What is the difference between A335 and SA335 pipe

1. Standard system and scope of application
ASTM A335: A standard developed by the American Society for Testing and Materials (ASTM), which mainly regulates the chemical composition, mechanical properties and process requirements of seamless ferritic alloy steel tubes for high temperature use, and is applicable to high temperature pipelines in non-nuclear energy industry areas (e.g. petrochemical, conventional boilers, etc.).
ASME SA335: Adopted and revised by the American Society of Mechanical Engineers (ASME), its technical content is basically the same as ASTM A335, but with the addition of nuclear energy, high pressure vessels, and other special applications of safety specifications (such as). The technical content is basically the same as ASTM A335, but with additional safety specifications for special applications such as nuclear energy, high-pressure vessels (e.g. welding process, non-destructive testing requirements, etc.), which is applicable to nuclear power plants, high-pressure boilers and other key equipment requiring ASME certification.
2. Differences between grades and technical requirements
Correspondence of grades:
ASTM A335 and ASME SA335 grades (such as P11, P22, P91, etc.) and chemical composition is the same, for example, P11 Cr content of 1.00 ~ 1.50%, Mo content of 0.44 ~ 0.65%.
Key difference: ASME SA335 imposes more stringent requirements on the manufacturing process (e.g. normalising + tempering temperature range) and the percentage of weld hardness testing (e.g. ≥10%) for some grades (e.g. P91) to ensure long-term safety in nuclear energy or high-pressure scenarios.
3. Application Scenarios and Certification Requirements
ASTM A335: Mostly used in conventional industrial pipelines (e.g. oil refineries, ordinary boilers), without mandatory ASME certification, but need to comply with the performance indicators in the ASTM standard.
ASME SA335: ASME BPV Code (Boiler and Pressure Vessel Code) certification is mandatory, especially in high-risk scenarios such as main steam piping in nuclear power plants, supercritical boilers, and other high-risk scenarios where SA335 tubes must be used.
4. Marking and Compliance
Material Identification: ASME SA335 tubing is marked with an 'SA' prefix (e.g., SA335 P11) to differentiate it from its ASTM A335 counterpart.
Compliance Documentation: ASME SA335 pipe is required to be accompanied by inspection reports (e.g., heat treatment records, impact test data) that comply with ASME specifications, whereas ASTM A335 is typically only required to meet general industry standards.