Heat Treatment of SS

Sandvik seamless heat exchanger tubing

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Contents

Strengthen your team 3

with a materials professional

Reliable and safe 4

a stainless alternative

Sizes and tolerances 5

Standards

From melting to finished product 6

Research and development, 7

Environment, Ethics, Quality,

Production facilities

Sandvik around the world

Grade selection 8Typical application areas

Effect of alloying elements 10

Life cycle cost considerations

PRE formula

Chemical compositions

Cost saving by using duplex 11

stainless steels

Mechanical properties

Electropolished stainless steel

Welding 12

U-bent tubes for heat exchangers 14

Seamless titanium and zirconium 16

alloy tubing

Steel grades – standard 20

manufacturing programme

Sandvik, Sanicro, SAF 2304, SAF 2205, SAF 2507, SAF 2906 are trademarks owned by Sandvik AB. 254 SMO is a trademark owned by Outokumpu Oy.

Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice.

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Strengthen your team with a materials professional Sandvik will be your partner in the market. We offer…

… technical expertise– assistance with trouble shooting or problem solving and advice on material selection, welding, material handling or processing.

… tailor-made products– specially developed to meet particular demands and applications.

… one stop shopping–a wide range of grades and sizes to cover most material needs.

… consistent material properties – products with consistent and reliable quality in every delivery – the result of full quality assurance and control throughout the whole manufacturing process.

… flexibility and easy access for you to reach our materials experts – a worldwide, local network of Sales Units.

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Reliable and safe a stainless alternative

Flexibility in the tube grades available and in our production processes mean that seamless tubes can be developed and produced for specific service conditions.

Long experience in the production of special stainless steels and tubes, our flexibility in raw material sourcing, our willingness and ability to find materials solutions result in special steel grades with chemical compositions tailored to specific applications, customer, market or country requirements.

Our tubes are suitable for all types of heat exchanger; coolers, condensers, evaporators, preheaters, reheaters, reboilers, steam generators, air coolers.

Extreme conditions can be handled; by developing competitive and innovative solutions through close cooperation with our customers, together we can achieve lower operating costs and increase future operating reliability.

Product delivery and advanced communication systems We are where you need us to be. Strategic production locations worldwide combined with sophisticated plant programming capabilities ensure reliable and efficient product supply. Advanced logistics provide global distribution.

Although the cost of a heat exchanger is comparatively low, in relation to the cost of a complete plant, its reliability can have a significant influence on operating costs.

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Sandvik Materials Technology has an extensive manufacturing programme for seamless heat exchanger tubes covering most types of standard austenitic, duplex (austenitic-ferritic) and high alloy auste-nitic stainless steels as well as titanium and zirconium.

Our main size range, produced in imperial and metric dimensions is from 12 mm (1/2”) up to 40 mm (11/2”) outside diameter. Special sizes can be made to order. Tubes are supplied in straight lengths up to 30 metres or as U-bends up to 27 metres.

Heat exchanger standard stock programme for straight tubes

Outside Wall Inner Imperial size Weight ASTM ASTM ASTM ASTM UNS UNS UNSdiameter thickness diameter TP TP TP TP N08028 S32205/ S32750 a) 304L 316L 321 (316Ti) S31803mm mm mm kg/m 3R12 3R60 6R35 5R75 Sanicro 28 SAF 2205 SAF 2507

19.05 1.65 15.8 3⁄4” 16 BWG 0,66 b,d b,d

19.05 2.11 14.8 3⁄4” 14 BWG b b,d 20.0 2.00 16.0 0,87 d d 25.0 1.50 22.0 1,04 c 25.0 2.00 21.0 1,88 d d 25.4 1.65 22.1 1” 16 BWG 0,79 b,d b,d

25.4 2.11 21.2 1” 14 BWG 0,97 b,d b,d

a) Calculated with min. wall. b) Stock standard = min. wall. c) Stock standard in lengths of 6 metres. d) Random lengths in 6-14 metres.

Tolerances

Outside Tolerances Wall thicknessdiametermm

Sandvik 3R12 and 3R60 in imperial sizes ASTM A450 < 25.4 ± 0.10 mm +20 / -0% (min. wall) 25.4 - 38 ± 0.15 mm +20 / -0% (min. wall) Sandvik 3R12, 3R60, 5R75 and 6R35 in metric sizes EN ISO 112720 & 25 ± 0.75%, min. ±0.30 mm (D3) ±10%, min. ±0.20mm (T3)Sandvik SAF 2205 and SAF 2507 acc. to ASTM A789 < 25.4 ± 0.13 mm ±10%Sandvik Sanicro 28 acc. to ASTM B668 / B829, ave. wall < 25.4 ± 0.19 mm ±10%

Standards for seamless tubes

Sandvik 3R12 and 3R60 (imperial sizes) ASTM A213 / A450Sandvik 3R12 and 3R60 (metric sizes) SS 219711 Condition 22 (e.g. 3R12 = SS 2352-22) DIN 17458 Pk1, Corrosion test acc. to DIN 50914 (EN ISO 3652-2, practice A)Sandvik 6R35 and 5R75 DIN 17458 Pk1, Corrosion test acc. to DIN 50914 (EN ISO 3652-2, practice A)Sandvik Sanicro 28 ASTM B668 / B829Sandvik SAF 2205 and SAF 2507 ASTM A789 / A450

Sizes and tolerances

Complementary products The Sandvik heat exchanger tubes supply package includes standard stainless steel and special grade complementary products – welded tubes, sheet and plate, tube fittings for butt welding and socket welding, threaded joints and flanges.

