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Line 3 Replacement Project Final Report:

Criteria for Pipe Wall Thickness ‐

Railroad Crossings Job #: 091510044

Submitted: May 1, 2015

Prepared for:

Enbridge Energy

Attention:

Mitch Repka, Manager Engineering and Construction

1409 Hammond Ave

Superior, WI 54880

Simonson Direct CN & PPL Testimony, Ex. ___, Schedule 3 Page 1 of 30

Excellence & Integrity

Criteria for Pipe Wall Thickness ‐ Railroad Crossings Page | 1

TABLE OF CONTENTS 1 EXECUTIVE SUMMARY ........................................................................................................................................... 3

2 BACKGROUND ....................................................................................................................................................... 3

3 OBJECTIVES AND APPROACH ................................................................................................................................. 3

3.1 PURPOSE ....................................................................................................................................................... 3

3.2 DESIGN CRITERIA ............................................................................................................................................ 3

3.3 ASSUMPTIONS ................................................................................................................................................ 4

3.4 ACCEPTABLE STRESS LEVELS – CODE AND STANDARDS REVIEW .............................................................................. 5

4 CONCLUSION ......................................................................................................................................................... 6

5 RECOMMENDATIONS ............................................................................................................................................ 6

APPENDIX I ‐ RESULTS ................................................................................................................................................... 7





1 Executive Summary

Wall thickness requirements for railroad crossings have been evaluated for the Line 3 Replacement Project

per the operating conditions outlined in the Class 3 Pipeline Hydraulic Proposal provided by Enbridge. Stress

calculations were completed for uncased pipeline crossings of railroads according to API 1102 Liquid

Pipelines Crossing Railroads and Highways from 6‐14 feet below the rail. A minimum wall thickness 0.741”

was determined based on applicable codes and standards. The most stringent requirement is Hoop Stress

calculated with a design factor of 0.50 based on Enbridge Design Standard D06‐103, which exceeds API 1102

and the AREMA manual minimum thickness requirements. For cased crossings of railroads the minimum

wall thickness of the casing pipe can be determined from the AREMA manual. For 46” casing the minimum

wall thickness for uncoated or not catholically protected pipe is 0.656” and must have a SMYS of at least

35,000 psi.

2 Background

The proposed common carrier pipeline, commercially known as the “Line 3 Replacement Project,” will have

a design capacity of 760,000 barrels per day of light/heavy crude oil blends. The proposed 36‐inch‐diameter

interstate crude pipeline originates at the end of the 34‐inch‐diameter Maintenance and Flexibility Project

near the Canadian/US Border, crosses North Dakota and Minnesota, and extends to a delivery point at the

Superior Terminal in Wisconsin. The project is integrity driven and will ultimately replace the existing

Enbridge 34‐inch Line 3.

3 Objectives and Approach

3.1 Purpose

The purpose of this analysis is to ensure that the pipe to be installed at railroad crossings is of adequate

strength to withstand the external and dynamic forces exerted by rail loads and soil overburden. In

addition, it serves to calculate the fatigue, circumferential, radial, longitudinal, and total effective

stresses and to ensure they are within acceptable limits as established by the applicable referenced

Codes and Standards.

3.2 Design Criteria

The applicable and governing Codes, Standards, and Reference Documents are as follows:

American Railroad Engineering and Maintenance‐of‐Way Association (AREMA)

Chapter 1 Part 5 – Pipelines, 2014 Edition

API Recommended Practice 1102

“Steel Pipeline Crossing Railroads and Highways”, Seventh Edition, March 2014

ASME B31.4

“Pipeline Transportation Systems for Liquid Hydrocarbons and Other Liquids”, 2012 Edition




Code of Federal Regulations (CFR)

Title 49 – Transportation, Part 195 – Transportation of Hazardous Liquids by Pipeline, February

9, 2015

Enbridge Design Standards

D06‐101 ‐ Piping Design and Construction, Mainline, December 17, 2014

o Enbridge Technical Standards Bulletin# ‐ BUL-065-2014


D06‐103 – Crossing Design, November 29, 2013

Enbridge Construction Specification

USPCS‐SPEC‐PIPELEINE‐001 – Pipeline Construction

Class 3 Pipeline Hydraulic Design Proposal, October 28, 2014

o Addendum to Hydraulic Design Proposal, March 3, 2015

Pressure Cycling Analysis Line 3R IP Worst Case, April 15, 2014

3.3 Assumptions

The following general assumptions were used for the pipe stress analysis:

