Development of Niobium-alloyed large diameter pipes Sandrine Bremer, Volker Flaxa; Salzgitter...

Development of Niobium-alloyed large diameter pipes

Sandrine Bremer, Volker Flaxa; Salzgitter Mannesmann Forschung GmbH Franz Martin Knoop; Salzgitter Mannesmann Grossrohr GmbH

London, 7th July 2010

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Content

Salzgitter Group

Organisation & Structure

Partners

Motivation

Large diameter line pipe

From ore to pipe

A novel, Nb-containing alloying concept

Technical realisation

Microstructure & properties

Benefits of novel steel composition

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• 2008: Crude steel production: 6.9 million tons; trading volume: 6.8 million tons• Among the top 3 producers of beverage filling und packaging machinery

Global Presence

Salzgitter Group

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• Total Sales:€ 4.3 billion

• External Sales:€ 3.0 billion

• Employees:6,949

Steel



• Employees:1,983

Trading



• Employees:4,003

Services



• Employees:4,907

Technology



• Employees:5, 929

Tubes

Group structure and key data FY 2008

Salzgitter AG Group

External Sales cons.: € 12.5 billionInternal Sales: € 3.9 billion

Employees: 23,915

All data about employees as per 31/12

Salzgitter Group

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The line pipe team

Salzgitter AG Group (Holding)

Motivation

SteelSalzgitter Stahl GmbH

Trading Services

Salzgitter Mannesmann GmbH – Intermediate holding company

TubesMannesmannröhren-

Werke GmbH

TubesMannesmannröhren-

Werke GmbH

Technology

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High-strength large diameter line pipe

Motivation

Transport of 51 mio. m3 gas/dayTotal length: 2,120 km (1,322 mls)Start of operation segment 1: 01/2008Start of operation: 06/2009Total costs: approx. 4 bn. US$

Salzgitter supply:168,500 t (ca. 420 km)1,067 x 14,1 / 18,8 mmX70, FBE/EP, 18m

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Motivation

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Application of high-strength line pipe steels saves resources and costs!


Motivation

Increasing operating pressure (from 80 bar to 100 bar) for constant wall thickness (20 mm)

efficiency

Reduction of pipe wall thickness (from 20 mm to 18 mm) for constant operating pressure (80 bar)

pipes` specific weight

shipping

investment costs for pipe laying

Optimised in-field welding processes for girth welding

time, material, testing and energy Strength [MPa]

Wei

gh

t [%

]

100

400 500 600

Steel grades accor. API 5L:

X60 X70 X80 X90

75

50

25

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From ore to pipe


Blast furnace

Iron ore

Pig iron

Spiral pipe mill

ø = 508 to 1676 mmt = 8 to 25 mm

Continuous Casting

Slab

Steel works

LD-Converter

Ferro-Niobium

Alloying stations

Alloyed steel

Hot-coiled strip

Hot rolling mill

Finishing train

Roughing mill

t = 1.5 to 25 mmw = 900 to 1,880 mml = 100 to 2,000 m

Furnace

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Steel making „The cooking recipe“

Basic ingredientsCarbon

Manganese

Silicon


Tramp elementsPhosphorus

Nitrogen

Sulphur

MicroalloysNiobium

Titanium

Vanadium

Add-onsNickel

Copper

Chromium

Molybdenum

Spiral pipes“API X70”

Basic ingredients Microalloys Add-ons

C Mn Si Nb V TiΣ Ni + Cu + Cr + Mo

Standard 0.11 1.75 0.30 0.05 0.10 0.00 ≤ 0.10

Novel alloy 0.05 1.80 0.30 0.10 0.00 0.02 > 0.10

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A novel alloying concept: Microstructure & Properties

Standard line pipe


Novel line pipe

Effect of high niobium, low carbon addition

Grain refinement if ferrite is present

Two phases (acicular ferrite + lower bainite)

Elimination of pearlite

Many homogenuous distributed precipitations

Change of dissolution (re-heating) temperature

Conclusions

Predominately bainitic microstructure with many precipitations (for example NbC)

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520

540

560

580

600

620

Strip Long Strip Trans Strip 30° Pipe Hoop

Yie

ld S

tre

ng

th R

t0.5

[M

Pa

]

D 30 MPa

D 3 MPa

f


Strength (Tensile testing)S

tan

dar

d

No

vel

Sta

nd

ard

No

vel

Sta

nd

ard

No

vel

Sta

nd

ard

No

vel

p

Conclusionsnovel strip 30° = novel pipe hoop

novel pipe > standard pipe Hot rollingdirection

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0

50

100

150

200

250

300

-100 -80 -60 -40 -20 0

Testing temperature [°C]

Imp

ac

t to

ug

hn

es

s A

V [

J]

Novel Strip Novel Pipe Standard Strip Standard Pipe

Toughness (Impact testing)

Hot rollingdirection

Conclusions

novel strip & pipe impact energy > standard strip & pipe impact energy

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Conclusions for …

… the steel producer (less costs)

Application of more expensive alloys (for example niobium)

Very smooth processing (increased processing temperatures, less wear)

Shorter production times leading to capacity increase

Benefits of novel steel composition

… the spiral pipe mill (competitive advantage)

Comparable welding and seam properties

Optimised strip quality resulting in less repair work on pipes

… the pipe layer (less costs)

Less pipe laying equipment necessary

Saving of welding material and energy

… the gas supplier (increase of efficiency & transmission volume)

Higher operating pressures for similar wall thickness

Light-weight line pipe design possible

Co

st redu

ction

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Many thanks to our excellent line pipe team from all the Many thanks to our excellent line pipe team from all the divisions involved for their support and help. divisions involved for their support and help.

Development of Niobium-alloyed large diameter pipes Sandrine Bremer, Volker Flaxa; Salzgitter...

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Transcript of Development of Niobium-alloyed large diameter pipes Sandrine Bremer, Volker Flaxa; Salzgitter...