OPERATION & MAINTENANCE SPECIFICATIONS MANUAL 05 10

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1 INTRODUCTION AND SCOPE The purpose of hot tapping is to provide a connection to an existing loaded line, where operating conditions so not permit the line to be taken out of service. The main applications of such a connection are for the provision of new sales take-off points, tie-over points, and as part of a stopple application. This section is intended to provide guidance on the safety, job planning, site preparation, installation and testing of hot tap connections that involve a welded connection of a branch to a mainline pipeline, and reinforced by means of a full-encirclement saddle, designed and manufactured in accordance with the requirements of WEI SP Figure 6A and 6B. SAFETY Operational Considerations The installation of steel pressure containing sleeves and hot tap fittings involve the deposition of weld metal directly on the carrier pipe. The installation of such fittings requires that welding be undertaken in such a manner that the possibility of burning through or cracking is eliminated. This may entail a reduction of flow rates (to prevent weld cracking), or a reduction in pressure (to prevent an unsafe condition in the event of burn-through). Care must be taken to ensure that the required flow rate restriction or pressure reduction has been effected prior to the start of the hot tap installation. Flow rate guidelines are presented in section Installation Requirements of this reference, and pressure reduction requirements are presented in the Section 12 Reference 07 - Safe Working Pressure. Orientation and Hazard Identification Once the hot tap site has been identified, the pipeline shall be located and staked by M&NP s Operations group. The Construction group will provide access with support from the Lands group as required. The Construction group shall also ensure that prior to the commencement of site work, the prime contractor conducts an initial, site-specific hazard assessment and continues to do so on a daily basis. All personnel involved in the site work must attend a general orientation that, as a minimum, includes delivery of both the M&NP and contractor s safety programs. All personnel working on site shall also be made aware of planned activities and site hazards on a daily basis. Excavation Excavation of the site shall be shall be undertaken in accordance with the requirements of the M&NP Pipeline Construction Specifications. The site of the excavation shall be away from bends and girth welds. Prior to mechanically excavating the operating pipeline, its location shall be physically confirmed by hand excavation, hydrovac or other approved method that will not mechanically damage the pipe. Mechanical excavation shall not be conducted within 5 meters of the pipeline until it can be seen. During mechanical excavation, both the top and side(s) of the pipeline shall remain in sight at all times. When mechanically excavating within 5 meters of an in-service pipeline, a signal person, who must maintain site of the part of the pipe closest to the excavator Page 1 of 14

2 bucket, shall direct the excavator operator. The excavator shall be operated so that the bucket moves away from the pipe when material is being removed. Ditches intended for entry by personnel shall conform with proper excavating requirements. GENERAL GUIDELINES The ditch shall be 10 meters long and shall have a minimum distance between the ditch wall and the pipe of 1 m. Steps shall be excavated at either end of the ditch to facilitate entry and egress. The ditch bottom shall be flat and horizontal with the bottom of the pipe, except that a bell-hole 2.5 m long and 0.6 m below the bottom of the pipe shall be excavated in the vicinity of the hot tap. If the excavation is in wet or muddy soil, the bell-hole in the vicinity of the hot tap shall be lined with a level platform so that the top of the platform is 0.6 m below the bottom of the pipe. Figure 1 shows the required ditch dimensions. If necessary, a wind/rain/snow shelter shall be erected over the site of the hot tap and shall remain in place if required until branch welding is complete. 1m Steps 1m Steps 10m Figure 1 Ditch Preparation Page 2 of 14

