Plastic piping characteristics: Plastic pipe is lightweight and corrosion-resistant; is it also typically resistant to many chemicals, contrary to the claim that plastics are “not resistant to chemicals”?

Question

Accepted Answer

Introduction / Context: Choosing pipe materials requires understanding chemical compatibility. Plastics such as PVC, CPVC, PP, PE, and PVDF are widely used precisely because they resist corrosion and a broad range of chemicals. The statement that plastic pipe is “typically not resistant to chemicals” is misleading. This question corrects that misconception for design and specification work. Given Data / Assumptions: Applications include water treatment, chemical processing, drainage, and venting. Chemical resistance depends on resin type, concentration, temperature, and exposure time. Manufacturers publish compatibility charts for specific chemicals and operating ranges. Concept / Approach: Plastics are inert to many aqueous solutions, salts, and acids; some resist bases and solvents as well. For example, PVC has broad acid/alkali resistance; PVDF resists many solvents; PP excels in many corrosive environments. Limitations exist (e.g., PVC and certain solvents, oxidizing agents at elevated temperatures), but the generalization that plastics lack chemical resistance is false. Proper selection ensures long life and low maintenance compared with many metals. Step-by-Step Solution: Identify the chemical, concentration, temperature, and pressure.Consult chemical resistance charts for candidate plastics.Select pipe/resin and joining method rated for the conditions.Document limitations and installation requirements on drawings/specifications. Verification / Alternative check: Field performance in harsh environments (e.g., acid waste systems with CPVC/PVDF) confirms plastics’ suitability when matched correctly to the chemical service. Why Other Options Are Wrong: Restricting resistance to cold water, lined pipe, or specific pH ranges oversimplifies the varied capabilities across plastic families. Common Pitfalls: Ignoring temperature derating; assuming all plastics behave the same; using incompatible cement/adhesives; neglecting permeation for certain gases/liquids. Final Answer: Incorrect

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