Xi'an Dongmeng Group Co., Ltd. is one of the most reliable manufacturers and suppliers of astm a335 p91 pipe in China, also supports customized service. With abundant experience, we warmly welcome you to wholesale cheap products in stock here and get free sample from our factory. For price consultation, contact us.
ASTM A335 P91 Seamless Alloy Steel Pipe
Xi'an Dongmeng Group Co., Ltd. supplies ASTM A335 P91 seamless alloy steel pipe for specified high-temperature pressure piping projects. We work with EPC contractors, piping fabricators, distributors and industrial maintenance buyers to define material requirements before quotation.
P91 is a modified 9Cr-1Mo steel strengthened with vanadium, niobium and nitrogen. It belongs to the creep-strength-enhanced ferritic steel family and develops its intended performance through controlled processing and heat treatment.
For purchasing, the grade name is only the starting point. The quotation should identify the standard edition, P91 type, dimensions, delivery condition, inspection requirements and documentation package.
Send your specification or piping MTO to check material availability and request a project quotation.
P91 Pipe Supply Specifications
| Item | Procurement Specification |
| Product | Seamless alloy steel pressure pipe |
| Material standard | ASTM A335/A335M; ASME SA335/SA335M when required |
| Grade | P91; specify Type 1 or Type 2 |
| Product form | Round pipe |
| Manufacturing route | Hot-finished or cold-drawn seamless |
| Enquiry size range | NPS 1/2–24, subject to individual size and condition confirmation |
| Wall thickness | Schedule designation or specified nominal/minimum wall |
| Length | 6 m, 12 m, random or cut lengths, as agreed |
| End preparation | Plain or beveled; special machining subject to review |
| Surface protection | Agreed temporary corrosion protection for storage and transport |
| Inspection documents | MTC and the reports agreed in the purchase order |
| Packing | End protection, identified bundles or project-specific export packing |
ASTM A335 covers seamless pipe for elevated-temperature service. Specify welded alternatives under their own applicable material standard and manufacturing requirements.
Chemical Composition and Grade Identification
The following values are Type 1 heat-analysis reference limits from ASTM A335/A335M-24b, expressed as mass percentages.
| Element | Reference Limit, % |
| C | 0.08–0.12 |
| Mn | 0.30–0.60 |
| P | ≤0.020 |
| S | ≤0.010 |
| Si | 0.20–0.50 |
| Cr | 8.00–9.50 |
| Mo | 0.85–1.05 |
| V | 0.18–0.25 |
| Nb | 0.06–0.10 |
| N | 0.030–0.070 |
| Ni | ≤0.40 |
| Al | ≤0.020 |
| Ti | ≤0.010 |
| Zr | ≤0.010 |
Type 2 has different Mn, S, Si, Ni and N limits, additional residual-element controls and an N/Al requirement. Apply the correct heat-analysis and product-analysis criteria.
UNS identification: The reference edition lists K90901 for P91 Type 1 and Type 2. Older editions used K91560. Check the standard edition recorded on the material certificate.
Mechanical Properties and Mill Heat Treatment
Reference values below follow ASTM A335/A335M-24b.
| Property or Process | Reference Requirement |
| Minimum tensile strength | 585 MPa / 85 ksi |
| Minimum yield strength | 415 MPa / 60 ksi |
| Brinell hardness | 190–250 HBW |
| Longitudinal elongation | 20% base requirement for qualifying specimens; thinner strips and other specimen configurations require separate evaluation |
| Normalizing/austenitizing temperature | 1040–1080°C |
| Tempering temperature | 730–800°C |
| Heat-treatment routes | Normalize and temper, or quench and temper |
Final acceptance follows the ordered edition, product condition and applicable testing provisions.
For project procurement, request records identifying the material heat, treatment batch, temperature cycle and associated test results. Hardness results should be reviewed together with chemistry, processing history and the required mechanical tests.
Site-weld post-weld heat treatment requires its own approved welding procedure and thermal cycle.
