ASTM A335 P5 / ASME SA335 P5 Seamless Alloy Steel Pipe
ASTM A335 P5, also designated ASME SA335 P5, is a seamless ferritic alloy steel pipe containing approximately 5% chromium and 0.5% molybdenum. This 5Cr-0.5Mo composition provides reliable elevated-temperature strength and improved resistance to oxidation and high-temperature sulfidation compared with lower-chromium Cr-Mo steels.
P5 seamless pipes are widely used in refineries, petrochemical plants, power-generation systems, boilers and high-temperature process piping. They can be supplied in hot-finished or cold-finished condition, with dimensions, testing and documentation tailored to project requirements.
We manufacture and supply astm a335 p5 alloy steel seamless pipe specification with material test certificates, nondestructive examination reports and third-party inspection when required.
ASTM A335 P5 Pipe Specification
| Item | Specification |
|---|---|
| Standard | ASTM A335/A335M |
| ASME Designation | ASME SA335 / SA-335 |
| Grade | P5 |
| UNS Number | K41545 |
| Material Type | Ferritic chromium-molybdenum alloy steel |
| Nominal Alloy Content | 5Cr-0.5Mo |
| Manufacturing Process | Seamless, hot-finished or cold-finished |
| Heat Treatment | Full annealed, isothermal annealed, or normalized and tempered |
| Dimensional Standard | ASME B36.10M or project specification |
| End Finish | Plain end, beveled end or threaded end |
| Certification | EN 10204 3.1; 3.2 when specified |
| Typical Service | High-temperature and high-pressure piping |
What Is ASTM A335 P5?
ASTM A335/A335M is the material specification for seamless ferritic alloy steel pipe intended for high-temperature service.
The standard covers several chromium-molybdenum grades, including P5, P9, P11, P22 and P91. The appropriate grade is selected according to:
- Design temperature
- Design pressure
- Required allowable stress
- Oxidation and corrosion conditions
- Process medium
- Welding requirements
- Applicable ASME piping code
- Project specifications
Pipes manufactured to ASTM A335 are suitable for bending, flanging, similar forming operations and fusion welding, provided that the correct fabrication and heat-treatment procedures are followed.
ASTM A335 P5 Material
Grade P5 is a ferritic Cr-Mo alloy steel containing:
- Chromium: 4.00–6.00%
- Molybdenum: 0.45–0.65%
Chromium improves resistance to oxidation and high-temperature corrosion, while molybdenum contributes to elevated-temperature strength and mechanical stability.
P5 should not be treated as stainless steel. Its chromium content is lower than that of conventional stainless grades, and corrosion suitability must be evaluated against the actual process environment.
Chemical Composition
| Element | ASTM A335 P5 Requirement |
|---|---|
| Carbon, C | 0.15% max |
| Manganese, Mn | 0.30–0.60% |
| Phosphorus, P | 0.025% max |
| Sulfur, S | 0.025% max |
| Silicon, Si | 0.50% max |
| Chromium, Cr | 4.00–6.00% |
| Molybdenum, Mo | 0.45–0.65% |
The final chemical composition must be confirmed by the material test certificate for the supplied heat.
Mechanical Properties
| Property | Minimum Requirement |
|---|---|
| Tensile Strength | 415 MPa |
| Yield Strength | 205 MPa |
| Longitudinal Elongation | 30% |
Elongation requirements may be adjusted according to specimen orientation, wall thickness and the provisions of the specified ASTM edition.
Design allowable stresses must be determined from the applicable ASME code and material tables rather than from room-temperature tensile properties alone.
Heat Treatment
ASTM A335 P5 seamless pipe is reheated and supplied in one of the following conditions:
- Full annealed
- Isothermal annealed
- Normalized and tempered
When supplied in the normalized and tempered condition, the minimum tempering temperature is 675°C [1250°F].