3 JOB PLANNING M&NP Responsibilities The division having responsibilities within M&NP shall consist of: 1. M&NP Design Engineering Group Identify the hot tap location, obtain and provide material parameters, including: o Pipe size, o Wall Thickness, o Grade, o Coating, o Materials Test Reports, and o Specifications for the branch connection and reinforcing sleeve 2. M&NP Construction Group Identify, qualify and retain the contractor/subcontractor that will perform the work; Ensure that regulatory agencies are made aware of the activities to be performed, provide the required information to them and obtain approvals as required; and, 3. M&NP Operations Group Ensure that all work conducted on and in the immediate vicinity of the operating facilities is safe and does not hamper M&NP s ability to maintain continuous uninterrupted service. Perform locates and stake the locations of pipelines Provide required inspection on the work to be performed to ensure it is carried out in accordance with all federal and provincial regulations, corporate policies and commitments; Ensure the work and inspection activities are appropriately documented; Ensure that access to the work site is provided. Site Organization A Contractor s Representative and an M&NP Operations Representative shall be appointed prior to the start of construction. The Contractor s Representative shall be responsible for ensuring that all equipment and material required for the job is available and in good working order. The Contractor s Representative shall also be responsible for organizing the crew(s) and scheduling the day s activities with the M&NP Operating Representative and Gas Control. As an aid to site planning, suggested lists of equipment and personnel are provided in Tables 1 and 2. Table 1 Typical Minimum Personnel Requirements Number of Type of Personnel Personnel 2 Welders 2 Welders Helpers 1 NDT Technician 2 Pipe Fitters 1 Crane or Picker Truck Operator 2 Labourers Page 3 of 14

4 Hot Tap Manual Table 2 Typical Minimum Equipment Requirements Number of Type of Equipment Units 1 Crane or Picker Truck 2 Welding Machines 1 NDT Unit 2 Oxy-acetylene sets 2 Spare acetylene bottles 1 Nitrogen bottle 4 Fire extinguishers 2 Hydraulic jacks 2 10 m length of chain 2 Power grinders 2 Power brushes 1 Pyrometer 1 Electrode hot box The Contractor shall prepare a Hot Tap Manual to ensure that the hot tap is performed in strict adherence with this section, M&NP Operation & Maintenance Specifications Manual, as well as the Contractor s Specifications. The purpose of the Hot Tap Manual is to collect all the above specifications and practices into one document. As a minimum, the Hot Tap Manual shall contain the following documents: M&NP Practice Installation of Hot Tap Connections (this document); Welding Procedure Specification; Welding Procedure Qualification Report; Contractor s Relevant Safety Procedures; Regulatory Permits (if any); Contractor s Tapping Procedure (in conformance with the Tapping Machine Manufacturer s Recommendations); Pipeline Technical Data and Maps (location, pipe diameter, pipe grade, pipe wall thickness, operating pressure, flow rate, coating type, mill test reports); and, Key Personnel Contact Information Scheduling of the hot tap installation shall be coordinated between the Contractor s Representative and the M&NP Company Representative along with M&NP s Gas Control Department. Page 4 of 14

5 SITE PREPARATION Pipe Preparation The coating shall be removed to allow for the necessary NDE work to be carried out, and proper fit-up of the fittings. After removal of the coating, the pipe surface shall be inspected to locate the seam weld. It is not permissible to weld a branch stub over an ERW seam. It is only permissible to weld a branch stub over a double submerged arc welded seam if the seam is positioned as indicated in Figure 2. Hot Tap Cutter A Longitudinal Seam 1/2 A 1/2 A Unacceptable Long Seam Location Acceptable Long Seam Location Figure 2 Acceptable Seam Orientation For Tapping Into DSAW Pipelines Page 5 of 14

