ASTM A234 WP11 Buttweld Pipe Fittings
We manufacture and supply ASTM A234 WP11 buttweld pipe fittings for refinery, petrochemical, power-generation, steam and elevated-temperature process piping systems.
Our product range includes ASTM A234 WP11 elbows, tees, reducers, caps and return bends manufactured in accordance with the applicable requirements of ASTM A234/A234M and dimensional standards such as ASME B16.9.
Both ASTM A234 WP11 Class 1 and ASTM A234 WP11 Class 2 pipe fittings can be supplied according to the specified dimensions, wall thickness, heat treatment, inspection and certification requirements.
ASTM A234 WP11 Pipe Fitting Specifications
| Item | Specification |
|---|---|
| Material standard | ASTM A234/A234M |
| ASME material designation | ASME SA-234/SA-234M |
| Grade | WP11 |
| Available classes | WP11 Class 1 and WP11 Class 2 |
| Alloy type | Chromium-molybdenum alloy steel |
| Dimensional standard | ASME B16.9 |
| Product type | Factory-made wrought buttweld fittings |
| Construction | Seamless or welded |
| Products | Elbow, tee, reducer, cap and return bend |
| End preparation | Beveled ends for butt welding |
| Size range | Standard and customized sizes |
| Wall thickness | SCH 10 to SCH XXS or specified wall thickness |
| Certification | Material Test Report and EN 10204 Type 3.1 |
| Inspection | Mill inspection or third-party inspection |
| Marking | ASTM, ASME and purchase-order requirements |
| Packaging | Export wooden cases or customized packaging |
Actual manufacturing availability depends on the fitting type, diameter, wall thickness, construction method, quantity and project requirements.
What Is ASTM A234 WP11?
ASTM A234 WP11 is a wrought chromium-molybdenum alloy steel grade used for piping fittings in moderate- and elevated-temperature pressure systems.
WP11 is commonly described as a 1.25Cr-0.5Mo alloy steel because it contains approximately 1.00–1.50% chromium and 0.44–0.65% molybdenum.
The chromium and molybdenum additions provide:
- Improved elevated-temperature strength
- Better oxidation resistance than carbon steel
- Improved resistance to high-temperature degradation
- Suitable performance in steam and hot hydrocarbon systems
- Compatibility with selected P11 alloy steel piping systems
ASTM A234 WP11 fittings are frequently installed with materials such as:
- ASTM A335 P11 alloy steel pipe
- ASTM A182 F11 forged flanges
- ASTM A182 F11 forged fittings and valves
- ASTM A193 B7 or project-specified bolting
Material compatibility, pressure-temperature ratings and welding procedures must be verified by the piping designer before components are combined in a pressure system.
ASTM A234 WP11 vs ASME SA-234 WP11
ASTM A234/A234M is the ASTM material specification for wrought carbon steel and alloy steel piping fittings used in moderate- and elevated-temperature service.
ASME SA-234/SA-234M is the corresponding material specification adopted within the ASME Boiler and Pressure Vessel Code.
| Item | ASTM A234 WP11 | ASME SA-234 WP11 |
|---|---|---|
| Issuing organization | ASTM International | ASME |
| Product | Wrought alloy steel piping fittings | Wrought alloy steel piping fittings |
| Material grade | WP11 | WP11 |
| Typical use | Industrial pressure piping | ASME boilers and pressure equipment |
| Main consideration | Applicable ASTM edition | Applicable ASME edition and construction code |
The specifications are closely related, but the purchaser should clearly state whether ASTM A234 WP11 or ASME SA-234 WP11 is required.
Material substitution should only be made when permitted by the project specification and governing design code.
ASTM A234 and ASME B16.9
ASTM A234 and ASME B16.9 perform different functions and should not be treated as interchangeable standards.
| Standard | Main Requirement |
|---|---|
| ASTM A234/A234M | Material grade, manufacturing, heat treatment, chemical composition, mechanical properties and testing |
| ASME SA-234/SA-234M | ASME-adopted material specification |
| ASME B16.9 | Dimensions, tolerances, ratings, testing and marking of factory-made wrought buttweld fittings |
| ASTM A960/A960M | Common requirements for wrought steel piping fittings |
A typical purchase description should therefore include both the material specification and dimensional standard.
Ordering Example
ASTM A234/A234M WP11 Class 2, 90° Long Radius Elbow, NPS 8, SCH 80, Seamless, ASME B16.9, Beveled Ends, EN 10204 3.1.
