PRODUCTION OF HELICAL TWO STEP PIPE USE OF MICROALLOYING ELEMENTS - - PowerPoint PPT Presentation

PRODUCTION OF HELICAL TWO STEP PIPE – USE OF MICROALLOYING ELEMENTS TO IMPROVE STRENGTH FOR GRADES UP TO X70 WITH SOUR SERVICE RESISTANCE

Franz Martin Knoop Salzgitter Mannesmann Grossrohr GmbH Djordje Mirkovic, Volker Flaxa Djordje Mirkovic, Volker Flaxa Salzgitter Mannesmann Forschung GmbH

Introduction

Contents

• Introduction
• History

Contents

• Development programme
• Manufacturing issues relevant for sour service resistance
• steel production
• steel production
• hot rolling
• pipe production
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• Mechanical and corrosion test results
• Summary and outlook

Introduction

Salzgitter's research and development activities for HSAW-pipe

• extending pipe/coil wall thickness up to 25.4 mm for grades X70 and X80
• steel grades with high strength and excellent low temperature toughness

Salzgitter s research and development activities for HSAW pipe

• sour service resistant steel and pipe
• enhancement of collapse resistance for shallow water off-shore applications
• use of FEM for simulation of pipe forming and welding
• use of FEM for simulation of pipe forming and welding
• reducing residual stresses in pipe and weld seam
• improving the strain capacity of pipes for strain based design requirements
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• reduction of geometrical tolerances on steel and pipe

History

Failures of helical welded pipe p p

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History

Cooking recipe for sour service material g p

Malcolm Gray „Full Scale Testing of Linepipe for Severe H2S Service“; NACE Canadian Regional Western Conference, A h Al k F b 19 22 1996 Anchorage, Alaska, February 19—22. 1996

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Development programme

Targeted pipe properties R&D and commercial projects

Quantity Grade / w th OD YS TS CVN DWTT HIC (base + weld) NACE TM248 SSC (base+weld)

g p p p p p j

Project Quantity (t) Grade / Standard w.th. (mm) OD (mm) YS (MPa) TS (MPa) CVN (J/cm2) DWTT (% shear area) TM248 (base+weld) (4 point bend.) CAR CLR CTR CSR X60MS ≥ 250; 0°C 85 @ at 80% SMYS SZ X60 200 X60MS API 5L/ISO3183 14.0 1067 ≥ 420 ≥ 520 ≥ 250; 0°C (base) 85 @ at

• 40°C

≤ 5

• 80% SMYS

No crack SZ X65 200 X65MS 14 1 813 ≥ 450 ≥ 535 ≥ 300; 0°C 85 @ at ≤ 5

• 80% SMYS

SZ X65 200 API 5L/ISO3183 14.1 813 ≥ 450 ≥ 535 (base)

• 40°C

≤ 5 No crack SZ X70 200 X70MS API 5L/ISO3183 16.0 1016 ≥ 485 ≥ 570 ≥ 300; 0°C (base) 85 @ at

• 40°C

≤ 5

• 80% SMYS

No crack ( ) Grade 1000 GR241 15 9 762 and ≥ 241 ≥ 414 ≥ 50; not ≤ 15 ≤ 5 ≤ 2 80% AYS 241 1000 CSA_Z245.1-07 15.9 and 914 ≥ 241 ≥ 414 0°C required

• ≤ 15

≤ 5 ≤ 2 No crack Grade 448 800 GR448 CSA Z245.1-07 13.7 1372 ≥ 448 ≥ 531 ≥ 50;

• 18°C

60 @ at

• 18°C
• ≤ 15

≤ 5 ≤ 2 not required

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448 CSA_Z245.1 07 18 C 18 C required (mechanical properties in hoop direction)

Development programme

Chemical composition for R&D and commercial projects

Project Purpose C wt % Si wt % Mn wt % P ppmw S ppmw Al wt % Cu + Cr + Ni wt % Mo wt % Nb wt % CEV (IIW) wt % CEV (Pcm) wt %

p p j

wt.% wt.% wt.% ppmw ppmw wt.% wt.% wt.% wt.% wt.% wt.% SZ X60 R&D 0.035 0.30 1.46 70 5 0.04 0.44 0.07 0.05 0.33 0.14 SZ X65 R&D 0.038 0.28 1.37 80 7 0.04 0.86 0.04 0.05 0.36 0.14 SZ X70 R&D 0.038 0.33 1.33 90 6 0.04 0.84 0.32 0.05 0.43 0.15 Grade Grade 241 Commercial 0.041 0.23 1.14 95 4 0.04 0.23 0.004 0.02 0.25 0.11 Grade 448 Commercial 0.060 0.32 1.55 150 8 0.04 0.36 0.005 0.05 0.35 0.16

