Analysis of Inconel Blind Flange

What is Inconel Blind Flange

Inconel blind flange is a flange component made of Inconel series nickel chromium molybdenum alloy without flow holes. It is mainly used to seal the ends of pipelines and achieve safe sealing during isolation, cutting or maintenance of pipeline systems. It combines the excellent high temperature and corrosion resistance of Inconel alloy with the structural function of blind flange, which can ensure the sealing and safety of pipeline systems under extreme working conditions, avoid medium leakage, and is a key sealing and isolation component in industrial pipeline systems.

ASTM B564: Inconel Blind Flange Material Standard

The standard name of ASTM B564 is "Standard Specification for Nickel Alloy Forgings", which stands for "Standard Specification for Nickel Alloy Forgings". This standard specifies the requirements for nickel based and nickel copper alloy forgings produced through forging processes. It covers a series of technical indicators such as chemical composition, mechanical properties, dimensional tolerances, heat treatment, non-destructive testing, and quality assurance.

Scope of Application and Materials

This standard applies to a range of high-performance nickel based alloys known for their excellent corrosion resistance, high strength, and high heat resistance. The common alloy grades covered in the standard include:

UNS N04400: commonly referred to as Alloy 400 or Monel 400. A nickel copper alloy with excellent resistance to seawater corrosion and alkaline solution.

UNS N06600: commonly referred to as Alloy 600 or Inconel 600. A nickel chromium alloy with excellent resistance to high temperature oxidation and corrosion.

*UNS N06625: commonly referred to as Alloy 625 or Inconel 625. A nickel chromium alloy reinforced with niobium and molybdenum, with extremely high fatigue strength and excellent resistance to pitting and crevice corrosion.

*UNS N08825: commonly referred to as Alloy 825 or Incoloy 825. A nickel iron chromium alloy with added molybdenum and copper, which has good corrosion resistance to both reducing and oxidizing acids.

UNS N10276: commonly referred to as Alloy C-276 or Hastelloy C-276. A nickel molybdenum chromium alloy, widely recognized as a "universal" corrosion-resistant alloy, performs exceptionally well in harsh oxidation and reduction environments.

And various other high-performance nickel alloys, such as UNS N06022 (C-22), UNS N06617 (617), UNS N07718 (718), etc.

These forgings are commonly used to manufacture key pressure bearing and rotating components such as valves, pump parts, flanges, fittings, shafts, turbine discs, etc.

Common Material Performance Analysis

Inconel 625

Characteristics: As one of the most widely used models in the Inconel family, it has excellent corrosion resistance and can resist various strong corrosive media such as hot seawater, washing environment, reducing acid, etc., especially pitting and crevice corrosion; Excellent high-temperature performance, with an antioxidant temperature of up to 1800 ° F (982 ° C) and high creep fracture strength, maintaining stable mechanical properties even in long-term high-temperature environments; Good processing performance, blind flange of different specifications can be made through welding, forging and other processes.

Chemical Composition

CHEMICAL	LIMITS	Ni	Fe	Mn	C	Si	S	Cr	Al	Ti	Nb+Ta	Mo	P
Inconel 625 (UNS N06025)	MIN							20.0			3.15	8.0
	MAX	58.0	5.0	0.50	0.10	0.50	0.015	23.0	0.40	0.40	4.15	10.0	0.015

Mechanical Properties

MATERIAL	T.S (MPA)	Y.S (MPA)	EL %
Inconel 625 (UNS N06025)	690 min	276 min	30 min

Inconel 718

Characteristics: It belongs to precipitation hardening nickel chromium alloy, with extremely high strength, about twice that of Inconel 625. It still has excellent creep fracture strength at temperatures up to 1325° F (760° C), and can be used up to 1800 ° F (982 ° C); Excellent corrosion resistance, able to cope with various oxidative and non oxidative corrosion environments; The mechanical properties can be further improved through precipitation hardening treatment, which is suitable for scenarios with strict requirements for strength and high temperature resistance.

