U Bend Stainless Steel Tubes By yaang.com

Surface condition Finished U-tubes shall be free of scale, without scratches after bending.

Dimensional tolerances U tubes acc. to TEMA R.C.B.
Length of straight part -0/+5 mm 
Flattening (also called “ovality”) at the bend shall not exceed 10% of the nominal tube outside diameter.
Wall thickness in bending part acc. to TEMA RCB 2.31 Minimum tube wall thickness in the bend part (T min)T(min) ≥ (SW × (2×R + D))/( 2× (R+D)where: 
SW is smallest wall thickness D Nominal outside diameter R radius
Radius tolerance 1) for R 100 mm +/- 3 mm
2) for R ≥ 100 mm +/- 5 mm
Straightness tolerance max. 1,5 mm per 1 m
U-Tubes ends: plain, vertically cut to the tube axis
Tube-bending line, installed at 2007, will allow to produce U-tubes as per such standards:
1. ASTM A688/A688M-08
2. ASTM A803/A803M
3. ASTM A556/A556M, ASME SA556
4. ASME SA-688

Initial Length
Maximum lengths of 27000mm can be supplied on request

Dimensions
Tubes OD in mm can be bent upon agreement: 15,8 - 16,0 - 17,0 - 18,0 - 19,05 - 20,0 - 21,3 - 25,4 -26,7 - 31,8 -38,1

Bending radius
Minimum: 1.5×OD
Maximum: 1500 mm

Heat treatment of the bend
U bend tubes with a bending radius up to maximum of 1500mm can be heat treated on request
The basic Testing and processing:
1. High Pressure Hydrostatic Test:Minimum:10 Mpa-25Mpa.
2. Air Under Water Test After Bending
3. U Tubes Wall Thickness Test
4. Eddy Current Test before U bend Formed 
5. Ultrasonic Test before U bend Formed
6. Heat treatment to stress relieved 
7. Ball passing test
The below sizes are those most frequently used,other sizes can be produced upon request.
The dimensions for heat exchanger tubes in special grades may differ from the above,please contact us: [email protected] .