Stainless steel bending tube are widely used in heat exchangers. For your reference, I will briefly introduce the bending processing and later inspection by Gaolin.
1. Dustproof, rust prevention treatment
2. Material identification, bending point marking and displacement
3. Cold Bending with not less than 5 samples for each radius
4. Bending requirement:
4.1 Bending radius
Radius <2.5OD, Tolerance: ±1mm
Radius≥2.5OD, Tolerance: ±1.5mm
4.2 Ovality: within 10%
4.3 Wall Thinning: within 17%
4.4 Leg length tolerance: -0/+3mm
5. Apply ball test when radius<=50mm,
6. Solution annealing for 150-300mm straight section and bending area
7. Leg cut with tolerance: +3/-0 mm
8. Hydraulic test at 7Mpa with 5s pressure holding
9. Penetration test applied if required
10. Packing.
