General Technical Specifications for Expansion Joints of Metal Corrugated Pipe is a national standard of China, the standard number is GB/T 12777-2019, which replaces the previous version of GB/T 12777-2008. This standard specifies in detail all aspects of the design, manufacture, inspection and use of metal bellows expansion joints, including the following main elements:
Terms and definitions： Specialized terms and definitions related to metal bellows expansion joints are provided to facilitate unified understanding and communication within the industry.
Classification and labeling： Corrugated pipe expansion joints are classified according to different characteristics and application areas, and how to mark products is specified to facilitate identification and traceability.
Material： The types, performance requirements and selection principles of materials used in the manufacture of bellows expansion joints are specified.
Dimensions and deviations： The dimensional range of bellows expansion joints and their allowable manufacturing tolerances are set.
Design： Including design principles, calculation methods, safety factors, etc., to ensure that the expansion joint can meet the expected performance and life requirements when designed.
Manufacturing： Guides process control and quality standards in the manufacturing process to ensure that the manufacture of products meets the design requirements.
Inspection and testing： It stipulates all kinds of inspection and test items that need to be carried out before leaving the factory, such as pressure resistance, fatigue performance test, etc., to verify the quality and performance of products.
Inspection rules： The frequency, methods and qualification criteria of inspection are defined to ensure that each batch of products has been properly inspected.
Flag： Request information that should be included on the product and packaging, such as manufacturer's name, product model number, date of manufacture, etc.
Packaging, Shipping and Storage： Guidance on packaging, shipping, and long-term storage is provided to protect the product from damage prior to delivery to the user.
Selection： Guide users how to choose the appropriate expansion joint type and specification according to the actual application requirements.
Installation and Use Requirements and Safety Recommendations： Provides precautions during installation and use, as well as safety guidance for operation and maintenance.
GB/T 12777-2019 standard is applicable to all expansion joints installed in pipes whose flexible elements are metal bellows. Whether in the design, manufacturing or inspection stage, this standard is an important reference basis, ensuring that the quality and performance of metal bellows expansion joints meet the industry standards.