P91 Pipe Dimensions and Schedules
The following selected dimensions help buyers prepare an enquiry. Availability is confirmed separately for each P91 size.
| NPS | DN | Outside Diameter, mm | SCH 40 Wall, mm | SCH 80 Wall, mm |
| 1/2 | 15 | 21.3 | 2.77 | 3.73 |
| 1 | 25 | 33.4 | 3.38 | 4.55 |
| 2 | 50 | 60.3 | 3.91 | 5.54 |
| 3 | 80 | 88.9 | 5.49 | 7.62 |
| 4 | 100 | 114.3 | 6.02 | 8.56 |
| 6 | 150 | 168.3 | 7.11 | 10.97 |
| 8 | 200 | 219.1 | 8.18 | 12.7 |
| 12 | 300 | 323.8 | 10.31 | 17.48 |
Dimensions follow the ASME B36.10 system. STD and SCH 40, or XS and SCH 80, have different relationships at different pipe sizes; confirm the actual wall thickness when ordering.
For heavy-wall or custom requirements, provide the required OD and wall thickness, indicate whether the wall is nominal or minimum, and state any additional dimensional tolerances.
Have a size list? Send your MTO with quantities, lengths and end preparation for an item-by-item quotation.
Where P91 Pipe Is Used
P91 is considered for engineered piping systems where elevated-temperature strength and long-term creep performance are important.
Typical project applications include:
Main steam and hot reheat piping.
Boiler external piping and header connections.
High-energy steam systems in power-generation facilities.
Replacement piping in approved plant maintenance projects.
P91 has a tempered martensitic microstructure in its properly treated condition. Its use in demanding service depends on preserving the required material condition through manufacture and fabrication.
Design temperature, pressure, allowable stress, wall thickness, corrosion allowance, operating cycles and required service life should be evaluated together. The material name alone does not establish a universal operating-temperature or pressure limit.
Welding and Fabrication Considerations
P91 fabrication requires control of the welding thermal cycle and the resulting material condition. Before fabrication, confirm that the qualified WPS/PQR addresses:
Base material identification and delivery condition.
Consumable selection and low-hydrogen handling.
Preheat and interpass temperature control.
Heat input and welding sequence.
Cooling requirements before subsequent heat treatment.
PWHT temperature, holding time and temperature monitoring.
Final inspection and acceptance requirements.
PWHT is generally required for Grade 91 fabrication. Welding can also create regions within the heat-affected zone that are vulnerable to long-term creep damage, including Type IV cracking. These considerations make fabrication records important alongside the original pipe MTC.
When purchasing replacement material, identify whether the pipe will connect to new or service-exposed components and provide the relevant project welding requirements.
Inspection and Material Traceability
The inspection plan should identify the applicable requirements, acceptance criteria and records for each purchase-order item.
| Check | Information to Review |
| Material identification | Standard edition, grade type, heat number and pipe marking |
| Chemical analysis | Required elements and the applicable heat/product-analysis limits |
| Heat-treatment records | Treatment batch and connection to the supplied material |
| Mechanical testing | Reported results, specimen information and acceptance basis |
| Hardness | Test method, results and material identification |
| Ultrasonic testing | Procedure, coverage, acceptance criteria and report |
| Hydrostatic testing | Applicability, specified requirements and test record |
| Dimensions and ends | OD, wall, length, end preparation and agreed tolerances |
| Final release | Quantity, marking, document completeness and packing condition |
For P91 under the reference edition, ultrasonic examination follows ASTM E213. Hydrostatic-test requirements depend on dimensions and purchase-order provisions.
What PMI Can Verify
Handheld XRF can help check measurable alloying elements and identify material mix-ups. Carbon and nitrogen require suitable alternative analytical methods.
Specify the elements, method and acceptance criteria needed for your project. Review PMI alongside the MTC and other required tests.
Documents to Specify Before Ordering
Depending on the project, request:
EN 10204 3.1 inspection certificate.
Heat-number traceability.
Chemical, tensile and hardness results.
Heat-treatment records.
UT and applicable hydrostatic-test reports.
PMI or additional laboratory analysis.
Dimensional inspection and packing records.
Third-party inspection or EN 10204 3.2 arrangements, where agreed.