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Production: Metallurgical process up to slab casting

Manufacturing issues relevant for sour service resistance

Production: Metallurgical process up to slab casting

1 2 3

• 1. Blast furnace

3 4

• 1. Blast furnace
• 2. Hot-metal mixer
• 3. Desulphurization facility

5

p y

• 4. BOF shop
• 5. Secondary metallurgy facilities

y gy

• 6. Continuous slab caster

6

High automatization level including close integration of steel plant control and supervision system with technical planning

6

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slab thickness: 250 mm

Steel plant: quality issues and measures

Manufacturing issues relevant for sour service resistance

Steel plant: quality issues and measures

Desired quality issues Consistently applied Salzgitter’s measures to attain them

Narrow steel composition tolerances High steel cleanliness

• lowering non-metal inclusions

Continuous composition control and adjustment Secondary metallurgy and appropriate casting procedure ti i t ith ti l ti

• lowering non-metal inclusions

( low [O] total)

• inclusion shape and size control
• gas stirring + caster with vertical section
• Ca – treatment for inclusion shape control
• vacuum degassing
• low tramp element steel contents

( especially P and S )

• low H content

vacuum degassing High slab centerline quality

• avoiding centerline segregation

Soft reduction at continuous slab caster (C, Mn, P)

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Steel cleanliness: non-metallic inclusions as HIC initiating sites

Manufacturing issues relevant for sour service resistance

Example: insufficient ladle rinsing and unsuitable degassing Steel cleanliness: non-metallic inclusions as HIC initiating sites

top view of US scan

Rolling direction

top view of US scan side view of US scan

HIC fracture surface

Al

consistent application of LM refining measures to remove inclusions from the steel melt, such as: bottom stirring with N2 and Ar f t h l lid t f i i i d l

O

use of tap hole slide gates for minimized slag carry over

• ptimized Ca-treatment with Ca-wire injection; high Ca recovery
• ptimized ladle rinsing procedure

use of argon shielded tundish for optimized flow pattern / inclusion removal

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HIC cracks primarily initiated at Al- O inclusions and are traced back to slab upper half

use of argon shielded tundish for optimized flow pattern / inclusion removal application of caster with 2.6 m long vertical section instead of bow casters

Slab centerline quality: segregation effects

Manufacturing issues relevant for sour service resistance

Slab centerline quality: segregation effects Example: casting without dynamic soft reduction

Martensite HIC crack at strip mid thickness

top view of US scan side view of US scan

consistent slab centerline quality optimization by application of Dynamic Soft Reduction consistent slab centerline quality optimization by application of Dynamic Soft Reduction dynamic segment regulation (soft reduction), particularly at the point of final solidification

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Production: layout of Salzgitter’s hot strip mill

Manufacturing issues relevant for sour service resistance

Production: layout of Salzgitter s hot strip mill

Reheating furnaces (4) Slab sizing press Slab sizing press R hi ill R hi ill Descaler Roughing mill Roughing mill C h C h Finishing train Crop shear Crop shear Run-out table: Laminar cooling unit descaler

Slab thickness = 250 mm St i thi k 1 5 25 Strip thickness = 1.5 - 25 mm Strip width = 900 - 2.000 mm Strip length = 100 - 2.000 m

3 Down coilers

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One of the world’s most modern high performance hot strip mills

Hot strip mill: quality issues and measures

Manufacturing issues relevant for sour service resistance

Consistently applied Salzgitter’s measures to attain them

Hot strip mill: quality issues and measures

Desired quality issues

Continuous control and adjustment of rolling parameters

• highly planar

strip profile

ness µm]

Narrow strip dimension tolerances

• lowering of residual stresses in the

pipe bodies and welds strip profile

Strip thickn variation [µ

pipe bodies and welds High strip surface quality

• prevention of surface defects e.g.

