Alloy Seamless Pipe
Chrome-moly alloy seamless pipes to ASTM A335 / DIN 17175 / EN 10216-2 for high-temperature creep service. Supplied normalized or normalized + tempered — for power plants, refineries, and petrochemical units worldwide.
ASTM A335 P5–P91
DIN 17175
EN 10216-2
Normalized / Q&T
Alloy Seamless Pipe
Alloy seamless pipe — the chrome-moly family (Cr-Mo steels) — is specified where carbon steel reaches its temperature and creep limits: superheated steam, furnace tubes, hydrogen service, and high-efficiency power cycles. CREATEEL supplies seamless alloy pipe to ASTM A335 P11 / P22 / P5 / P9 / P91 with DIN 17175 and EN 10216-2 equivalents, heat-treated to grade requirements and certified with EN 10204 3.1 mill test certificates.
- OD Range: 19mm – 720mm (3/4″ – 28″)
- Wall Thickness: 2.5mm – 60mm (SCH 40 – XXS)
- Grade: P11, P22, P5, P9, P91 · 13CrMo44, 10CrMo910
- Length: SRL 3–7m, DRL 6–18m, custom cut lengths
- Standard: ASTM A335, DIN 17175, EN 10216-2, GB/T 5310, JIS G3458
Technical Specifications
Standards
High-temperature alloy seamless pipe standards and grades supplied by CREATEEL.
| Standard | Available Steel Grades | Description |
|---|---|---|
| ASTM A335 | P5, P9, P11, P22, P91 | Standard specification for seamless ferritic alloy-steel pipe for high-temperature service |
| DIN 17175 | 13CrMo44, 10CrMo910 | German standard for seamless tubes of heat-resistant steels |
| EN 10216-2 | 13CrMo4-5, 10CrMo9-10 | European standard for seamless steel tubes with specified elevated temperature properties |
| GB/T 5310 | 15CrMoG, 12Cr1MoVG | Chinese national standard for seamless steel tubes for high-pressure boiler service |
| JIS G3458 | STPA22, STPA23, STPA25, STPA26 | Japanese standard for alloy steel pipes for high-temperature service |
Seamless Alloy Pipe Dimensions (OD × Wall Thickness, NPS)
Wall thickness in mm per ASME B36.10M, for P5/P9/P11/P22/P91/P92 seamless alloy pipe. – = not a standard schedule for that size. OD up to 720 mm on request.
| DN | NPS (in) | OD (mm) | SCH10 | SCH20 | STD | SCH40 | XS | SCH80 | SCH160 |
|---|---|---|---|---|---|---|---|---|---|
| 15 | 1/2 | 21.3 | 1.65 | – | 2.77 | 2.77 | 3.73 | 3.73 | 4.78 |
| 20 | 3/4 | 26.7 | 2.11 | – | 2.87 | 2.87 | 3.91 | 3.91 | 5.56 |
| 25 | 1 | 33.4 | 2.77 | – | 3.38 | 3.38 | 4.55 | 4.55 | 6.35 |
| 32 | 1-1/4 | 42.2 | 2.77 | – | 3.56 | 3.56 | 4.85 | 4.85 | 6.35 |
| 40 | 1-1/2 | 48.3 | 2.77 | – | 3.68 | 3.68 | 5.08 | 5.08 | 7.14 |
| 50 | 2 | 60.3 | 2.77 | – | 3.91 | 3.91 | 5.54 | 5.54 | 8.74 |
| 65 | 2-1/2 | 73.0 | 3.05 | – | 5.16 | 5.16 | 7.01 | 7.01 | 9.53 |
| 80 | 3 | 88.9 | 3.05 | – | 5.49 | 5.49 | 7.62 | 7.62 | 11.13 |
| 100 | 4 | 114.3 | 3.05 | – | 6.02 | 6.02 | 8.56 | 8.56 | 13.49 |
| 125 | 5 | 141.3 | 3.4 | – | 6.55 | 6.55 | 9.53 | 9.53 | 15.88 |
| 150 | 6 | 168.3 | 3.4 | – | 7.11 | 7.11 | 10.97 | 10.97 | 18.26 |
| 200 | 8 | 219.1 | 3.76 | 6.35 | 8.18 | 8.18 | 12.7 | 18.26 | 23.01 |
| 250 | 10 | 273.0 | 4.19 | 6.35 | 9.27 | 15.09 | 12.7 | 20.62 | 28.26 |
| 300 | 12 | 323.9 | 4.57 | 6.35 | 9.53 | 14.27 | 12.7 | 21.44 | 33.32 |
| 350 | 14 | 355.6 | 4.78 | 7.92 | 9.53 | – | 12.7 | 23.83 | – |
| 400 | 16 | 406.4 | 4.78 | 7.92 | 9.53 | – | 12.7 | 21.44 | – |
| 450 | 18 | 457.0 | 4.78 | 7.92 | 9.53 | – | 12.7 | 23.83 | – |
| 500 | 20 | 508.0 | 4.78 | 7.92 | 9.53 | – | 12.7 | 20.62 | – |
| 600 | 24 | 610.0 | – | – | 9.53 | – | 12.7 | 17.02 | – |
Chemical Composition (%)
Ladle analysis per heat. Full mill test certificate with heat traceability provided.
