In December 2025, one of our regular clients placed new order to us. This order covers most of our business scope from butt-weld steel fittings, flanges, stud bolts and nuts and so on. This page is concentrate on flange items which are both in ASTM A694 F52 material, following ASME B16.5 standard and with Class 2500 pressure.

ASME B16.5 Flanges Order List

ASME B16.5 Standard Overview

ASME B16.5 is the American standard for pipe flanges and flanged fittings, covering sizes NPS ½ to 24″. It standardizes dimensions, materials, pressure-temperature ratings, marking, and testing for steel flanges. This standard ensures safety and interchangeability in piping systems across industries.

ASME B16.5 Covered Pressure Classes

The standard defines seven standard pressure classes, indicating a flange’s pressure-containing capability at specified temperatures. These classes are designated in pound ratings: 

• Class 150, 300, 400 – Low to medium pressure
• Class 600, 900, 1500 – High pressure
• Class 2500 – Very high pressure

Class ratings represent pressure capacity in PSI at specified temperatures. Higher classes have thicker dimensions and stronger construction.

B16.5 Covered Flange Types

ASME B16.5 primarily standardizes the following common flange types:

• Weld Neck Flange
• Slip-On Flange
• Socket Weld Flange
• Threaded Flange
• Lap Joint Flange
• Blind Flange

ASME B16.5 Weld Neck Flanges

ASME B16.5 weld neck flange features a long, tapered hub for butt-welding to the pipe. They are designed for butt-welding to the pipe, providing excellent structural integrity and fatigue resistance. The long neck makes them ideal for high-pressure and extreme temperature applications.

B16.5 Weld Neck Flanges in Class 2500

ASME B16.5 Class 2500 weld neck flanges represent the highest pressure rating in the B16.5 standard, designed for extreme service conditions. Their robust construction, standardized dimensions, and reliable performance make them essential for critical high-pressure applications across multiple industries. Proper selection, installation, and maintenance ensure safe, long-lasting performance in demanding operational environments.

Advantages of Class 2500 Flanges

1. Extreme Pressure Containment
Withstands pressures up to 2500 PSI, making them suitable for critical high-pressure systems.

2. Superior Structural Integrity
The weld neck design provides optimal stress distribution, minimizing fatigue failure risk.

3. Leak Prevention
Precise machining and compatible gasket surfaces ensure reliable sealing under extreme conditions.

4. Temperature Versatility
Maintains performance across wide temperature ranges when properly specified.

5. Standardized Compatibility
ASME standardization ensures proper fit with valves, pumps, and other B16.5 components.

6. Reduced Turbulence
Smooth bore transition minimizes pressure drop and flow disturbance.

Inspections Photos

Applications

• Oil & Gas Industry
• Power Generation
• Chemical Processing
• Petrochemical
• Specialized Applications

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Hastelloy C276 is an alloy that stands out due to its unique combination of elements: its main components are nickel, molybdenum, and chromium, with trace amounts of iron, tungsten, cobalt, and other elements. This combination of elements gives Hastelloy C276 exceptional properties, which are extended to the flanges made from it. The two most commonly used thread standards globally are BSP and NPT threads. Although their purposes are similar, they have different characteristics and applications.

Specifications of Hastelloy C276 Flanges

Hastelloy C276 Flange Standards

Material Standards: ASTM B564 (forged flanges), UNS N10276, Werkstoff Nr. 2.4819, etc.

Dimension Standards:

ASME B16.5 (for pipe flanges and flange fittings from NPS 1/2“ to NPS 24”)

ASME B16.47 (for large-diameter steel flanges from NPS 26“ to NPS 60”)

EN 1092 (European flange standard)

DIN (German standard)

JIS (Japanese standard)

Common Types of Hastelloy C276 Flanges

Chemical Composition of ASME SB 564 N10276 Flanges

· High nickel (Ni) content: Ensures the stability of the alloy in reducing media, forming the foundation for corrosion resistance;

· Chromium (Cr): Provides oxidation resistance and corrosion resistance in oxidizing media (such as nitric acid);

· Molybdenum (Mo) + Tungsten (W): Significantly enhances resistance to localized corrosion (pitting corrosion, crevice corrosion), especially in chloride-containing environments;

· Low carbon (C): Prevents the formation of carbides between carbon and chromium, thereby preventing intergranular corrosion.