Thickness ± 60 µm

Precise temperature monitoring from furnace to coiler

Strip width [mm]

slivers, roll-ins Homogeneous strip temperature distribution

• highly desirable acicular ferrite microstructure along the

strip length and across the strip width

• Precise strip temperature prediction and control

distribution

• prevention of γ→α transformation

during the finishing p p p based on run-out table simulation

• strip microstructure adjustment

without undesirable phases

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Hot strip mill: strip profile and temperature distribution

Manufacturing issues relevant for sour service resistance

Hot strip mill: strip profile and temperature distribution

Temperature scan after finishing train

Example: two-phase finish rolling / undesirable phases at strip edge area

Rolling direction

Temperature scan after finishing train

iation

undercooled strip edges

• Temp. dev

strongly elongated α-grains, Martensite also observed precise temperature monitoring and control in every process phase and section to obtain fine-grain structure across the strip width to obtain fine grain structure across the strip width indispensable to prevent γ→α transformation already during the finishing to prevent undesirable phases, such as martensite Rolling direction

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properly cooled strip edges NO HIC cracks observed !

Pipe production: Helical seam Two Step (HTS) technology

Manufacturing issues relevant for sour service resistance

Pipe production: Helical seam Two Step (HTS) technology

B = 1200 - 1500 mm α = 20 - 40° D = f (B, α) ( , α) D = 610 - 1676 mm Second step: inside and outside Fi i f i i h i k ldi Second step: inside and outside submerged arc welding

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First step: pipe forming with continuous tack welding

Pipe mill: quality issues and measures

Manufacturing issues relevant for sour service resistance

Consistently applied SZ’ measures to attain them

Pipe mill: quality issues and measures

Desired quality issues

Quality controls and R&D

• use of FEM simulation methods
• consistent quality controls and recording of forming

controlled cold working

• during coil straightening and pipe

forming consistent quality controls and recording of forming parameters

• continuous control of pipe geometry using a patented in-situ

l di t t l forming

• minimized springback
• optimized pre-bending of coil edges to

id ki d d i l l laser diameter control

• peaking below 0.8mm

avoid peaking and reducing local stress which might affect sour gas resistivity at weld area (SOHIC) separating forming and welding by using the HTS –process no forming stresses during welding Material selection and welding process controls

• qualification and careful selection of coil material and

welding consumables maximum hardness of 248 HV

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g

• continuous recording and documentation of all essential

welding parameters

Pipe mill: reduction of residual stresses

Manufacturing issues relevant for sour service resistance

Pipe mill: reduction of residual stresses

640 720 800 240 320 400 480 560

Stress , MPa

0°

80 160 240 2,5 5 7,5 10 12,5 15 17,5 20

Strain  %

30° 45° 60° 90°

Strain , %

2 0 2.5 3.0 [-] Maximum value over wall thickness Inner surface Outer surface

Stress strain curves at different angles Simulation of different forming strategies

0.0 0.5 1.0 1.5 2.0

• op stressh / h(NF)

2 5

• 2.0
• 1.5
• 1.0
• 0.5

Relative residual ho

negative spring-back positive spring-back

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• 3.0
• 2.5

1.8E-03 1.9E-03 2.0E-03 2.1E-03 2.2E-03 2.3E-03 2.4E-03 2.5E-03 2.6E-03 2.7E-03 Curvature under load [1/mm]

Relative residual hoop stress as function of the curvature under load

R&D sour service trials: SZ X65

Mechanical and corrosion test results

Coil Pipe Type of samples & direction Rt0.5 [MPa] Rm [MPa] Rt0.5/Rm ADIN [%] AAPI [%] DWTT @ [% shear area];

• 60°C

CVN @ [J/cm2]

• 80°C

p direction [ ] [ ]

• 60 C
• 80 C

Strip 30° [rect.] 528 581 0.91 24 39 93 382 Pipe hoop [rect.] 483 575 0.84 24 38 75 379

HIC 24 HIC i t t d

Targeted API X65 grade reached reliably; excellent low temperature toughness

HIC: 24 HIC specimens were tested Result: mean CAR value ~0.1 % SSC (4-point-bending test): 9 specimens were tested at 85% of SMYS (383 MPa) R lt SSC k b d Result: no SSC cracks were observed Full ring test: 72% of SMYS (323 MPa) for 720h in

