Acceptance criteria for expansion joints typically include a series of technical requirements and tests to ensure that their quality and performance before installation meet design and safety specifications. These standards may vary depending on the type of expansion joint (metallic, non-metallic), the field of application (petroleum, chemical, power, construction, etc.), and country/region. Here are some common acceptance criteria and tests for expansion joints:
Acceptance criteria for metal corrugated expansion joints
Appearance check：
Check the bellows surface for defects such as cracks, depressions, scratches, weld splatters, etc.
Check the welding quality to ensure that the welds are free of obvious defects and are of normal color.
Dimensional inspection：
Use accurate measuring tools to measure parameters such as wave height, wave pitch and total product length to ensure that they meet the requirements of design drawings.
Weld flaw detection：
Nondestructive testing such as radiographic testing (RT), ultrasonic testing (UT), magnetic particle testing (MT), or penetration testing (PT) is performed on the weld area to check the weld quality.
Resistance voltage test：
Perform hydraulic or pneumatic tests to verify the strength of the expansion joint at higher than working pressures.
According to the standard, as specified in GB/T 150.4-2011, the expansion joint shall not have leakage or damage under the test pressure.
Leak test (airtightness test)：
Test the tightness of the expansion joint to ensure no leakage under working pressure.
Cyclic fatigue test：
The expansion joint is subjected to a certain number of tension and compression cycles to evaluate its fatigue life.
For example, tension and compression cycles of ±27.07 mm can be carried out at an internal pressure of 1.5 MPa, the number of cycles should be greater than 2000 times, and the expansion joint should not have cracks penetrating the wall thickness.
Acceptance criteria for non-metallic expansion joints
Appearance check：
The glue layer on the surface of the loop belt is not allowed to have scratches, cracks, interlayers and peeling phenomena, and braided ring seams are not allowed.
No cracks, unpenetrated, unfused, surface pores, craters, slag inclusions and splashes are allowed in the welded part of the metal frame.
Airtightness：
Non-metallic expansion joints shall be tested for airtightness to ensure that they do not leak under operating conditions.
Chemical composition and material inspection：
Confirm whether the material meets the specified chemical composition and material requirements.
Other General Requirements
Material identification: The material and specification of the expansion joint shall be clearly identified.
Document Review: Check the quality certificate, material test report, manufacturing record and other documents provided by the manufacturer.
Meets relevant standards: Ensure that the expansion joint is designed, manufactured and tested in accordance with relevant international or national standards, such as ASME, EN, GB, etc.
In practice, the specific acceptance criteria and test procedures should refer to the latest industry standards and regulations, as well as the technical requirements agreed in the procurement contract. In addition, the installation and maintenance of expansion joints also need to follow corresponding specifications to ensure the safety and reliability of long-term operation.