6 The area on the mainline upon which the welding shall be performed during the installation of the hot tap shall be ultrasonically examined to determine the wall thickness and the presence of laminations that would preclude hot tapping in that location. Ultrasonic inspection shall be undertaken in accordance with the requirements of O&MSM Section 09 Reference 07 - Ultrasonic Measurement Testers T-MIKE-E. Pipe seam welds shall be radio graphed in accordance with the requirements of M&NP s Pipeline Construction Specifications. Where the pipeline upon which the hot tap weld is to be completed contains laminations, unacceptable pipe seam defects, or pipe body defects, an alternate location shall be chosen. Non-destructive examination shall be continued until a sound site has been located for the hot tap. Determination of Carbon Equivalent The carbon equivalent of the pipeline being welded shall be determined. Where the pipe can be correlated to a mill test report by means of pipe location records, the carbon equivalent shall be determined by referring to the appropriate mill test record. Otherwise, pipe filings shall be obtained for analysis. Carbon equivalence shall be determined in accordance with the requirements of O&MSM Section 12 Reference 06 - Detection of Carbon Equivalency. The approved Welding Procedure shall be referenced to determine whether the carbon equivalent of the pipe is within the qualified range and to determine whether any flow reduction is necessary during in-service welding, given the carbon equivalent of the mainline pipe. If the carbon equivalent is outside the range qualified in the approved hot tap welding procedure, or if the required flow reduction cannot be achieved, then another pipe joint shall be selected. Pipe Seam Preparation After all nondestructive inspection and carbon equivalent testing has been conducted and the candidate pipe accepted, any weld reinforcement associated with the presence of a double submerged arc pipe seam shall be ground flush with the base metal throughout the length of the hot tap fitting. INSTALLATION REQUIREMENTS Welding Procedure Qualification and Limitations Welding procedures to be used for welding on live lines shall be qualified in accordance with the requirements of CSA Z662. The cooling rate at which the welding procedure was qualified must be equal to or more severe than the cooling rate experienced on the pipeline to be welded. In general, this will be the case for any flowing gas condition provided that the welding procedure was qualified while water was flowing through the qualification pipe. In order to confirm that this is the case, the heat sink capacity of the pipeline to be welded can be compared against the heat sink capacity that was recorded during the qualification of the welding procedure. 1 Heat Sink Capacity Test Method The cooling rate experienced during the qualification of a welding procedure must be greater than the cooling rate of an operating pipeline if that welding procedure is to be used to weld onto that particular pipeline while it is 1 Development of Simplified Cooling Rate Models For In-Service Gas Pipelines Pipeline Research Committee International Project , Cola, M.J., Keifner, J.F., Fischer, R.D., Bubanek, T.A., Jones, D.J., and Bruce, W.A., July, Page 6 of 14

7 operating. In order for this to be the case, the average T , as defined in the step-by-step procedure (below) must be greater for the operating pipeline than in the test pipe that was used to qualify the welding procedure. The Heat Sink Capacity Test Method is described below. The equipment necessary to carry out this test is as follows: Chalk or soap stone; Acetylene Torch (with rosebud tip); Digital Contact Thermometer/Temp Sticks; Stopwatch The procedure for determining the heat sink capacity is as follows: 1. Determine the direction of flow for the contents of the pipeline. 2. Using chalk or soapstone, scribe three 50 mm diameter circles approximately 30 cm apart on both sides of the pipe. 3. Starting with the downstream circle, use the acetylene torch and quickly heat the entire region within the circle to 300 o C using a circular motion. The maximum temperature should not exceed 325 o C. 4. After attaining a temperature of between 300 o C and 325 o C, remove the acetylene torch and apply the contact thermometer to the center of the circle. 5. While holding the thermometer in contact with the pipe, measure with the stopwatch the time required for the temperature to fall from 250 o C to 100 o C. This is the T time for that particular spot. 6. Repeat steps 3, 4, and 5 on the next untested upstream circle on the opposite side of the pipe. If the pipe is still warm, wait until the pipe returns to its normal operating temperature. 7. Once all the measurements are complete, determine the average T time from all the recorded readings. Welder Qualification Welders shall be qualified in accordance with the requirements of CSA Z662. Welding Consumables The use of low hydrogen welding consumables is mandatory for all passes of all welds that are conducted on inservice pipelines. Once removed from their hermetically sealed packages, all low-hydrogen electrodes must be held at a temperature of 100 o C to 150 o C until they are used. If any low-hydrogen electrode is removed from its holding oven for a period of more than four hours, it shall be re-baked at 350 o C to 425 o C. Welded Installation Requirements Installation of Reinforcing Ring When the outside diameter of the branch pipe is equal to or greater than ½ the outside diameter of the mainline pipe, a reinforcing ring should be welded to the mainline pipe. This will prevent excessive deformation from occurring in the coupon during the cutting process, and will facilitate the retrieval of the coupon. The reinforcing ring should be no longer than 50 mm, and shall be made of pipe whose outside diameter is the next nominal pipe diameter smaller than the inside diameter of the cutter. The reinforcing ring shall be centered on the pilot guide, and welded in place utilizing the approved in-service welding procedure. Page 7 of 14

