We were approached by a major international valve manufacturer that required new material to give increased life and performance to its range of conventional PTFE materials, enabling them to remain a market leader in its sector.
The project remit was to provide a material to equal or outperform competitor’s options. The material would need to allow our client’s range of butterfly valves to operate at increased pressures across a wider temperature range, and must not require any redesign of any of the existing valve to accommodate this.
FDA approval for the material was also required for food industry applications. If achieved, it would allow a single material solution to be used across all industry sectors and eliminate the need to stock different materials for different applications – cutting inventory quantity and cost. The comparative component cost was also a major factor that had to be considered.
HOW WE SET ABOUT THE TASK
From the information supplied by the client, we studied the positive and negative aspects of all the current materials being used in the valve seat application. Our technical team was then able to use this to define specific material physical property requirements, which would have to be achieved to meet the desired valve performance.
It was clear that the traditional route of adding different filler materials to PTFE would not give the desired results due to material porosity and the low gas permeation required. Chemical resistance was also a key consideration.
Working with all of these factors, we developed a special modified PTFE grade, which offered excellent mechanical characteristics including:
- Extremely low gas permeability
- Increased compressive strength
- Substantially lower deformation under load
- Better compression stress relaxation
- Increased modulus of elasticity
- Denser polymer structure
One of the biggest advantages of this material over conventional PTFE compounds was that the excellent mechanical property improvements were even greater at elevated temperatures. Add to this that the material compound qualified for FDA approval, and we were confident we had a solution.
THE RESULTS
We supplied a sample batch of seats for evaluation and testing in the most common 6” size of valve, which proved successful immediately. However, installation in larger size valves caused some problems. The material behaved differently to its predecessor and required new processes to be developed within our customer’s manufacturing plant. Committed to completing our task as solution providers, our technical team made numerous trips to the USA to help the engineers who were building the valves to understand the characteristics of the new fluoropolymer material.
Now AF614 Ultimate is the standard material used by our customer within their complete range of butterfly valves from 2” – 36” diameter.