Chemical Composition

CHEMICAL	LIMITS	C	Mn	Si	P	S	Cr	Co	Mo	Nb+Ta	Ti	Al	B	Fe	Cu	Ni
Inconel 718 (UNS N07718)	MIN						17.0		2.80	4.75	0.65	0.20		REM		50.0
	MAX	0.08	0.35	0.35	0.015	0.015	21.0	1.0	3.30	5.50	1.15	0.80	0.01		0.30	55.0

Mechanical Properties

MATERIAL	T.S (MPA)	Y.S (MPA)	EL %	RA	HARDNESS
Inconel 718 (UNS N07718)	1275 min	827 min	12 min	15 min	331min

Inconel 600

Characteristics: It has excellent high-temperature oxidation resistance, even under harsh thermal cycling conditions, it can maintain high oxidation resistance up to 2100 ° F (1150 ° C); Good high-temperature strength and good ductility even after long-term use; It has good tolerance to atmospheric, seawater isothermal and corrosive environments, and is suitable for pipeline sealing requirements in high-temperature oxidation environments.

Chemical Composition

CHEMICAL	LIMITS	Ni	Cu	Fe	Mn	C	Si	S	Cr
Inconel 600 (UNS N06600)	MIN			6.00					14.00
	MAX	72.00	0.50	10.00	1.00	0.15	0.50	0.015	17.00

Mechanical Properties

MATERIAL	T.S (MPA)	Y.S (MPA)	EL %
Inconel 600 (UNS N06600)	552 min	241 min	30 min

ASTM B564 Standard

The ASTM B564 standard mainly specifies the following requirements:

1. Smelting Process

It is required that the alloy must use advanced smelting processes such as electric arc furnace (EAF) with argon oxygen decarburization (AOD) or vacuum induction melting (VIM) to ensure metal purity and control gas and impurity content.

2. Chemical Composition

There are strict limits on the chemical composition of each alloy (such as the content of nickel, chromium, molybdenum, iron, carbon, etc.), which must comply with the requirements of the corresponding alloy grade in the standard. This is the foundation for ensuring material performance.

3. Heat Treatment

It specifies the heat treatment processes that forgings must undergo (such as solution treatment, aging treatment, etc.) to achieve the mechanical properties and microstructure required by the standards.

4. Mechanical Properties

This is one of the core requirements. The standard specifies the tensile strength, yield strength, elongation and other indicators of different grades of forgings at room temperature.

According to the shape and purpose of the forging, the mechanical performance requirements are divided into multiple levels (such as Class 1, Class 2, etc.), corresponding to different strength levels.

5. Non Destructive Testing

The standard requires liquid penetrant examination of forgings to detect surface defects.

For forgings with important applications, ultrasonic examination can also be conducted according to order requirements to detect internal defects.

6. Dimensions and Tolerances

The dimensions and tolerances of forgings shall comply with the drawing requirements on the purchase order or other standards agreed upon by both parties (such as ANSI B16.5 for flanges).

7. Testing and Certification

It specifies how to conduct mechanical performance testing (sampling location, testing method, etc.).

Manufacturers must provide a Material Test Report (MTR) to demonstrate that the product fully complies with all requirements of ASTM B564 standard. This report is a traceable document of product quality and is crucial.

ASTM B564 is a comprehensive quality specification for high-performance nickel based alloy forgings. It ensures that the final product has the required strength, toughness, and excellent corrosion resistance to meet the demands of the most demanding industrial applications by strictly regulating the smelting, composition, heat treatment, performance, and inspection requirements of materials.

Production Standards for Blind Flange

ASME B16.5: This is a widely used pipeline flange standard worldwide, which provides detailed specifications for the size, pressure rating (Class 150-2500), material requirements, sealing performance, tolerance range, etc. of Inconel blind flange, ensuring the interchangeability and safety of flanges under different working conditions. It is suitable for flange products with nominal diameters ranging from 1/2 " (DN15) to 24 " (DN600).

ASME B16.47: mainly for large diameter flanges, covering large-sized Inconel blind flanges from DN650 to DN4000, supplementing the blank in the field of large diameter flanges in ASME B16.5, specifying corresponding requirements for size, pressure rating, connection method, etc., to meet the needs of large industrial pipeline systems.

