EXECUTIVE SUMMARY The objective of this report is to demonstrate that sections of pipeline between MLV 401 and MLV 402 on the Canadian Mainline Line 400-2 meet the applicable requirements in CSA Z662-15 clause 10.7.1.for the section with the change of class. The class location change is as a result of residential and commercial development in the area, which is located just south of Ile Des Chènes, Manitoba. According to CSA Z662-15, Clause 10.7.2, if there is a class location change for a pipeline, the conformance or non-conformance to the requirements of clause 10.7.1. must be documented. Clause 10.7.1 requires the following items to be verified for the new location class: a) Design factor or location factor b) Valve spacing c) Depth of cover and clearance d) Pressure testing, and e) Evaluation and repair of imperfections TransCanada PipeLines Limited (TransCanada) has reviewed the class location change sites and determined that the location factor, depth of cover and clearance, and pressure testing for Line 400-2 meet the requirements of the new class locations. However as the depth of cover survey was done some time ago, a new survey is proactively recommended. The metal-loss corrosion features identified in the class location change site for Line 400-2 were evaluated using the location factor corresponding to the new class location. The features were found to be acceptable as per Clause 10.10.2.5 of CSA Z662-15. No dents and gouges were found in the 2013 Caliper in-line inspection (ILI) for the class location change site on Line 400-2. The review of the existing mainline block valves identified that valves MLV 401-2 and MLV 402-2 are equipped with automatic isolation capabilities. The existing valve spacing for the class location change sites do not meet the default valve spacing requirement for the new class location as specified in CSA Z662-15 Clause 4.4.5. Therefore, a valve spacing Engineering Assessment (EA) was conducted. The valve spacing EA addressed both Lines 400-2 and 400-3 and was submitted to the National Energy Board (NEB) on 16 July 2015. This valve spacing EA has been reformatted to include only Line 400-2 and it is provided in Appendix A of this report. The following actions are recommended by this class change assessment and the valve spacing EA for Line 400-2: 1. By March 31, 2016, complete depth of cover survey for the class change site on Line 400-2 to confirm that the depth of cover is still adequate and that the requirements outlined in Table 4.9 of CSA Z662-15 are met. 2. The inspection frequency of MLV 401-2 and MLV 402-2 isolation valves was increased in 2015 to semi-annual (every 6 months), including the associated tie-over valves. This increase in inspection frequency resulted in an increased assurance in the reliability of isolation valves and appropriate valve closure times. 3. The valve spacing will be maintained at 24.42 km. TransCanada will perform the actions identified and continue to manage the integrity of the class location change site according to the TransCanada s integrity management program (IMP). Page 1 of 15
APPROVALS Page 2 of 15
Table of Contents 1.0 INTRODUCTION... 4 1.1 Class Location Change Sites... 4 1.2 CSA Z662-15 Requirements... 4 2.0 EVALUATION OF CONFORMANCE TO THE NEW CLASS LOCATION REQUIREMENTS... 6 2.1 Design Factor or Location Factor... 6 2.2 Valve Spacing... 8 2.3 Depth of Cover and Clearance... 8 2.4 Pressure Testing... 8 2.5 Evaluation and Repair of Imperfections... 9 3.0 RECOMMENDATIONS... 10 4.0 REFERENCES... 10 APPENDIX A... 11 Page 3 of 15
1.0 INTRODUCTION 1.1 CLASS LOCATION CHANGE SITES TransCanada identified class location change sites for Lines 400-1, 400-2 and 400-3 between MLV 401 and MLV 402 on the Canadian Mainline System. The class location change sites are located just south of Ile Des Chènes, Manitoba. The class location change is a result of new residential and commercial development in the area. Note that the scope of this report is limited to only the class location change site on Line 400-2, as a previous class change assessment report covering Lines 400-1 and 400-3 was filed with the NEB on 15 December 2015 (Filing no. A74759). For the detailed location of the class location change sites for Line 400-2, see Table 1. For an image showing the location of the class location change sites, see Figure 1. Table 1: Pipeline Sections with the Class Location Designation Change Line Name Start chainage End chainage Class Location (m) (m) Change MLV 401 to 402 Line 400-2 (NPS 36) 527.300 1035.000 Class 2 to Class 3 MLV 401 to 402 Line 400-2 (NPS 36) 1035.000 1416.145 Class 1 to Class 3 MLV 401 to 402 Line 400-2 (NPS 36) 1416.145 1475.672 Class 1 to Class 2 1.2 CSA Z662-15 REQUIREMENTS CSA Z662-15 Clause 10.7 Change of Class Location describes the requirements for class location changes. 