When using expansion joints in shipyards and marine engineering, certain use codes and standards must be followed to ensure the correct installation, safe operation and extended service life of the expansion joints. Here are some general specifications for use, although the specifics may vary depending on the expansion joint type, ship design and international standards:
Design and selection
Environmental Adaptability: Choose an expansion joint suitable for the marine environment, taking into account factors such as salt spray, humidity, temperature changes, etc.
Media compatibility: Ensure that the expansion joint material is compatible with the transmitted medium and avoid corrosion or chemical reaction.
Pressure and temperature: The expansion joint shall be able to meet the requirements of working pressure and temperature range.
Displacement capacity: Expansion joints with appropriate displacement capabilities are selected according to vessel motion, thermal expansion and contraction and system operating conditions.
Installation Specifications
Check and match: Check the model, size and pipe configuration of the expansion joint before installation to ensure that it is consistent with the design requirements.
Directionality: For directional expansion joints (such as those with inner sleeves), ensure that the mounting direction is correct and consistent with the direction of media flow.
Pre-deformation: If pre-deformation (cold tightening) is required, It shall be carried out according to the design requirements, and the deformation auxiliary parts shall be removed after completion.
Avoid extra stress: Avoid applying additional torque or lateral force to the expansion joint during installation, ensuring its free movement.
Protective measures: During the installation process, avoid welding slag, dust and other foreign matters into the expansion joint to prevent damage.
Operation and maintenance
Step by Step: The opening and closing of the valve should be carried out slowly to avoid sharp changes in pressure and temperature in the pipeline.
Periodic inspection: Check the appearance of the expansion joint regularly and pay attention to any cracks, leaks or abnormal deformation.
Cleaning and anti-corrosion: Keep the expansion joint clean and perform regular anti-corrosion treatment, especially in harsh marine environments.
Temperature control: Ensure that the expansion joint works within the allowable temperature range and avoid overtemperature operation.
Testing and Acceptance
Stress testing: After installation, the expansion joint shall be subjected to a hydraulic test of not more than 1.5 times the nominal system pressure.
Water quality requirements: The test water should be clean and the chloride ion content should not exceed 25ppm to avoid corrosion.
Drain & Dry: Drain the water in the expansion joint in time after the test, and blow dry the inner surface to avoid corrosion.
Documentation
Installation Records: Keep all records during installation, including the model of the expansion joint, size, date of installation, etc.
Maintenance Log: Record the date of each maintenance inspection, problems found and actions taken.
Following these specifications helps ensure the effective operation and long-term reliability of expansion joints in shipyards and marine engineering. In addition, reference should be made to specific international standards such as ISO, ASME or DNV GL, etc., as well as instructions for use and maintenance guidelines provided by the manufacturer.