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U-bend tubes

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.

Tubes for heat exchangers are made of steel according to:

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

Measuring, Cutting, Deburring and Cleaning

We bring forth an exclusive range of U-bend tubes, which are known for their superior quality and excellent functionality.

After U bend (cold forming), heat treatment of bending portion may be required. Temperature is controlled through the entire heat treated area by fixed and portable infrared pyrometers.

SA213 T9 U bend tubes for heat exchanger

U bend dimension capablity

Tube OD Tube thickness Bending Radius U tube straight “leg” length Straight tube before U bending
Min. 12,7mm / Max. 31,75mm Min. 0,70mm / Max. 4,19mm Min. 1,5 x OD / Max. 1250mm Max. 12500mm Max. 27000mm

Dimensional controls on U bend tube

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

  • Hydrostatic Test
  • Air Underwater Test
  • Pulsating Pressure Test
  • Dye Penetrant Test
  • Magnetoscopic test
  • Dye penetrant of ‘U’ bend area
  • PMI testing
  • Heat Treatment

All tubes are cut to the specified leg lenghts, ends deburred and the bores are internally cleaned with dried air.

Heat Treatment

We are equipped to carry out heat treatment of bends plus a minimum 150mm of leg.

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.

All tubes are cut to the specified leg lenghts, ends deburred and the bores are internally cleaned with dried air.


U-Bend Fabrication Tolerances

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

Features :
  • ‘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.
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)

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.

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

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

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


U-bend tubes Usage

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

U tube 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.

“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

Fin tube

Fin tubes are used in applications involving the transfer of heat from a hot fluid to a colder fluid through a tube wall. Furthermore, finned tubes are used when the heat transfer coefficient on the outside of the tubes is appreciably lower than that on the inside.

Note:
We produced condenser tube, carbon steel by the material out into the condenser tube, stainless steel condenser tube and carbon steel and stainless steel tubular mixed condensation out of three, according to the form of fixed tube plate, floating head type, U-tube heat exchanger, according to the structure into a single tube, twin-tube and multi-way tube, heat transfer area of 1 ~ 500m2, can be customized according to user needs.


Stainless U bend tubes

Stainless Steel U Bend Tube are widely used in heat exchanger systems. Heat exchanger equipment on the basis of stainless steel U-tube is essential in strategically important and critical fields nuclear and petrochemical machine building.

Surface condition Finished U Bend Tube shall be free of scale, without scratches after bending

Dimensional tolerances U Bend Tube acc. to TEMA R.C.B. and ASTM A566, ASTM A688

3.1 Diameter of tube in the U bent portion

At the bent portion of a U-tube for R = 2 × D or greater, neither the major nor minor diameter of the tube shall deviate from the nominal diameter prior to bending by more than 10 %.

If less than 2 × D is specified, tolerances could be greater, provided that Entropie agrees prior to order.

3.2 Wall thickness in U bent portion

The wall thickness of the tube in the U-bent section shall not be less than value determined by the equation:

Where:

  • tf wall thickness after bending, in. [mm],
  • T specified minimum tube wall thickness, in. [mm],
  • R centerline bend radius, in. [mm], and
  • D nominal outside tube diameter, in. [mm].

3.3 Tube leg length

In the case of U-tubes, the length of the tube legs as measured from the point of tangency of the bend and the tube leg to the end of the tube leg, shall not be less than specified, but may exceed the specified values by the amount given here below :

Leg length [mm]

Up to and incl. 6000 mm : -0 / +3.2 mm

Over 6000 mm to 9000 (incl) : -0 / +4.0 mm

Over 9000 -0 / + 4.8 mm

3.4 Difference in leg length

Stainless Steel Tube U Bend | U Bend Heat Exchanger TubesThe difference in lengths of the tube legs of a U tube shall not be greater than 1⁄8 in. = 3.2 mm unless otherwise specified.

3.5 End of tube : squareness

The end of any tube may depart from square by not more than:

0.25 mm for tubes up to 5/8” [15.9 mm]
0.40 mm for tubes higher than 5/8” [15.9 mm]

3.6 Leg spacing

The leg spacing measured between the points of tangency of the bend to the legs shall not vary from the value (2 R − specified tube outside diameter) by more than 1⁄16 in.[1.5 mm] where R is the center-line bend radius.

3.7 Bent portion curvature

The bent portion of the U-tube shall be substantially uniform in curvature, and not to exceed 6 1⁄16 in. [1.5 mm] of the nominal center-line radius.

3.8 Deviation from the plane of bend

Permissible deviation from the plane of bend (Fig. 1) shall not exceed 1⁄16 in. [1.5 mm] as

measured from the points of tangency.

The dimensions for heat exchanger tube in special grades may differ from the above,please contact us.