10.7.1 Where class locations change, the pipeline system in such locations shall be subject to the following requirements for the new class location: a) design factor or location factor, as applicable; b) valve spacing;j c) depth of cover and clearance; d) pressure testing; and e) evaluation and repair of imperfections as specified in Clause 10.10 and Clause 10.11. 10.7.2 Conformance or non-conformance to the requirements of the new class location shall be documented, as applicable. 10.7.3 Where the affected portion of the pipeline does not conform to the requirements of the new class location, as described in Clause 10.7.1, either the non-conformance(s) shall be corrected in accordance with the requirements of Clause 4 or an engineering assessment (see Clause 10.1) shall be carried out to determine the suitability for continued service at the new class location designation in consideration of the: a) design, construction, and testing procedures followed in the original construction, compared with the applicable requirements of this Standard; b) condition of the pipeline system as determined by field inspections, examinations of operating and maintenance records, or other appropriate means; and c) type, proximity, and extent of the development that has increased the class location, giving consideration to concentrations of people, such as those associated with schools, hospitals, small subdivisions, and recreation areas built near existing pipelines. Page 4 of 15
Note: Annex O provides guidance on reliability-based design and assessment that can be a useful approach for an engineering assessment. Figure 1: Class Location Change Sites in Lines 400-1, 400-2 and 400-3 near Ile Des Chènes, Manitoba Page 5 of 15
10.7.4 Where the engineering assessment (see Clause 10.7.3) indicates that the section of the pipeline system is satisfactory for the changed class location, no change to the pipeline system shall be required. 10.7.5 Where the engineering assessment (see Clause 10.7.3) indicates that the portion of the pipeline system is not satisfactory for the changed class location, corrective actions shall be taken so that the affected portion of the pipeline system is suitable for continued service at the new class location designation. 10.7.6 Pipeline systems that can be subject to changes in class location, unless previously designed, tested, operated, and maintained for a Class 4 location, shall be inspected annually by the operating company to determine whether any change in class location has occurred. Records of such inspections and of any corrective action taken shall be retained. Note: CSA PLUS 663 provides guidance related to land use planning near to or surrounding existing pipeline. 2.0 EVALUATION OF CONFORMANCE TO THE NEW CLASS LOCATION REQUIREMENTS The following aspects on the class location change sites were reviewed to determine if the pipeline segments at the class location change sites are in conformance with the applicable requirements for the new class location in CSA Z662-15 Clause 10.7.1. a) design factor or location factor b) valve spacing c) depth of cover d) pressure testing e) evaluation and repair of imperfections Identified non-conformances and corresponding corrective actions are detailed below. 2.1 DESIGN FACTOR OR LOCATION FACTOR According to the Clause 4.3.5.1 of CSA Z662-15, the design pressure for a given design wall thickness or the design wall thickness for a given design pressure shall be determined by the following equation: St P = 2 F L J T (1) D where P design pressure, MPa S specified minimum yield strength, MPa t design wall thickness, mm D outside diameter of pipe, mm F design factor as per the Clause 4.3.6 of CSA Z662-15 Page 6 of 15
L location factor as per the Clause 4.3.7 of CSA Z662-15 J joint factor as per the Clause 4.3.8 of CSA Z662-15 T temperature factor as per the Clause 4.3.9 of CSA Z662-15 Therefore, the value of location factor corresponding to the design of a pipeline segment can be calculated as follows: PD L = 2 St F J T (2) For each class location change site, the location factor was calculated based on Eq. (2), using F = 0.8, J = 1.0 (submerged arc welded pipe), T = 1.0 (maximum operating temperature less than 120 degree Celsius), and other pipe properties listed in Table 2. The comparison between the calculated location factor values and the maximum allowable location factor values as per CSA Z662-15 Clause 4.3.7 Table 4.2 is summarized in Table 2. It should be noted that due to the class change, Line 400-2 