U-shaped heat exchanger tubes

U-shaped heat exchanger tubes

U-shaped heat exchanger tubes are a type of shell and tube heat exchanger that have a tube bundle made of continuous tubes bent into a U-shape.

The bend side is free-floating and this helps in thermal expansion without requiring expansion joints. U-tube heat exchangers have a simple structure which makes them easy to manufacture and maintain. They are commonly used in shell and U-tube heat exchangers.

U bent heat exchanger tubes are used in various industrial applications for heat transfer between fluids, such as in boilers and condensers. U bent heat exchanger tubes are made from a variety of materials including stainless steel, titanium, and copper alloys depending on the application and environmental factors. They are typically designed to withstand high temperatures and pressures and are used in both liquid and gas applications.

Both ends of the U-tube are fixed on the same tube plate, and the shell and heat exchange tubes are separated. This allows the tube bundle to freely expand and contract without generating temperature difference stress, which is a problem that can occur in other types of heat exchangers.

U-shaped heat exchanger tubes have a simple structure which makes them easy to manufacture and maintain. They are commonly used in shell and U-tube heat exchangers, which consist of a cylindrical shell with U-shaped tubes inside. The U-tube design allows for better heat transfer efficiency, and the compact size of the U-shaped tubes means that the heat exchanger can be very powerful despite its small footprint.

Overall, U-shaped heat exchanger tubes are a popular choice for many industrial applications due to their simplicity, efficiency, and compact size.

U-tubes are made of precision straight tubes. These precision straight tubes are completed after cold rolling and bright annealing. In order to meet the technical conditions of our customers, every step of the process is strictly controlled.

U-tubes are mainly divided into two categories according to materials: stainless steel U-tubes and alloy steel U-tube

Measuring, cutting, deburring and cleaning of U bent tube

U-shaped heat exchanger tubes drawing

Drawing

U-tube explanation

a...................The difference in length between two straight pipe sections
c..............The tangent spacing of the outer wall of the elbow
Da............nominal steel pipe outer diameter
E..............The distance between the outer diameters of the two straight ends
f...............the distance between the ends of the two straight ends
l............... straight tube length
Lg............. straight pipe section plus total length of pipe
Rm...........nominal bending radius
S.............nominal wall thickness
Smin.......The minimum wall thickness at the back of the elbow
t...............the bend deviates from the horizontal distance
So...........Standard minimum wall thickness

Heat treatment

If requested by the customer, we add a straight pipe section with a minimum of 150mm according to the elbow.
Heat treatment is performed.

The computer controls the heat treatment furnace and records all the data.
The tube is filled with a protective gas - argon.

We can provide all the forms of annealing

Technical Parameters

Outer diameter: 12.7-38 mm
The bending radius is from 1.5 times the outer diameter to 1250 mm. The outer diameter is over 28mm,
The minimum bend radius can be further discussed.
Straight pipe length is the shortest 1000mm
Straight pipe length up to 12000mm
The bending radius is below 1000mm and heat treatment is required.

Bent pipe technology standard

Hydrostatic test

Measuring, cutting, deburring, cleaning

U-tube heat exchanger

U-tube heat exchanger

U Tube Heat Exchanger

U-tube heat exchanger is a kind of tube and shell heat exchanger, which belongs to petroleum and chemical equipment.

This kind of heat exchanger is named after the "U" shape tube. U-tube heat exchanger is composed of some main components such as tube box, shell and tube bundle. What's more, it is easy to dry after the U-tube heat exchanger hydrotest.

Structure and Features

The most notable difference between U-tube heat exchangers and other shell-and-tube heat exchangers is the U-shaped configuration of the tubes. Key characteristics include:

  • Each tube is bent into a U shape.
  • Fluid inlet and outlet are located on both sides of the same end.
  • The head is divided into two chambers by partitions, allowing each tube to expand and contract freely, thus solving the thermal compensation issue.
  • The flow direction of the medium inside and outside the tube is countercurrent, enhancing heat transfer efficiency.
  • Double-row tube plates are connected by a liquid collecting shell to maintain parallelism and seal leaks.
  • Condensate oil shell with ports for venting and cleaning, preventing the overflow of toxic gases or liquids.