Further information: www.smt.sandvik.com/fittingswww.smt.sandvik.com/heatexchangers

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From melting to finished product

Our customers know that trouble free production, reduced maintenance costs and less downtime rely on the correct choice of construction materials. They know also that safe and reliable materials need a supplier known for their attention to every detail in the manufacturing process.

That is why many users turn to Sandvik. We have built our reputation on quality and product reliability and earned the trust of our customers by producing quality products and providing the best possible levels of technical and after-sales service.

Sandvik controls the whole production process from melting and alloying in the electric arc and high frequency furnaces, the AOD converter and continuous casting plant to the finishing operations such as cold rolling, cold drawing or heat treatment.

Further information:SMT world widewww.smt.sandvik.com

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Research and developmentSandvik has one of the largest steel research centres in Europe. New materials are constantly being developed and exist-ing materials and production processes improved. In addition, we have a compre-hensive programme of liaison and co-operation with universities, research institutions and specialised companies that possess particular expertise. During the coming years, we anticipate that a number of new materials will be introduced, where Sandvik will take material technology into the next generation and offer end user industries even better properties, improved efficien-cies and lower life cycle costs.

EnvironmentEnvironmental awareness is an integral part of our business and is at the forefront of all activities within our operation. Sandvik strives for high efficiency in the use of energy and natural resources and holds approval to ISO 14001:1996. Stainless steel can be 100% recycled, and our steel plant in Sandviken operates a full materials recovery process.

EthicsOur core values include promoting equality in all respects and operating in a highly ethical manner in relation to employees, customers, suppliers and all other industry contacts.

QualityOur fully integrated steel mill ensures close control of the entire production process, from melting of the steel to the finished product. Sandvik Materials Technology has quality systems accepted by internationally recognized bodies and holds an ASME Quality System Certificate as a Materials Organisation. Approval to ISO 9001 is also held, as well as product approvals from LRQA, JIS, RW-TÜV, Det Norske Veritas and other organisations. Quality, both in products and services, is a major objective for us and this is expressed in the company s̓ Quality Policy. All employees are involved and committed to continuous improvement.

Production facilitiesSandvik Materials Technology s̓ tube manufacturing facilities are located strategically around the world. Our combined resources, connected through a worldwide electronic network of information and planning systems enables us to offer a reliable supply of high quality products – no matter where in the world our customers are located.

Sandvik around the worldWithin Sandvik Materials Technologyʼs global operation, all disciplines work together – sales representatives, engineers, researchers and production, in order to satisfy customer demands.

We are where you need us to be

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Typical application areas forSandvik heat exchanger tubesl Seawater coolers

l Oil refining

l Petrochemicals

l Chemicals

l Power generation

l Gas processing

l Flue gas cleaning/desulphurisation

l Hydrometallurgy

l Recuperators

l Pulp and paper production

l Fertilizers

l Desalination/salt evaporation

When selecting a material grade for a heat exchanger operating under certain conditions, a number of considerations have to be made. The grade needs to have sufficient corrosion resistance combined with suitable mechanical and physical

properties. Sandvik Materials Technologyʼs global technical sales network can help to select the optimum grade for the application – based on extensive service experience from installations worldwide.

Grade selection depends on application

Seawater coolersGrades selected for seawater coolers need to have high resistance to chloride solutions. One such grade is Sandvik SAF 2507.

Oil refiningRefinery process streams involve many corrosive elements, which can shorten the lifetime of low alloyed steels. Stainless steels, and, in particular, duplex grades Sandvik SAF 2205 and SAF 2507, can overcome such problems.

Petrochemicals Corrosion in petrochemical plants can lead to contamination of manufactured products. Sandvik’s high quality, corrosion resistant stainless steels include a full range of standard austenitic grades up to the super duplex grade Sandvik SAF 2507.

Optimized materials enhance process performance

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Further information: www.smt.sandvik.com/heatexchangers

Chemicals Sandvik’s special grades are used in heat exchangers in many demanding chemical processes, including the production of inorganic acids and caustics. Sandvik seamless tubes offer the necessary high reliability in these often critical applications.

Power generation Sandvik heat exchanger tubes can be found in condensers, feedwater heaters and waste- water handling equipment. Sandvik steel grades fulfil the high quality standards for use in both conventional fossil fuelled power plants as well as nuclear power stations.

Gas processing Reliable operation is essential in gas processing equipment. For offshore equipment, duplex stainless steels have been shown to give weight saving benefits due to the wall thickness reductions possible from these high strength materials.

Pulp and paperDuplex stainless steel Sandvik SAF 2304 has been successfully used for kraft digesters,

preheaters and other equipment.

FertilizersThe urea process requires specific materials with low impurity levels for a long and safe service life. Sandvik 2RE69 has been devel-oped primarily to cope with the severely corrosive conditions existing in the industry. Sandvik 2RE10 has been developed for oxidizing environments and is widely used to replace corroding 304L in nitric acid plants.

Desalination /salt evaporationSalt production involves high chlorides, and materials with high resistance to localised corrosion in a hostile environment are necessary. Examples of such grades are Sandvik Sanicro 28, SAF 2507 and 254 SMO.

Flue gas cleaning/desulphurisationEnvironmental demands call for effective gas cleaning equipment. For heat exchangers handling sour gas under condensing conditions, high alloyed austenitic grades such as Sandvik Sanicro 41 and, in particular, Sandvik Sanicro 28 and 254 SMO should be considered. The higher alloyed duplex stainless steels can also be suitable.

