GB 12777 is the national standard of China, titled "Metal Bellows Expansion Joint". This standard specifies the requirements of design, manufacture, inspection and acceptance of metal bellows expansion joints (also known as corrugated compensators). Here are some key elements of the GB 12777 standard:
Scope of application：
This standard applies to the design, manufacture and acceptance of metal bellows type expansion joints.
It is mainly used in industrial pipeline systems to compensate the axial, transverse and angular displacements of pipelines.
Definition and Symbol：
The standard provides the definition of bellows expansion joints and the technical terms and symbols involved in their design and use.
Material selection：
Specifies standards and requirements for metal materials, sealing materials and filling materials used in bellows-type expansion joints.
Design Requirements：
Including the geometric parameters of the bellows, material thickness, corrugation shape, connection mode (such as flange connection or welding) and other design elements.
Manufacturing requirements：
Guide the manufacturing process of corrugated compensator, such as molding, welding, heat treatment and other process control.
Inspection and testing：
Describes the inspection items of the product, including dimensional inspection, appearance inspection, hydraulic test, airtightness test, etc.
Acceptance criteria：
Product acceptance conditions and procedures are provided to ensure that the product meets the design and quality requirements.
Marking, packaging, transportation and storage：
The requirements for product identification, packaging, transportation and storage are specified to ensure that the quality of the product is not compromised.
The GB/T 12777-2008 standard also specifies the size standard of bellows compensator in detail, including a series of values of nominal diameter (DN) and length (L), for example, the nominal diameter ranges from DN15 to DN2000, and the length is generally 200mm, 400mm, etc., depending on the manufacturer and design requirements.
When selecting and designing a corrugated compensator, GB 12777 standard must be followed to ensure that the quality and performance of the compensator meet the working conditions of the pipeline system. In addition, the working medium, temperature, pressure and expected displacement should be considered to ensure the correct selection and safe operation of the compensator. In special applications, other relevant standards or industry specifications may be required to be referred to.