High-Temperature Alloy Steel Seamless Pipes | Technical Specification PDF Download
The ASTM A335 Standard Specification PDF provides a comprehensive technical reference for seamless ferritic alloy steel pipes used in high-temperature and high-pressure service. This specification covers alloy grades, chemical composition, mechanical properties, manufacturing processes, dimensions and tolerances, testing requirements, and typical industrial applications such as power plants, refineries, and petrochemical facilities.
ASTM A335 Standard
ASTM A335 is the standard specification for seamless ferritic alloy steel pipe intended for high-temperature service. These pipes are commonly used in pressure piping systems where elevated temperature strength, creep resistance, and long-term reliability are required.
ASTM A335 is widely referenced in power generation, oil & gas refining, petrochemical, and thermal processing industries.
Common Grades Under ASTM A335
ASTM A335 includes several chromium-molybdenum (Cr-Mo) alloy steel grades, such as:
- P1
- P2
- P5
- P9
- P11
- P12
- P22
- P91
- P92
Each grade is designed for specific temperature and pressure ranges.
Material Description
- Material Type: Ferritic Alloy Steel
- Manufacturing Method: Seamless
- Product Form: Steel Pipes
- Delivery Condition: Normalized, normalized & tempered, or quenched & tempered (as required by grade)
ASTM A335 pipes provide excellent resistance to high-temperature oxidation, creep, and pressure-related deformation.
Chemical Composition
| Grade | UNS | C | Mn | P max | S max | Si | Cr | Mo | Others |
| P1 | K11522 | 0.10–0.20 | 0.30–0.80 | 0.025 | 0.025 | 0.10–0.50 | 0.44–0.65 | ||
| P2 | K11547 | 0.10–0.20 | 0.30–0.61 | 0.025 | 0.025 | 0.10–0.30 | 0.50–0.81 | 0.44–0.65 | |
| P5 | K41545 | 0.15 max | 0.30–0.60 | 0.025 | 0.025 | 0.50 max | 4.00–6.00 | 0.45–0.65 | |
| P9 | K90941 | 0.15 max | 0.30–0.60 | 0.025 | 0.025 | 0.25–1.00 | 8.00–10.00 | 0.90–1.10 | |
| P11 | K11597 | 0.05–0.15 | 0.30–0.60 | 0.025 | 0.025 | 0.50–1.00 | 1.00–1.50 | 0.44–0.65 | |
| P12 | K11562 | 0.05–0.15 | 0.30–0.61 | 0.025 | 0.025 | 0.50 max | 0.80–1.25 | 0.44–0.65 | |
| P22 | K21590 | 0.05–0.15 | 0.30–0.60 | 0.025 | 0.025 | 0.50 max | 1.90–2.60 | 0.87–1.13 | |
| P91 | K90901 | 0.08–0.12 | 0.30–0.60 | 0.020 | 0.010 | 0.20–0.50 | 8.00–9.50 | 0.85–1.05 | V, Nb, N, Al |
| P92 | K92460 | 0.07–0.13 | 0.30–0.60 | 0.020 | 0.010 | 0.50 max | 8.50–9.50 | 0.30–0.60 | W, V, Nb, N |
Mechanical Properties
Mechanical requirements differ depending on grade and heat treatment condition.
| Grade | Tensile Strength min (MPa) | Yield Strength min (MPa) |
| P1 | 380 | 205 |
| P2 | 380 | 205 |
| P5 | 415 | 220 |
| P9 | 585 | 415 |
| P11 | 415 | 220 |
| P12 | 415 | 220 |
| P22 | 415 | 220 |
| P91 | 585 | 415 |
| P92 | 620 | 440 |
Heat Treament
| Grade | Heat Treatment Type | Normalizing Temp (°C) | Cooling | Tempering / Subcritical Anneal (°C) |
| P1 | Anneal / Normalize + Temper | 650 | ||
| P2 | Anneal / Normalize + Temper | 675 | ||
| P5 | Anneal / Normalize + Temper | 675 | ||
| P9 | Anneal / Normalize + Temper | 675 | ||
| P11 | Anneal / Normalize + Temper | 650 | ||
| P12 | Anneal / Normalize + Temper | 650–705 | ||
| P22 | Anneal / Normalize + Temper | 675 | ||
| P91 | Normalize + Temper | 1040–1080 | Air | 730–800 |
| P92 | Normalize + Temper | 1040–1080 | Air | 730–800 |
Manufacturing Process
ASTM A335 alloy steel pipes are manufactured by:
- Seamless hot rolling or extrusion
- Heat treatment according to grade requirements
- Straightening and sizing
- Final inspection and testing
Dimensions & Tolerances
ASTM A335 pipes are typically ordered by NPS (Nominal Pipe Size) and Schedule (wall thickness).
Dimensional requirements commonly include:
- Outside Diameter (OD) tolerance
- Minimum Wall Thickness (WT)
- Ovality and straightness control
- Length options: random, double random, or fixed cut length
General dimensional tolerances for alloy steel pipes are often governed by ASTM A999 / A999M, unless otherwise specified.
Outside Diameter (OD) tolerance
| NPS [DN] Range | Over (in) | Over (mm) | Under (in) | Under (mm) |
| 1/8 to 1 1/2 [6–40] | 1/64 (0.015) | 0.4 | 1/64 (0.015) | 0.4 |
| Over 1 1/2 to 4 [40–100] | 1/32 (0.031) | 0.79 | 1/32 (0.031) | 0.79 |
| Over 4 to 8 [100–200] | 1/16 (0.062) | 1.59 | 1/32 (0.031) | 0.79 |
| Over 8 to 12 [200–300] | 3/32 (0.093) | 2.38 | 1/32 (0.031) | 0.79 |
| Over 12 [300] | ±1% of OD | ±1% of OD |
Wall Thickness (WT) tolerance
| NPS [DN] Range / Condition | Over (%) | Under (%) |
| 1/8 to 2 1/2 [6–65], all t/D ratios | 20 | 12.5 |
| Above 2 1/2 [65], t/D ≤ 5% | 22.5 | 12.5 |
| Above 2 1/2 [65], t/D > 5% | 15 | 12.5 |
Testing & Inspection
Each ASTM A335 pipe may undergo:
- Chemical analysis
- Tensile testing
- Hardness testing
- Hydrostatic testing or non-destructive testing (UT / ET)
- Dimensional and visual inspection
Mill Test Certificates (EN 10204 3.1) are typically provided.
Applications
- Power Plant Boilers
- Superheaters & Reheaters
- High-Temperature Steam Lines
- Oil Refineries
- Petrochemical Processing Units
- Pressure Piping Systems
ASTM A335 alloy steel pipes are essential materials for high-temperature service.
Download ASTM A335 Standard Specification PDF
Click below to download the complete ASTM A335 Alloy Steel Pipes Standard Specification PDF, including detailed grade tables, tolerances, and testing requirements.
👉 Download ASTM A335 Standard PDF
ASTM A335 – Seamless alloy steel pipe
├── ASTM A335 P5 Alloy Steel Pipe
├── ASTM A335 P22 Seamless Pipe
├── ASTM A335 P91 High Temperature Pipe
├── ASTM A335 P92 Pipe