API Recommended Practice 1102 was used as the basis for the pipe stress analysis, as referred

to in ASME B31.4 and Enbridge Design Standard D06‐103

The analysis was completed for uncased crossings, for cased crossings refer to the wall thickness

requirements in the AREMA manual

All railroad crossings will be installed by a method that will not create bending stress during or

after installation

Pipeline analysis was completed for main transit railroads, not industrial or secondary spurs

Railroad crossing stresses do not need to be reevaluated for locations with increased mainline

wall thickness per the Pressure Cycling Analysis

Cooper E‐80 live loading was used per API 1102

Railroad crossing stresses do not need to be reevaluated for locations with increased mainline

wall thickness per the Pressure Cycling Analysis Line 3R IP Worst Case

The following inputs were used for the steel pipe characteristics:

o Poisson’s Ratio, ν = 0.30

o Young’s Modulus of Elasticity, E = 29 x 106

o Coefficient of Thermal Expansion, α = 6.5 x 10‐6




The following Pipe Operating Condition assumptions were used for the pipe stress analysis:

The internal pressure used in the calculation will be the Maximum Operating Pressure (MOP)

for each segment, 1440psi

Pipe used will be pipe conforming to the API 5L specification with a weld joint factor, E=1

Design Factor of 0.50, as outlined in Enbridge Design Standard D06‐103

A pipe operating temperature of 140oF

The following Site and Installation assumptions were used for the pipe stress analysis:

Minimum depth of cover for uncased railroad crossings will be 10ft, per AREMA manual

Minimum depth of cover for cased crossings will be 6ft as specified in Enbridge Design Standard

D06‐103

A maximum overbore of 2 inches per Enbridge Construction Specification USPCS‐SPEC‐

PIPELEINE‐001

A conservative installation temperature of 0oF. Actual installation temperatures are expected to

be higher as the construction will be completed during the summer/fall months

Pipeline to cross a single track

Geotechnical data as assumed per API 1102

o Average Unit Weight of Soil, γ = 120 lb/ft3

o Modulus of Soil Reaction, E’=0.5 ksi

o Resilient Modulus of Soil, Er=5.0 ksi

3.4 Acceptable Stress Levels – Code and Standards Review

49 CFR 195 requires that any external pressure that is to be exerted on the pipe is to be provided for in

the design of such a system. ASME B31.4 and Enbridge Design Standard D06‐103 both reference the use

of API 1102 for determining the resultant stresses due to the external pressures applied by soil

overburden and rail loads. The required and/or recommended stress criterion for crossing analysis is

outlined in Table 1 below.

Table 1: Allowable Stress Criteria

Stress Type Allowable Stress ‐ Liquids Reference

Hoop Stress due to Internal Pressure 0.50 SMYS Enbridge Design Standard D06‐103*

Total Effective Stress due to Internal

Pressure, Wheel Loads, Earth Loads

and ΔT (US), Combined hoop and

Longitudinal Stress (CA)

0.90 SMYS ASME B31.4, API 1102

Fatigue Stress in Girth and

Longitudinal Welds

The general design check for

Fatigue on Girth (ΔSLh≤SFG x F) and

Long welds (ΔSHh≤SFG x F)

ASME B31.4, API 1102

*A design factor of 0.72 is used by API 1102 and 0.60 by AREMA




4 Conclusion

The wall thickness for railroad crossings is calculated to achieve the maximum operating pressure (MOP) in

accordance with applicable codes, standards, and projected operating conditions of the proposed Line 3

Replacement Project. The calculations were completed in accordance with AREMA, ASME – B31.4, API ‐

1102, Enbridge Design Standards D06‐101 – Piping Design and Construction and D06‐103 – Crossing Design,

and the Enbridge Construction Specification ‐ USPCS‐SPEC‐PIPELINE‐001.

