1) American standard (ASTM Sch 40 & Sch 80, SDR 21, SDR 26, SDR41)
2) British standard (BS 3505, BS 5255, 4515)
3) Singaporean standard (SS 141, SS 272, SS 213)
4) Australian standard (AS 1477, AS 1415)
5) Japanese standard (JIS K 6742, JIS K 6741, JIS K 6743, JIS K 6739)
6) National standard (GB 10002, GB 5836, GB 14823, GB 13664)
7) International standard (ISO 4422, ISO 3633, IEC 614, GY 3050)