Application of the 5 WHYs Problem-Solving Tool for Replacing PVDF with CPVC Material
Akif Ahmadzada, MBA, PMP?, GPM-b? ????
Project Interface Head @ Tecnicas Reunidas | Project Engineering & Management Department
Problem Statement:
Can we replace PVDF pipes and valves with CPVC if PVDF spare materials are unavailable, or must we wait 6 weeks for delivery?
First Why:
Why do we need to replace the PVDF pipes and valves?
Second Why:
Why are we considering using CPVC as a replacement for PVDF?
Third Why:
Why would using CPVC be problematic or a concern?
Fourth Why:
Why are the differences in chemical resistance, mechanical properties, and temperature ranges between PVDF and CPVC important?
Fifth Why:
Why is it critical to use materials (PVDF) that are specifically chosen for this system?
Conclusion:
Based on the Five Whys analysis, the root cause of the problem is the critical need for materials that can safely and effectively handle phosphoric acid. PVDF is selected for a reason, primarily due to its superior properties for this application.
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Recommendation:
It is not advisable to replace PVDF with CPVC due to the potential risks and incompatibility with the chemical and operational conditions. Therefore, it would be safer and more prudent to wait for the 6-week delivery of the correct PVDF materials to ensure the integrity and safety of the system.
Additional Steps:
Supporting Literature:
Chemical Compatibility and Material Properties
PVDF (Polyvinylidene Fluoride):
Chemical Resistance: PVDF is highly resistant to a wide range of chemicals, including acids, bases, and solvents. It is particularly suitable for handling phosphoric acid due to its excellent resistance to chemical corrosion.
Mechanical Properties: PVDF has superior mechanical strength and durability, making it ideal for applications involving high pressure and mechanical stress.
Temperature Range: PVDF can operate effectively in a wide temperature range, typically from -40°C to 150°C, maintaining its properties even at elevated temperatures.
CPVC (Chlorinated Polyvinyl Chloride):
Chemical Resistance: CPVC is resistant to many acids and bases but may not offer the same level of resistance to phosphoric acid as PVDF. Its chemical compatibility must be carefully evaluated for specific applications.
Mechanical Properties: CPVC has good mechanical strength but may not be as robust as PVDF, especially under high-pressure conditions.
Temperature Range: CPVC can typically handle temperatures up to 90°C, which may limit its use in applications requiring higher operational temperatures.
References: Chemical Resistance of PVDF and CPVC: "Chemical Resistance of Thermoplastics" by Plastics Design Library provides comprehensive data on the chemical compatibility of various thermoplastics, including PVDF and CPVC.
Mechanical Properties and Applications: "Polyvinylidene Fluoride (PVDF) Properties and Applications" by Arkema offers detailed information on the mechanical properties and suitable applications of PVDF. "Chlorinated Polyvinyl Chloride (CPVC) Technical Manual" by Lubrizol provides insights into the mechanical properties and uses of CPVC.
Temperature Performance: "Engineering Plastics Handbook" by James Margolis includes detailed sections on the temperature performance and durability of PVDF and CPVC. These references and analysis underline the importance of using the correct material (PVDF) for handling phosphoric acid in a chemical skid system, emphasizing safety, compatibility, and operational efficiency.
Project Engineer | EPC | Commissioning | ENTER Engineering Group
9 个月Recently we faced with similar problem, but the proposed change was to replace CPVC drain pipes to UPVC. After comprehensive analysis recommendation was made to leave CPVC for particular lines which can be affected by exothermal reaction in case of chemical-water mix.