Alloy 625 Steel Flange Order

In August 2025, we received an order from an old customer in Europe for Alloy 625 steel flange, which are required to comply with the EN1092-1 flange production standard. The product types include Type01 plate flat welding flanges and Type05 blind flange.

Purchase Details

Alloy 625 is a nickel based high-temperature alloy known for its extremely excellent strength, toughness, and outstanding corrosion and oxidation resistance. It is based on nickel element, with the addition of molybdenum and niobium and solid solution strengthening to achieve its excellent performance.

This alloy material has high value, and in order to ensure its authenticity, the customer requires third-party inspection of the product. We conduct inspections according to customer requirements and obtain testing reports to send to customers for confirmation. Our loyal customer has delivered this order to us for production, fully demonstrating their trust and support for us. This makes us feel honored and responsible.

Considering the high value of Alloy 625 steel flange and the direct impact of surface smoothness and structural integrity on their performance, in order to ensure transportation safety and prevent surface scratches, deformations, and other defects caused by bumps and collisions, we have implemented multiple protections in the packaging process to ensure the safety of the product during transportation

Surface cleaning: After cleaning the flange surface, wrap it separately with bubble wrap to protect the overall appearance of the flange;

Layered isolation: Fix flanges of different specifications with customized cardboard slots to prevent friction and collision during transportation;

Buffer reinforcement: Cover with EVA flange gasket to protect the flange sealing surface and bolt holes;

Wooden box reinforcement: Customize sturdy plywood wooden boxes with gaps filled with bubble wrap and other anti-collision materials. After sealing the box, perform secondary reinforcement on the outside of the wooden box to prevent deformation during loading and unloading stacking.

After receiving and inspecting the goods, the customer highly praised the quality and service of our products.

In industrial pipeline systems, the material and standards of flanges directly determine the stability of the system. Alloy 625 steel flanges, with their excellent performance, have become an ideal choice for high-pressure and strong corrosion conditions. The following analyzes their core values from multiple dimensions.

Analysis of Alloy 625 Steel Flange Material

Alloy 625 is a typical nickel based high-temperature alloy, corresponding to the American standard ASTM B564 UNS N06625 (forged pipe fitting standard). This standard strictly specifies the chemical composition, mechanical properties, and heat treatment requirements of UNS N06625, ensuring stable material quality and effectively connecting with the production requirements of European standard flanges. Nickel content exceeds 58%, supplemented by chromium (20-23%), molybdenum (8-10%), and niobium (3.15-4.15%). Niobium and molybdenum form stable intermetallic compounds, which not only endow the material with excellent high-temperature strength (room temperature tensile strength ≥ 827MPa), but also make it highly corrosion-resistant in strong acids (such as sulfuric acid, hydrochloric acid), seawater, and chlorine containing media. It also has excellent toughness at low temperatures and no risk of cold brittleness.

Chemical Composition

Mechanical Properties

Advantages

Strong performance adaptability: Combining the corrosion resistance and high temperature resistance characteristics of Alloy 625 material with European standard size design, the flange sealing surface tolerance is ≤ 0.1mm, and there is no risk of leakage after installation, which is suitable for the high standard docking requirements of European industrial equipment.

High structural reliability: Type05 with neck design disperses welding stress, avoiding long-term cracking during use; The flange thickness is optimized according to EN1092-1 load calculation, which reduces weight by 15% and increases strength by 20% compared to carbon steel flanges of the same specification.

Compliance guaranteed: The entire production process complies with EN1092-1 dimensional standards and ASTM B564 material standards, and can provide complete material reports (MTC) and non-destructive testing reports, meeting EU CE certification and industrial project compliance requirements.

Heat treatment process of Inconel 625 Steel Flange

Alloy 625, as a nickel based high-temperature alloy, has mechanical properties (such as tensile strength and corrosion resistance) closely related to its microstructure. It needs to be optimized through heat treatment processes to adapt to harsh working conditions such as high pressure and high temperature. The specific process is as follows:

purpose

Eliminate internal stresses generated during forging/processing, refine grain size, enhance the intergranular corrosion resistance and room temperature/high temperature mechanical strength of the alloy, and ensure that the flange is not easily deformed or cracked during long-term service.