HydrometallurgySlurry processing under high pressuresand temperatures may give rise to severely corrosive conditions. Duplex stainless steels such as Sandvik SAF 2304 and SAF 2906, with their combination of corrosion resistance, high strength and erosion resistance, are particularly suited to this type of service.

RecuperatorsSandvik high temperature grades are used in recuperators and air heaters serving the glass, carbon black and steel industries, and in the direct reduction of iron ore (Midrex process), chemical waste incineration and sewage sludge waste incineration.

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Effect of alloying elements

Life cycle cost considerationsThe two different ways of looking at the cost of products depends on whether a carbon steel grade is chosen or a stainless steel/special grade, particularly designed for the application.

Short term carbon steel optionl Low initial costl Increased inspection costl More frequent maintenance requiredl Greater risk of production stoppagesl Replacement cost

Long term stainless steel/special grades optionl Higher initial costl Less maintenance requiredl More reliable operationl Lower life cycle cost

ASTM G48, practice A (6% FeCl3) is one of the toughest

pitting corrosion tests for stainless steels. It gives the

same ranking order for the steels as in slightly chlorin-

ated seawater. In Sandvik’s laboratory, a modified

version of G48 is used, with a step by step raising of the

temperature. This allows the determination of the

critical pitting temperature. The results from such a test

are shown to the right.

The main alloying elements in stainless steel, which contribute to improving pitting and crevice corrosion resistance, are chromium, molybdenum and nitrogen. Chromium is the most important element for forming a protective oxide layer. In general, the higher the chromium content the better the corrosion resistance. A com-mon reason for corrosion is the presence of chlorides in a process. In that situation, molybdenum and nitrogen also contribute strongly to improved corrosion resistance. One way to define the pitting resistance of stainless steels is through the Pitting Resistance Equivalent, PRE. The PRE number is calculated from the chemistry of the steel according to the following formula: PRE=%Cr+3.3%Mo+16%N

The chemical compositions table provides approximate PRE values for ranking dif-ferent alloys. It can be seen that Sandvik SAF 2507, SAF 2906 and 254 SMO have the highest PRE values, while the PRE value for Sandvik Sanicro 28 is slightly lower. Sandvik SAF 2205 and 2RK65 represent an intermediate level, while SAF 2304 has a PRE value at the same level as 316L.

Pitting corrosion testsThere are many tests that can determine approximate ranking according to the PRE formula. A popular test method for deter-mining the performance of intermediate and high alloy grades, in particular, is ASTM G48A.

Chemical compositions

Grade Sandvik UNS C max Cr Ni Mo N PRE

Austenitic

3R65 (316L) S31603 0.030 17 11.5 2.1 - 242RK65 (904L) N08904 0.020 20 25 4.5 - 35254 SMO S31254 0.020 20 18 6.1 0.2 43

Duplex

SAF 2304 S32304 0.030 23 4.5 - 0.1 25SAF 2205 S32205/ 0.030 22 5 3.2 0.2 >35 S31803SAF 2507 S32750 0.030 25 7 4 0.3 >42.5SAF 2906 S32906 0.030 29 7 2.3 0.3 41

Ni-Alloy

Sanicro 28 N08028 0.020 27 31 3.5 - 39Sanicro 41 N08825 0.030 20 38.5 2.6 - 29

Formula: PRE=%Cr+3.3%Mo+16%N

Specimens of various stainless steels after G48 testing at 80°C for 24 hours.

Sand

vik

SAF

2507

Sand

vik

3R60

Sand

vik

SAF

2205

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Cost saving by using duplex stainless steelsCost savings can be achieved when design-ing a heat exchanger in duplex material. The cost effective combination of high mechanical strength, superior corrosion

resistance and fabricating compatibility of duplex stainless steels means that it is possible to reduce tube wall thickness and, therefore, design lighter equipment.

Mechanical properties

Grade Sandvik Proof strength Tensile strength Elongation Rp0.2 Rm A% MPa, min. MPa Min.

Austenitic 3R60 (316L) 220 515-690 45 2RK65 (904L) 230 520-720 35 254 SMO 300 650-850 35

Duplex SAF 2304 400 600-820 25 SAF 2205 485 680-880 25 SAF 2507 550 800-1000 25 SAF 2906 550 ≥750 25 Ni-Alloy Sanicro 28 220 550-750 40 Sanicro 41 240 590-750 30

Additional grades: 304/L, 321, UNS: N04400, N02200, N06600, N08800

Further information: www.smt.sandvik.com/calamoS-191-ENG High purity steel

Electropolished stainless steel heat exchanger tubes Sandvik’s manufacturing capabilities include electropolishing of stainless steel heat exchanger tubes. Sandvik Calamo, part of Sandvik Materials Technology, is one of the world’s leading electropolishing companies.

Key benefits that can be achieved by electropolishing stainless steel surfaces are :l Increased surface cleanlinessl Increased corrosion resistance l Improved surface roughness profile l Reduction of surface deposits l Reduced surface areal Improved micro surface

As one of the world s̓ first manufacturers of electropolished tubes, Sandvik Calamo has more than 35 yearsʼ experience in the market for clean and high purity materials

and specialises in electropolishing, clean-ing and surface treatment of stainless steel in the following areas: l Electropolished and high purity tubular productsl Subcontract electropolishing of components and vesselsl Electrolytes for electropolishing

Continuous development of the electropol-ishing process ensures that Sandvik Calamo is able to meet the latest and most demanding requirements. The different parameters during the electropolishing and cleaning processes are strictly measured, controlled and recorded. A unique passiva-tion method guarantees a chromium en-riched layer of the highest quality.

