What are the requirements for customized processing of elbows and flanges for stainless steel welded ventilation pipes?

This problem is very critical. The core requirements for the manufacture of elbows and flanges of stainless steel welded ventilation pipes are to ensure the sealing performance, structural strength and smooth airflow, and at the same time meet the industry norms.

Elbow fabrication requirements

Material matching: the elbow should be made of the same material as the main body of the pipeline, and stainless steel such as 304 and 316L is commonly used to avoid welding failure or corrosion caused by material difference.

Angle and curvature: control the angle (usually 90 and 45) according to the design requirements, and the radius of curvature is usually not less than 1.5 times the diameter of the pipeline, so as to reduce the airflow resistance.

Splicing and welding: Butt welding or socket welding shall be adopted, and the interface shall be smooth and free from wrong edges, and the weld height shall meet the design standards, without defects such as air holes, slag inclusion and cracks.

Dimensional accuracy: the deviation of inner diameter and wall thickness shall be controlled within 3%, and the end face shall be perpendicular to the pipeline axis to ensure the fitting.

Flange fabrication requirements

Structural specification: Flange types (flat welding and butt welding) shall be selected according to pipeline pressure grade, and the thickness, number and spacing of bolt holes shall conform to GB/T 9119 and other standards.

Welding requirements: When the flange is welded to the pipeline, the weld seam should be continuous all around, and there should be no incomplete penetration. After welding, the welding slag should be removed and polished smoothly.

Treatment of sealing surface: the sealing surface should be smooth and scratch-free, and the roughness should meet the requirements. Plane butt joint or tongue-and-groove structure is commonly used to ensure the gasket to fit tightly.

Dimensional consistency: the flange inner diameter matches the pipeline outer diameter, the bolt hole position is accurate, and the deviation between adjacent holes is less than ±2mm, which is convenient for installation and fastening.

General additional requirements

Surface treatment: after fabrication, burr and flash shall be removed, and the inner and outer surfaces shall be smooth without obvious unevenness. If necessary, pickling and passivation shall be carried out to enhance corrosion resistance.

Pressure test: air tightness test shall be conducted after fabrication, and the pressure value shall be implemented according to the design requirements to ensure no leakage.

Clear identification: information such as material, specification, pressure grade, etc. shall be marked on elbows and flanges for easy traceability and installation check.