EN10217-1 P195GH Spiral Submerged Arc Welding Pipe

EN 10217-1 P195GH Spiral Submerged Arc Welding Pipe

This is a specialized pressure pipe grade designed for elevated temperature service. Let's break down the technical details comprehensively.

1. Standard & Manufacturing Process

Standard: EN 10217-1 (but note special designation)

Designation: P195GH - The "GH" suffix is critical

Process: Spiral Submerged Arc Welding (SSAW/HSAW)

Important: P195GH is actually specified in EN 10216-2 (seamless) and EN 10217-2 (welded) for high-temperature applications. Its inclusion in EN 10217-1 orders would require special agreement.

2. Steel Grade: P195GH

P195: Minimum yield strength = 195 MPa at room temperature

GH: "G" = High temperature grade, "H" = Creep-resistant properties

Primary Application: Pressure equipment at elevated temperatures

3. Chemical Composition

Typical composition limits for high-temperature service:

Note: Exact composition varies by manufacturer and specification agreement.

4. Mechanical Properties

At Room Temperature:

Yield Strength (ReH): ≥ 195 MPa

Tensile Strength (Rm): 320–440 MPa

Elongation (A): ≥ 25% (min)

Impact Energy: Typically ≥ 27J at 20°C

At Elevated Temperatures:

Creep Strength: Designed for service up to 300–350°C

Proof Strength at Temperature:

100°C: ~185 MPa

200°C: ~165 MPa

300°C: ~140 MPa

350°C: ~125 MPa

5. Manufacturing Specifics for SSAW

Special Considerations:

Steel Making:

Fine grain practice mandatory

Vacuum degassing typically required

Low sulfur essential for high-temperature ductility

Forming & Welding:

Strict preheat control (minimum 100°C)

Low heat input welding procedures

Post Weld Heat Treatment (PWHT) often required

Temperature: 580–620°C

Time: 1–2 minutes per mm thickness

Heat Treatment:

Normalizing of plates before forming (typical)

Stress relieving after welding (mandatory for thickness > 15mm)

6. Testing Requirements

Mandatory Tests (Enhanced):

High-Temperature Tensile Tests:

At maximum design temperature

Typically at 350°C

Impact Tests:

Room temperature mandatory

Often additional tests at 0°C or -10°C

Non-Destructive Testing:

100% Ultrasonic Testing of weld and parent metal

Radiographic Testing of start/stop weld areas

Hardness Testing across weldment

Hydrostatic Test:

Higher safety factors for high-temperature design

Test pressure = 1.5 × design pressure at room temperature

7. Dimensions & Tolerances

Diameter Range: Typically 219mm (8") to 2000mm (78")

Wall Thickness: 5mm to 40mm (thicker than standard grades)

Special Tolerance Classes: Often Class C or special tolerances

Surface Finish: Superior to standard grades (lower roughness)

8. Applications

Primary Industries:

Power Generation:

Boiler tubes (low-pressure sections)

Steam piping (saturated steam)

Feedwater lines

Heat exchanger tubing

Petrochemical:

Process piping (300–350°C)

Heat transfer lines

Catalyst carrier lines

Industrial:

Hot oil systems

Thermal fluid piping

Waste heat recovery systems

Typical Service Conditions:

Temperature: Up to 350°C continuous

Pressure: Up to 50 bar (depending on temperature)

Cyclic Service: Suitable for thermal cycling applications

9. Welding & Fabrication

Critical Requirements:

Filler Metals:

Must match elevated temperature properties

Typically AWS ER70S-6 or equivalent with specified analysis

Welding Procedures:

WPS qualification at both room and elevated temperatures

PWHT mandatory for thickness > 10mm

Interpass temperature control: 150–250°C

Post-Weld Treatment:

Stress relieving: 580–620°C

Slow cooling rate: ≤ 100°C/hour

10. Supplementary Requirements

Typically specified for P195GH:

11. Comparison with Other Grades

12. Design Considerations

Pressure Design:

Design Code: EN 13480-3 (Metallic industrial piping)

Allowable Stress: Based on minimum of:

Rm/2.4 at room temperature

Rp0.2t/1.5 at design temperature

Rm,t/2.4 at design temperature

Creep rupture strength considerations

Thermal Expansion:

Coefficient: 12.5 × 10⁻⁶/°C (20–300°C)

Allowance for thermal stresses in design

13. Coating & Protection

High-Temperature Considerations:

External:

Heat-resistant paints (silicone-based, up to 400°C)

Hot-dip galvanizing NOT recommended (zinc embrittlement > 200°C)

Weathering steel option for unpainted service

Internal:

Often uncoated for process compatibility

Passivation for certain services

High-temperature linings for specific applications

14. Equivalent Grades