Tuf-Lok™ Pipe Couplings
Ring Grip Series 688

The Tuf-Lok ring grip pipe coupling is a rugged, heavy duty, self-aligning and self-grounded pipe coupling with a high end pull for almost any application where pipe ends need to be connected.

The Tuf-Lok pipe coupling installs quickly, reducing installation costs. Reinstallation is also fast and easy. This makes it ideal for applications where assembly and disassembly are required. Also, with the Tuf-Lok ring grip pipe coupling the pipe ends do not require machining or grooving and never become marred or damaged when making a connection. Pipeline integrity and reuse of the pipe is never questioned or compromised.

Strong and Rugged
The extremely high end pull capability is proof that the Tuf-Lok ring grip pipe coupling is one of the strongest and most rugged available. This toughness is important for many applications, including those with high dynamic loads or applications where the pipeline integrity is extremely important. Even vibration and excessive pipe movement can be accommodated by the Tuf-Lok pipe coupling.

Special Gasket Design
A special design feature built into the gasket of the Tuf-Lok ring grip pipe coupling allows it to accommodate both high pressure and full vacuum pressure conditions. Even high external pressure conditions are accommodated, so the Tuf-Lok pipe coupling is leakproof from the outside as well as the inside. The leakproof connection is maintained even when the Tuf-Lok pipe coupling is completely submerged under water, a feature not always achievable with other pipe couplings.

Cost Saving Feature
A special cost saving feature of the Tuf-Lok ring grip pipe coupling is that it can be installed on just about any kind of metal pipe irrespective of the wall thickness. It can also be used on mild steel, stainless steel, aluminum and most other thick or thin wall pipe.

Easy Assembly
The Tuf-Lok ring grip pipe coupling easily and simply aligns the pipe ends with little effort. The pipe ends are installed tightly together, which reduces the pressure drop and the energy or pumping pressure required to move media through the pipe. In addition, possible buildup of residual material in the pipeline where the butted pipe ends meet is almost totally eliminated. This feature resolves numerous plant process concerns regarding cleaner pipe connections for food, pharmaceutical or dairy applications. Even highly viscous slurries are easily accommodated, without fear of buildup, plugging, gasket interference or sanitary concerns.

Tuf-Lok Ring Grip Pipe Couplings Series 688


  • Self-aligning
  • Installs quickly
  • High end pull
  • High pressure rated
  • Full vacuum rated
  • Reusable
  • Absorbs vibration
  • Rigid
  • Usable on thin or thick wall pipe
  • Low cost
  • Externally leakproof
  • Self grounding
  • Smooth internal connection
  • Every coupling a union


  • Covers
    - Mild steel, zinc plated
    - Stainless steel

  • Rings
    - Mild steel
    - Stainless steel
    - Aluminum

  • Custom gaskets
    - EPDM
    - Buna-N
    - Silicone
    - Fluoroelastomer
    - Others

  • High temperature design to
    350° F (176° C)

Zinc Plated
Stainless Steel

Tuf-Lok Ring Grip Pipe Couplings       
Series 688  

Dimensions and Specifications

Tuf-Lok Couplings
Bulletin 150402-1
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