Case Study: Customized High-Pressure Vertical Multistage Pump System

A long-term client who previously used a Grundfos vertical pump system approached us with a new and highly demanding requirement. The client requested a replacement solution capable of delivering a flow rate of 180–200 m³/h and a head of 36–40 bar, while upgrading all wetted components to 316L stainless steel for superior corrosion resistance and durability in water treatment operations. These parameters exceed standard industrial ranges, requiring both hydraulic innovation and structural strength.

 

After receiving the request, our R&D and technical teams conducted a comprehensive engineering review. We determined that a standard vertical multistage centrifugal pump could not fully satisfy the hydraulic demands. Therefore, a new model was designed from the ground up, based on our largest existing frame size.

The new design involved increasing the number of diffuser stages, optimizing impeller geometry for better efficiency, reinforcing shafts and couplings to sustain 40 bar pressure, and ensuring full compatibility with 316L stainless steel construction. This configuration provided both mechanical robustness and long-term chemical resistance for continuous operation in water treatment environments.

Once the hydraulic design was complete, the engineering team conducted CFD simulations and mechanical stress analysis to validate the system's performance. Several stage combinations were evaluated to ensure the optimal balance between head and efficiency. After multiple optimization rounds, the configuration achieving 200 m³/h at 38 bar was finalized.

The new customized model was designated as CDLF200-6 + CDH200-6, representing a vertical multistage centrifugal pump delivering 200 cubic meters per hour at a maximum head of 40 bar, with all wetted parts made from 316L stainless steel. The design included extended diffuser sections, precision-balanced rotors, and modular discharge heads for easier maintenance. Complete 3D drawings and performance curves were provided to the client for review, and after several rounds of confirmation, the design was approved for production.

CFD simulations and internal hydraulic calculations validated stage head gain, efficiency, and NPSH behavior. 3D models, assembly drawings, and performance curves were issued for review. After several technical exchanges, the client approved the CDLF200-6 + CDH200-6 configuration with the following targets at duty: 190–200 m³/h, 38–40 bar, with NPSH margin ≥ 1.0 m.

Major design notes: extended diffuser section, precision‑balanced rotors (ISO G2.5), cartridge mechanical seals (SiC/SiC, Viton), and a modular discharge head to simplify service. All wetted parts are 316L stainless steel.

Following approval, production began with strict adherence to quality standards. All 316L materials underwent PMI testing before machining. Welding operations were carried out using TIG with argon back-purging to prevent oxidation, followed by surface passivation. Machining accuracy was held within 0.03 mm TIR, and all rotating assemblies were dynamically balanced to ISO 1940 G2.5 standards.

Pressure-bearing components were hydrostatically tested at 1.5× the design pressure (60 bar). Dimensional and assembly inspections were performed at multiple checkpoints, ensuring concentricity and proper clearances. Each pump underwent a no-load rotation test and electrical insulation check before moving to final assembly.

Mechanical Assembly

• Stage stacking: each impeller, diffuser, and sleeve was gauged and recorded; impeller‑to‑diffuser clearance was set per spec.
• Rotor build: wear rings measured and matched; axial float configured; keys fitted to tolerance.
• Bearing installation: heated mounting to avoid brinelling; preload verified by endplay measurement.
• Mechanical seal: cartridge seal installed with setting clips; seal chamber flushing provision retained.
• Discharge head & base: modular frame aligned to datum; lifting lugs verified and marked.

Electrical & Controls

• Motor wiring: phase sequence verified; insulation resistance > 100 MΩ @ 500 V.
• Instrumentation: pressure tappings at suction/discharge, PT100 on bearings, and vibration pickups mounted at DE/NDE.
• Control logic: supports alternating duty, parallel boosting, soft‑start/VFD, and protective interlocks (dry run, over‑temp, over‑vibration).

Laser Alignment

• Cold alignment performed with laser tool; final offset ≤ 0.03 mm and angularity within tolerance.
• Thermal growth compensation documented for hot alignment at site.

1) Pre‑Test Checks

• Oil/grease levels confirmed; couplings guarded; all gauges calibrated (traceable certs).
• Suction flooded, system vented; rotation verified; emergency stop tested.

2) Hydraulic Performance Curve Verification

Each vertical multistage centrifugal pump was tested across multiple points to map the H‑Q curve. Representative results:
• 70% flow (~140 m³/h): head ≈ 41.5 bar; efficiency within predicted band.
• 100% flow (~190 m³/h): head ≈ 38.2 bar; power draw nominal; BEP near duty.
• 120% flow (~225 m³/h): head ≈ 34.6 bar; stable operation, no cavitation onset.
Results remained within ±3% of design predictions.

3) Pressure Integrity & Leakage

• Hydrostatic test at 60 bar for 30 minutes on casing and discharge header-no leakage or permanent deformation.
• Static hold on mechanical seal: dry inspection post‑test confirmed zero visible seepage.

4) Vibration & Acoustic Limits

• Vibration: ≤ 4.3 mm/s at 100% duty (ISO 10816 compliant).
• Noise: < 85 dB(A) @ 1 m; bearing temperatures stable throughout.

5) NPSH & Cavitation Margin

• With induced suction lift and throttled tests, available NPSH exceeded required by ≥ 1.0 m. No cavitation signature in vibration spectrum.

6) Endurance & Parallel Running

• Continuous run: 3 hours at duty with periodic readings every 15 minutes-pressures, flows, vibration, bearing temperatures all stable.
• Parallel mode: both CDLF200-6 and CDH200-6 operated simultaneously; header pressure stability and flow sharing verified.
• Interlocks: dry‑run, over‑vibration, over‑temperature, and emergency shutdown tested and recorded.

Deliverables

• FAT report (H‑Q data, vibration logs, gauge calibration sheets), HD testing videos (assembly + performance), and maintenance checklist.

Before packaging, the client visited our factory in China for pre-shipment inspection. Together with our engineers, they reviewed mechanical construction, surface finish, and test records. Random pressure tests were repeated on-site. The client expressed high satisfaction with the build quality and documentation completeness.

 

Given the total weight (~3.5 tons) and footprint, full assembly shipment was impractical. Each vertical multistage centrifugal pump was packed separately in custom ISPM‑15 wooden crates with reinforced bases. Protective measures included VCI wrapping, desiccants, humidity indicators, and shock/tilt monitors. Electrical terminals were sealed; all crates were clearly labeled with serial numbers, gross weight, and handling symbols. Documentation-FAT reports, material certificates, installation drawings, and manuals-accompanied the shipment.

 

We supplied a quick start guide, recommended spares list, lubrication schedule, and alignment instructions. For site work, we offer live video support for reassembly and first start. SAT (Site Acceptance Test) can repeat duty‑point verification, parallel switching, and alarm logic checks.

The CDLF200-6 + CDH200-6 dual‑pump solution met the required 180–200 m³/h and 36–40 bar targets with a robust, maintainable design. The project demonstrates our capability to deliver customized, high‑pressure vertical multistage pump systems for water treatment applications.