How to verify the quality of used hydraulic pumps from Alang
December 18, 2025
Buying used hydraulic pumps from Alang, India—the world’s largest ship-breaking yard—can be a cost-effective way to source high-end marine components (like Rexroth, Kawasaki, or Parker). However, since these parts are salvaged from decommissioned vessels, a rigorous verification process is essential.1
Here is a guide on how to verify the quality of hydraulic pumps from Alang.
Before any mechanical testing, perform a detailed visual check to identify “red flags” that suggest internal damage.2
Housing Integrity: Look for cracks, weld repairs, or heavy pitting. Freshwater corrosion is manageable, but deep salt-water corrosion on the pump housing can compromise its structural integrity under pressure.
Shaft Condition: Inspect the drive shaft for “blueing” (a sign of overheating), scoring, or play. Rotate the shaft by hand; it should turn smoothly without clicking, grinding, or sticking.
Oil Port Residue: Inspect the intake and output ports. If you find metal shavings or “glitter” in the residual oil, it indicates internal catastrophic failure (likely the piston or vane assembly).
Nameplate Verification: Ensure the nameplate is original. Some sellers may re-stamp plates to match a higher-demand model. Cross-reference the serial number with the manufacturer’s database if possible.
Reputable dealers in Alang (such as Felicity Marine or Alang Hydraulic) often have in-house hydraulic test benches.3 Never buy a pump from Alang “as-is” without a performance report.
| Test Parameter | What it Reveals |
| Pressure Hold | Can the pump reach and maintain its rated pressure (e.g., 250–350 Bar) without leaking? |
| Flow Rate | Is the LPM (liters per minute) consistent with the manufacturer’s specs at rated RPM? |
| Volumetric Efficiency | A healthy used pump should ideally have >85–90% efficiency. |
| Case Drain Flow | High flow from the case drain port indicates internal wear and “bypassing.” |
If the pump is expensive or critical, ask the seller to open the back cover or dismantle the rotating group in your presence.
Check the Swash Plate & Pistons: Look for “smearing” or scratches on the brass/steel contact surfaces.
Valve Plate: This is the most critical wear part. Any deep grooves or “scoring” on the valve plate will lead to massive efficiency loss.
Bearings: Check for pitting on the rollers. Replacing bearings is a standard part of “reconditioning,” so ensure they are either new or in pristine condition.
Sellers often use the term “reconditioned.” You must clarify exactly what was done:
Seals & O-rings: Were they replaced with original manufacturer (OEM) kits or local cheap alternatives?
Lapping: Was the valve plate and barrel face “lapped” (resurfaced) to ensure a tight seal?
Warranty: While Alang is a “secondary market,” established dealers will often provide a 6-month or 1-year operational warranty. If they refuse any form of guarantee, treat the pump as “scrap value” only.
Class Certificates: Some pumps from newer ships might still have their original Lloyd’s Register, DNV, or ABS certificates. Ask if these are available.
Anti-Corrosion Prep: Ensure the seller drains the test oil and fills the pump with a VCI (Vapor Corrosion Inhibitor) or plugs the ports tightly before shipping to prevent internal rusting during transit.
Fresh Paint: Be wary of a “freshly painted” pump that looks too perfect; it is often used to hide weld repairs or heavy corrosion.
Missing Plugs: If a pump has been sitting in the yard with open ports, assume it is contaminated with sand and salt air.
Unusually Low Price: If a Rexroth A4V pump is being sold at 10% of its market value, it likely has a cracked block or a seized rotating group.