8 Preparation of Branch Stub The branch stub shall be pre-tested in accordance with the requirements of CSA Z662 Clause 8, and then contoured to fit the mainline pipe utilizing one of the following methods: By hand; By using templates; or, Machine cut on a profiler Regardless of what method is used to contour the branch stub, measurements must be taken to ensure that the branch is contoured to fit square and center to the mainline, and once square and center, the branch must be level on the face. Prior to the squaring of the branch stub, the pipe longitudinal seam shall be radiographed in accordance with the requirements of M&NP s Pipeline Construction Specifications, and if it passes the examination, any weld reinforcement shall then be ground flush with the base metal. The Branch must be perfectly centered on the mainline, at exactly right-angles to the mainline, and perfectly level coming off the mainline. The method to be used for lining up the branch is outlined in Figure 3. After the branch has been fitted to the mainline pipe, spacer tabs shall be welded to the contoured (i.e., fishmouth ) end of the branch and the mainline pipe. Welding is necessary, since the spacer tabs may fall out during preheating, resulting in misalignment of the branch. The spacer tabs shall all have thicknesses that are equal to the root opening specified in the approved welding procedure, and shall be placed at the 12:00, 3:00, 6:00, and 9:00 positions. Once this is complete, the squareness of the branch shall once again be checked in accordance with the requirements of Figure 3 before the branch can be considered to be ready for welding, in accordance with the requirements of the Welding Consumables section. If misalignment occurs during preheating, it may be necessary to secure the branch to the mainline pipe by means of a chain and hydraulic jack once the branch has been squared. Page 8 of 14

9 #4: Equal Distances B2 Branch Line-Up Procedure A1 B1 A2 1. Level on side of Branch Pipe 2. Level on Face of Branch Pipe 3. Branch Pipe Square to Run Pipe 4. Distances to Center Pin A1 and A2 Equal: B1 and B2 Equal Top view #2: Level #1: Level C L #3: Branch Square to Mainline Cross-sectional sideview Projected sideview Figure 3 Branch Line-Up Procedure Page 9 of 14

10 Welding of Branch Welding of the branch shall be completed in accordance with the requirements of the approved in-service welding procedure qualified in accordance with the requirements of the Welding Procedure Qualifications and Limitations section. If gas flow rate modifications are required to ensure that the heat sink capacity of the mainline is below that which occurred during the qualification of the approved in-service welding procedure, arrangements should be made with Gas Control to reduce the flow rate to an acceptable value prior to commencement of welding. Preheat shall be checked before each arc is struck. After the branch is in position, four substantial tacks, placed in pairs at opposite sides of the pipe, and separated from one another by 90 o are required to hold the branch in position. To minimize distortion and possible misalignment, it is important that the welder complete the weld in such a manner that they are always welding opposite quadrants. The welding sequence shall be in accordance with the requirements of Figure 4. During welding, it is critical that the same amount of filler metal is applied in all four positions indicated in Figure 4 at any given point in time. To further assist in minimizing distortion, it is recommended that an internal clamp should be placed inside the branch until welding is complete. Once welding has been competed, the area inside the branch must be clear of all foreign material (slag, sand, etc.) to prevent damage to the cutter. Page 10 of 14

11 12 O clock Hot Tap Branch 9 O clock 3 O clock 6 O clock Figure 4 Hot Tap Branch Installation Welding Sequence Page 11 of 14

