U-Tubesfor

Heat Exchangers

IN-HOUSE BENDING

Made in Germany

Technitube Röhrenwerke GmbH has always been a future-oriented and privately owned organisation, investing heavily in state-of-the-art machinery and equipment to achieve a leading position in its market.

In addition to the production of seamless stainless steel, nickel alloy and titanium alloy tubing manufactures U-tubes for the use in heat exchangers, condensers, pre-hea-ters and other applications.

These U-tubes are manufactured in accordance with the re-quirements of DIN 28179, TEMA R.C.B 2.31, ASTM A/ASME SA 688, ASTM B/ASME SB 163 or according to customer requirements.

The manufacture of U-tubes takes place in a separate facility, adjacent to the tube mill, on premises. uses ben-ding equipment which is used exclusively for stainless steel - nickel alloys and titanium alloys. Therefore, the risk of con-tact corrosion will be avoided.

For further technical details, please refer to our catalogue „Seamless Tubes“.

* In line with our general terms and conditions of sale we guarantee defect free materials and good workmanship

Your advantages, if you purchase U-tubes from TPS

1 You save money and time• You only have one contact person

• You avoid transport damages to the long initial tubes on the way to the bending company

• You do not have to pay extra costs for the carriage to the bending company

• You benefit from time saving due to the parallel production of the initial tubes and the U-tubes

• You may request spare tubes, which we stock for you

• You save space and time for assembling the heat exchangers as the U-tubes can be removed radius-wise from the wooden combs

2 Surface quality• You receive tubes which are free from oil and grease as well as free from debris

• You receive a metallic bright surface without discolouration on the inner and outer tube

3 Heat treatment of bending area• You can choose between solution or stress relief annealing depending on the material standard

• On demand, we also include the annealing charts

4 Packing• The U-tubes are secured to the transport-rack using wooden combs

in order to avoid damage

• Your incoming material inspection is faster and more efficiently due to the accurate packing sorted by radius

5 Quality• You receive a detailed test certificate with all the important measures

of the bend along with the inspection certificate 3.1

• You are given a warranty of up to 3 years*

U-tubes

Tolerances

Bending of the tubes is carried out according to the mentioned standards and requirements. The U-tubes are usually used in heat exchangers.

The requirements refer to seamless austenitic, du-plex, ferritic and martensitic steel tubes, nickel al-loys, titanium and titanium alloy U-bent tubes with

radii from 1,5 x D. Tolerances for smaller radii must be agreed with the customer. If customer requirements differ from these values, the customer requirements replace the standard.

Meaning of measurements and symbols:

A leg length difference

E (2R + D): 2x radius plus outside diameter

D nominal outside diameter

Dmax

max. outside diamater

Dmin

min. outside diamater

LD leg length distance measured from points of tangency

LL leg length

TL total length

R centerline bend radius

Rmin

min. radius

T wall thickness

Tmin

min. wall thickness in outside bending area

SW smalles wall thickness of straight tube

O ovality

DP deviation from plane of bend

Z section

U-bent tube with one 180 deg. bend

ScopeDefinition

Tolerance on total lengthTolerance on straight leg length

Wall thinning of bending area

Tolerance on ovalityRadii tolerance

Flattening on bend (TEMA R.C.B. 2.31 only)

Difference in leg lengthDeviation from plane of bend

Radius ≥ 1,5 D: max. 17% wall thinning

Tmin

≥ SW (2 R + D) 2 (R + D)

Flattening does not exceed 10% of the nominal diameter

straight leg ≤ 5000 mm - 0/+ 3 mmstraight leg > 5000 mm - 0/+ 5 mm ≤ 8000 mm

leg length ≤ 5000 mm - 0/+ 3 mmleg length > 5000 mm - 0/+ 5 mm

TL = LL + 0,5 D + R

Tolerances ≤ 6000 mm - 0/+ 5 mm > 6000 mm - 0/+ 8 mm

DP max 1/16“ = 1,5 mm

R 1,5 D - R 200 +/- 1,0 mm

R > 200 - R 400 +/- 1,5 mm

R > 400 +/- 2,0 mm

Allowable deviation from ovality in %

≤ 4 D D 100 = %

5 R

< 4 D ≤ 5 %

The deviation O of the ovality is calculated as follows:

O = 200 Dmax

- Dmin = %

D

max + D

min

inspection • documentation • packing

Heat treatment procedure of bending area

General

Partial heat treatment can be agreed upon on or-der placement indicating the corresponding radii. Austenitic U-tubes with radii > 1,3 x D usually are not sub-ject to heat treatment after bending acc. to the German regulation AD-Merkblatt HP 7/3.

