1
Overview
API 605 was the historical standard developed by the American Petroleum Institute for large diameter, compact flanges used in refineries. It has been officially withdrawn and incorporated into ASME B16.47 as "Series B".
2
Scope & Applicability
Applies To Industries
Refinery
Covers — legacy large diameter compact flanges (NPS 26 to NPS 60).
3
Key Requirements
For modern engineering and procurement, refer to ASME B16.47 Series B. The dimensions are identical to the legacy API 605 standard.
4
Technical Details
Knowledge of API 605 is only necessary when performing maintenance, turnarounds, or tie-ins on older refinery equipment manufactured before the mid-1990s.
5
Engineering Notes
If you see "API 605" on an old drawing or equipment nameplate, order an ASME B16.47 Series B flange to match it.
7
Source, Edition & Status
- Publisher
- API
- Industries
- Refinery
- Last Reviewed
- 2026-07-01
- Last Updated
- 2026-07-01
- Verified By
- Engineering content reviewer
- Content Status
- reviewed