ASTM B564 Hastelloy C276 Mechanical Properties

Equivalent Grades of Hastelloy C276 Flanges

Key Features

✅ Exceptional corrosion resistance: exhibits outstanding resistance to strong oxidizing and reducing media such as hydrochloric acid, sulfuric acid, chlorides, and chlorine gas.

✅ Superior mechanical properties: maintains stable strength and toughness even under high-temperature, high-pressure conditions or in strongly acidic environments.

✅ Strong resistance to localized corrosion: Effectively resists pitting corrosion, crevice corrosion, and intergranular corrosion.

✅ Good weldability: Easy to process and weld, with no reduction in corrosion resistance in the welded area.

✅ High-temperature performance: Hastelloy C276 exhibits excellent stability, particularly maintaining strength and structural integrity at high temperatures around 700°C.

Hastelloy C276 Flanges Dimension

Application Scenarios

Hastelloy C276 flanges, renowned for their exceptional corrosion resistance, are primarily used in extreme environments where conventional materials cannot withstand the conditions. Typical applications include:

Chemical and Petrochemical Industries

Environmental Protection Industry

Pharmaceutical and Food Industries

Marine Engineering

Nuclear Industry

Installation and Maintenance Guidelines

Avoid contact between dissimilar metals: When in contact with metals of lower potential, such as carbon steel, galvanic corrosion may occur. Insulating gaskets (e.g., PTFE) or coatings should be used to isolate the metals;

Gaskets selection: Prioritize gaskets with matching corrosion resistance, such as PTFE or metal-backed gaskets, to prevent gasket material corrosion by the medium and subsequent leakage;

Cleaning and Pre-Treatment: Before installation, remove oil stains and oxide scale from the flange surface using a stainless steel wire brush or specialized cleaner to prevent impurities from affecting sealing performance;

Torque Control: Apply tightening torque according to flange specifications and pressure ratings in accordance with standards to avoid over-tightening, which can cause flange deformation or bolt breakage.

You can get an offer for products in below material forms:

-Pipe and Tube (EN 10216-5, ASTM A213, ASTM A249, A312, A790,)

-Forged Fitting and Flange (ASTM A182 , ASTM A105,ASTM B564 )

-Butt Weld Fittings (ASTM A234, ASTM A403,ASTM A815)

-Round bar , Billet (ASTM A276, ASTM A479)

– Plate, Sheet, Strip(ASTM A240, EN 10028-7, A480)

-Bolting, Nuts（ASTM A193, A194, A320）

Hastelloy C276 Flanges Exported Countries

We Export  Hastelloy C276 Flanges to Saudi Arabia, United Arab Emirates, Qatar, Bahrain, Oman, Kuwait, Turkey, Egypt, Yemen , Syria, Jordan, Cyprus, Singapore, Malaysia, Indonesia, Thailand, Vietnam, South Korea, Japan, Sri Lanka, Maldives, Bangladesh, Cambodia, Argentina, Bolivia, Brazil, Venezuela, Colombia, Ecuador, Guyana, Paraguay, Uruguay, United States Of America, Canada, Mexico, Panama, Jamaica, Bahamas, Denmark, Norway, Germany, France,Italy, United Kingdom, Spain, Belgium, Greece, Czech Republic, Portugal, Hungary, Albania, Austria, Finland, Ireland, Croatia, Malta, Nigeria, Algeria, Angola, South Africa, Libya, Egypt, Sudan, Europe, Africa, Asia, North America, South America, Middle East.etc

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This customer has always been very demanding on product quality and material performance, and this time chose 904L flanges because of its excellent performance and extraordinary durability in extremely corrosive environments. We are well aware that these flanges will become an indispensable “connection point” in their key projects, carrying the safe transportation of fluids and the stable operation of equipment.

904L is a high alloy austenitic stainless steel, known for its excellent corrosion resistance, especially in dealing with strong acidic environments (such as sulfuric acid, phosphoric acid) and chloride corrosion (pitting, crevice corrosion and stress corrosion cracking). Therefore, 904L flanges are important components for connecting critical piping systems to ensure long-term stable operation under harsh conditions.

