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Colmonoy 6 Hard-Surfaced Plungers (4″ – 5″) for High-Pressure Hydraulic Fracturing

In the punishing environment of hydraulic fracturing, a plunger is only as good as its bond. Our Flame Sprayed Nickel-Based Alloy Plungers set the standard for reliability in 4″, 4.5″, and 5″ fluid ends.    

Technical Specifications

  • Coating Material: Nickel-Based Alloy (Ni-Cr-B-Si)
  • Surface Hardness: 58 - 62 HRC
  • Surface Finish: Ra 2 - 4 µin (Mirror Polish)
  • Core Material: AISI 1045 / 4140 Carbon Steel
  • Porosity: Near Zero (after fusing)
  • Available Sizes: 4.0
  • Compatible Pumps: SPM®, Gardner Denver®, FMC®, MSI®
  • Manufacturing Process: Flame Spray & Fuse (Thermal Spray)

Applications

  • Compatible Pumps: SPM®, Gardner Denver®, FMC®, MSI®

Colmonoy 6 Hard-Surfaced Plungers (4″ – 5″) for High-Pressure Hydraulic Fracturing

1. Executive Summary: The Industry Benchmark for Durability

In the world of high-pressure hydraulic fracturing, Colmonoy® 6 is synonymous with performance. It is the material standard against which all other hard-facing alloys are measured.

Our Colmonoy 6 Hard-Surfaced Plungers bring this legendary durability to your fluid end fleet. Specifically engineered for the demanding 4.0″, 4.5″, and 5.0″ bore sizes found in modern 2500HP+ frac pumps, these plungers feature a premium Nickel-Chrome-Boron-Silicon overlay. Applied via a rigorous Spray & Fuse process, they deliver a guaranteed surface hardness of 60 HRC and a friction coefficient so low it drastically extends packing life. This is the premium choice for fleets that refuse to compromise on quality.

2. Technical Deep Dive: The Chemistry of Colmonoy 6

Why is “No. 6” the Standard?

Colmonoy 6 (and its chemically equivalent Ni-Cr-B-Si alloys) offers a unique tribological balance that is perfect for fracking:

  • The Matrix: A Nickel-Chromium matrix provides excellent ductility and extreme corrosion resistance against H2S and Hydrochloric Acid.

  • The Hard Phase: Chromium Carbides and Chromium Borides precipitate throughout the matrix. These microscopic hard particles (harder than quartz sand) provide the abrasive wear resistance needed to handle proppants.

  • Low Friction: The presence of Boron and Silicon creates a “self-lubricating” effect. Even under high side-loads, a Colmonoy 6 plunger slides smoothly against the packing, reducing heat generation.

Spray & Fuse: A Metallurgical Bond

We do not rely on mechanical bonding. Our Colmonoy 6 coating is applied using the Thermal Spray and Fuse technique:

  1. Spray: The alloy powder is sprayed onto the steel core.

  2. Fuse: The plunger is heated to the alloy’s melting range (~1,900°F).

  3. Result: The coating wets the substrate and diffuses into the steel, creating a Metallurgical Bond (>60,000 PSI strength). This ensures the hard-facing will never delaminate, flake, or spall, even under the violent pulsation of a 15,000 PSI pump stroke.

3. Comprehensive Specifications

Technical Parameter Specification Notes
Hard-Facing Material Colmonoy® 6 (or AWS A5.13 NiCr-B) Nickel-Based Self-Fluxing Alloy
Coating Process Spray & Fuse (Spraywelding) 100% Dense, Non-Porous
Surface Hardness 58 – 62 HRC (Rockwell C) The Sweet Spot for Fracking
Surface Finish Ra 2 – 4 µin (Mirror Polish) Best for Packing Life
Friction Coefficient Low (Self-Lubricating properties) Reduces Heat Check
Corrosion Resistance Excellent (Acids & Chlorides) Superior to Chrome Plating
Core Material AISI 1045 / 4140 Carbon Steel High Yield Strength
Dimensional Sizes 4.00″, 4.50″, 5.00″ Standard Frac Sizes

4. Size Range & Pump Compatibility

We stock Colmonoy 6 plungers for the industry’s heaviest hitters. Whether you are running high-pressure completions or high-rate zipper fracs, we have the size you need.

  • 4.0″ Plungers (High Pressure):

    • Ideal For: Deep well fracturing requiring 13,000+ PSI.

    • Fits: SPM® QWS 2500, Gardner Denver® GD-2500, FMC® 2400.

  • 4.5″ Plungers (Standard Frac):

    • Ideal For: The most common configuration for 2250HP / 2500HP pumps.

    • Fits: SPM® TWS 2250, QWS 2700, GD-3000.

  • 5.0″ Plungers (High Rate):

    • Ideal For: Maximizing BPM (Barrels Per Minute) at lower pump RPMs to reduce fatigue.

    • Fits: SPM® QWS 2500 XL, GD-3000.

5. Operational Benefits (Why Pay for Premium?)

1. Acidizing Capability

Many frac fleets now double as acid crews. Standard carbon steel or iron-based coatings will pit and corrode when exposed to 15% HCl.

  • The Benefit: The high Nickel content in Colmonoy 6 makes it virtually immune to acid attack, allowing you to use the same plungers for Acidizing and Fracking.

2. Packing Protection

Packing is expensive; changing it is time-consuming.

  • The Benefit: The inherent lubricity and ultra-fine finish (Ra < 4) of our fused coating reduce friction drag. Field data shows Colmonoy 6 plungers can extend packing life by 30% or more compared to rougher spray coatings.

3. Regrind Value

Our Spray & Fuse process applies a thick overlay (typically 0.040″ – 0.060″).

  • The Benefit: When the plunger eventually shows wear, it has enough material to be ground down to an undersize spec (e.g., -0.010″), giving you a “second life” for a fraction of the cost of a new plunger.

6. Quality Assurance

  • Hardness Scan: Every plunger is tested at multiple points to ensure consistent 60 HRC hardness along the entire stroke length.

  • Dye Penetrant / UT: Verified to be free of surface cracks or subsurface delamination.

  • Dimensional Certification: OD tolerances held to strict OEM standards.