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NACE TM0177 solution A Result: No indications above threshold were found by ultrasonic examinations prior to and after the test

Very good sour gas resistivity

R&D sour service trials: SZ X70

Mechanical and corrosion test results

680 700 720

Rm 90 100

%]

580 600 620 640 660

API Samples DIN Samples

Rt0.5 , Rm [MPa] 70 80 90

DWTT transition

Coil 686056

acture area [%

500 520 540 560 580

Coil center Rectangular samples Hoop direction

Rt0.5 40 50 60 Coil 686056 Coil 686057 Coil 686059

Shear fra Test temperature: -50°C 100% shear area

6 8 6 5 6 6 8 6 5 7 6 8 6 5 8 6 8 6 5 9 6 8 6 6 500

Coil

• 60
• 50
• 40
• 30
• 20

40

Test temperature [°C]

Targeted API X70 grade reached reliably; excellent low temperature toughness

HIC: 112 HIC specimens (base and weld) tested Result: mean CAR value of 2.82 % (max. 13.1 %); mean average CAR value base material: 3.62%, mean CAR value for weld specimens: 1.16%

V d i ti it f API X70 d

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Very good sour gas resistivity, even for API X70 grade

Commercial projects: GR448

Mechanical and corrosion test results

p j

620 640 660

Rt0.5 Rm A

38 39 40 400 540 560 580 600 620

A [%]

5 , Rm [MPa]

34 35 36 37 38 350 375

VN aK [J/cm

2]

2 9 1 8 8 1 9 8 2 3

460 480 500 520

DIN rect. sample; hoop direction

Coil Rt0.

30 31 32 33 4 1 8 8 4 1 9 8 4 2 3 4 2 9 300 325

Mean value

Test temperature -18°C

CV 360 357 383 344 Coil

LOM Microstructure ¼ thick ½ width

Targeted GR448 grade reached reliably

9 5 7 4 / 9 8 4 2 9 5 7 1 / 9 8 4 1 8 9 5 7 2 / 9 8 4 1 9 9 5 7 3 / 9 8 4 2

Coil Heat

9 5 7 1 / 9 8 4 1 8 9 5 7 2 / 9 8 4 1 9 9 5 7 3 / 9 8 4 2 9 5 7 4 / 9 8 4 2

Heat Coil

LOM Microstructure ¼ thick., ½ width 50 % Ferrite; 40 % Bainite; 10 % Pearlite

HIC: 1 set for both base material and weld per heat were tested. Result: mean CLR and CSR values of all samples 3.5 , 0.7 and 0.3 %, respectively

G d i ti it ! (d it f l ti l hi h C d M t t )

Pipe DWTT [% shear area]; average of 2 specimens 0°C °C 10°C 20°C 40°C 60°C

E ll l DWTT l

Good sour gas resistivity! (despite of relatively high C and Mn contents)

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0°C

• 5°C
• 10°C
• 20°C
• 40°C
• 60°C

100 100 100 100 100 93 100 100 100 100 95 83

Excellent low temperature DWTT results

Summary

Summary and outlook

y

Large diameter helical line pipe for sour service up to X70 has been successfully d l d d d d developed and produced Critical parameters in steel production and hot rolling have been shown and their influence has been explained by means of examples. Well balanced microalloying and steel cleanness has been achieved in industrial trials and commercial projects All relevant process parameters during continuous casting and hot rolling were All relevant process parameters during continuous casting and hot rolling were effectively controlled and adjusted to the used chemistry an microalloying All necessary measures for the improvement of HIC and SSC resistance have been

• ptimized and managed during spiral pipe forming and welding
• ptimized and managed during spiral pipe forming and welding

Excellent mechanical properties (incl. low temperature toughness) and corrosion resistance have been achieved

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Outlook

Summary and outlook

Next milestones are defined on basis of actual and future market needs Growing interest for sour service resistant line pipe with heavy wall thickness up to 1’’ and grades up to X70 is expected Technical solutions require further development q p

• on chemical composition of the base material,
• on welding consumables
• on further production parameters at each stage of production
• and on suitable equipment at each stage of production

Pi ith ll di t i th f 26’’ d hi h ll thi k (hi h ld Pipes with smaller diameters in the range of 26’’ and higher wall thickness (high cold forming degree) need further development

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