The evaluation included reviewing Enbridge Design Standard D06‐101, to confirm adherence, it should be

noted that the current design temperature of 140°F is higher than the maximum allowable design

temperature of 100°F as stated in the Technical Standards Bulletin BUL‐065‐2014 associated with Enbridge

Design Standard D06‐101. It is LSC’s understanding that a project decision record is being developed. The

current design temperature is within the acceptable limits for railroad crossing pipe as outlined in ASME

B31.4 2012 Edition, such that it is not necessary to vary the design calculation.

The railroad crossing wall thickness is calculated to meet the minimum thickness required for the MOP,

operating conditions as defined in the Class 3 Hydraulic Design Proposal, and rail traffic and soil overburden

loading. In addition, it serves to calculate the fatigue, circumferential, radial, longitudinal, and total effective

stresses and to ensure they are within acceptable limits as established by the applicable referenced Codes

and Standards.

5 Recommendations

An analysis was completed to determine if the mainline nominal wall thickness of 0.515” met the strength

requirements for an uncased railroad installation for depths from 6‐14 feet. The stress analysis showed that

pipe with a wall thickness of 0.515” would not meet the hoop stress or total effective stress limits as defined

by the codes and standards.

A minimum wall thickness of 0.741” was found to meet the criteria of 50% hoop stress as described in

Enbridge Design Standard D06‐103, which is the most stringent specification. Other criteria that was

analyzed included Barlow stress, effective stress, and weld fatigue for uncased railroad installations. This

wall thickness is acceptable at depths from 6‐14 feet per the API 1102 stress calculations.

If the railroad is crossed using a casing pipe, the inside diameter of the casing pipe shall be large enough to

allow the carrier pipe to be installed within the casing, taking into account spacing between the carrier pipe

and casing pipe. The wall thickness of casing, pipe can be determined from the AREMA manual. A

recommended casing OD of 46” would require a wall thickness for uncoated or not catholically protected

pipe of 0.656”, and must have a SMYS of at least 35,000 psi.




APPENDIX I ‐ RESULTS

SUMMARY TABLE

Stress (psi) Allowable Calculated 0.688"

Calculated 0.741"

Barlow Stress 35,000 37,674 34,980

Effective Stress 63,000 55,711 52,707

Girth Welds 6,000 5,616 5,500

Long. Welds 11,700 8,388 8,136

Pass/Fail Fail Acceptable




0.688” ANALYSIS




0.741” ANALYSIS



Criteria for Pipe Wall Thickness –

Road Crossings Job #: 091510044


Prepared for:

Enbridge Energy

Attention:

Mitch Repka, Manager Engineering and Construction

1409 Hammond Ave

Superior, WI 54880



Criteria for Pipe Wall Thickness –Road Crossings Page | 1


2 BACKGROUND ....................................................................................................................................................... 3


3.1 PURPOSE ....................................................................................................................................................... 3

3.2 DESIGN CRITERIA ............................................................................................................................................ 3

3.3 ASSUMPTIONS ................................................................................................................................................ 4

3.4 ACCEPTABLE STRESS LEVELS – CODE AND STANDARDS REVIEW .............................................................................. 5

4 CONCLUSION ......................................................................................................................................................... 6

5 RECOMMENDATIONS ............................................................................................................................................ 6

APPENDIX I ‐ RESULTS ................................................................................................................................................... 7





1 Executive Summary

Wall thickness requirements for road crossings have been evaluated for the Line 3 Replacement Project per

the operating conditions outlined in the Class 3 Pipeline Hydraulic Proposal provided by Enbridge. Stress

calculations were completed for uncased pipeline crossings of roads according to API 1102 Liquid Pipelines

Crossing Railroads and Highways from 4‐10 feet below the road surface. Based upon applicable codes and

standards, the minimum wall thickness for 36” OD, API 5L X‐70 pipe is 0.550”. Additionally, installations

from 10‐20 feet below the road surface with a wall thickness of 0.550” were confirmed to be acceptable

using ANSI GPTC Z380.1 Uncased Crossing Design.

2 Background








3.1 Purpose

The purpose of this analysis is to ensure that the pipe to be installed at highway or road crossings is of

adequate strength to withstand the external and dynamic forces exerted by traffic loads and soil

overburden. In addition, it serves to calculate the fatigue, circumferential, radial, longitudinal, and total

effective stresses and to ensure they are within acceptable limits as established by the applicable

referenced Codes and Standards.

