ASTM A335 P91 Pipe Specifications

The ASTM A335 P91 Pipe specifications, including standards, lengths and surface finish, are listed in the table below.

Parameter Specification
Standards ASTM A335 / ASME SA335
Size Range 1/2" NB to 24" NB (12.7 mm OD to 609.6 mm OD)
Wall Thickness SCH 40, SCH 60, SCH 80, SCH 100, SCH 120, SCH 140, SCH 160, XXS
Length Single Random, Double Random, or Cut Length (up to ~12-16 meters)
End Type Plain End (PE), Bevelled End (BE), Threaded End (TE)
Surface Finish Black Painted, Varnished, Anti-corrosion Oil, Shot Blasted
Form Seamless

ASTM A335 P91 Pipe Sizes & Dimensions

The available ASTM A335 P91 pipe sizes and dimensions are listed in the table given below.

Parameter Range
Nominal Pipe Size 1/2" NB to 24" NB (DN15 to DN600)
Outer Diameter 21.3 mm to 610 mm
Wall Thickness 3 mm to 60+ mm
Schedule 40, 80, 120, 160, STD, XS, XXS
Length Single Random (5 to 7 m), Double Random (9 to 13.5 m), Cut Length
End Type Beveled End (BW), Plain End (PE)

We keep standard sizes in stock and can cut pipes to custom lengths for specific projects.

Dimensional Tolerances for ASTM A335 P91 Pipe

The table given below explains dimensional tolerances for ASTM A335 P91 pipe, including limits for outer diameter and wall thickness, as well as inspection requirements according to relevant standards.

Parameter Tolerance / Requirement
Applicable Standards ASTM A335 / ASME B36.10
Outer Diameter Tolerance (≤ NPS 4) ±1.0% (Hot-Finished Seamless Pipe)
Outer Diameter Tolerance (≥ NPS 5) ±0.75% (Hot-Finished Seamless Pipe)
Wall Thickness Tolerance -12.5% on minimum specified thickness (no positive limit)
Cold-Drawn Pipe OD Tolerance Typically ±0.5% for sizes up to NPS 4
Straightness As per ASTM A335 specification
Ovality Controlled within ASTM A335 limits
End Squareness As per the specification requirements
Dimensional Inspection Each pipe undergoes dimensional verification before dispatch

ASTM A335 P91 Pipe Weight Chart

Weight per metre for ASTM A335 P91 pipe depends on the outer diameter, wall thickness, and schedule. Standard weight calculation uses the formula: weight (kg/m) = (OD - WT) x WT x 0.02466, where OD and WT are in millimetres. A 6" NB Schedule 80 P91 pipe (168.3 mm OD, 10.97 mm WT) weighs approximately 42.56 kg/m. For 8" NB Schedule 120 (219.1 mm OD, 18.26 mm WT), the weight is approximately 90.44 kg/m. Contact our team for a complete weight chart covering all standard sizes and schedules.

ASTM A335 P91 Pipe Price

ASTM A335 P91 pipe prices are about ₹70-₹300 per kg in India and $1.00 to $9.00 per kg. It depends on OD, wall thickness, schedule, and order quantity. Final price depends on how much you order, any required certificates, the surface/end finish, alloy and raw material costs, and the agreed delivery terms (FOB/CIF/CFR).

Contact Sachiya Steel International for a competitive quotation on ASTM A335 P91 pipe in your required size and quantity.

ASTM A335 P91 Chemical Composition

The table below presents the chemical composition of ASTM A335 P91 pipe along with its symbol and proportion.

Carbon C
0.08% to 0.12%
Manganese Mn
0.30% to 0.60%
Phosphorus P
Max 0.020%
Sulphur S
Max 0.010%
Silicon Si
0.20% to 0.50%
Chromium Cr
8.00% to 9.50%
Molybdenum Mo
0.85% to 1.05%
Vanadium V
0.18% to 0.25%
Nickel Ni
Max 0.40%
Aluminium Al
Max 0.02%
Niobium (Columbium) Nb/Cb
0.06% to 0.10%
Titanium Ti
Max 0.01%
Zirconium Zr
Max 0.01%

ASTM A335 P91 Mechanical Properties

The mechanical properties given in the table below apply to ASTM A335 P91 pipe in the normalised and tempered condition.