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WeldingSandvik SAF 2205, 2304 and 2507

Sandvik SAF 2205, 2304 and 2507 duplex grades offer good weldability. Suitable welding methods include manual metal-arc welding (MMA/SMAW) with covered electrodes, submerged-arc welding (SAW), gas metal-arc welding (MIG/GMAW) and gas tungsten-arc welding (TIG/GTAW). For Sandvik SAF 2304 and 2205, welding should be performed with a heat input of 0.5–2.5 kJ/mm (10–65 kJ/inch) and for SAF 2507 0.2–1.5 kJ/mm (5–40 kJ/inch). The interpass temperature should be kept below 250°C (400°F) for Sandvik SAF 2304 and 2205 and below 150°C (300°F) for Sandvik SAF 2507. Preheating

or post-weld heat treatment are normally not necessary or recommended. If there is a risk of condensed moisture on the joint surfaces, a preheat of 50–70°C (90–150°F) can be introduced to avoid porosity. Preheating with an open flame should be avoided. Careful cleaning of the joint, before and after welding, is important for optimum corrosion resistance. Local defor-mation due to welding stresses will not be as pronounced as for austenitic stainless steels, but a proper welding plan is still recommended. Welding without filler metal is not recommended. Recommended weld-ing consumables are listed in the table.

Sandvik Sanicro 28 and Sandvik 2RK65

The weldability of both Sandvik Sanicro 28 and 2RK65 is good. Suitable welding methods include manual metal-arc welding (MMA/SMAW) with covered electrode, submerged-arc welding (SAW) and gas shielded-arc welding (MIG/GMAW and TIG GTAW). Welding should be per-formed with a low heat input, maximum 1 kJ/mm (25 kJ/inch) and the interpass temperature should not exceed 150°C (300°F). A stringer bead welding technique should be used. Preheating or post-weld heat treatment are normally not necessary or recommended. Since both alloys are intended for use under severely corrosive conditions, thorough cleaning,

before and after welding, is important for achieving a fully corrosion resistant joint. In common with all austenitic stainless steels, these alloys have low thermal con-ductivity and high thermal expansion. Welding should therefore be carefully planned in advance for minimum distor-tion of the welded joint. The welding of fully austenitic stainless steels usually involves the risk of hot cracking in the weld metal, particularly if the weldment is under constraint. However, Sandvik Sanicro 28 and 2RK65 are less prone to this type of cracking, due to their very low impurity content. Recommended welding consumables are listed in the table.

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Product programme Chemical compositions. Nominal values, weight %

Parent metal Recommended filler metal MIG/GMAW TIG/GTAW SAW MMA/SMAW Sandvik Sandvik Sandvik Sandvik Sandvik

UNS S31803 SAF 2205 22.8.3.L 22.8.3.L 22.8.3.L1) 22.9.3.LR UNS S32304 SAF 2304 22.8.3.L 22.8.3.L 22.8.3.L1) 22.9.3.LR UNS S32750 SAF 2507 25.10.4.L 25.10.4.L 25.10.4.L1) 25.10.4.LR UNS N08028 Sanicro 28 27.31.4.LCu 27.31.4.LCu 27.31.4.LCu2) 27.31.4.LCuR UNS N08904 2RK65 20.25.5.LCu 20.25.5.LCu 20.25.5.LCu2) 20.25.5.LCuR UNS S31254 254 SMO Sanicro 60 Sanicro 60 Sanicro 602) Sanicro 60 UNS S31050 2RE69 25.22.2.LMn 25.22.2.LMn 25.22.2.LMn3) 25.22.2.LMnB UNS S31002 2RE10 25.20.L 25.20.L 25.20.L1) 25.20.LR

1) Flux Sandvik 15W. 2) Flux Sandvik 50SW. 3) Flux Sandvik 31S

Further information:S-236-ENG. Stainless weldingS-91-57-ENG. Welding practiceSandvik duplex stainless steels.www.smt.sandvik.com/welding

Sandvik 2RE69 and Sandvik 2RE10

The weldability of Sandvik 2RE69 and 2RE10 is good. Suitable methods of fusion welding are manual metal-arc welding with covered electrodes and gas shielded-arc welding, with the TIG method as first choice. In common with all austenitic stainless steels, Sandvik 2RE69 and 2RE10 have low thermal conductivity and high

thermal expansion. Welding should there-fore be carefully planned in advance, so that distortion of the welded joint can be minimised. If, despite these precautions, it is believed that residual stresses may impair the function of the weldment, it is recommended that the entire structure is stress relieved.

Sandvik 254 SMO

Sandvik 254 SMO also has good weld-ability. The conventional welding methods for stainless steels can be used, including manual metal-arc welding (MMA/SMAW) with covered electrode, submerged-arc welding (SAW) and gas shielded-arc welding (MIG/GMAW and TIG/GTAW). Welding should be carried out with a max-imum heat input of 1.5 kJ/mm (40 kJ/inch) and the interpass temperature should be kept below 100°C (210°F). Stringer beads should be used. Preheating or post weld heat treatment is normally not necessary or recommended. Careful cleaning of the

joint, before and after welding, are impor-tant for the best corrosion resistance. Welding without filler metal is not recom-mended. If autogeneous welding with TIG or plasma-arc is necessary, solution annealing at 1150–1200°C (2100–2200°F) followed by cooling is recommended to restore the microstructure of the joint. Recommended welding consumables are listed in the table above. Whenever there are questions or advice is needed in connection with welding, Sandvik Materials Technologyʼs welding experts can assist with state of the art solutions.

