Superduplex stainless steels tubes for subsea umbilicals...— Raw material and its manufacturing process • ASTM A240, ASTM A789 and NORSOK M650 • Umbilical manufacturers and end-users

Superduplex stainless steels tubes for

subsea umbilicals

Jérôme Peultier, Olivier Wagner, Guy Durand and Gilles Thevenet

Vallourec Umbilicals

Journées annuelles des hydrocarbures – Porte Maillot, Paris, France.– 23th October, 2013

Summary

New technical challenges for umbilicals

Product characteristics


Process manufacturing

— Welding

— Annealing and quenching

— Non destructive testing

Mill and product qualification

Corrosion resistance in marine environment

— Crevice and pitting corrosion

— Hydrogen Induced Stress Cracking (HISC)

Savings

Conclusion

Journées annuelles des hydrocarbures – Porte Maillot, Paris – October 23th, 2013

* : courtesy DUCO

*

New technical challenge for umbilicals

Subsea umbilical systems for deep offshore

become more and more demanding regarding

— injection capacity

— number of functionalities

— water depth

— tiebacks length and number

operating conditions and requirements are significantly impacting the

performance of the main umbilical

The most common solution

— To design

• thicker tubes to improve the strength of the umbilical

• higher cross section to increase capacity

— Drawbacks :

• weight rise and fatigue performance degradation (higher loading)

• cross section increase unsuitable with packing constrains

Need to improve properties and geometry of the steel tube

reducing wall thickness and improving fatigue resistance

Courtesy DUCO


Product characteristics

On strip : grade 2507 (UNS S32750 / EN 1.4410)

— PREN (Cr + 3.3Mo + 16N) 42.5

— Suitable pitting and crevice corrosion resistance

— High mechanical properties (duplex microstructure + cold rolling)

On tube

— Optimised strength (whatever the tube sizes)

• YS0,2 > 750MPa

• UTS > 900MPa

— Elongation ≥ 25%

Tight dimensional tolerances

— 5% of the Wall Thickness (WT) compared with 10% required by ASTM

A789

— Internal Diameter (ID) : -0/+0.2mm



Vallourec (2012 figures)

— 5 326 M€

— Near 70% of sales in Oil& Gas and Petrochemicals

— More than 50 manufacturing facilities

— Presence in more than 20 countries

— 23200 employees worldwide

— 93M€ R&D investments

Pipe project division

— SURF market

— Strong local presence


— Steel tube for umbilicals

— Based on the experience of

Vallourec Heat Exchanger tubes (formerly Valtimet)

— With the technical support of

TOTAL SA headquarter Technology Division


Manufacturing process

Orbital Welding line

Tube ends

preparation(1)

Sizing &

Straightening

Defect

Cutting(1)

Final

(customer)

reel

Hydrostatic test bench

Packing

Finished

reels

storage

Laser longitudinal welding line

NDT &

Marking

Intermediate

reel

Strip

Decoiler

Strip Preparation &

Forming Laser welding

Sizing &

Finishing

(1) Only for segments with defect indications (and strip splice weld)

Moving units in case of bad weld (tube never rolls back)

Orbital

welding(1)

X Ray

control (1)

Pressure

test

Water

cleaning

Flushing &

Drying

Nitrogen

filling

360°

Polishing(1)

Weld bead

finishing Heat treatment


Manufacturing process - welding

Longitudinal laser weld Orbital TIG weld


Manufacturing process – Annealing and quenching

Objectives

— Annealing (AT : annealing temperature)

• Stress (brought to forming and welding) release

• Optimal ferrite – austenite ratio

• Dissolution of detrimental phases precipitated during

welding and cooling (if any)

— Cooling (CR = cooling rate)

• Avoid formation of detrimental phases


No phase 20% phase

[1]

[1] J.-O. Nilsson, Mater. Sci. Technol., 8, 685 (1992)

[2] Duplex stainless steels brochure, www.outokumpu.com

Min CR

Min AT [2]

Manufacturing process - NDT

In-line, real time non destructive test bench

— First EC

• Detection of punctual defects

— UT

• Phased array technology: control of 100% of the tube length and

circumference without any rotation of the tube or the UT head.

• To detect longitudinal or transversal defects inside and outside

• To check wall thickness and diameter outside (OD)

— Second EC

• Sigma phase detection

Defect marking

— Any defect detected by UT or EC controls is monitored and highlighted by

a red mark

NDT bench calibration

— On rails


Qualification

Protocol

— Raw material and its manufacturing process

• ASTM A240, ASTM A789 and NORSOK M650

• Umbilical manufacturers and end-users specifications

— Tube and its manufacturing process

• ASTM A789 and NORSOK M650

• Umbilical manufacturers and end-users specifications

3 tube dimensions / 250km / 10 heats

More than 11000 tests results:

— Tensile, hardness, burst and collapse tests

— Chemical composition

— Roughness measurements

— Dimensional checks

— Ferrite content

— Cleanliness

— Corrosion tests (according to ASTM G48 methods, SSC and HISC)

— « Technical » tests (i.e. reverse flattening, flaring, flange and bending)


