API 610 Requirements - Complete Engineering Reference

1. API 610 Standard Overview

1.1 Scope and Application

API 610 (12th Edition, January 2021) specifies requirements for centrifugal pumps for petroleum, petrochemical, and natural gas industries. This standard applies to:

• Overhung pumps (OH types)
• Between bearings pumps (BB types)
• Vertically suspended pumps (VS types)
• Hydraulic power recovery turbines (pumps running in reverse)

Important Note: The 12th Edition is no longer co-branded with ISO. Previous editions (9th, 10th, 11th) were co-branded as ISO 13709.

1.2 Design Objectives

2. Pump Type Classifications

2.1 OH - Overhung Pumps

Impeller cantilevered beyond bearings. Bearing housing must support all hydraulic and dynamic forces.

OH1 vs OH2 - Critical Selection Point:

OH1 (Foot-Mounted):
  └─ Thermal growth → Shaft rises → Misalignment with driver
  └─ Suitable for: T < 175°C (350°F)
  └─ Requires: Purchaser approval for API 610 use

OH2 (Centerline-Mounted):
  └─ Thermal growth → Symmetric expansion → Alignment maintained
  └─ Required for: T > 175°C (350°F)
  └─ Standard for: All API 610 hot services

2.2 BB - Between Bearings Pumps

Shaft supported by bearings on both sides of impeller(s). Superior shaft support for high-energy applications.

BB1 vs BB2 - Pressure Selection:

2.3 VS - Vertically Suspended Pumps

Casing and impeller suspended below support plate. Used for wet pit, sump, and deep well applications.

Types Requiring Purchaser Approval: OH1, VS4, VS5, BB4 do not meet all API 610 requirements.

3. Material Classes

3.1 Standard Material Classes

3.2 Material Selection by Service

3.3 Wear Ring Materials

4. Performance Requirements

4.1 Operating Regions

Flow Rate (% of BEP)
│
│  ◄─── Outside ───►◄── Allowable ──►◄─ Preferred ─►◄── Allowable ──►◄─── Outside ───►
│        Region           Region          Region          Region           Region
│                    │                │              │                │
├────────────────────┼────────────────┼──────────────┼────────────────┼────────────────
0%                  70%              80%           110%             120%
│
│  ❌ No continuous     ⚠️ May operate    ✅ Full API      ⚠️ May operate    ❌ No continuous
│     operation            briefly        compliance          briefly           operation

4.2 Head Curve Requirements (12th Edition)

4.3 Capacity Margin

All pumps must accommodate at least 5% head increase at rated flow through:

1. Larger impeller diameter replacement
2. Variable speed capability
3. Use of blank stage (for multistage)

5. Vibration Acceptance Criteria

5.1 Bearing Housing Vibration

5.2 Shaft Vibration (Proximity Probe)

5.3 Vibration Impact on Bearing Life

Critical Note: Small increases in vibration significantly reduce bearing life. Always target lowest achievable vibration.

6. Bearing Requirements

6.1 Life Requirements

6.2 Bearing Type Selection

6.3 Lubrication Requirements

7. Mechanical Seal Requirements (API 682)

7.1 API 682 Categories

API 610 references API 682 for mechanical seal specifications:

7.2 Seal Design Requirements

7.3 Common API 682 Flush Plans

Single Seal Plans:

Dual Seal Plans:

Flush Plan Selection Guide:

8. Testing Requirements (12th Edition)

8.1 Performance Test (HI 14.6 / ISO 9906)

Required Test Points:

1. Shut-off (0% flow)
2. 60% of BEP
3. 80% of BEP
4. 100% of BEP (rated)
5. 110% of BEP
6. 120% of BEP 7-9. Additional points per manufacturer

8.2 NPSH Testing Requirements

Additional Requirements:

• H vs. NPSH(A) curves at each test point
• NPSH margin verification per datasheet

8.3 Mechanical Running Test

Recorded Parameters:

• Suction and discharge pressure
• Power consumption
• Operating speed
• Vibration (filtered and unfiltered)
• Bearing temperature (all bearings)
• Lube oil temperature and pressure
• Seal chamber pressure

8.4 Optional Tests

9. Datasheet Requirements (12th Edition)

9.1 Operating Points

9.2 Key Datasheet Items Checklist

Process Data:

• All five operating points defined
• Liquid properties (SG, viscosity) at each point
• NPSH available at all conditions
• Maximum and minimum temperatures
• Vapor pressure at operating temperature

Mechanical Data:

• Driver type, power, and speed
• Coupling type (spacer for seal maintenance)
• Seal type and flush plan per API 682
• Material class selection
• Baseplate requirements

Instrumentation:

• Vibration monitoring (probe type, location)
• Temperature sensors (bearing, seal)
• Pressure transmitters
• Flow measurement requirements

9.3 Electronic Data Exchange (EDE)

The 12th Edition introduces standardized data lists supporting:

• Machine-readable format
• Direct import to engineering databases
• Reduced transcription errors
• Consistent data across parties

10. API 610 vs ANSI B73.1 Comparison

10.1 Design Philosophy Comparison

10.2 Technical Specification Comparison

10.3 Selection Guidelines

Use API 610 When:

• Petroleum refineries, petrochemical plants
• Flammable or toxic fluids
• Temperature >149°C (300°F)
• High consequence of failure
• Offshore platforms, remote locations
• LNG and cryogenic services
• High-speed (>3600 rpm) applications

ANSI B73.1 May Be Acceptable When:

• Water and utility services
• Non-hazardous chemicals
• General industrial applications
• Easily accessible for maintenance
• Lower capital budget constraint
• Interchangeability priority

11. Vendor Evaluation Guidelines

11.1 Compliance Verification Checklist

11.2 Common Non-Compliance Issues (Red Flags)

11.3 Questions for Vendor Clarification

1. What is the calculated L10 bearing life at rated AND maximum radial load?
2. What vibration level is expected at rated, minimum, and maximum flow?
3. What percentage of maximum impeller diameter is being offered?
4. What seal flush plan is recommended and why?
5. What is the MCSF (Minimum Continuous Stable Flow)?
6. Can you provide a reference list for similar applications?
7. What is the expected efficiency at rated point?
8. What are the spare parts recommendations for 2-year operation?

12. 11th vs 12th Edition Key Changes

13. Quick Reference Tables

13.1 Pump Type Quick Selection

13.2 Vibration Limit Quick Reference

13.3 Material Class Quick Reference

References

• API 610 12th Edition Overview - Hydrocarbon Processing
• API 610 Pump Classifications - Hard Hat Engineer
• API 610 Pump Configurations - Amarinth
• API 682 Piping Plans - AESSEAL
• IOGP S-615 Supplementary Specification