Joints or seams (e.g., vulcanized or bonded) must be seamless to avoid leakage points.

  2. Handling and Installation:

    • Requires heavy-duty tools (e.g., lifting equipment, specialized insertion guides) to avoid damage during placement.

    • Proper lubrication (e.g., silicone grease) is critical to prevent tearing in large grooves.

  3. Environmental Factors:

    • Thermal expansion/contraction in large systems may require materials with high elasticity.

    • Resistance to ozone, UV, or chemical exposure (e.g., in outdoor or corrosive environments).

  4. Pressure and Load Management:

    • Backup rings (e.g., PTFE or metal) are often used to prevent extrusion in high-pressure applications.

    • Calculating compression ratios (15–25% typical) is critical for effective sealing without overstress.

about (1)

VITON rubber is good performance in high temperature,oil ,were-resisting property

Temperature: -26–232  centigrade in stable sealing invironment and -15–200 centigrade in rotation sealing

Hardness: Shore A 50-90

Standard: GB/T 3452.1-2005,AS568,JIS B2401


 

 

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What factors influence the performance of industry rubber seals

The sealing effect of the sealing ring is related to the material characteristics of the sealing ring. There is also a close influence on other factors. For example, the speed of rotation, working temperature, working pressure, working medium, etc., today I will tell you about the four factors that affect the sealing performance of the sealing ring.

First, the speed of rotation

  When the rotation speed is very low (< 0.03m/s), it is necessary to consider the smoothness of the operation of the equipment and whether the operational appears "crawling" phenomenon. When the movement speed is very high (> 0.8m/s), the lubricating oil film may be destroyed, and the oil seal is not well lubricated and frictions heat, resulting in greatly reduced life. It is recommended that polyurethane or rubber and plastic oil seal work in the speed range of 0.03m/s ~ 0.8m/s. High-speed oil seals need to put forward higher requirements for structure and material, and the speed of household appliances oil seals can reach 20000rpm. Both wear and temperature resistance need to be met, and the concentricity requirements of dynamic sealing on the installation are relatively high.  

Second, the temperature of the working environment

  Low temperature will reduce the elasticity of rubber and plastic oil seals, resulting in leakage, and even the entire oil seal becomes hard and brittle. High temperature will make the oil seal volume expansion, soft, resulting in the oil seal friction resistance increases rapidly and the pressure resistance decreases. It is recommended that the continuous operating temperature range of ordinary polyurethane or rubber and plastic oil seals be -10 ° C to +80 ° C. For the high temperature and high speed requirements of the working environment, we need to choose to use fluorine rubber and PTFE, high temperature resistance and wear resistance is better, the low temperature environment is generally to -40 degrees, and the rubber performance is tested at high and low temperatures to ensure that the product quality meets the requirements.  

Third, the working pressure of machinery

  The oil seal has a minimum service pressure requirement. Oil seals with low friction and low starting resistance should be selected for low pressure work. Below 2.5MPa, polyurethane oil seal is not suitable; High pressure to consider the oil seal pressure deformation, need to use anti-extrusion stop ring, grooving processing also has special requirements.

Fourth, the working medium

  General sealing media are gasoline, oil, diesel, grease, and some static sealing dust. In addition to selecting the working medium strictly according to the manufacturer's recommendations, it is important to keep the working medium clean. Aging or contamination of the oil will not only cause the components in the system to fail, accelerate the aging and friction of the oil seal, but also the dirt in it may scratch or embed the oil seal, making the seal fail. Therefore, it is necessary to regularly check the quality of the oil and its cleanliness, and replace the oil filter or oil according to the maintenance specifications of the equipment. The air remaining in the oil in the cylinder will be compressed by high pressure, which will cause the oil seal to burn out or even carbonize. In order to avoid this situation, exhaust treatment should be carried out at the initial operation of the hydraulic system. The hydraulic cylinder should also run at low pressure and slow speed for a few minutes to confirm that the residual air in the oil has been drained before it can work normally.