The advantage of the shell and tube design cannot be ignored. Each unit comes with:

  • Connections that come in standardized sizes for easy assembly and feature additional thread and surface protection for clean installation
  • U-bend tubes expanded into a tubesheet which allow for tube expansions and contractions due to thermal fluctuations.
  • Gaskets that are made of high quality compressed fibres which lends to reusability.
  • A standard cast-iron or steel head for heavy duty services (also available as a spare part).
  • Saddle attaches which make for quick and easy mounting.
  • Punched baffles with minimal clearances between tubes guaranteeing correct fluid flow and minimized bypass
  • A welded shell protected with high quality paint for corrosion resistance.
  • Copper steel tubes which allow for strong, durable performance over a wide range of applications. Unique tube bundle layout (chevron corrugated pattern) minimizes deposit buildup at the edges and optimises media flow for high velocity flow turbulence.

ASTM A179 U Bend Tubes

We bend ASTM A179 U Bend Tubes with round, rectangular, square, plus oval cross sections used in medical, automotive, plus electronics industries.

ASTM A179 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-bent tube sizes (u-bending, u-bend)

Tube Outside 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. 11 000 mm max. 24 000 mm
max. 31,75 mm max 5,16 mm max. 1 250 mm

Sizes tolerances of U bend tubes are to fullfil the requirements of: ASTM A556 / 556M and DIN 28179

Heat treatment of U bent 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 bent tubes can be tested as follows

All materials are hydro-tested as standard. Stress relieving is carried out in a gas-fired furnace or solution annealed using an induction heat process. We can offer a range of additional testing on request, including dye penetrant and PMI testing.

Bending Type:

Cold Bending and Hot Bending.

Heat Treatment:

After Cold Bending, the bending area needs heat treatment.

Material & Standard

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

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

ASTM A556M-88/ASME SA556 Seamless cold drawn steel feedwater heater tubes

ASTM A556 is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.

ASME SA556 Chemical Compostion

Grade C % Si % Mn % P % S %
B2 0.27 max 0.10 min 0.29-0.93 0.030 max 0.030 max
C2 0.30 max 0.10 min 0.29-1.06 0.030 max 0.030 max

ASME SA556 Mechanical Properties

Grade Tensile Strength MPa Yield Strength MPa Hardness HRB
B2 410 min 260 min 79 min
C2 480 min 280 min 89 min

JIS Number and Corrensponding Foreign Standards

JIS
ASTM
BS
DIN
NF
ISO

Index Number

Standard Number

Grade

Tupe

Standard Number

Grade

Tupe

Standard Number

Grade

Tupe

Standard Number

Grade

Tupe

Standard Number

Grade

Tupe

Standard Number

Grade

Tupe

G3461
STB340
C
A161
LC
C
3059
HFS320
C
A49-245
TS34e
C
C010
(STB35)
A192
C
"
CFS320
C
"
TS34c
C
A226
C
"
ERW320
C
A556
GrA2
C
"
CEW320
C
A557
GrA2
C
"
S1 360
C
"
S2 360
C
"
ERW 360
C
"
CEW360
C
3606
ERW320
C
"
CEW320
C
"
CFS320
C
STB410
C
A179
GrC
C
3059
S1 440
C
17175
St45.8
C
A49-213
TU42c
C
2604/2
TS9H
C
(STB42)
A210
GrA1
C
"
S2 440
C
17177
St42.8
C
A49-215
TU42c
C
"
TW9H
C
A556
GrB2
C
"
ERW 440
C
A49-243
TS42c
A557
GrB2
C
"
CEW 440
C
A49-245
TS42c
3602
HFS 410
C
"
TS42c
"
CFS 410
C
"
ERW 410
C
"
CEW 410
C
3606
ERW 440
C
"
CEW 440
C
"
CFS 440
C
STB510
C
C
17175
19Mn5
C
A49-213
TU52C
C
2604/2
TS18
C
(STB52)
C
A49-248
TU52C
C

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. These U bend tubes can be custom designed in various diameters as per the requirements of our clients.

Well packing

We pack all U Tube bundles in bespoke wooden boxes and separate all U Tubes of different radii using finger pallets to facilitate easy assembly of bundles on receipt.

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

  • For roadfreight in timber fingers or skids.
  • In strong open or closed wooden boxes depending destination.
  • Each bundle is protected with plastic sheets.
  • Customers can provide their own packing or Salem can prepare a packing plan.
  • Detailed packings lists are attached to wooden cases to give quick and clear identification of contents.

ASTM A213 ASME SA213 Seamless Alloy Carbon Steel Heat Exchanger U Tubes for Boilers

With strong wood structure box packing by containers loading and shipping.

Hydraulic tubes, Hydraulic pipeline, cylinders Pneumatic cylinders, U tube