The common procedures carried out on austenitic, duplex, ferritic and martensitic steels, nickel alloys, titanium and titanium alloys are mentioned below. Any deviation or additional requirements must be agreed between TPS and the customer in written form. Usually, the bend portion plus 305 mm (1 ft) of each straight leg length is heat treated by electric resistance annealing.

Cleaning of tube surface

Dye penetrant test (optional)

Method

Procedure

Before heat treatment of the U-tube, the surface must be cleaned in order to remove any residue of lubricant and colour marking on the tube.

Dye penetrant testing of the bending area can be ag-reed indicating the corresponding radii.

Austenitic and duplex steels - solution annealing Heating to a temperature between 1040°-1080°C (min. 1904°F - 1976°F). Followed by quenching in water.

Ferritic and martensitic steels - stress relieving annealing Rapid heating to a temperature between 620°- 650°C (min. 1148°F - 1202°F) followed by slow coo-ling in still air.

Nickel alloys - stress relieving annealing Rapid heating to a temperature beyond the material specific transformation temperature, followed by slow cooling in still air.

Titanium and titanium alloys - stress relieving annealing Rapid heating to a temperature between 550° - 580°C (min. 1022°F - 1076°F) followed by slow cooling in still air.Electric resistance heat treatment without holding time;

temperature controlls by an automatic infrared camera.From the heating up to the removal of the bend from the annealing installation, the tube is rinsed inside with protective gas to avoid oxidation. The discolouration on the outer tube surface can be removed on request (see ASTM A 688).

Free passage (optional)

If requested, the free passage can be proven by a ball passage test. The diameter of the ball is as follows:Inside diameter - flattening - 2 mm

Tightness test (optional)

As final operation, a tightness test by cold water pres-sure testing with demineralized water can be performed according to specification or as agreed.

PackingDocumentation

The standard packing consists of transport racks with combs and foil protection. Other packing has to be indica-ted in order. The removal by radius is assured. If reques-ted, the tube ends may be protected with plastic plugs.

Dimensional inspection

The radius and total length are inspected on each U-bend tube. Usually one sample of the smallest radius of each thickness is inspected with regard to minimum wall thickness on the bend area and flattening.

Cleanliness

The cleanliness of the inside and outside surface is ins-pected on each U-tube. Impurities caused by oil and gre-ase are not considered acceptable.

Marking

If not agreed otherwise, the first layer of each radius of each pallet or case is labelled as follows: Row No. • Radius (mm) • Quantity of tubesThe packing list will be attached to each packing unit.

If not agreed otherwise, we provide an inspection certi-ficate 3.1., according to EN10204 and if requested, an inpection certificate 3.2, by third party inspection can be provided. The TPI (third party inspector) has to be nomina-ted; TPI fees are covered by the client.

TPS-Technitube Röhrenwerke GmbHJulius-Saxler-Str. 7 • 54550 Daun/Germany

P.O. Box 1509 • 54541 Daun/GermanyPhone: +49 65 92 71 20 • Fax: +49 65 92 1305

E-Mail: service@tpsd.de • www.tpsd.de20

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In additon to the production of seamless stainless steel, nickel and titanium alloy tubes, TPS keeps a large stock for heat exchanger tubes to assure a fast supply for our customers.

The wide stock range which includes all common mate-rial grades and dimensions, in connection with our spe-cial stock service guarantees a delivery „just in time“.

The U-tubes are manufactured in our own bending faci-lity within a short time. Therefore, they can be delivered at short notice based on the stock material.

You can order U-tubes in the following material grades:· Stainless steel· Nickel alloys· Titanium· Carbon steel· Low alloy steel· Aluminium brass· Admiralty brass· Copper-nickel alloys

U-tubes within in days – instead of months!

Very short delivery time for U-tubes – straight tubes ex stock

TPS - SHUTDOWN SERVICE