ASTM A234 WP11 Class 1 vs Class 2
WP11 pipe fittings may be specified in different strength classes.
| Comparison | WP11 Class 1 | WP11 Class 2 |
|---|---|---|
| Material family | 1.25Cr-0.5Mo alloy steel | 1.25Cr-0.5Mo alloy steel |
| Carbon range | Lower maximum carbon | Higher permitted maximum carbon |
| Minimum tensile strength | 415 MPa | 485 MPa |
| Minimum yield strength | 205 MPa | 275 MPa |
| General characteristic | Lower specified strength level | Higher specified strength level |
| Purchase requirement | Class must be stated | Class must be stated |
| Substitution | Requires approval | Requires approval |
The applicable class affects mechanical-property requirements and may affect the required manufacturing and heat-treatment process.
The purchase order must clearly identify the required class.
Chemical Composition of ASTM A234 WP11
| Element | WP11 Class 1 | WP11 Class 2 |
|---|---|---|
| Carbon, C | 0.05–0.15% | 0.05–0.20% |
| Manganese, Mn | 0.30–0.60% | 0.30–0.80% |
| Phosphorus, P | 0.030% maximum | 0.040% maximum |
| Sulfur, S | 0.030% maximum | 0.040% maximum |
| Silicon, Si | 0.50–1.00% | 0.50–1.00% |
| Chromium, Cr | 1.00–1.50% | 1.00–1.50% |
| Molybdenum, Mo | 0.44–0.65% | 0.44–0.65% |
The actual heat analysis should be reported in the Material Test Report and verified against the edition of ASTM A234/A234M specified in the purchase order.
Mechanical Properties
| Mechanical Property | WP11 Class 1 | WP11 Class 2 |
|---|---|---|
| Tensile strength | 415–585 MPa | 485–655 MPa |
| Yield strength, minimum | 205 MPa | 275 MPa |
Mechanical-property acceptance must be based on the applicable specification edition, fitting condition, heat treatment and test requirements stated in the purchase order.
Heat Treatment
ASTM A234 WP11 fittings must be supplied in the heat-treated condition required by the applicable material specification, fitting class, wall thickness and manufacturing process.
Depending on the product and applicable requirements, heat treatment may include:
- Normalizing
- Normalizing and tempering
- Quenching and tempering
- Other approved heat-treatment cycles
Heat-treatment parameters must be controlled to achieve the required microstructure and mechanical properties.
Heat-treatment records can be supplied when specified in the purchase order.
ASTM A234 WP11 Elbows
We manufacture and supply the following WP11 buttweld elbows:
- ASTM A234 WP11 45° elbow
- ASTM A234 WP11 90° long-radius elbow
- ASTM A234 WP11 90° short-radius elbow
- ASTM A234 WP11 180° return bend
- Customized-angle WP11 elbow
WP11 Long-Radius Elbow
A long-radius elbow generally has a centerline radius equal to 1.5 times the nominal pipe size.
Long-radius elbows are widely used because they provide a smoother change in flow direction and generally produce lower pressure loss than short-radius elbows.
WP11 Short-Radius Elbow
A short-radius elbow generally has a centerline radius equal to the nominal pipe size.
It is commonly considered where installation space is limited, subject to the piping design and project specification.
ASTM A234 WP11 Tees
Available WP11 tee products include:
- ASTM A234 WP11 equal tee
- ASTM A234 WP11 reducing tee
- Seamless buttweld tee
- Welded buttweld tee
- Customized branch fittings
An equal tee has the same nominal size at the run and branch connections.
A reducing tee has a branch connection smaller than the main run and is used where the branch pipe diameter differs from the header diameter.
The branch reinforcement, wall thickness, dimensions and manufacturing method must comply with the applicable design and purchase requirements.
ASTM A234 WP11 Reducers
We supply:
- ASTM A234 WP11 concentric reducer
- ASTM A234 WP11 eccentric reducer
- Seamless WP11 reducer
- Welded WP11 reducer
- Customized reducers according to project drawings
Concentric Reducer
A concentric reducer maintains a common centerline between the larger and smaller pipe ends.
It is commonly used in vertical piping and other systems where centered flow transition is required.
Eccentric Reducer
An eccentric reducer has offset centerlines and is commonly used in horizontal piping.
Depending on installation orientation, it can help prevent vapor pockets or liquid accumulation in pump suction and process piping.
