Criteria for non-metallic expansion joint skins typically involve multiple aspects such as material selection, design, manufacturing, testing, and installation. These standards are designed to ensure that the skin of non-metallic expansion joints can operate safely and reliably under a variety of operating conditions. Here are some of the key standards and requirements:
Material selection
Chemical stability: The skin material should have good chemical stability and be able to resist the corrosion of the medium in the pipeline.
Temperature resistance: The material shall be capable of maintaining performance over the operating temperature range of the expansion joint, typically covering the range from low temperatures to up to 1200°C.
Pressure resistance: The skin should be able to withstand the working pressure of the piping system up to 40000Pa or more.
Abrasion resistance: For the presence of particulate media or high flow rate, the skin material needs to have good wear resistance.
Sealability: The material shall ensure the tightness of the expansion joint and prevent media leakage.
Design and Manufacturing
Number of layers: Depending on the operating temperature, the skin may need to be constructed from multiple layers of material.
Reinforcement layer: Use of reinforcing materials such as steel wire or other reinforcing materials to increase the mechanical strength of the skin.
Sealing material: Use materials such as fluororubber cloth as a sealing layer to improve corrosion resistance and extend service life.
testing
Airtightness test: Make sure the skin is not leaking under working pressure.
Stress test: Verify the integrity of the skin at maximum working pressure.
Temperature testing: To evaluate the performance of the skin under extreme temperature conditions.
Installation
Adhesion: The skin should be firmly attached to the frame of the non-metallic expansion joint to prevent it from falling off during operation.
Correct alignment: Install to ensure that the skin is properly aligned to avoid twisting or wrinkling, which may affect the function and longevity of the expansion joint.
Acceptance criteria
Appearance check: The skin surface should not be scratched, cracked, sandwiched or peeled.
Welding inspection: If there is a weld at the joint between the skin and the metal frame, the quality of the weld should be checked to ensure that there are no problems such as cracks, non-penetration or non-fusion.
Industry standards
The manufacture and application of non-metallic expansion joint skin should follow relevant industry standards such as ASTM, ASME, ISO, etc, depending on the region and application area.
Please note that the above standards and requirements may change over time and technological advances, so the latest industry specifications and manufacturer's guidance documents should be referred to when designing and selecting non-metallic expansion joint skins.