has been de-rated to a revised operating pressure of 5374 kpa for an indefinite period. At this de-rated pressure, the pipeline segments for Line 400-2 meet the location factor requirements for the new classes as shown in the parentheses in Table 2. Table 2: Location Factor Review Summary Line Name Start chainage (m) End chainage (m) 400-2 527.30 1035.00 400-2 1035.00 1226.88 400-2 (road) 1226.88 1239.07 400-2 1239.07 1416.15 400-2 1416.15 1425.31 400-2 (road) 1425.31 1460.88 400-2 1460.88 1475.67 MOP (Reduced Operating Pressure) (kpa) 7030 OD (mm) WT (mm) Grade (MPa) New Location Class (5374) 1 914 10.97 448 3 7030 (5374) 1 914 10.97 448 3 7030 (5374) 1 914 11.91 414 3 7030 (5374) 1 914 10.97 448 3 7030 (5374) 1 914 10.97 448 2 7030 (5374) 1 914 13.16 448 2 7030 (5374) 1 914 9.14 448 2 Design Location Factor Maximum Allowable Location Factor 0.817 (0.625) 1 0.817 0.7 (0.625) 1 (General) 0.814 0.625 (0.622) 2 (Roads) 0.817 (0.625) 2 0.817 (0.625) 2 0.9 0.681 (General) (0.521) 2 0.625 0.981 (Roads) (0.750) 2 1 Reduced operating pressure is currently in place to restrict the operating pressure to location Class 3 requirements. Page 7 of 15
2.2 VALVE SPACING Due to the class location change, the requirements for valve spacing have also changed, according to Clause 4.4.5 and Table 4.7 of CSA Z662-15. The current isolation valve spacing and the required valve spacing as per Table 4.7 of CSA Z662-15 are given in Table 3 for Line 400-2. As shown in this table, the existing valve spacing does not meet the valve spacing requirement for the new class location. Therefore, a valve spacing EA was conducted. A valve spacing EA addressing both Line 400-2 and Line 400-3 was submitted to NEB on 16 July 2015. This valve spacing EA has been reformatted to include only Line 400-2, and it is provided in Appendix A of this report. Line Name Start Valve Table 3: Valve Section Details Start Chainage (m) End Valve End Chainage (m) Valve Section Length (km) Required Valve Spacing for Class 3 (km) Line 400-2 MLV 401-2 0 MLV 402-2 24418.96 24.42 13 2.3 DEPTH OF COVER AND CLEARANCE TransCanada performed a depth of cover survey for Line 400-2 in 2002. The survey showed that the minimum depth of cover in general locations was higher than the required minimum depth of cover of 0.6 m. The minimum depth of cover in the road crossing was also found to be higher than the required minimum depth of cover of 1.2 m. Given that the depth of cover survey was last performed over 10 years ago, it is recommended that a new survey be completed by March 31, 2016 for the class change site on Line 400-2 to ensure that the depth of cover is still adequate and meets the requirements outlined in Table 4.9 of CSA Z662-15. According to the as-built alignment drawing, the clearance of Line 400-2 from other underground structures and utilities are higher than the minimum required clearance of 300 mm, as specified in Table 4.9 of CSA Z662-15. Furthermore, TransCanada requires on-site supervision of all third party crossings, thus ensuring that this requirement is met for all third party crossings which ensures underground structures and utilities installed subsequently. 2.4 PRESSURE TESTING Table 4 shows the comparison between the minimum test pressure required by Table 8.1 of CSA Z662-15 and the minimum hydrostatic test pressure applied to the test section, which includes the class change site. Under the reduced operating pressure, the class change site meets the minimum hydrostatic test requirements for Class 3. The comparison shows that the minimum test pressure for the class change site meets the requirement for a Class 3 Location. Page 8 of 15
Line New Class Table 4: Hydrostatic Pressure Test Summary MOP (Reduced Operating Pressure) (kpa) Minimum Test Pressure (kpa) Minimum Test Pressure (% MOP) Required Minimum Test Pressure (%MOP) 400-2 Class 3 7030 (5374) 2 8788 1.25 (1.64) 2 140 2.5 EVALUATION AND REPAIR OF IMPERFECTIONS According to the Clause 10.7.1 e) of CSA Z662-15, the identified imperfections in the class location change sites are required to be evaluated and repaired, as necessary, according to the requirement specified in Clause 10.10 and Clause 10.11 of CSA Z662-15. According to these clauses, the class location change affects the safety factor for metal-loss corrosion anomalies. As such, the metal-loss corrosion hazard has been evaluated for the identified class location change sites. TransCanada manages corrosion imperfections identified by in-line inspection (ILI) using the ILI Corrosion program, which employs both a deterministic criteria, provided in CSA Z662-15 Clause 10.10, and a reliability based criteria as provided in TransCanada s