1. **Which is better, ERW or EFW?**
Neither is universally "better" – it depends on the application. ERW (Electric Resistance Welded) pipe is generally more cost-effective, has tighter dimensional tolerances, and is suitable for many standard pressure and structural applications. EFW (Electric Fusion Welded - typically Submerged Arc Welded, SAW pipe) is used for thicker walls, larger diameters, and higher pressure/vital service where a fusion weld offers advantages. ERW is often preferred for common sizes and pressures, while EFW is chosen for heavy-wall, large-diameter, or critical service pipes.
2. **What grade is ERW?**
ERW pipe isn't a single grade. It's manufactured to various material grades defined in standards like ASTM or API. Common grades for carbon steel ERW pipe include ASTM A53 Grade A or B, ASTM A135, ASTM A500 Grade A, B, C, or ASTM A787 for mechanical tubing. API 5L ERW pipes come in grades like B, X42, X52, X60, etc. The specific grade depends on the required strength and chemical composition.
3. **What is ERW pipe?**
ERW (Electric Resistance Welded) pipe is made by forming a flat steel strip (skelp) into a cylindrical shape. The seam is then welded by passing a high-frequency electrical current through the edges, causing them to heat up and fuse together under pressure without adding filler metal. This creates a strong, continuous weld along the pipe's length.
4. **How many grades are in SS pipe?**
Stainless steel pipes come in *numerous* grades, categorized into series like 200, 300, 400, Duplex, etc. Each series contains multiple specific grades (e.g., 304/304L, 316/316L, 430, 2205) with different compositions and properties. There are easily over 50 commonly used grades and hundreds more specialized alloys, making it impractical to state a single total number.
5. **Is ERW steel strong?**
Yes, ERW steel pipe can be very strong. Modern high-frequency ERW (HF-ERW) produces high-quality welds. ERW pipes are manufactured to specific ASTM or API material grades (like A53 Grade B or API 5L X52) that define their minimum yield and tensile strength requirements. While seamless pipe may be preferred for the most extreme pressures or critical applications, ERW pipe offers excellent strength for a vast range of uses in construction, oil & gas (lower pressure lines), water transmission, and structural applications.
