These terms are commonly used in the fields of piping, welding, and mechanical engineering. Here’s a breakdown:
ASTM (American Society of Testing and Materials) 🧪
Material standards and testing
Definition of mechanical, chemical, and physical properties
Examples include ASTM A106 (Carbon Steel) and ASTM A312 (Stainless Steel).
ASME (American Society of Mechanical Engineers)
Design & fabrication codes
Safe rules for boilers, vessels & piping
Example: ASME BPVC, ASME B31 (Piping Codes)
ANSI (American National Standards Institute)
Approves & coordinates standards
Doesn’t write specs, but endorses (ASME, ASTM, API)
Example: ANSI/ASME B16.5 (Flanges)
ISO (International Organization for Standardization)
International standards for industry
Ensures compatibility & global quality
Example: ISO 3183 (Pipeline transport of oil & gas)
DN (Diameter Nominal)
Metric nominal pipe size
Number for reference, not exact dimension
Example: DN50 ≈ NPS 2″