| Grade | C | Mn | Si | Cr | Mo |
|---|---|---|---|---|---|
| P11 | ≤0.15 | 0.30–0.60 | 0.50–1.00 | 1.00–1.50 | 0.44–0.65 |
| P22 | ≤0.15 | 0.30–0.60 | ≤0.50 | 1.90–2.60 | 0.87–1.13 |
| P5 | ≤0.15 | 0.30–0.60 | ≤0.50 | 4.00–6.00 | 0.45–0.65 |
| P9 | ≤0.15 | 0.30–0.60 | 0.25–1.00 | 8.00–10.00 | 0.90–1.10 |
| P91 | 0.08–0.12 | 0.30–0.60 | 0.20–0.50 | 8.00–9.50 | 0.85–1.05 |
Mechanical Properties
Minimum values at room temperature per ASTM A335. Elongation requirements (longitudinal/transverse) per specification.
| Grade | Tensile Strength (MPa) | Yield Strength (MPa) |
|---|---|---|
| P11 | ≥415 | ≥205 |
| P22 | ≥415 | ≥205 |
| P5 | ≥415 | ≥205 |
| P9 | ≥415 | ≥205 |
| P91 | ≥585 | ≥415 |
Heat Treatment
Every pipe is heat-treated to grade requirements; the delivery condition is stated on the mill test certificate.
P11 / P22 — Normalized
Normalized at approximately 900°C minimum, air cooled. The industry workhorse condition for steam and process service.
P5 / P9 — Normalized
Normalized at approximately 900–950°C for refinery furnace-tube and hydrogen service grades.
P91 — Normalized + Tempered
Normalize 1040–1080°C, temper 730–800°C. Mandatory condition for Grade P91 creep-resisting performance.
Hardness Control
P91 hardness verified per heat (≤250 HB / 248–265 H band per project spec); hardness testing on request for other grades.
Testing & Certification
Quality assurance applied to every alloy seamless order.
Hydrostatic Test
Every length pressure-tested per ASTM A335 or purchaser requirement.
Ultrasonic Examination
100% ultrasonic testing of body and ends; eddy current testing for small-diameter sizes.
Impact & Hardness
Charpy V-notch on request; hardness testing standard for P91, on request for other grades.
Certification
EN 10204 3.1 mill test certificate standard; 3.2 third-party inspection (SGS / BV / TÜV) on request.
Manufacturing Process
Our seamless steel pipes are manufactured through a rigorously controlled 12-step hot rolling process — from billet heating to final inspection — ensuring uniform mechanical properties, precise dimensions, and defect-free surfaces.
Billet Inspection & Cutting
Continuous-cast round billets are ultrasonically tested for internal defects, then cut to required lengths by abrasive sawing or shearing.
Rotary Hearth Heating
Billets are heated uniformly to 1200–1280°C in a rotary hearth furnace to achieve optimal plasticity for piercing while preventing overheating or decarburization.
Mannesmann Piercing
The heated billet is pierced over a pointed mandrel between two skewed rolls to form a hollow shell (mother tube), typically achieving a 3–4:1 elongation ratio.
