Description

Each U bend tube of our range is rigorously quality checked by our team of talented professionals on every stage of production to deliver the clients defect free best quality products. U bend tubes are mainly used to enhance the design of heat exchangers where is there are space constraints and heat transfer are required to be done on faster basis.

OD 9.5mm – 38.1mm
WT up to 6.35mm
Bending radii 1.25 x OD up to 1700mm
Bends can be supplied in accordance with TEMA R / ASTM SA/A556
Leg length up to 15000mm
Heat treatment where required by electric furnance or direct resistance
Hydrotesting up to 10,000 psi

Standard for 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:

ASTM A688/A688M
ASTM A803/A803M
ASTM A556/A556M, ASME SA-556
ASME SA-179/SA213

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.

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.

Heat Treatment Equipment

Heat treatment equipment is computer controlled with the added facility of data recording.
An argon protective atmopshere is used inside stainless and special alloy tubes during heat treatment.
We can provide all types of annealing; solution annealing and stress relieving.

U bend tubes can be tested as follows

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

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

u bend

Appication

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.

“U bend tubes for heat exchangers applied mostly in Oil & Gas plants, Chemical & Petrochemical plants, Refineries, Power plants, Renewable energy plants.”

Object medium: 10% sodium
hydroxide+5% sodium hypochlorite
Shell Diameter: ø 800
Working Pressure: 1.5mpa
Working Temperature: 40º C-90º C
Heat Exchange Surface Area: 100M2
Material: Gr1\Gr2

Materials of U bend tubes

‘U’ bends are produced, controlled and measured fully in accordance with relevant standards.

Material / Grade

Carbon Steel – SA 179 / A 179
Carbon Steel – SA 210 / A 210
Carbon Steel – SA 334 / A 334
Stainless Steel – SA 213 / A 213
Duplex Stainless Steel – SA 789 / A 789
Copper & Cu Alloys – SB 111 / B 111
Titanium & Ti Alloys – SB 338 / B 338

U-Bend fabrication tolerances

Here is a list for providing ovality, minimum wall thickness, bending radius, distance between legs, wall thinning of bending area and so on. Thus, we can figure out which kind of type would be our final choice for our engineering project.

‘U’ bending is done by cold working process.
‘U’ bending is done to the required radius as per customer drawings.
The bend portion and six inch leg is stress relieved by resistance heating.
Inert gas (Argon) is passed through it at the required flow rate to avoid oxidation in ID.
The radius is checked for its OD and wall thinning with the recommended specification.
The physical properties and micro-structure is checked at three different position.
Visual inspection for waviness and cracks is done with Dye Penetrant Test.
Each tube is then hydro tested at the recommended pressure to check for leakage.
Cotton ball test is done to check the ID cleanliness of the tube.
Thereafter pickled, dried, marked and packed.

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.

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)

Packing

Any type of packing is available according to customer need to worldwide destinations.

Stainless steel U bend tubes

SA 213 TP347H stainless tubes

ASTM A179 U bend tubes

U bend tubes are packed in wooden cases

ASTM standards for Heat-exchanger and condenser tubes

Abbr.	Corresponding	Application
A179	ASTM A179 / A179M	Standard Specification for Seamless Cold-Drawn Low-Carbon Steel Heat-Exchanger and Condenser Tubes
A213	ASTM A213/A213M	Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes
A214	ASTM A214 / A214M	Specification for Electric-Resistance-Welded Carbon Steel Heat-Exchanger and Condenser Tubes
A249	ASTM A249 / A249M	Specification for Welded Austenitic Steel Boiler, Superheater, Heat-Exchanger, and Condenser Tubes
A498	ASTM A498 / A498M	Specification for Seamless and Welded Carbon, Ferritic, and Austenitic Alloy Steel Heat-Exchanger Tubes with Integral Fins
A851	ASTM A851 / ASME SA851	Specification for High-Frequency Induction Welded, Unannealed, Austenitic Steel Condenser Tubes