Sandvik 304L and Sandvik 316L

The weldability of Sandvik 3R12 and 3R60 is good. Suitable welding methods are manual metal-arc welding with covered electrodes and gas shielded-arc welding with the TIG and MIG methods as first choice. Preheating and post-weld heat treatment are normally not necessary. Since the material has low thermal conduc-tivity and high thermal expansion, welding

must be carried out with a low heat input and with welding plans well thought out in advance, so that the deformation of the welded joint can be kept under control. If, despite these precautions, it is believed that the residual stresses might impair the function of the weldment, we recommend that the entire structure is stress relieved.

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Rmax = 200 x (%)da max - da min

da max + da min

Description of U-bend:a. . . . . . . . . difference in length of legs

c. . . . . . . . . distance between points of tangency

da. . . . . . . nominal outside diameter of tube

e. . . . . . . . . distance between legs

measured on outside diameter

f. . . . . . . . . distance between legs

l. . . . . . . . . leg length

lg. . . . . . . .developed length

rm . . . . . . .nominal bend radius

s. . . . . . . . . nominal wall thickness

s min. . . .minimum wall thickness

at the back of the bend

t. . . . . . . . .deviation from plane of the bend

so. . . . . . .minimum wall thickness

defined by specif ication

Sandvik Materials Technology is one of the world’s leading suppliers of U-bent tubes. U-bends are manufactured from Sandvik precision straight tubes and are produced by the cold-pilgering method with a bright annealed surface. Production is strictly controlled, step-by-step, in order to fulfill all the technical demands from our customers.

U-bent tubesfor heat exchangers

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U-bend definitions

Technical parametersOD 12.7-38 mm, see the size range tableBending radii from 1.5xOD up to 1250 mm. Minimum bending radii for OD´s over 28 mm after agreement.Leg length min. 1000 mmLeg length max. 12000 mm Heat treatment for radii up to 1000 mm

Standards and gradesSandvik has extensive experience in the production of U-bends.We manufacture and supply according to the heat exchanger standards and steel

grades listed on pages 18-19.

Standards for bendingOur basic specification isSandvik spec. 7-2-1179.We can use alsoDIN 28179, TEMA RCB 2.31or various customer specifications. Copies of all specifications are available on request.

U-bend tolerancesAcc. to Sandvik steel spec. 7-2-1179

Permissible ovality

how to define ovality:

rm ≤ 2 da Rmax ≤ 12%rm > 2 da ≤ 4 da Rmax ≤ 10%rm > 4 da Rmax ≤ 5%

Minimum wall thickness of WT

rm ≤ 2 da smin = 0.75 x srm > 2 da ≤ 4 da smin = 0.80 x srm > 4 da smin = 0.90 x s

Tolerance (D) of bending radii (rm)

rm ≤ 100 mm D ± 1.0 mmrm > 100 ≤ 300 mm D ± 1.5 mmrm > 300 mm D ± 2.0 mm

Distance between legs

f = max. 1.5 mm

Tolerance of length (lg), difference in length of legs (a)

all lengths: lg= +3/-0 mm, a = +3/-0 mm

Tolerance of deviation (t)from plane of the bend

t ≤ 1.5 mm

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14 15

Size rangeU-tubes can be produced within the size range specified in the table above. The sizes marked in light blue can be produced by special agreement.

Heat treatmentIf specified, we are equipped to carry out heat treatment of bends plus min. 150 mm of leg.l Furnace is computer controlled and all data is recorded.l We use an argon protective atmosphere inside the tubes.l We can provide all types of annealing: Solution Stress relieving

Stabilisation

Hydrotestingl After heat treatment all U-tubes are hydrotested. l Minimum holding time at the required pressure is 5 seconds.l All tubes are dried and carefully cleaned after hydrotesting.

Measuring, cutting, deburring, cleaningl U-bends are measured exactly in accordance with relevant standards, or to customer’s specification. l All tubes are cut to the specified leg lengths, ends are deburred and the tubes are finally internally cleaned with air.l Before packing, both ends of U-bends are capped with plastic caps.

Packingl In strong, open or closed, wooden boxes depending on destination - max. 8000 kg.l Ends of tubes protected by plastic caps.l Vertical separators for each radius.l Chloride free plastic separators between each row, every 2 metres.l Each bundle is covered with plastic.l Customers can provide a packing drawing or Sandvik can prepare a packing plan. l Packing lists, covered with plastic, are placed on each wooden box for easy identification of order details – including exact list of radii and lengths inside.

Benefi ts of Sandvik U-tubesthe whole package from Sandvik Straight tubes and bends are supplied as a package from a single producer:

l No yield losses from separate bending operation l Guaranteed qualityl Lower transport costs from one location

Heat treatment of U-bent tubesO.D. Wall thickness (mm) (mm) 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5

12.70

14.00

15.00

15.88

16.00

18.00

19.00

20.00

25.00

25.40

28.00

30.00

32.00

33.40

33.70

35.00

38.00

16 17

Seamless titanium and titanium alloy tubing

The manufacture of seamless titanium and zirconium heat exchanger tubes at Sandvik Materials Technology in Sandviken, Sweden, is carried out through a com-pletely integrated process. It starts with melting of raw materials in high vacuum furnaces and ends with the finished seam-less tubes. The manufacturing process is specially designed to work with non-fer-

rous metals like titanium and zirconium. The Sandvik group has been the world s̓ largest independent manufacturer of seamless zirconium and titanium tubing for over 35 years, supplying to a wide range of industries including chemical, petro-chemical, aerospace and nuclear.

