1. Raw Material Selection & Cutting
Selection: High-quality seamless steel pipes (e.g., Carbon Steel, Stainless Steel, or Alloy Steel) are selected based on project specifications. Cutting: The pipe is cut into specific lengths (pipe blanks) using mechanical or saw cutting to ensure clean, square ends.
2. Hydraulic Bulging Process
This is the core cold-forming stage for small to medium-sized tees:
Molding: The pipe blank is placed into a hydraulic mold with a T-shaped cavity.
Internal Pressure: Ultra-high pressure liquid is injected into the blank, forcing the pipe wall to expand outward.
Axial Compensation: Simultaneously, horizontal cylinders apply axial thrust to both ends, "feeding" metal into the center to ensure the branch pipe reaches the required height and wall thickness.
3. Branch Trimming & Sizing
Opening: The enclosed top of the formed branch is removed via plasma or mechanical cutting.
Sizing: The tee undergoes a sizing process in a precision die to ensure the dimensions and the 90-degree angle meet
international standards (e.g., ASME B16.9).
4. Heat Treatment
Purpose: To eliminate internal stresses and work hardening caused by the cold forming process.
Methods: Depending on the material, processes such as Normalizing, Tempering, or Solution Annealing (for stainless steel) are performed to restore the mechanical properties and corrosion resistance.
5. Beveling & Machining
Beveling: The three ends of the tee are machined to create welding bevels (typically at a 37.5° angle) to facilitate subsequent butt-welding at the job site.
Surface Finishing: The product is shot-blasted to remove scale and may be coated with anti-corrosion oil or paint.
6. Inspection & Testing
NDT (Non-Destructive Testing): Methods like Ultrasonic Testing (UT) or Magnetic Particle Inspection (MT) are used to check for cracks or defects.
Dimensional Check: Verification of outer diameter (OD), wall thickness (WT), and center-to-end dimensions.