TEP-INT-ILI-CDN Analysis of MFL In-Line Inspection for CDN Pipelines (CDN) procedure. Line 400-2 was last inspected with Rosen AFD and CDG (MFL) tools on 24 June 2013. The metal-loss corrosion features identified in the class location change site for Line 400-2 were evaluated using the location factor corresponding to the new class location, and the features were found to be acceptable as per Clause 10.10.2.5 of CSA Z662-15. Furthermore, CP is continuously and effectively managed on the Line 400-2 in accordance with TransCanada s CP criteria specifications, which adhere to CSA Z662-15 Clause 9.9, and Canadian Gas Association (CGA) recommended practice OCC-1-2013. The annual test lead CP survey data from 2005 to 2015 were reviewed as an indication of the CP maintenance history for the affected segments of Line 400-2. The data showed no persistent sub-criteria pipe-toelectrolyte potentials, which is indicative of a CP system that is performing well and therefore minimizing the corrosion hazard in the class change site. No dents or gouges were found in the 2013 Caliper ILI for the class location change site on Line 400-2. 2 Reduced operating pressure is currently in place to restrict the operating pressure to location Class 3 requirements. Page 9 of 15
3.0 RECOMMENDATIONS The review of class location change sites in accordance with CSA Z662-15 Clause 10.7.1 a) through e) has determined that the location factor, depth of cover and clearance, and pressure testing for the class location change sites in Line 400-2 meet the requirement of the new class location. However as the depth of cover survey was done some time ago, a new survey is proactively recommended. The metal-loss corrosion features identified in the class location change site for Line 400-2 were evaluated using the location factor corresponding to the new class location, and there are currently no known unrepaired metal-loss anomalies that require mitigation for the new class location under the reduced operating pressure. The existing valve spacing for the class location change sites does not meet the default valve spacing requirement for the new class location. Therefore, a valve spacing EA was conducted. The following actions are recommended by the class change assessment and the valve spacing EA: 1. By March 31, 2016, complete depth of cover survey for the class change site on Line 400-2 to confirm that the depth of cover is still adequate and that the requirements outlined in Table 4.9 of CSA Z662-15 are met. 2. The inspection frequency of MLV 401-2 and MLV 402-2 isolation valves was increased in 2015 to semi-annual (every 6 months), including the associated tie-over valves. This increase in inspection frequency resulted in an increased assurance in the reliability of isolation valves and appropriate valve closure times. 3. The valve spacing will be maintained at 24.42 km. 4.0 REFERENCES CSA. 2015. Z662-15 Oil and Gas Pipeline Systems. Rexdale, Ontario. Eiber, R. et al (2000), Valve Spacing Basis for Gas Transmission Pipelines, Pipeline Research Council International, Report no. L51817 TransCanada. Gas Control Overpressure Procedure. Internal document. TransCanada. TransCanada Engineering Procedure: Analysis of MFL In-Line Inspection for CDN Pipelines. Internal Document TransCanada. TransCanada Engineering Procedure: External Corrosion Threat Management Program. Internal Document TransCanada. TED-MECH-VS-GAS Gas Valve Spacing Directive (CDN US MEX). Internal document. TransCanada. TER-RISK-CON Thermal Radiation Consequence Models for Natural Gas Pipelines (CDN US MEX. Internal document. TransCanada. TOP Pipeline Operations (Gas Handling) (CDN US MEX). Internal document. TransCanada. 2015. TransCanada Operating Procedure: Pipeline Restriction Procedure. Internal document Page 10 of 15
APPENDIX A Valve Spacing Engineering Assessment Page 11 of 15
A.1 Valve Spacing Engineering Assessment The valve spacing engineering assessment for valves MLV 401 and MLV 402 on Line 400-2 was carried out in accordance with CSA Z662-15 Clause 4.4.4, which states that in order to determine the proper valve spacing, the following factors are to be considered: a. The nature and amount of fluid released due to a blowdown or a failure b. The time to blowdown the isolated section c. The effects on the inhabitants of the area from gas release d. Continuity of service e. Operating and maintenance flexibility f. Future development within the valve spacing section g. Significant conditions that could adversely affect the operation and security of the pipeline In addition to these Operations and Maintenance considerations, it is also necessary to consider the effect of increased valve