Issuing body
API
Latest edition
12th Edition (2021)
Region
USA, Global
Equipment items
3
Scope
Workhorse standard for heavy-duty process centrifugal pumps. Pump types OH1–OH6, BB1–BB5, VS1–VS7.
Key requirements (13)
- Pump types: OH (overhung), BB (between bearings), VS (vertically suspended) — 13 configurations.
- OH1 = foot-mounted, OH2 = centerline-mounted, OH3 = vertical inline rigid coupling.
- BB1 = axially-split single-stage, BB2 = radially-split, BB3 = axially-split multistage, BB5 = barrel (double-casing) multistage.
- VS = vertically suspended (sump, can-type, etc.) — VS1 to VS7.
- Minimum design pressure: max suction + 1.5 × differential, or maximum discharge — whichever is greater.
- Hydrostatic test: 1.5 × maximum allowable working pressure, ≥ 30 minutes.
- L10 bearing life: ≥ 25,000 hrs continuous operation; ≥ 16,000 hrs at maximum loads.
- Shaft deflection: ≤ 50 µm (0.002 in) at primary seal faces under maximum hydraulic loads.
- Allowable nozzle loads per Table 5 (forces and moments on suction & discharge).
- Performance test per ISO 9906 Grade 2B (typical).
- Vibration limits per API 670 — overall < 3 mm/s RMS for new pumps typically.
- Materials: Annex H — material classes A (CI), B (CS), C (12Cr), D (austenitic SS), S (duplex), etc.
- Sealing: per API 682 (mechanical seal piping plans 11, 13, 21, 23, 32, 52, 53A/B/C, 54).
Note
Default for refinery, petrochemical and oil & gas pumps.