Q: What is the latest Chinese national standard for seamless steel tubes in petrochemical and chemical facilities?
A: It is GB/T 9948-2025 (effective Jan 1, 2026), which replaces the older version and covers pipes for petroleum cracking, high-pressure fertilizer equipment, etc.-7
Q: Which important international code governs the design and construction of process piping in plants?
A: The ASME B31.3 Process Piping Code is the key international standard referenced for the manufacture, testing, and in-service activities of process piping-3-10.
Q: What is the purpose of normalizing heat treatment for alloy steel pipes like 15CrMoG?
A: Normalizing refines the grain structure, improves uniformity, and enhances mechanical properties (strength and toughness) to meet the required specifications for high-temperature service.
Q: What non-destructive tests (NDT) are commonly specified for seamless steel pipes?
A: Common NDT includes hydrostatic testing (pressure test), eddy current testing (ET), ultrasonic testing (UT), and magnetic particle inspection. ASTM A312, for example, requires either a non-destructive electric test or a hydrostatic test-2.
Q: What mechanical tests are typically performed on seamless pipes according to standards like ASTM A312?
A: Required tests include transverse or longitudinal tensile tests and a flattening test. Hardness tests and impact tests may also be specified-2.