ASTM A234 WP11 Caps and Return Bends
WP11 Pipe Cap
A WP11 pipe cap is used to close the end of an alloy steel piping system.
Available caps can be supplied according to ASME B16.9 dimensions or project-specific drawings.
WP11 Return Bend
A 180° return bend changes the piping direction by approximately 180 degrees.
Return bends are commonly used in heater coils, process piping, heat-transfer systems and compact piping layouts.
Size and Wall-Thickness Range
Standard ASME B16.9 Fittings
ASME B16.9 covers factory-made wrought buttweld fittings from NPS 1/2 through NPS 48.
Standard products can be supplied in wall thicknesses corresponding to the connected pipe, including:
- SCH 10
- SCH 20
- SCH 30
- SCH 40
- SCH 60
- SCH 80
- SCH 100
- SCH 120
- SCH 140
- SCH 160
- STD
- XS
- XXS
- Customized wall thickness
Buttweld fittings are normally specified by nominal pipe size and matching pipe wall thickness rather than by a separate pressure class.
Manufacturing Range
Our typical manufacturing range includes:
| Construction | Typical Supply Range |
|---|---|
| Seamless buttweld fittings | NPS 1/2 to NPS 24 |
| Welded buttweld fittings to ASME B16.9 | NPS 1/2 to NPS 48 |
| Large fabricated fittings | Up to NPS 72, subject to drawing and project specification |
Fittings larger than the standard dimensional range should not be described as standard ASME B16.9 products unless their dimensions and compliance have been specifically agreed.
Large-diameter fittings may be manufactured according to approved drawings, MSS requirements or project specifications.
Manufacturing Methods
ASTM A234 WP11 fittings may be manufactured from suitable:
- Seamless alloy steel pipe
- Welded alloy steel pipe
- Plate
- Forgings
- Tubular products
Common manufacturing processes include:
- Hot forming
- Cold forming followed by heat treatment
- Forging
- Extrusion
- Mandrel forming
- Press forming
- Welding and fabrication
Elbows, return bends and tees must not be represented as products machined directly from solid bar stock.
The manufacturing route should provide a sound fitting with the required dimensions, mechanical properties and material traceability.
Inspection and Testing
Inspection is performed according to ASTM A234/A234M, ASTM A960/A960M, ASME B16.9 and the agreed purchase specification.
Standard Inspection
Inspection may include:
- Heat chemical analysis
- Mechanical-property testing
- Dimensional inspection
- Wall-thickness measurement
- Visual and surface inspection
- Heat-treatment verification
- Marking verification
- Material traceability review
- Material Test Report review
Optional Inspection
The following inspection and testing can be arranged when specified:
- Positive Material Identification
- Ultrasonic examination
- Radiographic examination of welds
- Magnetic particle examination
- Liquid penetrant examination
- Hardness testing
- Additional product analysis
- Independent third-party inspection
- Customized Inspection and Test Plan
- Pre-shipment inspection
Not every inspection method is mandatory for every fitting.
The required examination must be stated in the purchase order and should reflect the fitting construction, dimensions, service conditions and project specification.
Material Certification
ASTM A234 WP11 pipe fittings can be supplied with:
- Manufacturer’s Material Test Report
- EN 10204 Type 3.1 inspection certificate
- EN 10204 Type 3.2 inspection document when specifically arranged
- Chemical-composition results
- Mechanical-property results
- Heat-treatment records
- Nondestructive examination reports
- Dimensional inspection reports
- Third-party inspection release notes
- Country-of-origin documentation
All products should maintain traceability between the fitting, heat number, production records and inspection documentation.
Marking
Product marking can include:
- Manufacturer identification
- ASTM A234 or ASME SA-234
- WP11 material grade
- Class 1 or Class 2
- Nominal pipe size
- Wall thickness or schedule
- Seamless or welded construction
- Heat number
- Applicable dimensional standard
- Purchaser’s identification
- Additional project markings
Marking methods may include stamping, low-stress stamping, paint stenciling or other methods specified by the purchaser.
Packaging
Standard export packaging includes:
Applications of ASTM A234 WP11 Pipe Fittings
ASTM A234 WP11 fittings are commonly used in:
- Oil refineries
- Petrochemical plants
- Power-generation facilities
- Steam piping systems
- High-temperature process piping
- Heat exchangers
- Boilers and related piping
- Hot-oil systems
- Hydrocarbon-processing equipment
- Chemical-processing plants
- Pressure-vessel piping connections
WP11 material should only be selected after reviewing the design temperature, pressure, process medium, corrosion allowance, welding requirements and applicable design code.