12 Installation of Reinforcing Sleeve The following procedure shall be used when installing reinforcing sleeves: 1. The portion of the pipeline on which the split sleeve is to be installed, including the branch weld area shall be coated with an approved coating system. The area of the branch where the sleeve-to-branch weld will be completed should be cleaned, but not coated. 2. The open neck section of the sleeve shall be installed first, and then the back of the sleeve shall be installed. The two halves shall be brought together as tightly as possible using chains and hydraulic jacks. The gap between the two halves of the sleeves shall be adjusted so that it is even along its length on each side of the sleeve. Also, the gap between the outlet of the sleeve and the branch shall be evenly spaced around the circumference of the branch. 3. The two halves of the sleeve shall be welded together using an approved welding procedure. Welding of the two halves shall be accomplished with either a backing bar or by means of lap bars to prevent the root bead from damaging the pipe. To minimize distortion, each welding pass shall be deposited in accordance with the sequence shown in Figure The outlet of the split sleeve shall be fillet welded to the branch pipe once the longitudinal welds have been cooled. Page 12 of 14

13 Mainline Pipe Spli Sleev Sequence 2 Sequence 2 Sequence 4 Sequence 4 Sequence 5 Branc Pip Sequence 5 Sequence 3 Sequence 3 Sequence 1 Sequence 1 Plan View Progression of Welding Passes Welding shall be completed by depositing one pass at a time, starting at t location, and then progressing to the Sequence 2, Sequence 3, Sequence 4 and Sequence 5 locations before beginning the next pass. pass. Figure 5 Sequence for Welding Longitudinal Seams of Split Sleeve Reinforcing Tee Page 13 of 14

14 Nondestructive Testing Requirements Qualification of NDT Technicians Nondestructive inspection of welds shall be performed by personnel who: a) Are qualified to at least Level II of CGSB Standard CAN/CGSB in the applicable inspection method; and, b) Have demonstrated their ability to interpret indications correctly in accordance with the guidelines of Canadian Association of Petroleum Producers Recommended Practice for Qualification of Technicians for Nondestructive Examination of Pipeline Full Encirclement Fitting Fillet Welds to Identify Cracks. Preliminary MPI Inspection Nondestructive testing of the branch-to-carrier pipe weld and the sleeve outlet-to-branch pipe weld shall not commence until a period of 48 hours has elapsed since the completion of the weld. Once this period of time has elapsed, the entire circumference of the weld shall be inspected using magnetic particle inspection, using wet fluorescent techniques in accordance with the requirements of ASME Boiler and Pressure Vessel Code, Section V, Article 7. Ultrasonic Inspection Ultrasonic inspection shall be conducted on the entire circumference of the branch-to-mainline weld in accordance with the requirements of ASME Boiler and Pressure Vessel Code Section V Article 5. The weld shall be inspected from both the branch and mainline sides, utilizing a minimum of two shear wave probes, having angles of 45 and 70 degrees, and having probe frequencies of 2 MHz. PRESSURE TESTING Once nondestructive inspection has been completed in accordance with the requirements of the Nondestructive Testing Requirements section, and prior to starting the hot tap, the tapping machine, fittings, and hot tap valve shall be leak tested using nitrogen. The leak test shall be conducted with the boring bar extended and the pilot touching the pipe. During the leak test, nitrogen shall be injected through the purge valve on the tapping machine, which pressurizes the branch fitting, hot tap valve, and tapping machine adaptor. Unless a detailed engineering assessment indicates otherwise, the test pressure shall not exceed 60 percent of the operating pressure in the line at the moment of test. After pressurizing, all mechanical and welded joints shall be tested for soundness by means of a soap test. The tapping may not proceed unless the assembly is leak-free. TAPPING PROCEDURE Hot tapping shall be undertaken in accordance with the Contractor s approved procedure, and in accordance with the hot tap equipment manufacturer s recommended practice. Prior to undertaking the tapping procedure, the tapping equipment shall be checked to ensure that it is in good working order. Consideration shall be given to completing the tapping operation while the branch area is pressurized with nitrogen to a pressure equal to the current operating pressure of the pipeline. This will reduce or eliminate any pressure differential across the pipeline wall while the cutting operation is being conducted. Page 14 of 14