EN10217-1 P265GH Spiral Submerged Arc Welding Pipe

EN 10217-1 P265GH Spiral Submerged Arc Welding Pipe

Important Note: P265GH is primarily specified in EN 10217-2 for welded tubes at elevated temperatures, not EN 10217-1. However, it can be manufactured as SSAW pipe with special agreement and additional requirements.

1. Standard & Classification

Correct Standard: EN 10217-2 - Welded steel tubes for pressure purposes at elevated temperatures

Manufacturing Process: Spiral Submerged Arc Welding (SSAW/HSAW)

Grade: P265GH

P265: Minimum yield strength = 265 MPa at room temperature

GH: Elevated temperature, creep-resistant steel

Temperature Range: Up to 450–480°C

2. Chemical Composition

Enhanced composition for high-temperature performance:

Note: Typically vacuum degassed, fine grain practice (ASTM 5 or finer).

3. Mechanical Properties

Room Temperature (20°C):

Yield Strength (ReH): ≥ 265 MPa

Tensile Strength (Rm): 410–530 MPa

Elongation (A):

t ≤ 16mm: ≥ 22%

t > 16mm: ≥ 20%

Impact Energy (KV):

Minimum: 40J average at 20°C

Individual: ≥ 28J at 20°C

Often specified at 0°C: ≥ 27J

Elevated Temperature Properties:

Proof Strength (Rp0.2) Examples:

100°C: ~240 MPa

200°C: ~215 MPa

300°C: ~190 MPa

350°C: ~175 MPa

400°C: ~160 MPa

450°C: ~145 MPa

Creep Rupture Strength:

450°C/100,000h: ~110 MPa

480°C/100,000h: ~85 MPa

4. Manufacturing Requirements (SSAW)

Special Processing for P265GH:

Steel Making:

Vacuum degassing mandatory

Fine grain practice (ASTM 6-8 typical)

Calcium treatment for sulfide shape control

Low sulfur (<0.012%) essential

Plate Preparation:

Normalizing at 890–930°C

100% ultrasonic testing of plates

Surface inspection for defects

SSAW Production:

Preheat: 120–180°C minimum

Low hydrogen SAW process

Double-sided welding (inside and outside)

Tandem SAW often used for productivity

Heat Treatment:

Stress relieving: 600–640°C

Normalizing + tempering optional for heavy wall

Furnace control: ±8°C uniformity

Cooling rate: ≤ 80°C/hour to 400°C

5. Testing & Inspection (Enhanced)

Mandatory per EN 10217-2:

Tensile Tests:

Room temperature (per batch)

Elevated temperature (per heat, at max design temp)

High-temperature tensile specimens aged 1,000h at 50°C above design temp

Impact Tests:

Room temperature (mandatory)

0°C or -10°C (typically specified)

+20°C for drop weight tear test (if required)

Creep Tests:

Often specified for critical applications

Creep rupture testing at design temperature

Minimum creep rate determination

Non-Destructive Testing:

100% automated UT of weld and parent metal

100% radiographic testing or TOFD

Hardness survey: HAZ, weld, base metal

Ferrite measurement in weld metal

Metallurgical Examination:

Macro-examination of weld cross-section

Micro-examination for grain size, inclusions

Replica tests for microstructure verification

6. Dimensions & Capabilities

Special Tolerances (typically Class B or better):

OD: ±0.5% or ±3mm (whichever smaller)

WT: +10%/-5% for t > 12mm

Ovality: ≤ 0.8% of OD

Straightness: ≤ 0.1% of length

7. Applications

Primary Sectors:

Power Generation:

Superheater and reheater tubing

Main steam lines (up to 180 bar, 540°C)

Hot reheat lines

Boiler headers (moderate temperature)

Petrochemical:

Hydroprocessing units (reactor effluent lines)

Catalytic reformers

Cracking furnace outlets

High-temperature heat exchangers

Industrial:

Waste-to-energy plants

Chemical process lines (350–480°C)

Thermal oil systems

High-pressure steam systems

Typical Service Conditions:

Temperature: -10°C to 480°C (design max)

Pressure: Up to 200 bar (depending on diameter)

Cyclic Service: Designed for 10,000+ cycles

Design Life: 30+ years (100,000+ hours at temp)

8. Welding & Fabrication

Critical Fabrication Requirements:

Filler Metal Selection:

Matching composition with controlled residuals

Low hydrogen electrodes: AWS E7018, EN ISO 2560-A E42 4 B 42 H5

SAW wires: EN 760 S1/S2, AWS ER70S-G

Flux: Basic agglomerated fluxes (CaF₂-CaO-Al₂O₃ system)

Welding Procedure Specification:

Qualification at both RT and elevated temp

PWHT mandatory for all thicknesses > 8mm

Preheat: 150–200°C (depending on thickness)

Interpass temp: 200–250°C maximum

Heat Treatment Regimes:

Stress relief: 610–630°C for 2 hours per 25mm

Normalize + temper: 900–920°C, then 630–670°C

Post-weld cooling rate: ≤ 100°C/hour

Inspection & Testing:

100% RT or UT of all fabrication welds

Hardness limits: ≤ 225 HV10 in weld area

Ferrite content: 8–12% in weld metal

9. Supplementary Requirements

Essential for P265GH SSAW:

10. Comparison with Related Grades

11. Design Considerations

Pressure Design (EN 13480-3):

Allowable Stress (S): Lowest of:

Rm/2.4 at 20°C = ~170–220 MPa

Rp0.2t/1.5 at design temp (e.g., 160/1.5 = 107 MPa at 450°C)

Rm,t/2.4 at design temp

Rdt/1.25 (creep range)

Thermal Analysis:

Expansion Coefficient: 13.2 × 10⁻⁶/°C (20–450°C)

Thermal Conductivity:

20°C: 51 W/m·K

450°C: 42 W/m·K

Specific Heat: 460–520 J/kg·K (20–450°C)

Modulus of Elasticity:

20°C: 210 GPa

450°C: 170 GPa

Weld Joint Efficiency:

SSAW with full NDT: 0.85–0.95

Critical service: Typically 0.85 maximum

Seamless reference: 1.00

12. Corrosion & Protection

High-Temperature Corrosion:

Oxidation Resistance:

Good to ~480°C in air/steam

Scale formation rate: ~0.1 mm/year at 450°C

Chromium content provides moderate protection

Coatings & Protection:

External:

High-temp aluminum paint (500°C)

Inorganic zinc silicate (400°C)

Glass flake coatings (300°C)

Internal:

Often uncoated for steam service

Passivation for certain chemicals

Oxide layer provides natural protection

Insulation Systems:

Mineral wool with SS cladding

Calcium silicate for higher temps

Expansion joint consideration critical

13. Equivalent Grades