ASTM A234 WP91 Caps | SA234 WP91 Pipe Caps Manufacturer & Exporter | ASME B16.9

We are a professional manufacturer and exporter of ASTM A234 / ASME SA234 WP91 Pipe Caps and X10CrMoVNb9-1 Alloy Steel Caps in China. Our high-temperature chrome moly alloy steel pipe fittings are widely used in power plants, petrochemical industries, refineries, pressure vessels, and boiler piping systems.

An ASTM A234 WP91 cap ,functionally like the A182 F91 Blind flanges  Butt welded chome moly steel fitting designed to seal the end of a pipe run in high-temperature applications. WP91 offers enhanced strength and creep resistance at temperatures up to 750 °F (400 °C).

What Is ASTM A234 WP91 Pipe Cap?

ASTM A234 WP91 Pipe Cap is a butt weld alloy steel fitting designed to close the end of a piping system in high-temperature and high-pressure service conditions. Similar in function to A182 F91 blind flanges, WP91 caps provide excellent creep strength, oxidation resistance, and long-term thermal stability.

SA234 WP91 is a ferritic alloy steel commonly referred to as 9Cr-1Mo-V steel. It is engineered for elevated temperature service and offers superior mechanical strength that remains stable over long operating periods.

Equivalent Grades:

• ASTM A335 P91
• ASTM A213 T91
• UNS K90901
• X10CrMoVNb9-1
• EN 1.4903

Our ASTM A234 WP91 Caps are manufactured as seamless fittings and hot formed from ASME SA387 Grade 91 steel plates in accordance with ASME and ASTM standards.

ASTM A234 WP91 Caps Specifications

• Standard: ASTM A234 / ASME SA234
• Manufacturing Standards: ASME B16.9, ASME B16.28, MSS SP-43
• Product Type: Butt Weld Pipe Caps
• Type: Seamless
• Size Range: NPS 1/2″ to 48″ (DN15 to DN1200)
• Wall Thickness: SCH 10 to XXS
• Ends: Bevel Ends according to ASME B16.25
• Material Grade: WP91 / F91 / X10CrMoVNb9-1
• Certifications: EN 10204 3.1 / 3.2 MTC
• Inspection: Radiographic Testing (RT), Ultrasonic Testing (UT), PMI available
• Surface Finish: Plain / Black Painted / Anti-rust Oil
• Packing: Fumigation-free wooden cases or export seaworthy packing
• Origin: China

ASTM A234 WP91 Caps Chemical Composition (%)

ASTM A234 WP91 Pipe Fittings Mechanical Properties

Heat Treatment for ASTM A234 WP91 Pipe Fittings

ASTM A234 WP91 alloy steel pipe fittings shall be heat treated after forming to ensure proper mechanical properties and creep resistance.

• Normalizing Temperature: 1900°F (1040°C) minimum to 1975°F (1080°C) maximum
• Tempering Temperature: 1350°F (730°C) to 1470°F (800°C)

After hot forming, fittings shall be cooled under controlled conditions to avoid defects caused by rapid cooling.

Inspection & Testing for A234 WP91 Pipe Caps

All ASTM A234 WP91 pipe fittings undergo strict quality control and inspection procedures, including:

• Dimensional Inspection
• Visual Examination
• Positive Material Identification (PMI)
• Liquid Penetrant Testing (PT)
• Magnetic Particle Examination (MT)
• Ultrasonic Testing (UT)
• Eddy Current Testing
• Hardness Testing
• Radiographic Testing (RT)

Third-party inspection can be arranged upon request.

Applications of ASTM A234 WP91 Pipe Caps

ASTM A234 WP91 Caps are widely used in:

• Thermal Power Plants
• Superheater & Reheater Systems
• Petrochemical Plants
• Refineries
• High Pressure Steam Pipelines
• Boiler Systems
• Heat Exchangers
• Oil & Gas Industries

Why Choose Our ASTM A234 WP91 Caps?

• Professional manufacturer and exporter in China
• Competitive factory direct prices
• Large stock for standard sizes
• Fast delivery time
• Complete EN 10204 3.1 certification
• Strict quality inspection
• OEM & customized dimensions available
• Exported to Europe, Middle East, Southeast Asia, and South America

How to Order ASTM A234 WP91 Pipe Caps?

Example:

6″ Pipe Cap, SCH160, ASTM A234 WP91, Seamless, ASME B16.9, Bevel Ends according to ASME B16.25

When sending inquiries, please specify:

• Size
• Wall Thickness
• Material Grade
• Standard
• Quantity
• End Type
• Inspection Requirements