When purchasing steel, you may come across the term Pickled and Oiled (P&O). This finishing process improves the surface quality and corrosion resistance of hot-rolled steel, making it more suitable for fabrication, welding, and painting.
But what exactly is pickling and oiling, and why do customers specifically request it? In this blog, we’ll break down what P&O is, how it works, and its benefits for different industries.
What Is Pickling and Oiling (P&O)?
📌 Pickling and oiling is a process that removes mill scale and applies a protective oil coating to hot-rolled steel.
🔎 Step-by-Step Process:
1️⃣ Pickling – The steel is dipped in an acid solution (usually hydrochloric or sulfuric acid) to remove mill scale, rust, and impurities.
2️⃣ Rinsing & Neutralization – The acid is removed to prevent further chemical reactions.
3️⃣ Oiling – A thin layer of protective oil is applied to prevent rust before the steel is used.
💡 Why It’s Needed: Hot-rolled steel develops mill scale, a rough, oxidized layer formed during high-temperature rolling. Pickling removes this scale, while oiling prevents rust.
Why Do Customers Request P&O Steel?
Many manufacturers and fabricators prefer pickled and oiled steel because it offers better surface quality and workability compared to standard hot-rolled steel.
🔹 1. Improved Surface Quality
✔ Smoother than standard hot-rolled steel.
✔ Easier to paint, powder coat, or apply coatings.
✔ Reduces surface defects in final products.
💡 Best For: Automotive parts, appliances, and exposed metal components.
🔹 2. Better Weldability
✔ Removes mill scale, which can cause welding defects.
✔ Reduces spatter and improves weld penetration.
💡 Best For: Structural steel, pipes, and pressure vessels.
🔹 3. Easier Forming & Fabrication
✔ Uniform surface allows better bending, stamping, and machining.
✔ Reduced wear on tools and dies compared to untreated hot-rolled steel.
💡 Best For: Metal stamping, sheet metal fabrication, and tubing.
🔹 4. Corrosion Protection
✔ The oil coating prevents rust during storage and transportation.
✔ Helps keep the steel in good condition before further processing.
💡 Best For: Warehouses, distributors, and manufacturers who need clean, rust-free steel.
Industries That Use P&O Steel
📌 Pickled and oiled steel is widely used in industries where surface quality and processability are important.
IndustryCommon Uses of P&O Steel
AutomotiveFrames, brackets, body panels
ManufacturingStamped parts, enclosures, appliances
ConstructionStructural components, bridges, guardrails
AgricultureEquipment frames, tubing, support structures
Pipe & TubingWelded steel pipes, mechanical tubing
💡 Pro Tip: If your project involves welding, painting, or forming, P&O steel is a better choice than untreated hot-rolled steel.
How P&O Compares to Other Steel Finishes
📌 How does pickled and oiled steel compare to other steel types?
Steel TypeSurface FinishBest For
Hot-Rolled Steel (HR)Rough, mill scaleStructural, heavy-duty applications
Pickled & Oiled (P&O)Smooth, rust-protectedWelded, painted, or formed parts
Cold-Rolled Steel (CR)Very smooth, precise tolerancesHigh-precision applications, aesthetic use
💡 Key Difference: Cold-rolled steel is smoother and more precise but costs more. P&O steel is a great middle option—better than hot-rolled but more affordable than cold-rolled.
Final Thoughts: Why Choose Pickled and Oiled Steel?
📌 Pickling and oiling improves hot-rolled steel by removing mill scale and adding rust protection, making it ideal for welding, painting, and forming.
💡 Key Takeaways:
✅ P&O steel has a smoother, cleaner surface than untreated hot-rolled steel.
✅ It’s easier to weld, bend, and machine.
✅ The oil coating helps prevent rust before fabrication.
✅ Common in automotive, construction, manufacturing, and tubing applications.
🚀 Need high-quality pickled and oiled steel for your next project? Let’s talk!