3.2 Design Criteria


API Recommended Practice 1102

“Steel Pipeline Crossing Railroads and Highways”, Seventh Edition, March 2014

ASME B31.4


ANSI GPTC Z380.1 Appendix G‐192‐15

“Guide for Gas Transmission and Distribution Piping Systems”, 2012

American Lifelines Alliance

"Guideline for the Design of Buried Steel Pipe" 2001






9, 2015





D06‐103 – Crossing Design, November 29, 2013

Enbridge Construction Specification

USPCS‐SPEC‐PIPELEINE‐001 – Pipeline Construction




3.3 Assumptions

The following general assumptions were used for the pipe stress analysis:

API Recommended Practice 1102 was used as the basis for the pipe stress analysis, as referred

to in ASME B31.4 and Enbridge Design Standard D06‐103 for depths from 4‐10 feet

ANSI GPTC Z380.1 was used as the basis for pipe stress analysis to confirm use of the API 1102

specified wall thickness for depths from 10‐20 feet

All highway or road crossings will be uncased

All highway or road crossings will be installed by a method that will not create a bending stress

during or after installation

Highway or road crossing stresses do not need to be reevaluated for locations with increased

mainline wall thickness per the Pressure Cycling Analysis Line 3R IP Worst Case

The following inputs were used for the steel pipe characteristics:

o Poisson’s Ratio, ν = 0.30

o Young’s Modulus of Elasticity, E = 29 x 106

o Coefficient of Thermal Expansion, α = 6.5 x 10‐6

The following Pipe Operating Condition assumptions were used for the pipe stress analysis:

The Internal pressure used in the calculation will be the Maximum Operating Pressure (MOP)

for each segment, 1,440 psi

Pipe used will be pipe conforming to the API 5L specification with a weld joint factor, E=1

Design Factor of 0.72 as outlined in API 1102




A pipe operating temperature of 140oF;

The following Site and Installation assumptions were used for the pipe stress analysis:

Minimum depth of cover for highway and road crossings will be 4 feet as specified in API 1102

and Enbridge Design Standard D06‐103

A maximum overbore of 2 inches per, Enbridge Construction Specification USPCS‐SPEC‐

PIPELEINE‐001

A conservative installation temperature of 0oF. Actual installation temperatures are expected to

be higher as the construction will be completed during the summer/fall months

Design wheel load for a single axle of 12,000lbs, as recommended by API 1102 for the maximum

design load for a single axle

Design wheel load for a tandem axle of 10,000lbs, as recommended by API 1102 for the

maximum design load for a tandem axle

Tandem axle loading is the critical loading for all diameters at depths greater than 4 feet, per

API 1102 Table 1

Unpaved Roads. By API 1102 this would be the most conservative approach as asphalt or

concrete would not be present to aid in distributing the traffic loads

Geotechnical data as assumed by API 1102:

o Average Unit Weight of Soil, γ = 120 lb/ft3

o Modulus of Soil Reaction, E’=0.2 ksi

o Resilient Modulus of Soil, Er=5.0 ksi

3.4 Acceptable Stress Levels – Code and Standards Review

CFR 195 requires that any external pressure that is to be exerted on the pipe to be provided for in the

design of such a system. ASME B31.4 and Enbridge D06‐103 both reference the use of API 1102 for

determining the resultant stresses due to the external pressures applied by soil overburden and traffic

loads. The required and/or recommended stress criterion for crossing analysis is outlined in Table 1

below.

Table 1: Allowable Stress Criteria

Stress Type Allowable Stress ‐ Liquids Reference

Hoop Stress due to Internal Pressure 0.72 SMYS CFR 195, ASME B31.4

Longitudinal Stress due to ΔT, Wheel Loads

and Earth Loads 0.90 SMYS ASME B31.4

Total Effective Stress due to Internal

Pressure, Wheel Loads, Earth Loads and ΔT

(US), Combined hoop and Longitudinal

Stress (CA)

0.90 SMYS ASME B31.4, API 1102

Fatigue Stress in Girth and Longitudinal

Welds

The general design check for Fatigue on Girth

(ΔSLh≤SFG x F) and Long welds (ΔSHh≤SFG x F) ASME B31.4, API 1102




4 Conclusion

The wall thickness for road crossings is calculated to achieve the MOP in accordance with applicable codes,

standards, and projected operating conditions of the proposed Line 3 Replacement Project. The calculations

were completed in accordance with ASME – B31.4, API ‐ 1102, ANSI ‐ GPTC Z380.1 Appendix G‐192‐15,

Enbridge Design Standards D06‐101 – Piping Design and Construction and D06‐103 – Crossing Design, and

the Enbridge Construction Specification ‐ USPCS‐SPEC‐PIPELINE‐001.