585
MPa / 85 ksi
Tensile Strength (min)
415
MPa / 60 ksi
Yield Strength (min, 0.2% offset)
20%
min
Elongation (2" gauge)
250
HBW / 25 HRC
Hardness (max)
Property Value
Tensile Strength (min) 585 / 85 MPa / ksi
Yield Strength (min, 0.2% offset) 415 / 60 MPa / ksi
Elongation (min, 2" gauge) 20%
Hardness (max) 250 HBW / 25 HRC
Request a Quote for ASTM A335 P91 Pipe Request a Quote

ASTM A335 P91 Equivalent Designations

ASTM A335 P91 pipe has equivalent designations in international standards, allowing global buyers to cross-reference specifications for procurement.

Standard Designation
UNS UNS K91560
EN 10216-2 X10CrMoVNb9-1
Werkstoff Nr. 1.4903
GB 5310 10Cr9Mo1VNb

ASTM A335 P91 Pipe Applications

ASTM A335 P91 pipe is used in industries where piping systems operate at elevated temperatures and pressures.

Power Generation & Ultra-Supercritical Boiler Systems

P91 chrome moly pipe is used in main steam and hot reheat lines of USC boilers, steam outlet manifolds, and high-temperature connecting piping.

Oil & Gas and Petrochemical Processing

Refineries and petrochemical plants, catalytic reformer charge heaters, hydrogen generation units and high temperature reactor outlet use ASTM A335 P91 pipe.

ASTM A335 P91 Type 1 vs Type 2

The table below compares the differences between ASTM A335 P91 Type 1 and Type 2 in composition, creep strength, hardness, and suitability for high-temperature applications.

Parameter P91 Type 1 P91 Type 2
Standard ASTM A335 / ASME SA335 ASTM A335 / ASME SA335
Base Composition 8.00-9.50% Cr, 0.85-1.05% Mo Same as Type 1
Trace Element Control Standard limits Stricter limits on Mn, S, Si, N, Sn, Sb
Residual Elements Less tightly controlled More tightly controlled for improved purity
Creep Performance Good Enhanced long-term creep strength
Type IV Cracking Resistance Standard resistance Improved resistance (especially in welded joints)
Hardness Requirement Not specifically tightened beyond standard P91 limits 190-250 HBW or 196-265 HV
Weld Joint Reliability Adequate Superior long-term weld integrity
Typical Applications Conventional high-temperature service Ultra-supercritical boilers, advanced power plants
Industry Preference Widely used Increasingly preferred for critical high-temperature applications

ASTM A335 P91 vs P22 Pipe - Key Differences

P91 (9Cr-1Mo-V) offers significantly higher creep strength and service temperatures up to 600°C compared to P22 (2.25Cr-1Mo), which is limited to approximately 565°C. The table below summarises the key differences between these two A335 grades.

Property A335 P91 A335 P22
Composition 9Cr-1Mo-V-Nb 2.25Cr-1Mo
Max Service Temperature Up to 600°C Up to ~565°C
Tensile Strength (min) 585 MPa (85 ksi) 415 MPa (60 ksi)
Yield Strength (min) 415 MPa (60 ksi) 205 MPa (30 ksi)
Wall Thickness (for same pressure) Thinner Thicker
PWHT Required Yes (730 to 770°C) Yes (675 to 730°C)
Welding Complexity Higher Lower

ASTM A335 P91 vs P9 Pipe

Compare ASTM A335 P9 and P91 differences in composition, alloying elements, creep strength, and suitability for high-temperature service applications.

