1. **EN 10217-7 material:**
EN 10217-7 specifies requirements for **welded stainless steel tubes** for pressure purposes. The materials covered are **austenitic** and **austenitic-ferritic (duplex) stainless steels**. Common grades include 1.4301 (304), 1.4401 (316), 1.4462 (2205), etc. Tubes are delivered in the heat-treated condition and are suitable for elevated temperatures and corrosive environments.
2. **Size of EN 10217-2 pipe:**
EN 10217-2 covers **welded non-alloy and alloy steel tubes with specified elevated temperature properties**. Sizes are defined by **outside diameter (OD)** and **wall thickness**, conforming to the **EN 10216 series** dimensional standards. Common OD ranges are **21.3 mm to 1219 mm** (DN 15 to DN 1200). Exact dimensions depend on the specific tube designation (e.g., diameter/thickness combination).
3. **Difference between HDPE and steel pipe:**
| **Property** | **HDPE Pipe** | **Steel Pipe** |
| **Material** | High-Density Polyethylene (thermoplastic) | Carbon/alloy/stainless steel (metallic) |
| **Corrosion Resistance** | Excellent (immune to electrochemical corrosion) | Prone to rust/chemical corrosion (requires coatings) |
| **Weight** | Lightweight (density ~0.95 g/cm³) | Heavy (density ~7.85 g/cm³) |
| **Installation** | Flexible; fusion-welded joints | Rigid; threaded/welded/flanged joints |
| **Max. Temperature** | Typically ≤60°C (140°F) | Can exceed 500°C (932°F) |
| **Pressure Rating** | Lower (suited for medium/low pressure) | Higher (handles high-pressure systems) |
| **Applications** | Water/gas distribution, drainage | Oil/gas, high-temp/pressure, structural |
4. **Wall thickness of EN 10217-1:**
EN 10217-1 covers **welded non-alloy steel tubes with specified room temperature properties**. Wall thickness is **not a fixed value** but depends on:
- **Tube outside diameter (OD)**
- **Designation** (e.g., T1, T2, T3, T4 defining pressure classes)
Thicknesses range from **≈1.8 mm (small OD)** to **>40 mm (large OD)**. Specific values are tabulated in the standard based on OD and designation.
5. **Minimum recommended wall thickness:**
The minimum wall thickness depends on:
- **Design pressure** and **temperature**
- **Pipe material strength** (yield/tensile)
- **Safety factors/codes** (e.g., ASME B31.3, EN 13480)
- **Corrosion/erosion allowance**
A general formula is:
\[ t_{min} = \frac{P \cdot D}{2 \cdot (S \cdot E + P \cdot Y)} + A \]
Where:
- \( P \): Design pressure
- \( D \): Pipe OD
- \( S \): Allowable stress
- \( E \): Weld joint factor
- \( Y \): Material coefficient
- \( A \): Corrosion allowance
**Never use a thickness below code-calculated \( t_{min} \).** Industry standards (e.g., ASME B36.10M) also provide standardized thickness schedules (e.g., SCH 40).
For precise values in projects, consult the specific EN 10217 part, material grade, and applicable design codes.