The evaluation included reviewing Enbridge Design Standard D06‐101, to confirm adherence, it should be

noted that the current design temperature of 140°F is higher than the maximum allowable design



current design temperature is within the acceptable limits for road crossing pipe as outlined in ASME B31.4

2012 Edition, such that it is not necessary to vary the design calculation.

The road crossing wall thickness is calculated to meet the minimum thickness required for the MOP,

operating conditions as defined in the Class 3 Hydraulic Design Proposal, and traffic and soil overburden

loading. In addition, it serves to calculate the fatigue, circumferential, radial, longitudinal, and total effective

stresses and to ensure they are within acceptable limits as established by the applicable referenced Codes

and Standards.

5 Recommendations

An analysis was completed to determine if the mainline nominal wall thickness of 0.515” met the strength

requirements for uncased road crossing installations up to 20 feet depth. At depths below 20 feet a site

specific engineering design is required. The stress analysis showed that pipe with a wall thickness of 0.515”

would not meet the effective stress limits as defined by Codes and Standards.

A minimum wall thickness of 0.550” was found to meet the criteria of fatigue, circumferential, radial,

longitudinal, and total effective stresses as established by the applicable referenced Codes and Standards.

This wall thickness is acceptable at depths from 4‐20 feet per API 1102 and ANSI GPTC Z380.1 Appendix G‐

192‐15 calculations.




APPENDIX I ‐ RESULTS

SUMMARY TABLE

Stress (psi) Allowable Calculated 0.515"

Calculated 0.550"

Barlow Stress 50,400 50,330 47,127

Effective Stress 63,000 66,419 62,927

Girth Welds 8,640 1,458 1,458

Long. Welds 11,700 2,327 2,329

Pass/Fail Fail Acceptable




0.515” ANALYSIS




0.550” ANALYSIS






Criteria for Pipe Wall Thickness ‐ MainlineJob #: 091510044


Prepared for:

Enbridge Energy

Attention:

Mitch Repka, Manager Pipeline Engineering & Construction

1409 Hammond Ave.

Superior, WI 54880



Criteria for Pipe Wall Thickness ‐ Mainline Page | 1


2 BACKGROUND ....................................................................................................................................................... 3


3.1 PURPOSE ....................................................................................................................................................... 3

3.2 DESIGN CRITERIA ............................................................................................................................................ 3

3.3 ASSUMPTIONS ................................................................................................................................................ 4

3.4 APPROACH .................................................................................................................................................... 4

4 CONCLUSION ......................................................................................................................................................... 5

5 RECOMMENDATION .............................................................................................................................................. 5

APPENDIX I ‐ LINE DESCRIPTION SUMMARY .................................................................................................................. 6

APPENDIX II ‐ PRESSURE PROFILE .................................................................................................................................. 7

APPENDIX III ‐ SUMMARY OF RESULTS .......................................................................................................................... 8





1 Executive Summary

The minimum wall thickness requirements for mainline pipe have been evaluated for the Line 3 Replacement

Project per the operating conditions outlined in the Class 3 Pipeline Hydraulic Design Proposal provided by

Enbridge. Based upon applicable codes and standards, the minimum wall thickness for 36” OD, API 5L X‐70

pipe is 0.515”.

2 Background








3.1 Purpose

To determine a nominal wall thickness for mainline pipe satisfying requirements for the maximum

operating pressure (MOP) in accordance with applicable codes, standards, and projected operating

conditions of the proposed Line 3 Replacement Project.