In environments where not even the best stainless steels meet the corrosion resistance requirements, titanium and zirconium can be used.

Sandvik ASTM/ASME defined titanium gradesGrade 1 Unalloyed titanium, low oxygen, low strength

Grade 2 Unalloyed titanium, standard oxygen, medium strength

Grade 3 Unalloyed titanium, medium oxygen, high strength

Grade 4 Unalloyed titanium, high oxygen, extra high strength

Grade 5 Titanium alloy (6% aluminium, 4% vanadium)

Grade 7 Unalloyed titanium, plus 0.12% to 0.25% palladium, standard oxygen, medium strength

Grade 9 Titanium alloy (3% aluminium, 2.5% vanadium), high strength

Grade 11 Unalloyed titanium plus 0.12% to 0.25% palladium, low oxygen, low strength

Grade 12 Titanium alloy (0.3% molybdenum, 0.8% nickel), high strength

Grade 16 Unalloyed titanium plus 0.04% to 0.08% palladium, standard oxygen, medium strength

Grade 17 Unalloyed titanium plus 0.04% to 0.08% palladium, low oxygen, low strength

Grade 26 Unalloyed titanium plus 0.08% to 0.14% ruthenium, standard oxygen, medium strength

Grade 28 Titanium alloy (3% aluminium, 2.5% vanadium) plus 0.08% to 0.14% ruthenium

Titanium has a unique set of properties that makes it suitable for a variety of applications. It has a high environmental resistance, relying primarily on a very thin, tenacious and highly protective surface oxide film. Titanium is highly resistant to wet chlorine chemicals, practically all salt solutions, seawater, a range of acids, organic and inorganic chemicals and gases. The same oxide film provides a high

resistance to erosion in high velocity process streams. The corrosion and erosion resistance makes titanium a pre-ferred heat transfer material for shell/tube heat exchangers, since it permits the use of thin heat transfer walls and high fluid flow rates. In addition, titanium has only half the weight of steel, is non-magnetic, has a high melting point, high strength-to-weight ratio and a low modulus of elasticity.

Sandvik titanium tubing is

characterized by:

l Excellent resistance to general

corrosion in seawater applications

l High resistance to stress corrosion

cracking in chloride and sour gas

environments

l Excellent resistance to pitting,

crevice and erosion corrosion

l High heat transfer efficiency

l Good formability and weldability

l Very low thermal expansion

l High strength-to-weight ratio

Practical benefits of using

titanium and Ti-alloys

The elimination or reduction of:

l Fatigue

l Stress corrosion cracking

l Fretting fatigue

l Corrosion fatigue

l Fretting

l Cavitation erosion

l Galling

l Porosity

l Spalling

l Wear

Titanium

16 17

l The range of dimensions is outside diameters from 8 mm up to 40 mm in tube lengths up to 28 meters for titanium and 16 meters for zirconium with certain OD/L and OD/Wt limitations. l All tubing can be supplied as straight lengths or as U-tubes.l Non-destructive testing facilities include ultrasonic testing, Eddy Current testing and hydropressure testing.l Tubes are normally supplied as cold pilgered, vacuum annealed and cleaned with the OD in the as polished condition.

Zirconium Zirconium is highly resistant to a wide range of acids and bases, both organic and inorganic, which makes it an interest-ing and exceptional long life alternative to other materials in highly demanding

applications. The seamless tube zirco-nium grade, produced for heat exchanger applications, is Sandvik Zirconium 702*, which offers the process industry a high quality and competitive product concept.

Sandvik Zirconium 702 seamless

tubing is characterized by:

l High heat transfer efficiencyl Very low thermal expansionl Immunity to stress corrosion crackingl High resistance to localized (pitting and crevice) forms of corrosionl Very good corrosion resistance in most organic acidsl Exceptional corrosion resistance in mineral acidsl Good corrosion resistance in strong alkalisl Interchangeability between acid and alkali conditions

Main application areas

l Acetic acidl Ureal Formic acidl Sulphuric acidl Nitric acidl Citric acid l Methyl methacrylate

* As per ASTM/ASME B, SB523 or equivalent.

Further information: www.smt.sandvik.com/heatexchangers

18 19

1) DIN 174592) Sanicro 31H

3) 1.4465 can be certified.4) Pressure Equipment Directive 97/23/EC 5) Also Code Case exist

Austenitic stainless steels These steels have many applications in heat exchangers, piping, hydraulic systems and other equipment for the chemical, petrochemical, pulp and paper and food processing industries. The Mo-alloyed grades have higher resistance to general corrosion in non-oxidising acids and to pitting and crevice corrosion. Ti- and Nb-alloyed grades have good strength at high temperature.

Duplex stainless steels Considerably higher strength and lower thermal expansion compared with auste-nitic grades. Very high corrosion resist-ance in chloride-containing solutions and weak organic acids. Sandvik SAF 2507 has superior corrosion resistance in seawater. Used for heat exchangers and also offshore oil and gas exploration. Duplex steels have a maximum service temperature of 250-300 °C.

