... , according and conforming to the following international standards:1) American standard (ASTM Sch 40 & Sch 80, SDR 21, SDR 26, SDR41 ... ) 2) British standard (EN 1452, EN 1401, BS 3505, BS 5255, 4515) 3 ... K 6743, JIS K 6739) 6) National standard (GB/T 10002, GB/T 5836, GB/T 14823, GB/T 13664) 7) International standard (ISO 4422, ISO 3633, IEC 614, GY ...