What is the A126 standard?
I. Standard Definition and Scope
ASTM A126 is a standard developed by the American Society for Testing and Materials (ASTM) to specifically regulate the quality and technical requirements for grey iron castings for valves, flanges and fittings. Its core scope of application includes:
Pressure-bearing parts for valves (e.g., valve bodies, bonnets);
Grey cast iron parts such as flanges and pipe fittings in piping systems.
Second, technical requirements and classification
Material grade:
The standard is divided into three grades of Class A, B and C according to the mechanical properties, of which Class B is the commonly used grade, applicable to medium and low pressure scenarios.
Performance indicators:
Grey cast iron composition: carbon content ≥ 3.0%, need to meet the specific graphite morphology and matrix organisation requirements;
Mechanical properties: tensile strength, hardness, etc. need to meet the standards of different grades (e.g. Class B tensile strength ≥ 207 MPa).
Third, the field of application
ASTM A126 grey iron castings are mainly used in the following scenarios:
Low pressure fluid control: such as valves and fittings for water treatment, water supply and drainage systems;
Industrial piping: transmission of non-corrosive media such as fire-fighting systems and irrigation equipment;
General mechanical components: adapted to ANSI 125/150LB flange connection of low-pressure piping systems.
Fourth, the connection with other standards
American Standard System: often used with ANSI standards (such as ANSI 125/150LB flange) to ensure interface compatibility;
International projects: in line with the European and American market for low-pressure valve castings of the general technical requirements, applicable to export equipment manufacturing.
V. Restrictions
Pressure restrictions: only for low-pressure environment ≤ 1.6 MPa;
Temperature restrictions: not recommended for high temperature (>200 ℃) or strong corrosive media (such as acid, alkali) scenarios.
Summary: ASTM A126 is a key standard for the manufacture of grey cast iron valves and fittings, with low cost, corrosion resistance and low pressure sealing as the core advantages, widely used in municipal and industrial fluid control areas.