High-alloy austenitic stainless steels and nickel alloys Sandvik 2RK65 – Phosphoric andsulphuric acid, seawater, refineries and petrochemical plants.

Sandvik Sanicro 28 – Very good resistance to all types of corrosion. Wide range of applications including refinery industry. Excellent performance in phosphoric acid.

Sandvik 2RE10 – Extremely low carbon and impurity content, excellent resistance to corrosion in strongly oxidising acids. Widely used as coolers/condensers and intail gas preheating in nitric acid plants.

Steel gradesStandard manufacturing programme

Designation Chemical composition (nominal), % Standards* Pressure Mechanical properties Sandvik C Cr Ni Mo Others UNS ASTM TP EN Steel W.-Nr. AFNOR purpose Proof Tensile Elongation number PED4) ASME strength strength A

prEN Rp0.2 Rm

10216-5 MPa min. MPa %, min.Austenitic stainless steels 3R12 ≤0.030 18.5 10 – – S30403 304/304L 1.4306/1.4301 1.4306/1.4301 Z2CN18-10 X X 210 515–680 453R60 ≤0.030 17.5 13 2.6 – S31603 316/316L 1.4435 1.4435/1.4436 Z2CND17-13 X X 220 515–690 453R65 ≤0.030 17 11.5 2.1 – S31603 316/316L 1.4404 1.4404/1.4401 Z2CND17-12 X X 220 515–690 456R35 0.05 17.5 10.5 − Ti S32100/S32109 321/321H 1.4541/1.4940 1.4541/1.4878 1) Z6CNT18-10 X X 210 515–690 35 5R75 0.05 17 12 2.1 Ti (S31635)** (316Ti)** 1.4571 1.4571 Z6CNDT17-12 X – 220 510–710 353R19 ≤0.030 18.5 9 – N S30453 304LN 1.4311 1.4311 Z2NC18-10AZ* X X 275 550–750 405R60 0.04 17 12 2.6 – S31600/S31609 316/316H 1.4436 1.4436 Z6CND17-12 X X 220 515–690 403R64 ≤0.030 18.5 14.5 3.1 – S31703 317L 1.4438 (1.4438)* – – X 220 515–690 358R40 0.06 17.5 11 – Nb S34700/S34709 347/347H 1.4550/1.4912 1.4550 Z6CNNb18-10 X – 220 515–690 35

Duplex stainless steels

SAF 2304 ≤0.030 23 4.5 – N S32304 – 1.4362 1.4362 Z2NC23-04AZ X X 400 600–820 25SAF 2205 ≤0.030 22 5 3.2 N S31803/S32205 – 1.4462 1.4462 Z2CND22-05-03 X X 485 680−880 25SAF 2507 ≤0.030 25 7 4 N S32750 – 1.4410 – – X X 550 800–1000 253RE60 ≤0.030 18.5 4.5 2.6 Si, N S31500 – 1.4424 1.4417 Z2CND18-05-03 X X 450 700−800 30

High-alloy austenitic stainless steels and nickel alloys

2RK65 ≤0.020 20 25 4.5 Cu N08904 – 1.4539 1.4539 Z1NCDU25-20-04 X X 230 520–720 35Sanicro 28 ≤0.020 27 31 3.5 Cu N08028 – 1.4563 1.4563 Z1NCDU31-27-03 X X5) 220 550−750 402RE10 ≤0.015 24.5 20.5 – – S31002 – 1.4335 1.4335 – X – 210 500–670 352RE69 ≤0.020 25 22 2.1 N S31050 – 1.4466 1.4466 3) Z1CND25-22AZ X X 270 580–780 30254 SMO ≤0.020 20 18 6.1 N, Cu S31254 – (1.4547)* (1.4529)* Z1CNDU20-18-06AZ X X 310 655–850 35Sanicro 30 ≤0.030 20 32 – Ti,Al N08800 Alloy 800 1.4558 1.4558 – X X5) 205 520–690 30Sanicro 41 ≤0.030 20 38.5 2.6 Cu,Ti N08825 Alloy 825 – 2.4858 – – X 240 590–750 30

High temperature grades

4C54 ≤0.20 26.5 – – N S44600 446–1 1.4749** 1.4749 – X X 275 500–700 207RE10 0.06 24.5 21 – – S31008/S31009 310S, 310H 1.4845** 1.4845 Z12CN25-20 X X 220 515–750 35253 MA 0.08 21 11 – Si,N,Ce S30815 – 1.4835** (1.4893) – X X5) 310 650–850 40353 MA 0.05 25 35 – Si,N,Ce S35315 – 1.4854** – – X - 270 650–750 40Sanicro 31HT 0.07 21 31 – Ti,Al N08811/N08810 – 1.4959 1.49591)1.48761)2) – X X5) 170 500–700 35Sanicro 70 ≤0.05 16.5 72.5 − Fe N06600 Alloy 600 – 2.4816 − X X 245 >560 35

