SST Series Twin Screw Pump

Model: SST Series Pumps

The SPEW SST Series Twin Screw Pump is a heavy-duty rotary positive displacement pump designed for continuous, stable, and efficient transfer of fluids across an extremely wide viscosity range. The pump is specifically engineered to handle low-viscosity, non-lubricating liquids as well as very high-viscosity and shear-sensitive fluids, making it suitable for a broad spectrum of industrial applications.

Unlike centrifugal pumps, the SST pump delivers predictable, pressure-independent flow, ensuring stable operation even under fluctuating system pressures. The pump utilizes two synchronized, non-contacting screws rotating in opposite directions inside a precision-machined casing. Fluid is transported axially in sealed cavities from suction to discharge with minimal internal turbulence, negligible pulsation, and low shear stress.

External timing gears ensure accurate synchronization of the screws, eliminating metal-to-metal contact and reducing wear. Bearings are positioned outside the pumped fluid zone, allowing the SST pump to operate reliably in high-temperature, abrasive, or contaminated services. The design supports bi-directional operation, self-priming capability, and tolerance to entrained gas, making it ideal for terminals, marine duty, oil & gas installations, and demanding process applications.

Features

1. Non-Contacting Twin Screw Design

Feature:
Two precision-machined screws rotate without physical contact, synchronized by external timing gears.

Benefit:

  • Eliminates internal wear between rotors
  • Allows handling of low-lubricity fluids
  • Ensures long service life and high reliability
  • Maintains consistent performance over time

 

2. Wide Viscosity Handling Capability

Feature:
Capable of pumping fluids from 1 cSt up to 3,000,000 cSt.

Benefit:

  • One pump design covers multiple applications
  • Reduces need for multiple pump types
  • Excellent for lubricants, bitumen, additives, polymers, and heavy fuels

 

3. Near Pulsation-Free Flow

Feature:
Axial displacement of fluid through continuous cavities.

Benefit:

  • Smooth and steady flow
  • Reduced vibration and noise
  • Ideal for metering, blending, and circulation duties
  • Protects downstream instruments and piping

 

4. Bi-Directional Operation

Feature:
Pump can operate in both rotational directions without modification.

Benefit:

  • Suitable for loading/unloading operations
  • Simplifies piping layouts
  • Flexible system design for terminals and marine installations

 

5. Self-Priming Capability

Feature:
Positive displacement principle with excellent suction characteristics.

Benefit:

  • Capable of lifting fluid from lower levels
  • Reliable operation during start-up and tank stripping
  • Reduced need for auxiliary priming systems

6. Low Shear & Gentle Product Handling

Feature:
Minimal internal turbulence and controlled cavity movement.

Benefit:

  • Preserves product integrity
  • Suitable for shear-sensitive fluids
  • Prevents emulsification or degradation of product

7. External Bearings & Gearbox

Feature:
Bearings and timing gears are located outside the pumped fluid.

Benefit:

  • Enhanced reliability and serviceability
  • Bearings protected from corrosive or abrasive media
  • Easy inspection and maintenance

8. Flexible Sealing Arrangements

Feature:
Supports single, double, and cartridge mechanical seals with API flush plans.

Benefit:

  • Suitable for hazardous, toxic, or high-temperature fluids
  • Meets emission control and safety requirements
  • Compatible with API Plan 11, 52, 53 systems

9. VFD Compatibility

Feature:
Linear relationship between speed and flow.

Benefit:

  • Precise flow control
  • Energy-efficient operation
  • Wide turndown capability without performance loss

Structures

1. Pump Structure Type

  • Type: Horizontal Twin Screw Pump
  • Design: Rotary Positive Displacement
  • Shaft Arrangement: Parallel synchronized shafts
  • Flow Direction: Axial
  • Operation: Continuous duty, bi-directional

 

2. Casing Structure

  • Rigid, pressure-rated pump casing
  • Precision-machined internal profiles
  • Designed to withstand high pressure and temperature
  • Flanged suction and discharge nozzles (ANSI / DIN / JIS)

 

3. Rotor & Shaft Structure

  • High-strength alloy steel rotors
  • Optimized screw profile for volumetric efficiency
  • Accurate rotor alignment via timing gears
  • Shaft design accommodates high torque and hydraulic loads

 

4. Bearing & Gear Arrangement

  • External antifriction bearings
  • Hardened and ground timing gears
  • Oil bath lubrication as standard
  • Optional forced lubrication for severe service

5. Sealing Structure

  • Seal chamber designed for mechanical seals
  • Single or double seal configurations
  • Cartridge seal compatibility
  • Optional packed gland for specific services

 

6. Mounting Structure

  • Baseplate-mounted pump and driver
  • Flexible coupling with guard
  • Suitable for motor, diesel engine, or hydraulic drive
  • Designed for easy alignment and installation

 

7. Protection & Auxiliary Structures

  • Integral or external relief valve options
  • Heating jacket for high-viscosity or solidifying fluids
  • Temperature and pressure monitoring provisions
  • Optional insulation and tracing connections