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.

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

Tubes for heat exchangers are made of steel according to:

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.

U-bend or U-shape

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

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

Carbon & Alloy

Ferrite

TP 410

Austenite

Duplex

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.

Packing

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.

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

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.

Stainless U bend tubes

Our U Bend Tube Tube-bending production line, installed at 2007. Solution annealing after bend will be process to lower the residual stress, and followed by hydrostatic testing and dye penetrant testing if required.

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.

Materials - U Bend Tube

‘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

ASTM A556M-88/ASME SA556 Seamless cold drawn steel feedwater heater tubes ¹

(ASTM A 556 ]M - 88 / ASME 556 /ASTMA556M-88/ASME556)

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.

Feedwater Heater Tubes

Standard: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

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

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.

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)
Difference between leg lengths at the ends	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)
Straight leg length	>5m	+3/16(5mm)
Total tube length including radius	≤6m	+3/16(5mm)
Total tube length including radius	>6m	+5/16"(8mm)