spacing on public safety. This effect is evaluated primarily by determining the Individual Risk (IR) and Societal Risk (SR). IR is the annual probability of a fatality to an individual located on top of the pipeline. It is a baseline risk assessment performed for every pipeline. On the other hand, SR is the annual risk to a group of structures, or a settlement, due to its proximity to the pipeline. Combined, IR and SR will capture the acceptability of risk from a safety perspective for both sparsely and densely populated areas. Both of these risk measures are then compared to the industry accepted risk criteria to determine the acceptability of risk. For more background on IR and SR, as well as the IR and SR criteria, please refer to TER-RISK-CON. In the following sections, the above-mentioned considerations were addressed for the section of pipeline on Line 400-2 between valves MLV 401 and MLV 402. A.2 Operation and Maintenance Considerations a) The nature and amount of fluid released due to a blowdown or a failure The service fluid in the pipelines is sweet natural gas. If a blowdown is required for planned maintenance activities, a transfer compressor will be utilized to draw the valve section down to 1000kPa. The remaining gas would then be vented to the atmosphere. At this pressure, the volume of gas vented for the two compared valve spacings would be: o 24.42 km valve spacing: 165 x 10 3 m 3 o 13.00 km valve spacing: 88 x 10 3 m 3 In the event of an emergency blowdown, the volume of the gas released from the line would be dependent on the pressure in the line. At 90% of the MOP, the volume the gas vented for the two compared valve spacings, assuming that the isolation valves have closed, would be: o 24.42 km valve spacing: 1076 x 10 3 m 3 o 13.00 km valve spacing: 573 x 10 3 m 3 Page 12 of 15
b) The time to blowdown the isolated section For both the actual valve spacing of approximately 24.42 km and the required Class 3 valve spacing of 13 km, the blowdown times would be less than eight hours. It should be noted that this applies to both blowdowns with and without silencers. The implication of the blowdown time being less than eight hours is that the blowdown could be performed during normal daylight working hours, which would prevent undue disturbance to residents during non-working night time hours. Time to blow down an isolated section is also associated with emergency response, which is discussed in Section A3. c) The effects on the inhabitants of the area from gas release A silencer would be installed (if planned maintenance is to occur) on MLV 401 vent piping at Compressor Station 41 (near Ile Des Chènes), due to the proximity of the structures to the station. The closest residence from MLV 402 is approximately 500 meters away. Local landowners and relevant government agencies will be advised at least 48 hours prior to the planned blowdown operation according to the TransCanada Pipeline Operations Gas Handling TOP. These installations will be implemented in order to minimize effects to inhabitants in the area of the blowdown gas release. d) Continuity of service In the case of either planned or unplanned maintenance activities, the continuity of service would not be affected due to the redundancy of the design. All of these pipelines have a tie-over to a parallel pipeline, so the service would not be interrupted by taking any of the lines temporarily out of service for maintenance activities. In addition, the sales meter stations in this valve section are supplied from multiple lines, therefore adding redundancy if one of the lines is temporarily taken out of service. e) Operating and maintenance flexibility Current system design allows sales meter stations to be fed from both Lines 400-1 and 400-2, which offers operating and maintenance flexibility. In addition, tie-over valves are present at each isolation valve location on Line 400-1 and Line 400-2; therefore, allowing for isolation of a single valve section without affecting the delivery of gas and continuity of service. f) Future development within the valve spacing section It is not anticipated that any section of the pipe in this valve section will undergo a further class location upgrade in the foreseeable future, as there is no anticipated multi-floor building construction in this area. Thus, it is not anticipated that further development in the area will have additional impacts on the class location designation of this valve section. g) Significant conditions that could adversely affect the operation and security of the pipeline Conditions that may affect pipeline operation are addressed above in sections (d) and (e) above. In addition, if MLV 401 and MLV 402 on Line 400-2 and the associated tie-over valves fail to operate properly, that could adversely affect the operation of the pipeline for this valve section. It is thus recommended to increase the valve maintenance/inspection from an annual to a semiannual (every 6 months) frequency to reduce the probability of isolation valves MLV 401 and MLV 402 on Line 400-2 and the associated crossover valves failing to operate properly. Page 13 of 15
