Caps
Alloy Steel Caps are butt-welding pipe fittings used to seal the end of a piping system or pressure vessel. Manufactured to ASTM A234 / ASME SA234, these caps are designed for high-temperature and high-pressure service in refinery, petrochemical, power generation and hydrogen-related process piping.
Product Overview
Alloy Steel Caps are butt-welding pipe fittings used to seal the end of a piping system or pressure vessel. Manufactured to ASTM A234 / ASME SA234, these caps are designed for high-temperature and high-pressure service in refinery, petrochemical, power generation and hydrogen-related process piping.
Hongcheng supplies alloy steel caps in chromium-molybdenum grades including WP11, WP5 and WP91, which are commonly specified together with ASTM A335 alloy steel pipes and ASTM A234 alloy steel fittings of corresponding material grades. Each product form is governed by its respective ASTM / ASME material specification, while caps provide a pressure-tight termination for the pipeline.
Hongcheng delivers 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 Grades
Alloy steel caps are available in the following grades:
• A234 WP11 Alloy Steel Cap – 1.25Cr-0.5Mo alloy steel grade for high-temperature service.
• A234 WP5 Alloy Steel Cap – 5Cr-0.5Mo alloy steel grade for high-temperature refinery and petrochemical service.
• A234 WP91 Alloy Steel Cap – 9Cr-1Mo-V alloy steel grade for high-temperature and high-pressure steam service.
Material selection depends on operating conditions, design requirements and applicable project specifications.
Manufacturing Process
Raw Material Inspection → Cutting → Forming / Hot Pressing → Sizing & Calibration → Heat Treatment → End Beveling → Inspection & Testing → Marking → Packing
Seamless or welded construction may be supplied according to size, manufacturing process and applicable specifications. Heat treatment is performed according to the applicable ASTM A234 / ASME SA234 requirements, qualified manufacturing procedures and purchaser specifications. Typical processing may include normalizing, tempering or other treatments specified by the material grade and applicable standard.
Technical Parameters
|
Parameter |
Specification |
|
Product |
Alloy Steel Cap / Pipe Cap |
|
Material Grades |
ASTM A234 WP11 / WP5 / WP91 |
|
Manufacturing Standard |
ASTM A234 / ASME SA234 |
|
Construction |
Seamless or welded construction, subject to size, manufacturing process and applicable specifications |
|
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 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
Alloy steel caps are commonly used in:
• Refinery Process Piping
• Hydrogenation Units and Hydrocrackers
• Catalytic Reformer Systems
• Power Generation and High-Temperature Steam Piping
• Boiler and Steam Piping Systems
• Petrochemical High-Temperature Reactors
• Pipeline Termination and Pressure Vessel Closures
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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 WP11, WP5 and WP91 caps?
WP11, WP5 and WP91 are different chromium-molybdenum alloy steel grades specified under ASTM A234. WP11 is commonly used in high-temperature process piping, WP5 is used in high-temperature refinery and petrochemical applications, and WP91 is commonly used for high-temperature and high-pressure steam service. Material selection must be based on operating conditions and project specifications.
Are alloy steel 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 requirements.
What post-weld heat treatment is required for alloy steel caps?
PWHT may be required depending on the applicable construction code, wall thickness, welding procedure and project requirements. Where welding is required, alloy steel 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 alloy steel caps according to customer drawings and technical specifications, including custom wall thickness, end preparation and marking requirements.
What standards are supported?
Alloy steel 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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