reliability based design for pipelines canadian standard … · 2021. 2. 2. · –nen 3650-1...

Reliability Based Design for Pipelines – Canadian Standard Association Approach, Industry Response, and Comparison

with ISO 16708

International ISO Standardization Seminar for

the Reliability Technology and Cost Area

NEN - Vlinderweg 6 - 2623 AX Delft

29th March 2017

Maher Nessim

Francisco Alhanati

C-FER Technologies

Current Onshore Pipeline Design Approach

Applied hoop stress Specified MinimumYield Strength

Safety factor(Design factor x location factor)

Prevent yielding / rupture of new pipe under internal pressure

SMYSt

PD

2

Pipelines are designed using the Barlow Equation

2ISO Standardization Seminar - Delft NLMarch 2017

Pipeline Failure Stats

Most failures are associated with mechanical damage by external forces, corrosion and other deterioration mechanisms

36%

26%

6%

11%

4%

5%1%

11%

External Interference

External Corrosion

Internal corrosion

Manufacturing Defects

Geotechnical Hazard

Construction Defects

Operator Error

Other

Reportable Incidents for Natural Gas PipelinesUS DOT (2002 – 2008)


Key Limitation

• Pipeline reliability with respect to the dominant failure mechanisms is far more sensitive to wall thickness than to other parameters, such as hoop stress

• The current design approach is not the most effective safety control parameter – results in widely varying risk levels for different pipelines

ISO Standardization Seminar - Delft NL 4March 2017

Implied Safety Levels


Resistance to dominant failure causes is more dependent on the wall thickness than the hoop stress factor

Hoop stress design factor not the most effective safety control parameter

Reliability Based Design

• Key features– Design for actual failure mechanisms (limit states)– Use reliability as a safety control parameter– Evaluate options based on meeting a specified reliability target

• Benefits– Known and consistent safety levels– Guidance for all relevant design and assessment conditions– Effective allocation of resources to maximize safety– Well suited to new situations (new technologies, materials or loads)

• Limitations– Requires probability calculations (data / expertise / effort)– Potential for different users to get different answers


Reliability Based Design Standards

• Reliability based design is permitted in many standards, e.g.– ISO 13623 / CSA Z662 / IGE TD1 / AS 2885.1

• Guidance is provided in a few standards, e.g.

– CSA Z662 (1995). Oil and gas pipeline systems – Annex C: Limit States design

– IGE/TD/1 (2001) – Steel pipelines and associated installations for high pressure gas transmission – Appendix 4: Structural reliability analysis

– ISO 16708 (2006) - Petroleum and natural gas industries - Pipeline transportation systems - Reliability-based limit state methods

– NEN 3650-1 (2006) – Requirements for pipeline systems – Section 8: Structural design

– CSA Z662 (2007). Oil and gas pipeline systems – Annex O: Reliability based design and assessment of onshore natural gas pipelines


Comparison Between ISO and CSA

Topic ISO CSA

Scope - pipelines All pipelinesBuried onshore pipelines (no crossings or

above-ground sections)

Scope - fluids All oil and gasSpecific fluids (Natural Gas / non-volatile

LVP / more to come)

Reliability targetsTo be defined by user – optional specific

guidance given for some casesPrescribed – defined as function of pipeline and location parameters

Loads, load combinations and

limit states

Generic definitions with illustrative examples

Comprehensive listing of potentially applicable loads, load combinations and

corresponding limit states

Reliabilityestimation

Detailed description of distribution and reliability theories – implementation left

to the user

Reference to reliability texts – specific limit state functions and input

distributions for key design conditions

Reliability checking

Generic checkSpecific methodology addressing pipeline

segmentation and length averaging


CSA Approach - Highlights

• Limit States

• Reliability targets

• Reliability checking (demonstrating compliance)


Loads and Limit States

ISO Standardization Seminar - Delft NL 10

Life Cycle

Phase

Pipe

Configuration

Companion

LoadsLimit State

Limit State

Type

Stress

limit

Strain

limit

Time

Dependent

1 Cyclic bending Fatigue crack growth SLS Yes

2 Stacking weight Ovalization SLS No

Plastic collapse SLS No

Local Buckling SLS No

Girth weld tensile rupture SLS No

Local buckling SLS No

Testing All 3 Hydrostatic test Excessive plastic deformations SLS No

All 6 Internal pressure Burst of defect free pipe ULS No

7 Equipment Impact 6 Burst of a gouged dent2 ULS No

Local buckling SLS or ULS1

No

Upheaval buckling SLS or ULS1

No


Yes

Girth weld tensile rupture ULS Yes


Yes



Yes



No

Girth weld tensile rupture ULS No


Yes


Failure of a weld defect ULS Yes

Plastic collapse SLS or ULS1

No

Ovalization SLS No

Dynamic instability SLS or ULS1

No

Formation of mechanism by yielding SLS or ULS1

No


No


Waterway

crossing or

wetlands

16 Buoyancy 6,8 Floatation SLS or ULS1 No


No


No

Girth weld tensile rupture SLS or ULS1

No


Yes



No

Burst of crack by fatigue ULS Yes

1 Starts as a serviceability limit state, but could progress to an ultimate limit state

Primary Load

Transportation

All

Installation

4 Bending during installation

Buried (installed

by directional

drilling)

