U-Tubes made acc. to drawings from cold drawn seamless steel tubes acc. to ASME SA179/SA179M, SA192/SA192M, SA213/SA213M, SA556/SA556M, EN10216-2, EN10216-5, etc.

Heat treatment
Stress relive annealing of U-tubes after bending – only for all positions with radius ≤ 100 mm

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 (Tmin)

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 1000 mm

U-Tube ends: plain, vertically cut to the tube axis

Repairs by welding: prohibited