API 610 OH2 Pump Factory Acceptance Test: Witness Items and Documentation

A factory acceptance test (FAT) is the last chance to verify a pump before it ships to your site. For API 610 pumps, the FAT is not optional — it is required by the standard. Witnessing the FAT is your opportunity to confirm the pump meets your specification. Missing the FAT means discovering problems on site, where corrections cost 10x more and delay startup.

This guide covers what to witness at an API 610 OH2 pump FAT and what documentation to require.

What Is a Factory Acceptance Test?

The FAT is a series of tests performed at the manufacturer's factory before shipment. The pump is mounted on a test bench, connected to suction and discharge piping, and run at various operating points. Performance data is recorded and compared to the specification.

For API 610 pumps, the FAT includes:

• Hydrostatic pressure test
• Performance test (flow, head, power, efficiency)
• NPSH test (if required)
• Vibration test
• Mechanical running test
• Auxiliary system test (seal flush, bearing cooling)

You can witness the FAT in person or via video. For critical pumps (refinery service, high cost), in-person witnessing is recommended.

Test 1: Hydrostatic Pressure Test

What it is: The pump casing is filled with water and pressurized to 1.5x the design pressure. Held for 30 minutes. No leakage or permanent deformation is allowed.

What to witness:

• Verify test pressure = 1.5 × maximum allowable working pressure (MAWP)
• Verify hold time = 30 minutes minimum
• Check all flanges, gaskets, and plugs for leakage
• Check casing for visible deformation or cracks
• Verify pressure gauge is calibrated (check calibration sticker)

API 610 requirement: Hydrotest at 1.5x MAWP for 30 minutes. All wetted pressure-containing parts must pass.

Test 2: Performance Test

What it is: The pump is run at multiple flow points (shutoff, 60%, 80%, 100%, 120% of rated flow). At each point, flow, head, power, and efficiency are recorded. The results are plotted on the performance curve and compared to the guaranteed curve.

What to witness:

• Verify test fluid is water (SG = 1.0) at ambient temperature
• Verify flow measurement device (venturi, magnetic flowmeter) is calibrated
• Verify pressure gauges are calibrated and at the correct elevation
• Check that the rated point (design flow and head) is within tolerance:
  • Head tolerance: ±3% at rated flow
  • Efficiency tolerance: 0 to -3% (no negative tolerance below guaranteed)
  • Power: not exceeding motor nameplate at any point up to 120% flow
• Check that the curve is smooth — no bumps or dips (indicates hydraulic problems)
• Verify shutoff head is within 120–140% of rated head

Common problem: The pump meets head at rated flow but efficiency is 5% below guarantee. This means the pump uses 5% more energy than expected. Over 10 years, this is significant. Reject the pump if efficiency is below tolerance.

Test 3: NPSH Test (If Required)

What it is: The suction pressure is gradually reduced until the pump head drops by 3%. The NPSH at this point is the NPSHr (required). This is compared to the guaranteed NPSHr.

What to witness:

• Verify test is run at rated flow
• Verify the 3% head drop criterion is used (API 610 standard)
• Check that NPSHr is within tolerance: 0 to +10% (NPSHr must not exceed guarantee by more than 10%)
• Check that NPSHr does not increase sharply at higher flows (indicates suction recirculation)

NPSH test is not always required — specify it in the purchase order if your NPSHa is marginal.

Test 4: Vibration Test

What it is: Vibration is measured at the bearing housings (horizontal, vertical, axial) at various flow points. Compared to API 610 limits.

What to witness:

• Verify vibration is measured at bearing housings, not the casing
• Verify measurement points: drive end (horizontal, vertical, axial) and non-drive end (horizontal, vertical, axial)
• Check API 610 limits:
  • Unfiltered vibration: ≤ 4.5 mm/s RMS at rated flow
  • At any flow from minimum to 120%: ≤ 7.1 mm/s RMS
• Check vibration at shutoff — should not exceed 7.1 mm/s
• Look for vibration spikes at specific frequencies (indicates bearing defects, misalignment, or vane pass issues)

Common problem: Vibration is 5.5 mm/s at rated flow — above the 4.5 mm/s limit. This indicates a problem with balance, alignment, or hydraulic design. Reject the pump.

Test 5: Mechanical Running Test

What it is: The pump runs continuously for 1–2 hours at rated flow. Bearing temperature and seal leakage are monitored.

What to witness:

• Bearing temperature stabilizes below 80°C (API 610 limit: 90°C alarm, 100°C trip)
• No seal leakage (mechanical seal should be dry — no visible leakage)
• No unusual noise (grinding, rattling, or whistling)
• No oil leakage from bearing housing
• Motor current is stable and within nameplate

Test 6: Auxiliary System Test

What it is: Seal flush, bearing cooling, and other auxiliary systems are tested for flow and pressure.

What to witness:

• Seal flush flow rate matches the seal plan specification (e.g., Plan 11, Plan 23, Plan 53B)
• Seal flush pressure is correct (typically 1–2 bar above seal chamber pressure)
• Bearing cooling water flow and temperature are correct
• All auxiliary piping is properly supported and labeled

Documentation to Require

After the FAT, require these documents:

Common FAT Problems

Problem 1: Efficiency below guarantee. The pump uses more energy than specified. Reject — the manufacturer must modify the impeller or casing and retest.

Problem 2: Vibration above limit. Indicates balance, alignment, or hydraulic issues. Reject — manufacturer must investigate and correct.

Problem 3: Head below guarantee at rated flow. The pump cannot deliver design flow and head. Reject — impeller modification or speed increase needed.

Problem 4: Seal leakage during running test. The seal is not properly installed or incompatible. Reject — seal replacement and retest.

Problem 5: Missing documentation. The FAT is complete but material certificates are missing. Reject shipment — require all documents before release.

For API 610 pump FAT support and witnessing, our API 610 OH2 pump range includes full FAT documentation and test reports. For FAT preparation and witness checklist, talk to our engineers with your pump specification.