GB Standards
1): Design & Manufacture: GB12239
2): Face to Face Dimension: GB12221, JB1688
3): Flanged Dimension: GB4216, JB78
4): Inspect & Test: GB/T13927

BS Standards:
1): Design & Manufacture: BS5156
2): Face to Face Dimension: BS5156
3): Flanged Dimension: BS4504, DIN2532, JIS B2212, ANSI B16.1, ISO2004
4): Inspect & Test: BS6755

API Standards
1): Design & Manufacture: BS5156
2): Face to Face Dimension: BS5156
3): Flanged Dimension: ANSI B16.1
4): Inspect & Test: API598