API 605: Developed by the American Petroleum Institute, it is a large-diameter steel flange specifically designed for the oil and gas industry. It has strict requirements for the material properties, manufacturing processes, and inspection standards of Inconel blind flanges, with particular emphasis on the reliability and corrosion resistance of flanges under harsh oil and gas conditions such as high pressure and sulfur.

DIN EN 1092-1: A commonly used flange standard in Europe that specifies the type, size, pressure rating, and sealing surface form of Inconel blind flange. It differs from ASME standards in some parameters and is applicable to Europe and regions and industries that follow European standards.

Dimension of Inconel Blind Flange

Nominal diameter (NPS/DN): covering 1/8 " (DN6) to 60 " (DN1500), with common specifications ranging from 1/2" (DN15) to 24" (DN600) according to ASME B16.5 standard. Large diameter specifications (such as 26" to 60") mostly follow ASME B16.47 or API 605 standards, and are suitable for pipeline systems of different diameters.

Pressure Class: Common grades include Class 150, 300, 600, 900, 1500, and 2500. Different pressure grades correspond to different flange thicknesses, bolt quantities, and sizes. For example, the DN100 (4-inch) Inconel blind flange thickness of Class 150 is about 19mm, while the same specification flange thickness of Class 300 is about 27mm to ensure strength under corresponding pressures.

Flange thickness: It depends on the nominal diameter and pressure rating. The larger the nominal diameter and the higher the pressure rating, the thicker the flange. Taking DN200 (8 inches) as an example, the thickness of Class 150 is about 22mm, and the thickness of Class 600 can reach 48mm, ensuring that the flange can withstand the corresponding pressure without deformation or damage.

Bolt hole parameters: The number of bolt holes is usually an even number such as 4, 8, 12, 16, etc., and the number increases with the nominal diameter. For example, a DN50 (2 inches) Class 150 blind flange has 4 bolt holes, while a DN200 (8 inches) Class 150 flange has 8 bolt holes; The diameter of the bolt hole is determined according to the pressure level. The diameter of the DN100 flange bolt hole for Class 150 is about 18mm, while the same specification for Class 300 is about 22mm, ensuring the strength and sealing of the bolt connection.

ASME B16.5 Blind Flange Dimension and Weight

Class 150

Class 300

Class 600

Class 900

Class 1500

Class 2500

Advantages of Inconel Blind Flange

Super corrosion resistance: The synergistic effect of nickel, chromium, molybdenum and other elements in Inconel alloy can resist various harsh corrosive environments such as seawater, hydrochloric acid, sulfuric acid, and sulfur-containing media. Compared with ordinary stainless steel blind flanges, the service life is greatly extended, reducing the risk of leakage and replacement costs caused by corrosion.

Excellent high temperature resistance: It can work stably in high temperature environments up to 2200 ° F (1204 ° C), maintaining high tensile strength, yield strength, and toughness under high temperature conditions, without softening, deformation, or other problems due to high temperature. It is suitable for high temperature scenarios such as aerospace and petroleum refining.

High strength and toughness: Inconel material itself has high mechanical strength, especially Inconel 718, which has much higher strength than ordinary alloys. At the same time, it has good toughness and can withstand extreme mechanical stresses such as high pressure and impact. It can be reliably sealed in high-pressure pipeline systems to avoid flange rupture caused by excessive pressure.

Good processing and welding performance: Most Inconel models (such as Inconel 625) can be accurately processed into blind flanges of different specifications through forging, cutting and other processes, and have good welding performance, which can achieve firm welding with pipelines or other fittings, ensuring the sealing and integrity of the connection parts.

Long term stability: Inconel alloy is less prone to intergranular corrosion, stress corrosion cracking, and other problems during long-term use, with slow performance degradation. It can maintain the sealing function of blind flanges for a long time, reduce maintenance frequency, and lower industrial production downtime costs.

Application

Oil and gas industry

chemical industry

Aerospace and Energy Industry

Marine engineering field

Metallurgical and industrial furnace field