1. **Is ERW carbon steel?**
Yes, ERW (Electric Resistance Welded) pipe is primarily made from **carbon steel**. The ERW process describes how the seam is welded, not the material. Carbon steel is the most common base material for ERW pipes.
2. **Why not use galvanized pipe?**
Galvanized pipe is often avoided for potable water plumbing today primarily due to **corrosion and scale buildup** over time (leading to reduced water pressure and flow), potential **lead contamination** from the zinc coating (especially in older pipes), and **limited lifespan** compared to alternatives like copper, PEX, or CPVC. It's also generally **more expensive** and **harder to work with** than modern plastic pipes.
3. **When did we stop using galvanized pipes?**
The widespread use of galvanized pipes for *new* potable water plumbing in homes **primarily stopped in the 1970s to 1980s**, coinciding with the rise of copper and later plastic (CPVC, PEX) pipes. Many building codes restricted or prohibited new galvanized water lines by the 1980s due to corrosion and lead concerns, though it remained in use for other applications (like gas lines or structural uses) and existing systems persisted.
4. **Is galvanized pipe rust proof?**
No, galvanized pipe is **not rust-proof**. It is **rust-resistant**. The zinc coating provides a sacrificial barrier that corrodes *before* the underlying steel rusts, significantly extending its lifespan. However, the zinc coating eventually degrades (especially in acidic, basic, or aggressive water/soil), allowing the steel to rust and leak.
5. **Why use galvanized steel over stainless steel?**
Galvanized steel is primarily chosen over stainless steel due to **significantly lower cost**. It offers good corrosion resistance for many non-critical applications (like fencing, handrails, structural supports, outdoor frames, some agricultural uses) where the extreme corrosion resistance of stainless steel is unnecessary. It's also generally **easier to fabricate and weld** (with precautions for zinc fumes) than some grades of stainless steel.
