Pump Material Matters – Choosing the Right Alloy for Plant Longevity

Premature pump failure is a plant manager’s headache. Often, the culprit is right in front of you: the material of the pump’s wetted parts. Corrosion is a constant threat, but the right material can protect your equipment. Let’s discuss three common pump materials – 316 stainless steel, Alloy 20, and PVDF (Kynar) – to help you choose wisely for service life, safety, and cost savings.

316 Stainless Steel – Your Reliable All-Rounder

What is it? A common iron-based alloy with chromium and molybdenum for corrosion resistance.

What it offers:

• Handles many diluted acids, caustics, and clean water.
• Easily found in various pump types, including booster pumps.
• Cost-effective compared to specialized alloys.

Things to watch out for:

• Can corrode with high chloride levels (above ~200 ppm).
• Not ideal for strong acids (e.g., >20% sulfuric acid) or hot bleach.

When to use it: For mildly corrosive environments, moderate downtime costs, and general applications like food and beverage wash-down or water pressure boosting.

Alloy 20 – The Acid Specialist

What is it? A nickel-rich stainless alloy made for sulfuric acid.

What it offers:

• Excellent resistance to sulfuric acid across many concentrations.
• Better resistance to phosphoric, nitric, and chloride-bearing acids than 316 steel.
• Available in heavy-duty chemical feed pumps and dosing modules.

Things to watch out for:

• More expensive and longer lead times than 316 steel.
• Not suitable for strong alkalis or hydrofluoric acid.

When to use it: When pump failure means major losses – for example, in fertilizer production or battery acid transfer. The higher cost pays for itself in reduced maintenance and fewer leaks.

PVDF (Kynar) – The Tough Thermoplastic

What is it? A fluoropolymer that resists chemicals without adding metal ions.

What it offers:

• Resistant to most inorganic acids, bleach, chlorides, and bromides.
• Lightweight and non-conductive, great for ultra-pure water or semiconductor chemicals.
• Available in specific thermoplastic pumps and static mixers.

Things to watch out for:

• Temperature limit of ~110°C (230°F); higher temperatures can shorten its life.
• More expensive upfront than PVC or polypropylene.

When to use it: When you must avoid metal contamination or handle chlorinated oxidizers, like bleach dosing in water treatment or ultra-clean water systems.

Making the Right Decision – Key Questions

1. What is the exact fluid composition? Even trace elements matter.
2. What are the temperature and pressure conditions? Heat speeds up corrosion.
3. How much does downtime cost? Higher costs justify premium materials.
4. Are there abrasive solids in the fluid? These cause erosion and corrosion.
5. Are there regulations to meet? Certain industries have specific requirements.

Think About the Whole System

It’s not just the pump. Seals, valves, and pipes need to be compatible. A PVDF pump with carbon steel piping won’t work. Consider the entire system’s materials.

Choosing the right material saves money in the long run. You’ll have fewer leaks, less downtime, and longer equipment life.

Need help deciding? To learn more about choosing the right solutions for your business, contact us today using our website or toll-free number 1-800-367-4180. We can help you determine the best material for your application, whether it’s 316 steel, Alloy 20, PVDF, or something else.