Contact us

Purchase List

Dimensional Inspection of 904L Flange

1. Outer Diameter
   Ensure overall compatibility: Verify that the flange can be properly installed within the reserved space in the piping system without interference from surrounding equipment or structures.
2. Thickness
   Ensure pressure resistance: Flange thickness is a critical factor in determining its pressure-bearing capacity. Sufficient thickness ensures the flange will not deform or crack under rated pressure, maintaining system sealing performance.
3. Sealing Face Diameter
   Ensure sealing integrity: This is one of the most critical inspection points. The sealing face diameter must precisely match the selected gasket size to ensure uniform compression under pressure and form an effective seal to prevent fluid leakage.
4. Bolt Circle Diameter (BCD)
   Ensure bolt hole alignment: This is a decisive factor for proper flange connection. An accurate bolt circle diameter ensures full alignment with the mating flange’s bolt holes, allowing bolts to pass through smoothly and be evenly stressed, avoiding damage from forced installation.
5. Number and Diameter of Bolt Holes
   Ensure connection strength: The number and diameter of bolt holes must meet the standard to ensure enough bolts are available to bear the stress at the flange connection and to apply uniform preload on the gasket.
6. Pipe End Outside Diameter
   Ensure match with pipe OD: This is the core objective. The outside diameter of the weld neck portion of the flange must closely match the pipe’s outside diameter to ensure proper alignment during welding, reduce misalignment, and achieve a high-quality weld joint.

Specification of Forged Steel Flange

ASTM A182 F904L Flange Chemical Composition

ASTM A182 F904L Flange Mechanical Property

PN16 Forged Flange Dimensions

Applications of 904L Weld Neck & Blind Flanges

Sulfuric acid treatment and production

Seawater and brine treatment

Marine engineering and offshore platforms

Desalination plants

Coastal power plants

Pollution control equipment

Flue gas desulfurization (FGD) systems

Chemical and petrochemical industries:

Pharmaceutical industry

Food and beverage industry

Pulp and paper industry

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Product Descriptions

Weld Neck Flange Chemical Composition

Weld Neck Flange Mechanical Properties

316L Weld Overlay Chemical Composition

316L Weld Overlay Mechanical Properties

Weld Neck Flange with 316L Weld Overlay Inspection

According to ASME B16.5, the flange dimensions have been inspected, and all critical measurements including outside diameter, inside diameter, bolt circle, flange face height, and sealing surface dimensions are within the specified tolerance range. And these product passed inspection and are qualified.

Weld Neck Flange with 316L Weld Overlay Package

We package our export flanges in sturdy wooden boxes to prevent shipping damage and ensure easier handling and stacking. They also provide reliable protection against shock and moisture, helping to ensure your products arrive safely and intact.

Class 150 lb Weld Neck Flange Dimensions & Weight 

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ASME B16.5 Class 150 Weld Neck Flange

ASME B16.5 is a standard developed by the American Society of Mechanical Engineers for pipe flanges and flange connections. This standard provides detailed specifications for flanges of various sizes, pressure levels, materials, and surface types to meet the needs of various industrial applications. ASME B16.5 Class 150 weld neck flange, as an important type, is widely used in industries such as petroleum, chemical, natural gas, power, pharmaceuticals, and food.

Specification

Material Grade of ASTM A182 Flange

Alloy Material For Class 150 Weld Neck Flange

ASTM A182 F11 is a relatively common alloy flange, which is divided into three grades, each with different chemical composition and mechanical property requirements, to accommodate different environments for pipeline systems.

Chemical Composition

Mechanical Properties

Alloy steel class 150 weld neck flange have strong corrosion resistance, high temperature resistance, excellent sealing performance, and rigid and elastic requirements, and are widely used in various industrial fields.

ASTM A182 Stainless Steel Flange

ASTM A182 F304/304H/304L are all austenitic stainless steel materials, which are commonly used in the raw materials of ASTM A182 class 150 weld neck flange. Their prices are relatively cheaper than stainless steel materials such as 316 and 904, so they are widely used in pipeline systems.

Chemical Composition

Mechanical Properties

Duplex Stainless Steel Class 150 Weld Neck Flange

ASTM A182 F51/53/55 is a duplex stainless steel that is commonly used for forging ASTM A182 class 150 weld neck flange. Duplex steel is more commonly used in pipelines used in some special environments, where higher material requirements are imposed, and it can play a greater role.

Chemical Composition

Mechanical Properties

Class 150 Weld Neck Flange Dimension List

Notes

1) Dimension B corresponds to the pipe inside diameter. Values quoted assume 40S/Standard wall thickness.
2) Weights are based on manufacturer’s data and are approximate .
3) Flat face flanges may be provided at full thickness, C, or with raised face removed (the latter is nonstandard).
4) The blank space needs to be provided by purchaser.
5)  If you need class 300 ,600 ,900 ,1500 ,2500 flange dimensions & weight,please contact us.

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