Screw Pump Seal Failure: It’s Usually Not the Seal—But the Operating Conditions Behind It

Screw Pump Seal Failure: It’s Usually Not the Seal—But the Operating Conditions Behind It

In industries such as wastewater treatment, oil transfer, and chemical processing, screw pumps are widely used for their stable flow and ability to handle viscous media.

However, a common issue many sites face is:

👉 Seal leakage after a period of operation

Even after replacing the seal, the problem often returns quickly.

👉 Reference analysis:

https://www.scpv.cn/news/874.html

From real engineering experience, this is rarely a “seal quality issue.” More often, it is:

👉 Operating conditions continuously damaging the seal

1. Key point: seal failure is a result, not the root cause

For a seal (mechanical seal or packing) to work properly, it requires:

Proper lubrication

Stable temperature

Balanced pressure

Consistent mechanical alignment

If any of these conditions are compromised:

👉 Seal failure becomes inevitable

2. Cause #1: Dry running (most critical factor)

When the pump operates under:

Insufficient suction

Startup without priming

Interrupted fluid supply

It leads to:

👉 Lack of lubrication at the seal faces

Result:

Rapid temperature rise

Seal face damage or burn

This is one of the most common causes of sudden seal failure.

3. Cause #2: Abrasive particles in the fluid

Screw pumps are often used with:

Slurries

Fluids containing solids

Contaminated liquids

When particles enter the seal area:

👉 They cause abrasion

Leading to:

Scratched sealing surfaces

Increased leakage

4. Cause #3: Temperature and fluid property changes

Operating conditions such as:

High temperature

Rapid temperature fluctuations

Corrosive media

can cause:

👉 Degradation of sealing materials

Typical effects:

Loss of elasticity

Deformation

Cracking

5. Cause #4: Pressure fluctuations

If the system experiences:

Sudden pressure spikes

Frequent pressure variation

It leads to:

👉 Unstable loading on the seal

Consequences:

Seal face separation

Accelerated wear

6. Cause #5: Cavitation, suction issues, or overpressure

Common system problems include:

Insufficient suction → dry running or cavitation

Blocked discharge → overpressure

These conditions cause:

👉 Shock loads and temperature rise

Which ultimately:

👉 Damage the seal structure

7. Cause #6: Misalignment and improper installation

Many early failures are linked to:

Shaft misalignment

Incorrect installation

Improper tightening

These result in:

👉 Uneven seal face contact

And lead to:

👉 Premature leakage

8. Cause #7: Wear and internal clearance changes

Over time:

Screw wear

Stator wear

Shaft sleeve wear

will cause:

👉 Increased internal clearance

Resulting in:

Higher internal leakage

Increased load on the seal

9. A key insight: most issues come from the system

A common mistake in many plants is:

❌ Replacing the seal repeatedly

Without addressing:

Operating conditions

System design

Fluid characteristics

In reality:

👉 The seal is often the “victim,” not the cause

10. Practical engineering recommendations

To reduce seal failures:

Ensure proper priming before startup

Control fluid cleanliness or install filtration

Maintain stable temperature and viscosity

Avoid frequent start-stop cycles

Ensure proper alignment and installation

Experienced manufacturers like Shanghai Shangcheng Pump & Valve typically consider these factors during system design, minimizing long-term risks.

Conclusion

Seal failure in screw pumps is not a single-component issue. It is:

👉 The result of combined effects from system, fluid, and operating conditions

If only the seal is replaced without addressing root causes:

👉 The problem will keep recurring

Reliable operation depends not on how “strong” the seal is, but on:

👉 Whether the entire system operates within safe conditions