U bend tubes

The semi-finished product for U bend tubes are heat exchanger tubes, manufactured and supplied according to DIN 28180 and ASTM A179. Tubes for heat exchangers are made of steel according to:

EN 10216-2: P235GH
DIN 1629: St 37.0
DIN 17175: St35.8, 15Mo3
DIN 17173: TTSt35N
A / SA179, steel grades acc to standard
A / SA 213: T2, T11,T12, T21, T22
A / SA 334: Grade 6
A / SA 556: A2, B2, C2

other types of steel can be supplied by agreement.

U bend tubes for heat exchangers applied mostly in oil and gas plants, chemical and petrochemical plants, refineries, power plants and renewable energy plants. Low fin tubes can be supplied in the form of U bends.

U bend tube sizes



Tube outer diameter
Tube wall thickness
Bending Radius
U tube straight “leg” length
Straight tube before U bending
min. 12,70 mm
min. 0,70 mm
min. 1,5 x D
max. 9 500 mm
max. 20 000 mm
max. 31,75 mm
max 5,16 mm
max. 1 250 mm
for heat exchanger - U bends

Dimension control on U bend tubes


  • Ovality of straight and bending tube parts
  • Thinning of straight and bending tube parts
  • Leg spacing length
  • U bend tube length (leg + radius + (0,5 x OD))
  • Difference between legs length
  • Straightness of legs
  • Deviation from bend plane
  • Twist of bending portion
  • Squareness and cleanliness of tube ends
  • Complete visual control

Sizes tolerances of U bend tubes are to fulfil the requirements of: ASTM A556 / 556M and DIN 28 179

Heat treatment of U bend tubes



Post bending heat treatment by electrical resistance (Joule effect) is applied. The temperature is monitored and controlled during the process. It is possible to perform the heat treatment in a nitrogen atmosphere.

U bend tubes can be tested as follows


  • Hydrostatic Test
  • Air Underwater Test
  • Pulsating Pressure Test
  • Dye Penetrant Test
  • Magnetoscopic test




U bend tubesFor heat exchanger - U bendsU bend tubes for heat exchangers