Main results – Tensile tests

• Dim

– 1 = 15.25mm OD x 1.15mm WT

– 2 = 28.5mm OD x 1.45mm WT

– 3 = 18.1mm OD x 1.00mm WT

• PP = pre production

• FP = full production

700

720

740

760

780

800

820

PP dim 1 FP dim 1 PP dim 2 FP dim 2 PP dim 3 FP dim 3

MPa

YS0,2 average Min acceptance

880

900

920

940

960

980


MPa

UTS average Min acceptance

22

23

24

25

26

27

28

29

30

31


%

E% average Min acceptance

UTS YS0.2

E


Main results – Burst and collapse

Burst resistance

900

1100

1300

1500

1700

1900

FP dim 1 FP dim 2 FP dim 3

Bars

1492

963 1049

Pressure level Acceptance criteria (calculated as per ISO 13628-5)

Collapse resistance

0

200

400

600

800

1000

1200

1400

FP dim 1 FP dim 2 FP dim 3

Bars

975

465

563

Pressure level Acceptance criteria (calculated as per ISO 13628-5)



Operating conditions

Immersion in natural seawater

— 3 months

— Heated at 30°C and 50°C

— One complete renewal of seawater

every two days

— Open circuit potential (OCP)

Crevcorr type assembly (30°C test)

— Torque = 1Nm ( 550N)

— PVDF crevice washer

— Ti fasteners

Tubes

— 25.4mm OD x 2mm WT x 300mm L

— Seam welded (VU)

— Seamless tubes

Evaluation

— Max crevice depth



Open circuit potential

Seam welded tubes

-150

-50

50

150

250

350

0 10 20 30 40 50 60 70 80 90 100

Po

ten

tia

l [m

V v

s A

g/A

gC

l]

Time [Day]

T = 30°C

(crevice test)

-150

-50

50

150

250

350

0 10 20 30 40 50 60 70 80 90 100

Po

ten

tia

l [m

V v

s A

g/A

gC

l]

Time [Day]

Seamless tubes



Observations

Seam welded tubes

Seamless tubes

Laser weld

Max corrosion attack

Average maximum

crevice depth

355µm 360µm

Laser weld seam

is not

especially sensitive

to crevice corrosion



Observations

-100

-60

-20

20

60

100

0 10 20 30 40 50 60 70 80 90

Po

ten

tia

l [m

V v

s A

g/A

gC

l]

Time [Day]

OCP 50°C (pitting test i.e. no crevice washers)

No corrosion

Seam welded

Seamless


Subsea HISC failures – Examples

Statoil REX[3]

1. Leakage from a 25Cr duplex 2” methanol line on umbilical termination head

— Very high local stresses due to accidental loads (heavy rock dumping)

2. Leakage in MEG line in umbilical due to cracked 25Cr duplex compact flange

— FEA analysis: Large hoop stresses in transition between flange ring and neck

1 2

[3] Lene A. Marken & Øystein Strandmyr, Statoil ASA, “30 years of in-field experiences with duplex stainless steels”,

Duplex Seminar & Summit, Stresa, Italy, September 26th & 27th, 2012


Hydrogen Induced Stress Cracking (HISC) resistance

Operating conditions

Aim : study the influence of accumulated plastic strain (APS)

resulting from

— tube steel production

— umbilical manufacturing

— laying-out processes

on HISC resistance of seam welded tubes

HISC procedure

— H2 pre charging :

• 20mA/cm²

• 0,5M H2SO4 and 3g/L of KSCN

• 24h at room temperature

— Constant load test

• -1050 +0 /-50 mV vs SCE

• 0.9AYS0.2

• 500h at room temperature

Reference electrode

Counter electrode

Working electrode

(tube sample)



Pre straining

Load and strain history

Straining conditions

— Strain variation ± 1%

— Frequency 0.07Hz

— Accumulated plastic strain (APS) = 20%



Results

I and E vs time during precharging

I and E vs time during CLT

Seam weld

Base metal

Tube surface at the end of the test

No cracks


Examples of savings[4]

ID DWP Water depth

½’’ 690 bars

1500m ¾’’ 400 bars

1’’ 345 bars

1.5’’ 345 bars

Wall Thickness according to DNV OS F101

taking into account:

— Increased YS0.2

— Tight tolerances

— Reduced ovality

Results

— Wall Thickness vs Internal Diameter

[4] O. Wagner, G. Durand, J. Peultier, A. Courbot, J.-P. Roques and H. Romazotti, “Design advantages on umbilical

systems brought by a new high performance SDSS tube”, OMAE conference, Nantes, France, July 9 – 14, 2013.

1.22 1.05

1.41

2.17

1.05 0.90

1.22

1.85

1.22 1.05

1.41

2.17

1.05 0.90

1.22

1.85

WT (mm) WT (mm)

— Weight of the tube vs Internal Diameter


This innovative technology is proposing a new product offering :

— a significant reduction of weight

— combined with an increased strength

Added valued :

— easier installation and manufacturing for the umbilicals manufacturer (i. e.

radius reduction)

— improved fatigue resistance for the end-user (reduced number of girth welds

taking benefit of strip length)

The manufacturing process and product have been certified by

Bureau Veritas in October 2012 and qualified by TOTAL in April

2013

meet the new challenges linked to ultra deep water developments

Conclusion

BV

ap

pro

ved

Are

a


THANK YOU

Documents

Superduplex stainless steels tubes for subsea umbilicals...— Raw material and its manufacturing process • ASTM A240, ASTM A789 and NORSOK M650 • Umbilical manufacturers and end-users