**1. Is ASTM A335 carbon steel?**
No, ASTM A335 is not carbon steel. It is a specification for **seamless ferritic alloy-steel pipe** designed for high-temperature service. The pipes under this standard are made from alloy steels, typically containing chromium and molybdenum, to provide strength and resistance to oxidation and corrosion at elevated temperatures.
**2. What is the ASTM code for carbon steel pipe?**
There isn't just one single code, as different codes serve different purposes. However, the most common and standard ASTM codes for carbon steel pipe are:
* **ASTM A106:** For seamless carbon steel pipe for high-temperature service.
* **ASTM A53:** For both seamless and welded (ERW) carbon steel pipe, typically for general and low/medium-temperature service.
* **ASTM A333:** For seamless and welded carbon steel pipe intended for low-temperature service.
**3. What is the ASTM A335 grade P11 equivalent to?**
ASTM A335 Grade P11 is equivalent to several international standards, with the most common being:
* **DIN / EN:** 1.7381 or 13CrMo4-5
* **JIS:** STPA 22
* **UNS:** K11597
This grade is a chromium-molybdenum alloy steel with a nominal composition of 1.25% Chromium and 0.5% Molybdenum.
**4. Which is better, seamless or ERW pipe?**
There is no absolute "better" option; the choice depends entirely on the application.
* **Seamless Pipe (SMLS)** is stronger and more reliable at higher pressures and temperatures because it has no weld seam, which is a potential point of weakness. It is the preferred choice for critical applications like high-pressure steam lines, oil and gas exploration, and power plants.
* **ERW Pipe (Electric Resistance Welded)** is more cost-effective and perfectly suitable for most low to medium-pressure applications, such as water pipelines, structural uses, and fencing. Modern ERW processes have significantly improved the quality and reliability of the weld seam.
In summary, choose seamless for critical, high-stress services, and choose ERW for economical, general-purpose applications.
**5. What does ERW stand for?**
ERW stands for **Electric Resistance Welding**. It is a manufacturing process where a pipe is formed from a rolled steel plate and the seam is welded by applying pressure and an electric current that generates heat through resistance.