Correct heat treatment is necessary to achieve:
- Uniform microstructure
- Required mechanical properties
- Stable hardness
- Reliable elevated-temperature performance
- Suitable fabrication and welding characteristics
The heat-treatment condition should be recorded on the material test certificate.
Manufacturing Process
ASTM A335 P5 pipe must be manufactured by a seamless process.
Available finishing routes include:
Hot-Finished Pipe
Hot-finished pipe is commonly used for larger diameters and heavier wall thicknesses. It provides efficient production for high-temperature pressure-piping applications.
Cold-Finished Pipe
Cold finishing may be used where closer dimensional tolerances, improved surface condition or specific mechanical-property control is required.
The required manufacturing condition should be stated in the purchase order when it is critical to the application.
Typical Supply Range of ASTM A335 P5 Pipes
| Parameter | Available Range |
|---|---|
| Outside Diameter | 21–509 mm |
| Wall Thickness | 2.1–20 mm |
| Length | 6 m, 9–12 m or specified length |
| Schedules | SCH 40, SCH 80, SCH 120, SCH 160, STD, XS and project-specified walls |
| Ends | Plain, beveled or threaded |
| Surface | Black, shot-blasted, machined or protected with temporary anti-rust coating |
| Packing | Steel-banded bundles, wooden crates or project-specific packing |
The above figures represent a typical commercial supply range rather than the dimensional limits of ASTM A335.
Inspection and Testing
ASTM A335 P5 pipe is subject to material, mechanical and nondestructive examination requirements.
Standard Inspection Items
- Heat chemical analysis
- Product analysis when required
- Tensile testing
- Flattening or bend testing, as applicable
- Hardness testing
- Dimensional inspection
- Visual surface inspection
- Hydrostatic testing
- Nondestructive examination
Each pipe must be examined using an accepted nondestructive examination method in accordance with the applicable standard requirements.
Additional Project Tests
The following inspections can be specified when required:
- Ultrasonic testing
- Eddy-current testing
- Magnetic-flux-leakage testing
- Positive material identification
- Magnetic particle testing of pipe ends
- Hardness mapping
- Metallographic examination
- Additional product analysis
- Third-party inspection
- Supplementary tests under ASTM A335
Optional tests and supplementary requirements must be clearly identified in the enquiry and purchase order.
Hydrostatic and Nondestructive Examination
Each length of ASTM A335 P5 pipe is required to undergo a hydrostatic test. Each pipe must also be examined by an applicable nondestructive examination method within the dimensional limitations of that method.
The inspection method and acceptance criteria should be stated in:
- The material specification
- ASTM A999/A999M general requirements
- The purchase order
- The project inspection and test plan
Marking and Traceability
Pipe marking should include, as applicable:
- Manufacturer’s name or trademark
- ASTM A335/A335M
- Grade P5
- Pipe size and wall thickness or schedule
- Heat number
- Manufacturing identification
- Hot-finished or cold-finished condition when required
- Additional project markings
Marking must maintain traceability between the finished pipe, heat number and material test certificate.
Applications of ASTM A335 P5 Pipe
ASTM A335 P5 seamless alloy steel pipe is commonly used in:
Refineries
- High-temperature process piping
- Furnace and heater piping
- Hydrocarbon transfer lines
- Crude and vacuum units
- High-temperature sulfur-containing service
- Process headers
Petrochemical Plants
- Reactor piping
- High-temperature transfer systems
- Process heater lines
- Hot-gas and hot-oil systems
- Chemical process piping
Power and Boiler Systems
- Boiler piping
- Steam piping
- High-temperature headers
- Heat-recovery systems
- Auxiliary pressure piping
Industrial Pressure Systems
- High-temperature pressure lines
- Process equipment connections
- Compressor and pump piping
- Heat-treatment and thermal-processing systems
Actual suitability depends on the design code, allowable stress, process medium, operating temperature and corrosion conditions.
Welding and Fabrication
ASTM A335 P5 pipe is suitable for fusion welding, but welding must be performed using a qualified procedure.