3.2 Design Criteria


ASME B31.4




9, 2015





D06‐104 – Pipe and Fittings, Steel, December 18, 2013


Enbridge Equipment Standard

EES 103 – Submerged‐Arc‐Welded Steel Pipe, November 29, 2013







3.3 Assumptions

36” outside diameter (OD), in accordance with API 5L X‐70

Maximum operating pressure of 1,440 psi, as outlined in the hydraulic summary

Maximum operating temperature of 140°F, as outlined in the hydraulic summary

Design Factor of 0.72, as outlined in ASME B31.4

Weld Joint Factor of 1, as outlined in ASME B31.4

D/t ratio of less than 100, as outlined in Enbridge Design Standard D06‐101

Additional mainline wall thickness requirements downstream of pump stations were required

from the Pressure Cycling Analysis Line 3R IP Worst Case completed by Enbridge

Wall thickness is rounded up to the nearest thousandth to meet the 0.72 design factor

3.4 Approach

The minimum mainline wall thickness requirement is calculated in accordance with ASME B31.4 and

Enbridge Design Standard D06‐101, using Barlow’s equation and checking the D/t ratio as shown below.

2

Where:

t nominal wall thickness (in)

Pi internal design pressure (psi)

D nominal outside diameter of pipe (in)

S yield strength (psi)

Where:

F design factor based from Table 403.3.1‐1

E weld joint factor

Sy = specified minimum yield strength of the pipe (psi)




100

Where:

D nominal outside diameter of pipe (in)

t nominal wall thickness (in)

4 Conclusion

The nominal wall thickness for mainline pipe is calculated to achieve the MOP in accordance with applicable

codes, standards, and projected operating conditions of the proposed Line 3 Replacement Project. The

calculation was completed using Barlow’s equation as outlined in ASME B31.4 2012 Edition and the Enbridge

Design Standard D06‐101 – Piping Design and Construction.

The evaluation included reviewing Enbridge Design Standard D06‐101, to confirm adherence, and it should

be noted that the current design temperature of 140°F is higher than the maximum allowable design



current design temperature is within the acceptable limits for mainline pipe as outlined in ASME B31.4, such

that it is not necessary to vary the design stress calculation.

The pipe wall thickness was designed to accommodate the MOP profile defined in the Class 3 Hydraulic

Design Proposal, ensuring the MOP between pump stations accounts for elevations at the required discharge

pressures to meet the proposed design capacity (see Appendix I ‐ Line Description Summary and Appendix

II ‐ Pressure Profile).

Further, the diameter to thickness ratio (D/t ratio) was evaluated to determine whether or not the calculated

thickness is susceptible to flattening, ovality, buckling, and denting; a D/t ratio greater than 100 may require

additional protective measures during construction. The D/t ratio for the Line 3 Replacement Project is less

than 100; therefore, as outlined in ASME 31.4 and Enbridge Design standard D06‐101, normal construction

procedures can be followed.

5 Recommendation

The minimum wall thickness for mainline pipe has been evaluated for the Line 3 Replacement Project per

the operating conditions outlined in the Class 3 Pipeline Hydraulic Proposal provided by Enbridge. Based

upon applicable codes and standards, the minimum wall thickness for 36” OD API 5L X‐70 pipe is 0.515”,

resulting in a D/t ratio of 64.1. See Appendix III ‐ Summary of Results for calculations.

The Enbridge Pressure Cycling Analysis recommends additional wall thickness downstream of Clearbrook,

Two Inlets, Backus, and Palisade Stations. Wall thicknesses of 0.750” and 0.600” are specified as mainline

thicknesses to be used. The specific distances downstream of each station can be found in the Pressure

Cycling Analysis Line 3R IP Worst Case, April 15, 2014.




APPENDIX I ‐ LINE DESCRIPTION SUMMARY

The following Line Description Summary taken from the Hydraulic Design Proposal outlines the required wall thicknesses for eight (8) different segments

of the proposed Line 3 Replacement Pipeline. Segment 8 references the US portion of the Line 3 Replacement Project, starting at the end of the Line 3

Maintenance and Flexibility Project terminating at the Superior Terminal.




APPENDIX II ‐ PRESSURE PROFILE

The following Pressure Profile taken from the Hydraulic Design Proposal illustrates the MOP along the entire Line 3 Replacement Project route. The

profile shows that at no point will the pressure exceed the designed MOP of 1,440 psi, further validating the current design wall thickness criteria.




APPENDIX III ‐ SUMMARY OF RESULTS
