GB 13021 — 聚乙烯管材和管件碳黑含量测定 GB 13021-1991 聚乙烯管材和管件碳黑含量测定. CNAS-accredited laboratory test standard. Version reference only. No standard text. GB 1033.1 1462 13657 5169.16 5349 228.1 7690.3 GB 9274 1771 1452 5169.12 4618.2 Testing: info@leisa.com