Caps
A234 WP91 Alloy Steel Cap is a 9Cr-1Mo-V-Nb alloy steel butt-weld pipe fitting manufactured to ASTM A234 / ASME SA234, used to seal the end of a piping system. Hongcheng manufactures and supplies WP91 alloy steel caps for power generation, high-temperature steam piping, hydrogen processing and other elevated-temperature, high-pressure industrial piping applications.
Product Overview
A234 WP91 Alloy Steel Cap is a 9Cr-1Mo-V-Nb alloy steel butt-weld pipe fitting manufactured to ASTM A234 / ASME SA234, used to seal the end of a piping system. Hongcheng manufactures and supplies WP91 alloy steel caps for power generation, high-temperature steam piping, hydrogen processing and other elevated-temperature, high-pressure industrial piping applications.
ASTM A234 WP91 is the wrought alloy steel fitting grade associated with the P91 alloy system. ASTM A335 P91 applies to seamless ferritic alloy-steel pipe, while ASTM A234 WP91 applies to wrought butt-welding fittings. These grades are commonly specified together in high-temperature and high-pressure piping systems, while each product form is controlled by its respective ASTM / ASME material specification.
Hongcheng supplies WP91 alloy steel caps with heat treatment performed in accordance with applicable material specifications and purchaser requirements. Full material traceability, inspection documentation and project-specific technical support are available. Custom wall thickness, end preparation and marking can be supplied according to project drawings and specifications.
Material & Heat Treatment
A234 WP91 is a 9Cr-1Mo-V-Nb alloy steel grade containing Chromium (Cr), Molybdenum (Mo), Vanadium (V), Niobium (Nb), Manganese (Mn), Silicon (Si) and Carbon (C) within the limits specified by the applicable material standard.
Chromium, molybdenum and vanadium contribute to the material's elevated-temperature mechanical properties and creep strength. Material suitability for hydrogen service depends on operating conditions, design requirements and applicable project specifications.
Heat treatment is performed according to the applicable ASTM A234 / ASME SA234 requirements, qualified manufacturing procedures and purchaser specifications. Actual heat-treatment conditions depend on the applicable material specification, product size, manufacturing route and project requirements.
Manufacturing Process
Raw Material Inspection → Cutting → Forming / Hot Pressing → Sizing & Calibration → Heat Treatment → End Beveling → Inspection & Testing → Marking → Packing
Formed construction is supplied according to product size, manufacturing route and applicable specifications. Welded construction may be supplied for applicable sizes and designs according to project requirements.
Hongcheng controls forming, heat treatment, dimensional accuracy and inspection throughout the manufacturing process to meet applicable standards and purchaser specifications.
Technical Parameters
|
Parameter |
Specification |
|
Product |
A234 WP91 Alloy Steel Cap |
|
Material Standard |
ASTM A234 / ASME SA234 |
|
Material Grade |
WP91 (9Cr-1Mo-V-Nb) |
|
Construction |
Formed construction; welded construction may be supplied for applicable sizes and designs according to project requirements |
|
End Preparation |
Butt-Welding Ends, ASME B16.25 |
|
Dimensional Standard |
ASME B16.9 where applicable |
|
Size Range |
NPS 1/2–48 (DN15–DN1200), subject to size, applicable standard and manufacturing capability |
|
Wall Thickness |
SCH 40, SCH 80, SCH 160, XXS and Custom |
|
Heat Treatment |
According to applicable ASTM A234 / ASME SA234 requirements |
|
Surface |
Black Painted / Anti-Rust Oil / Natural Finish |
|
MTC |
EN 10204 3.1 available |
|
Customization |
Custom Wall Thickness, End Preparation and Marking Available |
Inspection & Testing
Inspection and testing are performed according to ASTM A234 / ASME SA234, applicable dimensional standards and purchaser requirements.
Available inspection and testing services may include:
EN 10204 Type 3.1 Material Test Certificates (MTC) can be provided according to purchase requirements. Third-party inspection and additional NDT are available upon request.
Applications
A234 WP91 alloy steel caps are commonly used in:
• Power Generation and High-Temperature Steam Piping
• Ultra-Supercritical and Supercritical Boiler Systems
• Refinery Process Piping
• Hydrogen Processing and High-Temperature Process Service
• Petrochemical High-Temperature Reactors
• High-Temperature Piping Systems
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Projects of Caps
Power Plant Projects
Products: P91 Pipes · P92 Pipes · Pipe Fittings · Pipe Spools
FAQs
What is the difference between WP91 and P91?
WP91 and P91 refer to related grades within the same 9Cr-1Mo-V-Nb alloy system, but they are specified under different ASTM product standards. ASTM A335 P91 is used for seamless alloy steel pipe, while ASTM A234 WP91 is used for wrought butt-welding fittings. They are commonly specified together in high-temperature and high-pressure piping systems.
Are WP91 caps suitable for hydrogen service?
Material suitability for hydrogen service depends on operating conditions, design requirements, material compatibility and applicable project specifications. The selected grade should be confirmed against the applicable design code and project specifications.
What post-weld heat treatment is required for WP91 caps?
PWHT may be required depending on the applicable construction code, wall thickness, welding procedure and project requirements. Where welding is required, WP91 caps should be welded using qualified procedures with preheating and PWHT applied as required by the applicable code and project specifications.
Can custom wall thickness and end preparation be supplied?
Yes. Hongcheng can manufacture custom WP91 alloy steel caps according to customer drawings and technical specifications, including custom wall thickness, end preparation and marking requirements.
What standards are supported?
A234 WP91 caps can be supplied according to ASTM A234 / ASME SA234, with dimensional requirements based on ASME B16.9 and butt-welding end preparation according to ASME B16.25, where applicable.
Wuliyao Industrial Zone, Yanshan County, Cangzhou City, Hebei Province, China.
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