There are many standards for steel products in the United States, mainly in the following categories:
ANSI - American National Standard
AISI - American Steel Standards Association
ASTM - American Association of Testing and Materials
ASME - American Association of Mechanical Engineers
AMS - Aerospace Material Specification (one of the most commonly used material specifications in American aviation industry developed by SAE)
API - American Petroleum Association Standards
AWS - American Welding Association Standard
SAE - American Association of Automotive Engineers Standards
MIL - US Military Standards
Qq - US Federal Government Standard
API - American Petroleum Association Standards
ANSI - American National Standard
ASME - American Association of Mechanical Engineers
ASTM - American Association of Testing and Materials


These standards belong to American steel standards, such as ASME from ASTM in the materials used in the standard, valves in the standard reference API and pipe fittings in the ANSI standard. The difference lies in the different focus of the industry, so different standards are adopted. API, ASTM and ASME are members of ANSI. The vast majority of NISA standards come from professional standards.  On the other hand, professional associations, associations and organizations can also formulate certain product standards according to existing national standards.  Of course, we can't formulate our own Association standards according to the national standards. The ANSI standard is voluntary. The United States believes that mandatory standards may limit productivity gains. However, it is generally mandatory for laws and government departments to set standards.