Welding Considerations
WP11 is a chromium-molybdenum alloy steel and requires a properly qualified welding procedure.
The welding plan should consider:
- Base-material class
- Filler-metal selection
- Preheat temperature
- Interpass-temperature control
- Hydrogen control
- Post-weld heat treatment
- Joint thickness
- Hardness control
- Applicable construction code
- Required nondestructive examination
Welding and heat-treatment requirements must be determined by the equipment designer or welding engineer.
ASTM A234 WP11 vs WP22
| Comparison | WP11 | WP22 |
|---|---|---|
| General alloy system | Approximately 1.25Cr-0.5Mo | Approximately 2.25Cr-1Mo |
| Chromium content | Lower | Higher |
| Molybdenum content | Lower | Higher |
| Elevated-temperature capability | Suitable for selected elevated-temperature service | Generally selected for more demanding elevated-temperature service |
| Typical matching pipe | ASTM A335 P11 | ASTM A335 P22 |
| Typical matching flange | ASTM A182 F11 | ASTM A182 F22 |
WP11 and WP22 are not automatically interchangeable.
The correct material must be selected according to allowable stress, design temperature, process conditions, corrosion environment and project specifications.
How to Order ASTM A234 WP11 Fittings
A complete inquiry should include:
- Material specification
- WP11 class
- Fitting type
- Nominal pipe size
- Wall thickness or pipe schedule
- Seamless or welded construction
- Dimensional standard
Ordering Example 1
ASTM A234/A234M WP11 Class 1
Product: 90° Long-Radius Elbow
Size: NPS 6
Wall Thickness: SCH 40
Construction: Seamless
Dimensions: ASME B16.9
Ends: Beveled
Certificate: EN 10204 Type 3.1
Quantity: 20 pieces
Ordering Example 2
ASME SA-234/SA-234M WP11 Class 2
Product: Equal Tee
Size: NPS 10
Wall Thickness: SCH 80
Construction: Welded or seamless as specified
Dimensions: ASME B16.9
Inspection: PMI and third-party inspection
Quantity: As required
Frequently Asked Questions
What is ASTM A234 WP11?
ASTM A234 WP11 is a chromium-molybdenum alloy steel grade for wrought piping fittings used in moderate- and elevated-temperature pressure systems.
What products are available in ASTM A234 WP11?
Common products include 45° elbows, 90° long-radius elbows, short-radius elbows, 180° return bends, equal tees, reducing tees, concentric reducers, eccentric reducers and pipe caps.
What is the difference between WP11 Class 1 and Class 2?
Both classes belong to the same general chromium-molybdenum alloy family, but Class 2 has higher specified minimum tensile and yield strength.
The required class must be stated in the purchase order.
Is ASTM A234 WP11 the same as ASME SA-234 WP11?
ASME SA-234/SA-234M is the ASME-adopted material specification corresponding to ASTM A234/A234M.
The required designation and applicable edition should be confirmed from the project specification.
Does ASME B16.9 specify the WP11 material?
No. ASME B16.9 mainly specifies dimensions, tolerances, ratings, testing and marking for factory-made wrought buttweld fittings.
ASTM A234 or ASME SA-234 specifies the WP11 material requirements.
Are WP11 fittings seamless or welded?
WP11 fittings may be manufactured in seamless or welded construction, depending on the fitting type, dimensions, manufacturing route and purchase specification.
Can WP11 fittings be supplied with EN 10204 Type 3.1 certification?
Yes. Material Test Reports and EN 10204 Type 3.1 inspection certificates can be supplied when required by the purchase order.
Can third-party inspection be arranged?
Yes. Third-party inspection can be arranged according to an agreed Inspection and Test Plan.
ASTM A234 WP11 Pipe Fitting Supplier
We supply ASTM A234 WP11 Class 1 and Class 2 buttweld fittings for refinery, petrochemical, power-generation and elevated-temperature piping projects.
Our product range includes:
- WP11 elbows
- WP11 tees
- WP11 reducers
- WP11 pipe caps
- WP11 return bends
- Seamless and welded fittings
- Standard and customized dimensions
For quotation, provide the required standard, class, fitting type, nominal size, wall thickness, quantity, inspection and certification requirements.
