General engineering orientation to help you specify and enquire with confidence. Guidance only — selection, configuration and scope are confirmed against your project specification at quotation.
Why the governing standard matters
A flange is only interchangeable with its counter-flange when both are made to the same governing standard, size and pressure designation. Stating the standard and its edition at enquiry stage removes ambiguity from quotation, manufacture and inspection.
ASME flange standards
The ASME family covers the majority of imperial-designated industrial flanges.
- ASME B16.5 — pipe flanges and flanged fittings, NPS ½ to 24, Classes 150 to 2500; the core reference for most process pipework.
- ASME B16.47 — large-diameter flanges, NPS 26 to 60. Series A and Series B are dimensionally different and are not interchangeable.
- ASME B16.36 — orifice flanges with pressure tappings for differential-pressure flow measurement.
- MSS SP-44 — steel pipeline flanges, dimensionally aligned to B16.47 Series A.
European and international standards
European metric pipework is specified to EN 1092-1, which designates flanges by type number and PN rating rather than ASME class.
- EN 1092-1 Type 11 — welding-neck; Type 12 — hubbed slip-on; Type 05 — blind; Type 01 — plate flange.
- JIS B2220 — Japanese industrial flange dimensions.
- SANS 1123 — South African flange tables.
- AWWA C207 — steel flanges for waterworks service.
- GOST 12820 / 12821 — regional standards specified on some export projects.
Legacy references
Older UK and German installations may be dimensioned to BS 10 table flanges or the DIN series (for example DIN 2633). These remain valid as project-specified references for matching existing pipework, but new projects normally specify EN 1092-1 where a metric flange is required. BS 3293 covers large-diameter carbon-steel petroleum flanges, NPS 26 to 48.
Stating a standard on an enquiry
A complete flange reference includes each of the following.
- Governing standard and edition (e.g. ASME B16.5 or EN 1092-1)
- Nominal size (NPS or DN) and quantity
- Pressure class or PN designation
- Flange type and facing
- Material grade and documentation requirement
These are buyer-input prompts only and are confirmed against your project specification. Send them with your enquiry for engineering review.