Core Requirements of API Pumps

The core requirements of API pumps are primarily reflected in their design, manufacturing, and testing, aiming to ensure high reliability, safety, and long service life in industries such as petroleum, petrochemical, and natural gas. Below is an overview of the core requirements based on the API 610 standard (11th or 12th edition):

1. Design Reliability Priority

API pumps prioritize safety and reliability, even at the expense of some efficiency. For example:

• Rigid Shaft Design: Ensures rotor system stability during operation

• Increased Wear Ring Clearance: Prevents dynamic/static component seizure under any operating conditions, though this increases internal leakage and reduces efficiency

• Service Life Requirement: The design life is typically 20 years, with a continuous operation period of at least 3 years

2. Performance Curve Stability

• Flow-Head Curve: Must be continuously rising to the shut-off point without any 'hump' to ensure operational stability. For pumps operating in parallel, the head rise from the rated point to the shut-off point must be at least 10% of the rated head

• Operating Range Requirement: The rated flow point should be between 80% and 110% of the best efficiency point (BEP) flow, with the preferred operating range being 70%–120% of BEP flow.

3. Shaft Sealing System

• Mechanical Seals: Must comply with API 682 standards, use cartridge seals, and include corresponding flush, cooling, and leakage management systems (e.g., PLAN 11, PLAN 23, etc.)

• Seal Chamber Dimensions: Must comply with standard specifications to ensure interchangeability and reliability of seal components.

4. Material Selection

• Material Grades: API 610 provides 14 material grades (e.g., S-1, A-8) selected based on medium corrosiveness, pressure, temperature, etc. Materials must exhibit corrosion resistance, wear resistance, and high-temperature resistance.

• Corrosion Allowance: Pump casings typically require a 3 mm corrosion allowance

5. Structural Types

API pumps cover various structural types, including:

• Overhung (OH Series): e.g., OH1 (foot-mounted), OH2 (centerline-mounted), OH3 (vertical inline pump), etc.

• Between-Bearings (BB Series): e.g., BB1 (axially split), BB2 (radially split), BB3 (multistage horizontally split), BB5 (double-casing multistage pump), etc.

• Vertical Suspended (VS Series): e.g., VS1 (diffuser casing), VS4 (vertical submerged pump), etc.

6. Vibration and Reliability

• Vibration Limits: Vibration values must be strictly controlled within standard limits (e.g., below 4.5 mm/s). High-energy pumps (single-stage head >200 m or single-stage power >225 kW) require special treatment, such as increased radial clearance between impellers and diffusers/volutes (at least 3% for diffuser pumps and 6% for volute pumps)

• Critical Speed: The first critical speed of the rotor must be at least 20% higher than the operating speed.

7. Testing and Acceptance

• Performance Test: Each pump must undergo performance testing with at least five points (including shut-off, minimum continuous flow, rated point, etc.). Test speed deviation must not exceed 3% of the rated speed.

• Mechanical Run Test: Operate for at least 4 hours at rated flow to check vibration, bearing temperature, and other parameters.

• NPSH Test: Must provide a flow-NPSH3 curve. The NPSH safety margin is typically required to be ≥1.0 m or 15% of NPSHa (whichever is greater).

8. Suction Performance

• Suction Specific Speed (S): The limit is usually no more than 13,000 (m³/h, rpm, m). For water or media with water content exceeding 50% and single-stage power >75 kW, the limit is 11,000. High suction specific speed increases the minimum continuous stable flow and affects operational stability.

9. Auxiliary Systems

• Bearing Lubrication: Bearing housings must have self-contained cooling systems; lip seals are prohibited

• Baseplate Design: Baseplates must have sufficient rigidity, use epoxy grouting, and include jacking screws for motor alignment

10. Documentation and Data

Manufacturers must provide complete performance curves (including flow-head, efficiency, NPSH3, and power curves), material reports, welding inspection reports, and installation/maintenance manuals

Summary

The core requirements of API pumps focus on high reliability, long service life, and safety. Their design, materials, and testing standards exceed those of ordinary industrial pumps. These requirements make API pumps particularly suitable for high-temperature, high-pressure, high-speed, and hazardous media applications. However, they also result in higher costs and may not meet the energy efficiency standards of general water pumps (e.g., GB 19762).

For users, selecting API pumps requires comprehensive consideration of life cycle cost (LCC) rather than focusing solely on the initial purchase price.

Hunan CME's API pumps are designed using advanced hydraulic modeling technology and manufactured in an Industry 4.0 digital factory. They fully meet the above standard requirements and maximize pump efficiency within the stability and precision deviation limits specified by API 610, achieves higher pump efficiency than many other brands.