High pressure butt welding flanges are key connecting components used in pipeline systems for harsh working conditions such as high pressure and high temperature. Here is a detailed introduction about it:

Structural characteristics

Neck design: With a conical neck, the neck gradually transitions to the thickness of the flange, which can effectively reduce stress concentration and make the connection between the flange and the pipeline more stable.

Docking weld: The flange and pipeline are connected by groove welding, with high welding strength. The quality of the weld can be strictly controlled through X-ray and other testing methods to ensure the reliability of the connection.

Sealing surface types: Common types include protruding surface (RF), ring connecting surface (RTJ), flat surface (FF), etc. Suitable sealing surface types can be selected according to different pressures, medium characteristics, etc. to meet sealing requirements.

Main advantages

High strength: The butt welding connection method provides excellent structural integrity and fatigue resistance, and can withstand complex working conditions such as high pressure, high temperature, and vibration.

Good sealing: When used in conjunction with suitable gaskets, it can effectively prevent medium leakage and ensure the sealing of the pipeline system.

Strong deformation resistance: The design of the neck can disperse stress and reduce the risk of flange deformation under high pressure.

Application field

Petrochemical industry: suitable for high-temperature and high-pressure pipeline systems, such as refining units, crude oil transportation pipelines, etc.

Power industry: commonly used in steam pipelines, boiler systems, etc., capable of withstanding the pressure of high-temperature steam.

Long distance pipelines: widely used in high-pressure transmission pipelines such as natural gas and crude oil to ensure the reliability of pipeline connections.

In other fields such as chemical, pharmaceutical, and shipbuilding, high-pressure butt welding flanges are also used for high-pressure pipeline systems that require reliable connections.

Standards and specifications

International standards: mainly include ASME B16.5 (American standard, NPS1/2 "~24"), ASME B16.47 (large diameter flange), EN1092-1 (European standard), HG/T20592~20635 (Ministry of Chemical Industry standard, China), etc.

Pressure rating: The American standard includes classes 150, 300, 600, 900, 1500, 2500, etc; European standards include PN6~PN100, etc.

Materials and Selection

Materials: Commonly used materials include carbon steel (such as A105), stainless steel (such as 316L), alloy steel, etc. The flange material needs to match the pipeline material to meet the requirements of different media and working conditions.

Selection precautions: The appropriate sealing surface type and size should be selected based on factors such as medium characteristics, pressure, temperature, etc., to ensure that the flange aperture, thickness, bolt hole spacing, etc. are compatible with the pipeline system.

Installation key points

Welding process: It is necessary to strictly follow the specifications for groove processing, pre weld cleaning, and post weld inspection, such as X-ray testing, to ensure the quality of the weld seam.

Bolt tightening: The bolts should be tightened in diagonal order to ensure even force distribution and avoid flange deflection or leakage.

Gasket installation: Select suitable materials for gaskets, such as graphite, metal wrapped gaskets, etc., and install them correctly to avoid excessive compression or improper installation of gaskets that may affect sealing performance.

Production process

High pressure butt welded flanges are generally made by forging or rolling processes to ensure their internal structure is dense and mechanical properties are good. When steel plates or sections are used for manufacturing, they must undergo ultrasonic testing to ensure no delamination defects, and be cut into strips along the rolling direction of the steel, bent and welded into circular rings. The butt welds of the circular rings should be full penetration welds, and undergo post weld heat treatment and 100% radiographic or ultrasonic testing.