Typical applications

18 19

Steel gradesStandard manufacturing programme

Designation Chemical composition (nominal), % Standards* Pressure Mechanical properties Sandvik C Cr Ni Mo Others UNS ASTM TP EN Steel W.-Nr. AFNOR purpose Proof Tensile Elongation number PED4) ASME strength strength A

prEN Rp0.2 Rm

10216-5 MPa min. MPa %, min.Austenitic stainless steels 3R12 ≤0.030 18.5 10 – – S30403 304/304L 1.4306/1.4301 1.4306/1.4301 Z2CN18-10 X X 210 515–680 453R60 ≤0.030 17.5 13 2.6 – S31603 316/316L 1.4435 1.4435/1.4436 Z2CND17-13 X X 220 515–690 453R65 ≤0.030 17 11.5 2.1 – S31603 316/316L 1.4404 1.4404/1.4401 Z2CND17-12 X X 220 515–690 456R35 0.05 17.5 10.5 − Ti S32100/S32109 321/321H 1.4541/1.4940 1.4541/1.4878 1) Z6CNT18-10 X X 210 515–690 35 5R75 0.05 17 12 2.1 Ti (S31635)** (316Ti)** 1.4571 1.4571 Z6CNDT17-12 X – 220 510–710 353R19 ≤0.030 18.5 9 – N S30453 304LN 1.4311 1.4311 Z2NC18-10AZ* X X 275 550–750 405R60 0.04 17 12 2.6 – S31600/S31609 316/316H 1.4436 1.4436 Z6CND17-12 X X 220 515–690 403R64 ≤0.030 18.5 14.5 3.1 – S31703 317L 1.4438 (1.4438)* – – X 220 515–690 358R40 0.06 17.5 11 – Nb S34700/S34709 347/347H 1.4550/1.4912 1.4550 Z6CNNb18-10 X – 220 515–690 35

Duplex stainless steels

SAF 2304 ≤0.030 23 4.5 – N S32304 – 1.4362 1.4362 Z2NC23-04AZ X X 400 600–820 25SAF 2205 ≤0.030 22 5 3.2 N S31803/S32205 – 1.4462 1.4462 Z2CND22-05-03 X X 485 680−880 25SAF 2507 ≤0.030 25 7 4 N S32750 – 1.4410 – – X X 550 800–1000 253RE60 ≤0.030 18.5 4.5 2.6 Si, N S31500 – 1.4424 1.4417 Z2CND18-05-03 X X 450 700−800 30

High-alloy austenitic stainless steels and nickel alloys

2RK65 ≤0.020 20 25 4.5 Cu N08904 – 1.4539 1.4539 Z1NCDU25-20-04 X X 230 520–720 35Sanicro 28 ≤0.020 27 31 3.5 Cu N08028 – 1.4563 1.4563 Z1NCDU31-27-03 X X5) 220 550−750 402RE10 ≤0.015 24.5 20.5 – – S31002 – 1.4335 1.4335 – X – 210 500–670 352RE69 ≤0.020 25 22 2.1 N S31050 – 1.4466 1.4466 3) Z1CND25-22AZ X X 270 580–780 30254 SMO ≤0.020 20 18 6.1 N, Cu S31254 – (1.4547)* (1.4529)* Z1CNDU20-18-06AZ X X 310 655–850 35Sanicro 30 ≤0.030 20 32 – Ti,Al N08800 Alloy 800 1.4558 1.4558 – X X5) 205 520–690 30Sanicro 41 ≤0.030 20 38.5 2.6 Cu,Ti N08825 Alloy 825 – 2.4858 – – X 240 590–750 30

High temperature grades

4C54 ≤0.20 26.5 – – N S44600 446–1 1.4749** 1.4749 – X X 275 500–700 207RE10 0.06 24.5 21 – – S31008/S31009 310S, 310H 1.4845** 1.4845 Z12CN25-20 X X 220 515–750 35253 MA 0.08 21 11 – Si,N,Ce S30815 – 1.4835** (1.4893) – X X5) 310 650–850 40353 MA 0.05 25 35 – Si,N,Ce S35315 – 1.4854** – – X - 270 650–750 40Sanicro 31HT 0.07 21 31 – Ti,Al N08811/N08810 – 1.4959 1.49591)1.48761)2) – X X5) 170 500–700 35Sanicro 70 ≤0.05 16.5 72.5 − Fe N06600 Alloy 600 – 2.4816 − X X 245 >560 35

* In brackets, nearest equivalent steel grade.** Not applicable for tube and pipe. Only for information.

Sandvik 2RE69 – Fertilizer industry, urea strippers. Superior to 3R60 U.G.

Sandvik 254 SMO – Higher strength, very good resistance to pitting corrosion in seawater and brackish water.

Sandvik Sanicro 30 − Nuclear PWR steam generators.

Sandvik Sanicro 41 – Superheater tubes, very good resistance to stress corrosion cracking in acidic media such as sulphuric and phoshoric.

High temperature gradesSandvik 4C54 − Sulphurous gases, recuperators, thermocouple protection tubes. Ferritic. Up to 1100oC in air.

Sandvik 7RE10 − Good oxidation resistance. Up to 1100oC in air.

Sandvik 253 MA – Very versatile; furnace tubes, recuperators, heat treat-ment furnaces. Up to 1150oC in air.

Sandvik 353 MA – Ethylene and petrochemical furnace tubes, recuperator tubes. Up to 1175oC in air.

Sandvik Sanicro 31HT − Furnace tubes, pigtails and headers for synthesis gas production, fluidised bed combustion. Up to 1100o C in air.

Sandvik Sanicro 70 – Vinyl chloride plants, furnaces. Up to 1175oC in air.

Sandvik Mater ia ls TechnologySE-811 81 Sandviken, Sweden, Phone +46 26 26 39 00, Fax +46 26 26 02 20

www.smt . sandv ik .com S-1

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Documents

Heat Treatment of SS