Mandrel Mill Rolling
The hollow shell is rolled over a retained mandrel through a 5–8 stand continuous mandrel mill to reduce wall thickness and achieve uniform OD/WT dimensions.
Mandrel Extraction & Reheating
The mandrel is stripped from the shell; the shell is then reheated to ~950°C in an induction furnace before entering the stretch-reducing mill.
Stretch Reducing / Sizing
The pipe passes through 20–24 stands of stretch-reducing mill to achieve the final OD with tight tolerance (±0.5% OD) and uniform wall thickness, without an internal mandrel.
Cooling Bed Cooling
Pipes are transferred to a walking-beam cooling bed for slow, uniform air cooling to prevent bending and residual stress buildup.
Hot/Cold Straightening
Pipes are straightened by multi-roll cross-roll straighteners (6-roll or 10-roll) to achieve straightness ≤1 mm/m and eliminate ovality.
Cutting & End Facing
Pipes are cut to commercial lengths (5.8m/6m/11.8m/random) and both ends are faced and beveled (30°+5°) for welding, with burrs removed.
NDT & Hydrostatic Testing
100% ultrasonic testing for wall thickness and laminations, eddy current testing for surface cracks, and hydrostatic pressure testing to API/GB standards.
Surface Inspection & Marking
Visual and dimensional inspection of OD, WT, length, and surface quality; stenciling grade, heat number, OD×WT, standard, and manufacturer mark.
Final Packaging & Shipping
Pipes are bundled with steel strips, end-protected with plastic caps or bevel protectors, slung with lifting tags, and loaded for shipment with mill test certificates.
Applications
Where alloy seamless pipe delivers proven high-temperature performance worldwide.
Power Plant Boilers & Superheaters
Main steam, reheater, and superheater piping operating at 540–600°C where creep strength governs design.
✓ P11 / P22 / P91
Refinery Furnace Tubes
Cracking-furnace and reformer tubes in hydrogen and hydrocarbon service at tube-wall temperatures beyond carbon steel limits.
✓ P5 / P9
Hydroprocessing & Catalytic Units
Hydrogen service piping and reactor-loop systems requiring elevated-temperature strength and hydrogen resistance.
✓ P22 / P9
High-Temperature Process Piping
Refinery and chemical process lines designed to ASME B31.3 at design temperatures above 425°C.
✓ ASME B31.3
Boiler Headers & Heat Exchangers
Header and exchanger piping in 13CrMo4-5 / 10CrMo9-10 equivalents for European-coded projects.
✓ EN 10216-2
Advanced Power Cycles
Ultrasupercritical (USC) plants using Grade P91 for higher steam conditions and thermal efficiency.
✓ Normalized + tempered
Frequently Asked Questions
When is A335 alloy pipe required instead of A106 carbon steel?＋
Above roughly 425°C, or where hydrogen attack and creep become design factors. Chrome-moly grades P11/P22 extend service to ~550–600°C, and P91 beyond that with far higher creep strength.
Which P-grade should I choose?＋
P11 (1.25Cr-0.5Mo) and P22 (2.25Cr-1Mo) are the power and process workhorses. P5/P9 serve refinery hydrogen and sulfur environments. P91 is specified for high-efficiency power cycles at ~600°C.
What heat treatment condition do you supply?＋
P5/P9/P11/P22 in the normalized condition; P91 mandatorily normalized + tempered. The delivery condition is stated on the EN 10204 3.1 mill test certificate.
Do you perform hardness and impact testing?＋
Hardness testing is standard for P91 (≤250 HB). Charpy V-notch impact tests are available on request for all grades.
What sizes and lengths are available?＋
OD 19–720 mm, wall 2.5–60 mm (SCH 40–XXS). SRL 3–7 m, DRL 6–18 m, and custom cut lengths.
What certificates come with the order?＋
EN 10204 3.1 MTC with full heat traceability as standard; 3.2 third-party inspection (SGS / BV / TÜV) on request.
Ready to Order Alloy Seamless Pipes?
Get competitive pricing on ASTM A335 P11 / P22 / P5 / P9 / P91 seamless pipes. Heat treatment and full MTC documentation included.
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