Processing, Packing and Delivery
Include cutting, beveling, marking and packing requirements in the RFQ so they can be reviewed with the material specification.
For project deliveries, request identification by purchase-order item, grade, size and heat number. Where material is cut, traceability should remain connected to the original certified heat.
Packing can be specified around the pipe dimensions, shipment method and handling conditions. Typical requirements include protected ends, secure bundling, readable labels and suitable storage or transport protection.
External coating systems should be selected separately for their intended service conditions. State whether protection is required for transport, storage or operation.
Price and lead time depend on size, wall thickness, grade type, available material, manufacturing route, inspection scope, processing and destination. MOQ and delivery timing are confirmed against the complete enquiry.
Project Procurement with Dongmeng Group
Dongmeng Group supports specification-based enquiries for industrial piping projects.
Send your material requisition or MTO to define:
The required material and standard edition.
Item-by-item dimensions and quantities.
Delivery condition and inspection scope.
Processing, marking and packing requirements.
Required documents and delivery destination.
A clearly defined enquiry helps the quotation address the technical and commercial requirements together.
Frequently Asked Questions
1. Is ASTM A335 P91 pipe seamless or welded?
ASTM A335 P91 is seamless pipe. For a welded Grade 91 requirement, specify the applicable welded-pipe standard, grade and class, and confirm project acceptance.
2. What is the difference between ASTM A335 and ASME SA335?
They are corresponding material specifications used in different standards frameworks. State the specification and edition required by the project, and confirm that the material certification supports that requirement.
3. Should I specify P91 Type 1 or Type 2?
Use the type required by the project material specification. Ask the supplier to confirm the type against the certified chemistry and applicable requirements before accepting a quotation.
4. Can P91 replace P9 or P22?
Substitution requires engineering approval. Review design stresses, dimensions, component compatibility, fabrication requirements and service conditions before changing the specified material.
5. Are P91 pipe and T91 tube interchangeable?
They belong to the Grade 91 family but use different product specifications. ASTM A213 covers boiler, superheater and heat-exchanger tubes; ASTM A335 covers high-temperature pipe. Confirm the required product form and standard.
6. What is the maximum operating temperature of P91?
There is no single operating limit applicable to every P91 pipe. The allowable condition depends on the governing design code, stress, wall thickness, service environment and required operating life.
7. Is a PMI result sufficient for material acceptance?
Material acceptance requires the specified combination of identification, chemistry, treatment and inspection records. Confirm that the analytical method can measure every element required by the inspection plan.
8. Can I request both UT and hydrostatic testing?
Yes, include both requirements in the RFQ. The inspection plan should identify the mandatory material-standard requirements and any additional purchaser requirements.
9. Can EN 10204 3.2 certification be arranged?
State this requirement before order confirmation. The verification parties, inspection stages and documentation arrangements must be agreed in advance.
10. Can P91 pipe be supplied cut to length or beveled?
These requirements can be included for quotation. Provide the required length tolerance, bevel geometry and any requirements for preserving material identification after cutting.
11. What are the MOQ and delivery time?
They depend on the requested sizes, quantities, material availability, treatment, processing and inspection scope. Send the complete specification to obtain an item-specific proposal.
12. What affects the price of P91 pipe?
Major factors include dimensions, wall thickness, grade type, quantity, supply route, treatment, inspection, processing and freight. Compare quotations against the same specification and document requirements.
Request an ASTM A335 P91 Pipe Quotation
Send the following information:
Standard and edition + P91 type + NPS/OD + wall thickness + quantity + length + ends + inspection requirements + destination.
For project enquiries, attach your MTO, BOM or piping material specification.
Example enquiry:
ASTM A335 P91 Type 1, edition to be confirmed / NPS 6 / SCH 80 / 6 m lengths / beveled ends / 10 MT / EN 10204 3.1 / project inspection requirements attached / destination: Jebel Ali.
Xi'an Dongmeng Group Co., Ltd.
Phone: +86 157 6921 4734
Email: office@dongmjd.com
WhatsApp: Contact Dongmeng Group
Office: Room 4107, Runfeng Building, Sanqiao New Street, Weiyang District, Xi'an City, Shaanxi Province.
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