Parameter ASTM A335 P9 ASTM A335 P91
Base Composition 9Cr-1Mo Modified 9Cr-1Mo
Alloying Elements No V, Nb, or controlled N V (0.18-0.25%), Nb (0.06-0.10%), N (0.030-0.070%)
Microstructure Strengthening Limited Carbonitride precipitates improve creep strength
Creep Strength Lower Significantly higher at elevated temperatures
Allowable Stress Values Lower Higher
High-Temperature Suitability Suitable for moderate temperatures Suitable for ultra-supercritical conditions
Service Temperature Range Typically below ~540°C Suitable for service above 540°C
Typical Applications Conventional power plants, lower stress service Advanced power plants, ultra-supercritical boilers
Material Selection Used where lower strength is acceptable Preferred for long-term high-temperature and high-pressure applications

Heat Treatment of ASTM A335 P91 Pipe

ASTM A335 P91 pipe undergoes normalising at 1040–1080°C and tempering at 730–780°C to form a tempered martensitic structure with MX carbonitrides and M23C6 carbides for creep strength up to 600°C. Incorrect temperatures cause premature failure, so Mill Test Certificates must confirm proper normalising and tempering ranges.

Shipping & Packaging

Main export packaging setup Heavy-duty wooden boxes Packing
Export Packaging Standard

We strictly follow seaworthy export handling standards to protect ASTM A335 P91 Pipe from transit damage, moisture ingress, and surface contamination during long-distance dispatch.

  • Heavy-duty wooden boxes with moisture barrier lining
  • HDPE stretch film wrapping on all bundles
  • Plastic end caps on threaded and plain-end pipes
  • Silica gel desiccants to minimize moisture exposure
  • ISPM-15 fumigated wooden packaging for export
Bundle Yard Staging Pipe Bundle Yard Staging
Bundle Edge Protection Container End-Cap Protection
Export-Ready Bundles Wrapped Export-Ready Bundles

We Export Worldwide

Sachiya Steel International supplies ASTM A335 P91 pipes to major industrial markets across North America, Europe, the Middle East, Asia and Africa with export-ready documentation and logistics support.

  • USA flagUSA
  • Canada flagCanada

Frequently Asked Questions - ASTM A335 P91 Pipe

What is ASTM A335 P91 Pipe?+
ASTM A335 P91 is a seamless CSEF ferritic alloy steel pipe with 8-9.5% Cr, 0.85-1.05% Mo, V and Nb, suited for high-temperature, high-pressure power, boiler, and refinery applications.
What is the difference between ASTM A335 P91 Type 1 and Type 2?+
Compared to Type 1, P91 Type 2 has tighter limits on Mn, S, Si, N, Sn, and Sb, needs a hardness of 190-250 HBW (196-265 HV), and gives better long-term creep resistance.
What sizes are available for ASTM A335 P91 Pipe?+
ASTM A335 P91 pipes are available from 1/2" to 24" NB in schedules 40, 80, 120, 160, XS, and XXS, with wall thicknesses of about 3-60+ mm. Custom sizes and cut-to-length pipes are also available.
What is the tensile strength of ASTM A335 P91 pipe?+
ASTM A335 P91 pipe has a minimum tensile strength of 585 MPa (85 ksi).
What is the difference between P91 and P9 pipe?+
P91, an improved 9Cr-1Mo steel, adds vanadium, niobium, and controlled nitrogen, resulting in much higher creep strength and allowable service temperatures, making it ideal for ultra-supercritical boiler service.
What welding rod is used for P91 Pipe?+
P91 pipe welding requires matching 9Cr-1Mo-V filler metals. For SMAW, the standard electrode is AWS E9015-B9. For GTAW/TIG welding, AWS ER90S-B9 filler wire is used.
What material is equivalent to ASTM A335 P91?+
ASTM A335 P91 is equivalent to EN 10216-2 X10CrMoVNb9-1 (W.Nr. 1.4903) in Europe and GB 5310 10Cr9Mo1VNb in China. The grade was originally developed as NF616 in Japan.
Can ASTM A335 P91 pipe be used in place of P22?+
P91 can substitute P22 for high-temperature service, offering greater creep strength, up to 600°C use, and thinner walls for weight savings, but demands more stringent welding and heat treatment controls.
What are the recommended preheat, interpass temperature, and PWHT requirements for welding ASTM A335 P91 pipe?+
ASTM A335 P91 welding requires 200-250°C preheat, 200-300°C interpass control, and compulsory PWHT at 730-770°C (1 hour per 25 mm). Proper PWHT and controlled air cooling or a furnace prevent cold and hydrogen-induced cracking.

Contact Us for Stock Availability Request a Quote