1. **What is the carbon content of steel pipe?**
* The carbon content of standard **carbon steel pipe** typically ranges from **0.05% to 1.0%**. Most common grades fall between 0.10% and 0.30%. Higher carbon increases strength but reduces weldability and ductility.
2. **What is the composition of 304 stainless steel pipe?**
* The typical chemical composition range (by weight) for **304 stainless steel pipe** is:
* **Chromium (Cr):** 18.0% - 20.0%
* **Nickel (Ni):** 8.0% - 10.5%
* **Manganese (Mn):** ≤ 2.0%
* **Silicon (Si):** ≤ 1.0%
* **Carbon (C):** ≤ 0.08%
* **Phosphorus (P):** ≤ 0.045%
* **Sulfur (S):** ≤ 0.030%
* **Iron (Fe):** Balance (~67-71%)
3. **What is the composition of stainless steel pipe?**
* "Stainless steel pipe" is a broad term. All stainless steels must contain a **minimum of 10.5% Chromium (Cr)** for corrosion resistance. Beyond that, composition varies *significantly* by type and grade:
* **Austenitic (e.g., 304, 316):** High Chromium (16-26%), Nickel (6-22%), may contain Molybdenum (Mo), low Carbon. Most common type for piping.
* **Ferritic (e.g., 430):** High Chromium (10.5-27%), very low Carbon, little or no Nickel.
* **Martensitic (e.g., 410):** Moderate Chromium (11.5-18%), higher Carbon (0.1-1.2%), low Nickel.
* **Duplex (e.g., 2205):** High Chromium (21-23%), moderate Nickel (4.5-6.5%), Molybdenum (2.5-3.5%), Nitrogen (N).
* Key elements besides Cr & Ni often include: Molybdenum (Mo), Nitrogen (N), Manganese (Mn), Silicon (Si), Carbon (C), with limits on Phosphorus (P) and Sulfur (S).
4. **What is the difference between 304 and 316 piping?**
* The primary difference is the addition of **Molybdenum (Mo)** in 316 stainless steel:
* **304:** Contains **no Molybdenum** (Mo ≤ 0.10%).
* **316:** Contains **2.0% - 3.0% Molybdenum**.
* **Consequence of Molybdenum:**
* **Significantly improved corrosion resistance**, especially against chlorides, acids (like sulfuric), and saltwater (pitting/crevice corrosion). 316 is much better suited for marine or chemical processing environments.
* Slightly higher Nickel content (10-14% vs 8-10.5% in 304) also contributes to better corrosion resistance and formability.
* **Cost:** 316 is generally more expensive than 304 due to the Molybdenum and extra Nickel.
5. **What is the composition of ASTM 304?**
* "ASTM 304" refers to the chemical composition requirements specified in ASTM material standards (like A312 for pipe or A240 for plate/sheet) for grade 304 stainless steel. It is identical to the standard 304 composition given in answer 2:
* **Chromium (Cr):** 18.0% - 20.0%
* **Nickel (Ni):** 8.0% - 10.5%
* **Manganese (Mn):** ≤ 2.0%
* **Silicon (Si):** ≤ 0.75% (A240) / ≤ 1.0% (A312)
* **Carbon (C):** ≤ 0.08%
* **Phosphorus (P):** ≤ 0.045%
* **Sulfur (S):** ≤ 0.030%
* **Iron (Fe):** Balance