5Directional drilling tension and

bending

9 Slope instability, ground movement 6,8,12

Operation

Buried

8 Restrained thermal expansion 6

10 Frost heave 6,8.12

12 Seismic loads6,8, 9 or10

or 11

Waterway

crossings15 River bottom erosion 6,8,16

Wind loads

11 Thaw settlement 6,8,12

13Loss of soil support (e.g.,

subsidence)6,8

Buried rail or road

crossings, or in

farmland

14 Overburden and surface loads 6

6,17

Above ground

17 Gravity loads 6

18 Support settlement 6,17

19

March 2017

Loads and Limit States

ISO Standardization Seminar - Delft NL 11

Life Cycle

Phase

Pipe

Configuration

Companion

LoadsLimit State

Limit State

Type

Stress

limit

Strain

limit

Time

Dependent

1 Cyclic bending Fatigue crack growth SLS Yes

2 Stacking weight Ovalization SLS No

Plastic collapse SLS No

Local Buckling SLS No

Girth weld tensile rupture SLS No

Local buckling SLS No

Testing All 3 Hydrostatic test Excessive plastic deformations SLS No

All 6 Internal pressure Burst of defect free pipe ULS No

7 Equipment Impact 6 Burst of a gouged dent2 ULS No


No

Upheaval buckling SLS or ULS1

No


Yes



Yes



Yes



No



Yes


Failure of a weld defect ULS Yes

Plastic collapse SLS or ULS1

No

Ovalization SLS No


No


No


No


Waterway

crossing or

wetlands

16 Buoyancy 6,8 Floatation SLS or ULS1 No


No


No

Girth weld tensile rupture SLS or ULS1

No


Yes



No

Burst of crack by fatigue ULS Yes

1 Starts as a serviceability limit state, but could progress to an ultimate limit state

Primary Load

Transportation

All

Installation

4 Bending during installation

Buried (installed

by directional

drilling)

5Directional drilling tension and

bending

9 Slope instability, ground movement 6,8,12

Operation

Buried

8 Restrained thermal expansion 6

10 Frost heave 6,8.12

12 Seismic loads6,8, 9 or10

or 11

Waterway

crossings15 River bottom erosion 6,8,16

Wind loads

11 Thaw settlement 6,8,12

13Loss of soil support (e.g.,

subsidence)6,8

Buried rail or road

crossings, or in

farmland

14 Overburden and surface loads 6

6,17

Above ground

17 Gravity loads 6

18 Support settlement 6,17

19

March 2017

Risk Based Reliability Targets – ULS

• Based on benchmarking to current practice

– Match or exceed average safety associated with a new pipeline network designed to acceptable standards and operated to best industry practices

– Maintain a uniform safety level for all pipelines


Risk Benchmarking Example –Total Societal Risk

1E-10

1E-09

1E-08

1E-07

1E-06

1E-05

1E-04

1E-03

1E-02

1.E+05 1.E+06 1.E+07 1.E+08 1.E+09

PD3 (psi-in

3)

Av

era

ge 5

0-y

r R

isk

(per

km

-yr)

Class 1Class 2Class 3Class 4Weighted average risk - 1.6E-5

1000 psi, 10 in 1200 psi, 20 in 1400 psi, 42 in

Calculated Risk Levels for Wide Range of Natural Gas Pipeline Designs and

Corresponding Average Risk Level and Length-weighted AverageISO Standardization Seminar - Delft NL 13March 2017

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E+06 1.E+07 1.E+08 1.E+09 1.E+10 1.E+11 1.E+12 1.E+13

Allo

wab

le P

rob

abili

ty o

f Fa

ilure

(pe

r km

-yr)

rPD3 (people/ha-Mpa-mm3)

Allowable Failure Probabilities –Natural Gas


Allowable Failure Probabilities –Non-volatile LVP Liquids

15

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Allo

wab

le P

rob

abili

ty o

f Fa

ilure

(pe

r km

yr)

b D1.6 (mm)

ISO Standardization Seminar - Delft NLMarch 2017

Reliability Checking – Issues

• Pipeline segmentation based on potential consequence severity– Population density for natural gas– Environmental sensitivity for liquids

• Reliability checking for different threat types– Localized threats – point source (moving slope)– Distributed threats

• Continuous (internal pressure)• Randomly located (equipment impact)

• Reliability checking for different failure modes– Leaks– Ruptures


Validation and Scrutiny

• Developed under PRCI project – directed and supervised by industry

• Tested extensively to evaluate the impact on design and operational decision making

• Published in a series of 7 conference and 2 journal peer-reviewed papers –more to come

• Reviewed by 3 independent consultants and researchers

• Presented and debated in multiple sessions of the CSA Z662 Technical Committee

• Debated in a public forum sponsored by CSA in 2005

• Approved unanimously by the Z662 Technical Committee for adoption in 2007 edition of the Standard


Application

• Adoption initially slow– Apprehension about the use of firm reliability targets– Skepticism about the required probabilistic calculations– Lack of expertise in potential user organizations

• First applications were for arctic pipeline design against frost heave and thaw settlement loads because the current standards do not provide any guidance in this area

• Significant momentum over the past 2 to 3 years for application to conventional pipeline issues such as class location changes and management or corrosion and cracks– Heightened public awareness of pipeline risk– More recognition of the benefits of reliability– Improvements in data acquisition techniques


Future Direction

• Include non-volatile liquid in Annex O of full reliability based design and assessment (2019)

• Adopt a new version of Annex C on limit states design (2019)

• Develop a new risk based safety class and design factor system for the main body of the standard (2023?)


Questions ?

March 2017 ISO Standardization Seminar - Delft NL 20

reliability based design for pipelines canadian standard … · 2021. 2. 2. · –nen 3650-1...

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