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Standard for U bend Tubes

U-bend or U-shape
View our U bend Steel Tubes for Heat exchanger...

U-bend tubes are widely used in heat-exchanger systems. Heat-exchanger equipment on the basis of seamless stainless U-tubes is essential in strategically important and critical fields — nuclear and petrochemical machine building.

A tube-bending line, that was installed at Huawei in the end of 2007, allows to produce U-tubes as per such standards:

U-Bend Fabrication Tolerances:
Item Condition (when) Tolercance
  Nominal bend radius ≤ 2 x nominal OD less than or equal to 12%
Ovality 2 x nominal OD < Nominal bend radius ≤ 4 x nominal OD less than or equal to 10%
  Nominal bend radius > 4 x nominal OD  less than or equal to 5%
  Nominal bend radius ≤ 2 x nominal OD 0.75 x nominal wall
Mimimum wall thickness 2 x nominal OD < Nominal bend radius ≤ 4 x nominal OD 0.8 x nominal wall
  Nominal bend radius > 4 x nominal OD 0.9 x nominal wall
  Nominal bend radius ≤ 8" (200mm) +/-3/64"(1mm)
Bending Radius 8" (200mm) < Nominal bend radius ≤ 16" (400mm) +/-1/16"(1mm)
  Nominal bend radius >16" (400mm) +/-5/64"(1mm)
Disrance between legs   Max 1/16"(1.5mm)
Wall thinning of bending area   Max 17%
Difference between leg lengths at the ends Leg length ≤ 16' (4.88m) +1/8"(3mm)
Leg length > 16' (4.88m) +3/16"(5mm)
Deviation from plane of bend   ≤ 3/16"(1.5mm)
Flattening on bend   ≤ 10% nominal diameter
Straight leg length ≤5m +1/8"(3mm)
>5m +3/16(5mm)
Total tube length including radius ≤6m +3/16(5mm)
>6m +5/16"(8mm)

At present Sunny Steel has purchased the equipment for production of the following product range:

Carbon & Alloy Ferrite Austenite Duplex Super Duplex
ASTM A179
ASTM A213 T11
ASTM A213 T12
ASTM A213 T22

TP410

TP 304 / 304L

TP 316 / 316L

TP 316Ti

TP 317 / 317L

TP 321

TP347

S31803

S32205

S32750

S32760

Tubes of other alloys and steel grades can be produced upon agreement.
Technical requirements

Straight tubes for bending:
ASTM/ASME SA 179; SA 213; ASTM B 163; ASTM B 729; ASTM B 407; ASTM B 423; ASTM A 789

U-bend Tubes:

-TEMA RCB 2.31 Standards of the Tubular Exchanger Manufacturers Association (9th edition).
-ASTM A688 Standard specification for welded tubes of austenite corrosion resistant steel grade designed for feed water boilers.
-ASTM B163 Standard technical requirements for tubes of nickel and nickel alloy for condensers and heat exchangers.
-Customer specifications.


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