Advantages

  • Effective thermal compensation due to the flexible U-tube design.
  • Efficient heat transfer with countercurrent flow.
  • Enhanced safety with leak prevention features.
  • Convenient maintenance and inspection with dedicated ports.

Sunny Steel can manufacture U tube heat exchanger in accordance with the ASME standard, TEMA, and API for 1, 2, or 4 pass U tube heat exchanger, other special requirements are also available.

U bend tube packing

Standard for U-shaped heat exchanger 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:

Standard Application
ASTM A179 Seamless Cold-Drawn Low-Carbon Steel Heat-Exchanger and Condenser Tubes
ASTM A192 Seamless Carbon Steel Boiler Tubes for High-Pressure Service
ASTM A210 Seamless Medium-Carbon Steel Boiler and Superheater Tubes
ASTM A213 seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes
ASTM A334 Seamless Steel Pipe for Low-Temperature Service and other Applications with Required Notch Toughness
JIS G3461/2 carbon steel tubes used for heat exchange in boilers, heat exchangers, condensers, and similar equipment
EN10216-1/2 specified the standard of cold processed precision steel tubes in a wide range of sizes
DIN17175 seamless tubes for high-pressure and high-temperature applications, specifically for boilers and heat exchangers

Chemical Composition and Mechanical Properties (Part)

Standard Grade Chemical Components (%) Mechanical Properties
C Si Mn P S Mo Cr V T.S. (Mpa) Y.S. (Mpa) E.L. (%) Hardness (HRB)
ASME SA179 SA179 0.06-0.18 / 0.27-0.63 ≤0.035 ≤0.035 / / / ≥325 ≥180 ≥35 ≤72
ASME SA192 SA192 0.06-0.18 ≤0.25 0.27-0.63 ≤0.035 ≤0.035 / / / ≥325 ≥180 ≥35 ≤77
ASME SA210 A1 ≤0.27 ≥0.10 ≤0.93 ≤0.035 ≤0.035 / / / ≥415 ≥255 ≥30 ≤79
C ≤0.35 ≥0.10 0.29-1.06 ≤0.035 ≤0.035 / / / ≥485 ≥275 ≥30 ≤89
ASTM A333 /A334 GR.1 ≤0.30 / 0.4-1.06 ≤0.025 ≤0.025 / / / ≥380 ≥205 ≥35 -45°
GR.6 ≤0.30 ≥0.10 0.29-1.06 ≤0.025 ≤0.025 / / / ≥415 ≥240 ≥30 -45°
GR.8 ≤0.13 0.13-0.32 ≤0.90 ≤0.025 ≤0.025 / / 8.40-9.60 ≥690 ≥515 ≥22 -195°

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 Fabrication Tolerances

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 tube drawing
Item Condition (when) Tolerance
 Ovality   Nominal bend radius ≤ 2 x nominal OD less than or equal to 12%
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 for U bend Tubes

We packs 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.

Wooden Cases for U-Bent Tubes

Wooden Cases for U-Bent Tubes

U bend tube packing
U bend tube packing
U bend tube packing
U bend tube packing
U bend tube packing

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

【H】 Ceramic lined pipe

Ceramic lined pipe is made through self-propagating high-temperature synthesis (SHS) technique.

【H】 Cast basalt lined steel pipe

Cast basalt lined steel pipe is composed by lined with cast basalt pipe, outside steel pipe and cement mortar filling between the two layers.

【H】 Ceramic Tile Lined Pipes

Ceramic tile lined pipes have very uniform coating of specially formulated ceramic material that is affixed to the inner of the pipe.

【H】 Rare earth alloy wear-resistant pipe

The material of the rare earth alloy wear-resistant pipe is ZG40CrMnMoNiSiRe, which is also the grade of rare earth alloy steel.

【H】 Tubes Erosion Shields

Tubes Erosion Shields are used to protect boiler tubing from the highly erosive effects of high temperatures and pressures thereby greatly extending tube life.

【H】 ASTM A213 T91 Alloy Tube

The ASTM A213 T91 seamless tubes are primarily used for boiler, superheater, and heat-exchanger.