Important fabrication considerations include:
- Correct filler-metal selection
- Qualified WPS and PQR
- Controlled preheating
- Interpass-temperature control
- Hydrogen-controlled consumables
- Post-weld heat treatment where required
- Hardness control
- Suitable nondestructive examination
Welding and heat-treatment requirements depend on the pipe thickness, joint design, service environment and applicable construction code.
ASTM A335 P5 vs ASME SA335 P5
| Item | ASTM A335 P5 | ASME SA335 P5 |
|---|---|---|
| Issuing Organization | ASTM International | ASME |
| Designation | A335/A335M P5 | SA-335 P5 |
| Product Form | Seamless ferritic alloy steel pipe | Seamless ferritic alloy steel pipe |
| Primary Use | High-temperature piping | ASME code pressure piping and equipment |
| Material Grade | 5Cr-0.5Mo P5 | 5Cr-0.5Mo P5 |
ASME SA335 is the ASME-adopted material specification used within the ASME Boiler and Pressure Vessel Code framework.
The required designation and edition should be stated in the purchase order, particularly when the material will be used for ASME-certified construction.
ASTM A335 P5 vs P9
| Property | ASTM A335 P5 | ASTM A335 P9 |
|---|---|---|
| Chromium | 4.00–6.00% | 8.00–10.00% |
| Molybdenum | 0.45–0.65% | 0.90–1.10% |
| Common Name | 5Cr-0.5Mo | 9Cr-1Mo |
| Relative Oxidation Resistance | Higher than lower-Cr Cr-Mo grades | Higher than P5 |
| Grade Selection | Based on design and process conditions | Based on design and process conditions |
P9 is not automatically a substitute for P5. Material substitution requires engineering approval because allowable stresses, welding procedures, heat treatment and service behavior differ.
Ordering Information
A complete enquiry should include:
- Standard and required edition
- ASTM A335 P5 or ASME SA335 P5 designation
- Quantity or total length
- NPS or outside diameter
- Schedule or wall thickness
- Hot-finished or cold-finished condition
- Random or fixed length
- End finish
- Heat-treatment condition
- Inspection and testing requirements
- Supplementary requirements
- Material certificate type
- Third-party inspection requirements
- Packing and marking instructions
Ordering Example
Product: Seamless ferritic alloy steel pipe
Standard: ASTM A335/A335M
Grade: P5
Size: NPS 6
Wall Thickness: SCH 120
Length: 9–12 m
Ends: Beveled ends
Quantity: 120 m
Testing: Hydrostatic test and nondestructive examination
Certification: EN 10204 Type 3.1
Frequently Asked Questions
What is ASTM A335 P5 pipe?
ASTM A335 P5 is a seamless ferritic alloy steel pipe containing approximately 5% chromium and 0.5% molybdenum. It is intended for high-temperature pressure-piping applications.
Is ASTM A335 P5 the same as ASME SA335 P5?
They identify the same general P5 material grade and product form. ASTM A335 is issued by ASTM International, while SA335 is the ASME-adopted specification used in ASME code construction.
The required designation and edition must be confirmed in the purchase order.
Is ASTM A335 P5 seamless or welded?
ASTM A335 covers seamless pipe only. A welded pipe should not be certified as ASTM A335.
What is the chromium content of P5?
ASTM A335 P5 contains 4.00–6.00% chromium and 0.45–0.65% molybdenum.
Can ASTM A335 P5 pipe be welded?
Yes. P5 is suitable for fusion welding, but the welding procedure, filler metal, preheat and post-weld heat treatment must comply with the applicable construction code and project requirements.
What industries use P5 pipe?
P5 pipe is commonly used in refineries, petrochemical plants, boilers, power stations and high-temperature industrial pressure-piping systems.
Does every P5 pipe require testing?
Yes. ASTM A335 requires chemical and mechanical verification, hydrostatic testing and applicable nondestructive examination. Additional tests may be specified by the purchaser.