A.3 Effect on the Public Safety The effects of changing the valve spacing on public safety are minimal if the valve spacing is more than 10 km, as shown in Pipeline Research Council International (PRCI) report entitled Valve Spacing Basis for Gas Transmission Pipelines. This is because the greatest consequence of a pipeline rupture occurs within the first 30 seconds after the failure and the subsequent ignition. This initial stage following the failure will be independent of the valve spacing, therefore making the effects on the population independent of valve spacing. The following three arguments are proposed by Valve Spacing Basis for Gas Transmission Pipelines report as to why the impact of valve spacing is minimal on the population: 1. The primary consequence of a natural gas pipeline failure is related to the effects of thermal radiation exposure of the fire ball following ignition. The hazard zone is largest immediately following ignition. Reduction of valve spacing does not diminish the size of the hazard zone immediately following ignition. 2. The jet fire that follows the initial release phase after ignition has a smaller hazard zone. This jet fire could hinder emergency personnel from entering the site so it is important to reduce the duration of a fire. A key factor in reducing jet fire duration is cutting off fuel supply by quickly closing proximate valves. Automatic shutoff valves (ASVs) close more quickly than remotely controlled valves and manual valves. MLV 401 and MLV 402 on Line 400-2 are both ASVs. 3. According to the PRCI study: as the valve closure time increases beyond 7.5 minutes (10 minutes is the practical minimum valve closure time), the risk level is independent of valve spacing and thus valve spacing does not affect the risk to the public. Changing the valve spacing, therefore, will not affect the risk in this case. This has been reinforced by first determining the individual risk for both the current valve spacing of 24.42 km and the Class 3 compliant valve spacing of 13 km. This comparison demonstrated that there is no appreciable difference if the individual risk resulted from decreasing the valve spacing. Furthermore, the Individual Risk is acceptable and below the IR tolerance limit for both cases and for both of these pipelines. In addition to Individual Risk, the Societal Risk was also evaluated for the Class 3 segments with both the actual valve spacing of 24.42 km and the Class 3 compliant valve spacing of 13 km. The evaluation demonstrated that there is no appreciable difference if the societal risk resulted from decreasing the valve spacing. Furthermore, the Societal Risk is acceptable and below the SR tolerance limit for both valve spacing cases and for both pipelines. A.4 Conclusion An isolation valve spacing EA was performed for sections of pipeline between isolation valves MLV 401 and MLV 402 on Line 400-2 due to a change in class location. In accordance with Clause 4.4.4 of CSA Z662-15, an EA has been conducted to demonstrate that the current valve spacing of approximately 24.42 km is safe for the surrounding population and will not adversely affect the operation and maintenance activities on these pipelines. This EA demonstrated that: Page 14 of 15
There is no increased risk to the population due to the current valve spacing compared to the Clause 4.4.5 compliant valve spacing. Both individual and societal risk changes were insignificant due to reduction of isolation valve spacing. There is no adverse impact to operation and maintenance activities on the pipelines with regard to the higher valve spacing. A.5 Recommendations TransCanada has determined the appropriate approach to maintain safety for the valve sections. The following actions will be implemented for the sites to achieve satisfactory levels of safety and reliability: 1. The inspection frequency of MLV 401-2 and MLV 402-2 isolation valves was increased in 2015 to semi-annual (every 6 months), including the associated tie-over valves. This increase in inspection frequency resulted in an increased assurance in the reliability of isolation valves and appropriate valve closure times. 2. The valve spacing will be maintained at 24.42 km. Page 15 of 15