Key Process Steps and Parameters

Preheating

When the wall thickness of the flange is greater than 50mm, in order to avoid cracking caused by excessive temperature difference between the inside and outside during subsequent heating, the insulation should be maintained at a temperature of 650-700 ℃ for 2-4 hours (the insulation time is calculated based on an increase of 1 hour for every 25mm of wall thickness), and the heating rate should be slowly increased (≤ 100 ℃/hour) to make the temperature inside and outside the workpiece uniform.

Solution Treatment

This is the key step for optimizing the performance of Alloy 625: place the flange in a vacuum heat treatment furnace (or inert gas protection furnace to prevent oxidation), heat it up to 1050-1100 ℃ at a rate of 80-120 ℃/hour, and hold it for 1-2 hours (ensuring that the carbides in the alloy are fully dissolved into the matrix); After the insulation is completed, immediately use water quenching cooling (cooling rate ≥ 50 ℃/min) to quickly suppress carbide precipitation, obtain uniform austenite structure, and improve corrosion resistance and strength.

Stress Relief Annealing

After the completion of lathe machining, drilling and other processes, the internal stress of the flange needs to be eliminated: it should be kept at a temperature of 700-750 ℃ for 1.5-3 hours, and then slowly cooled in the furnace to below 300 ℃ before air cooling to avoid deformation or cracking caused by stress, while not affecting the core performance after solution treatment.

Process Quality Control

Throughout the process, a furnace temperature tracker is used to record the temperature curve, ensuring that the heating, insulation, and cooling parameters of each flange meet the requirements of ASTM B443 (Alloy 625 plate/forging standard); After processing, sample and test the hardness (required to be ≤ 290HB) and grain size (required to be ≥ 5 levels). Unqualified products should be reworked immediately to ensure that the performance meets the standards after heat treatment.

Introduction to EN1092-1 flange Type01 and Type05

EN1092-1 is the core standard for flange design and manufacturing in Europe, among which Type01 (plate flat welding flange) and Type05 (neck butt welding flange) are the mainstream types of Alloy 625 European standard flanges:

Type 01: Plate type flat welding flange

Structural features: The flange is flat, with bolt holes in the center, and is connected to the pipeline by flat welding (the weld seam is at the junction of the flange and the outer wall of the pipeline). The structure is simple and lightweight.

Sealing surface type: commonly used protruding surface (RF), with a few cases using full flat surface (FF). The sealing surface processing accuracy is moderate and suitable for non-metallic gaskets (such as asbestos rubber gaskets).

Applicable : Low pressure and normal temperature scenarios with pressure ≤ 16 bar and temperature ≤ 400 ℃, such as ordinary fluid transportation pipelines in the chemical industry and civil water supply pipelines; The Type 01 flange made of Alloy 625 material, with its corrosion resistance, can be used in mildly corrosive saltwater and weak acid delivery systems.

Advantages: Easy installation, low cost, suitable for low-pressure scenarios with low sealing requirements.

Type05: Blind flange

Structural features: A solid flange without a central hole, connected to pipeline or equipment ports, used for sealing pipelines and facilitating maintenance. It can be sealed with bolts and gaskets.

Sealing surface type: protruding surface (RF), concave convex surface (MFM), the sealing surface matches the corresponding type of flange.

Applicable: Pipeline sealing scenarios for all pressure levels, such as maintenance ports of chemical reaction vessels and pipeline end sealing; Type 11 blind flange made of Alloy 625 material, due to its strong corrosion resistance, can be used for sealing pipelines in highly corrosive media to prevent the contact surface between the gasket and the flange from being corroded and damaged.

Application

Alloy 625 steel flanges are widely used in high-end industrial fields

Petrochemical industry: high-temperature and high-pressure pipelines for crude oil refining and ethylene plants;

Ocean engineering: seawater desalination equipment, seawater transportation pipelines for ocean platforms;

Energy and electricity: secondary circuits of nuclear power plants, high-temperature flue gas pipelines of gas turbines;

Pharmaceutical and chemical industry: connection between strong acid medium reaction kettle and conveying pipeline.