Canadian Gas Association Recommended Practice OCC–1–2013 Control of External Corrosion on Buried or Submerged Metallic Piping Systems Distributed by Canadian Gas Association OCC-1 Task Force JUNE 2013 This “Recommended Practice” applies to the control of external corrosion on buried or submerged metallic piping systems. This Recommended Practice is intended as a reference only. It is a company’s own responsibility to produce procedures that will satisfy all regulations and their own requirements for effective, safe, and proactive corrosion control. This Recommended Practice should be adapted to each user’s requirements. The CGA does not assume any liability for the application or suitability of the Recommended Practice. Responsibility and liability for the use and interpretation of this Recommended Practice rests with each user. The Canadian Gas Association, its members, respective employees, and contractors disclaim any liability for any damages, costs, or actions which may result, either directly or indirectly, in any way, from the use of these Recommended Practices, and specifically states that the reader makes use of these materials at his, her, or its own risk. OCC-1-2013 supersedes OCC-1-2005. i | Page Canadian Gas Association OCC-1 Task Force Brad Jefferies Enbridge Gas Distribution, Chairperson Chad Khattar TransCanada Clay Smith Pacific Northern Gas Ltd. David McConkey Canadian Gas Association Fernando Velandia Manitoba Hydro Jim Phillipchuk ATCO Gas Mike Novakowicz AltaGas Utilities Inc. Rob Wakelin Gull River Engineering Inc. Scott Bowing Fortis BC Scott Walker Union Gas Stéphanie Dontigny Gaz Metro ii | Page CONTENTS SECTION 1: GENERAL ............................................................................................................................... 1 1.1 Introduction ............................................................................................................................... 1 1.1.1 Scope of the Recommended Practice .......................................................................... 1 1.1.2 Application of Corrosion Control .................................................................................. 2 1.1.3 Deviation from Recommended Practice ...................................................................... 2 1.2 External Corrosion Control Practices......................................................................................... 2 1.2.1 New Piping Systems ..................................................................................................... 2 1.2.2 Existing Coated Piping Systems .................................................................................... 3 1.2.3 Existing Bare Piping Systems ........................................................................................ 3 SECTION 2: DESIGN OF CORROSION CONTROL SYSTEMS ...................................................................... 4 2.1 Introduction ............................................................................................................................... 4 2.2 Coatings ..................................................................................................................................... 4 2.2.1 General ......................................................................................................................... 4 2.2.2 Selection and Evaluation .............................................................................................. 4 2.3 Cathodic Protection ................................................................................................................... 5 2.3.1 General ......................................................................................................................... 5 2.3.2 Cathodic Protection Design Requirements .................................................................. 6 2.3.3 Selection of Cathodic Protection Systems.................................................................... 6 2.3.3.1 Galvanic Anode Systems .............................................................................. 7 2.3.3.1.1 General Description ................................................................... 7 2.3.3.1.2 Galvanic Anodes ......................................................................... 7 2.3.3.2 Impressed Current Systems ......................................................................... 8 2.3.3.2.1 General ....................................................................................... 8 2.3.3.2.2 Direct Current Sources ............................................................... 8 2.3.3.2.3 Impressed Current Anodes ........................................................ 9 2.3.3.3 Electrical Isolation ........................................................................................ 9 2.3.3.3.1 Separation from Foreign Structures......................................... 10 2.3.3.3.2 Within a Piping System ............................................................ 10 iii | Page 2.3.3.3.3 Casings...................................................................................... 11 2.3.3.3.4 Safety Practices ........................................................................ 12 2.3.3.3.5 Coordination of Cathodic Protection Design and Electrical Grounding Design ....................................................................................... 12 2.3.3.3.6 Coordination of Cathodic Protection Design and Electrical Utility Design .............................................................................................. 12 2.3.3.3.7 Structural Supports and Pilings ................................................ 13 2.3.3.4 Auxiliary Facilities ....................................................................................... 13 2.3.3.4.1 Test Stations ............................................................................. 13 2.3.3.4.2 Wires and Cables ...................................................................... 14 2.4 Other Considerations .............................................................................................................. 16 2.4.1 In-Line Inspection ....................................................................................................... 16 2.4.2 Alternating Current Corrosion .................................................................................... 16 SECTION 3: INSTALLATION OF CORROSION CONTROL SYSTEMS ......................................................... 17 3.1 Introduction ............................................................................................................................. 17 3.2 Installation and Inspection of Coating Systems ...................................................................... 17 3.2.1 Application ................................................................................................................. 17 3.2.2 Installation .................................................................................................................. 17 3.2.3 Inspection ................................................................................................................... 18 3.3 Installation and Inspection of Cathodic Protection Systems ................................................... 19 3.3.1 Introduction ................................................................................................................ 19 3.3.2 Impressed Current Systems........................................................................................ 19 3.3.2.1 Rectifiers and Power Sources ..................................................................... 19 3.3.2.2 Impressed Current Anodes ........................................................................ 20 3.3.3 Galvanic Anode Systems ............................................................................................ 21 3.3.4 Auxiliary Facilities ....................................................................................................... 21 3.3.4.1 Wires and Cables ........................................................................................ 21 3.3.4.2 Connections ............................................................................................... 22 3.3.4.3 Casings ....................................................................................................... 23 3.3.4.4 Test Stations ............................................................................................... 24 iv | Page 3.3.4.5 Bonds.......................................................................................................... 24 3.3.4.6 Below Ground Electrical Isolation .............................................................. 24 3.3.5 Inspection ................................................................................................................... 24 SECTION 4: OPERATION AND MAINTENANCE OF CORROSION CONTROL SYSTEMS ........................... 25 4.1 Introduction ............................................................................................................................. 25 4.2 Coatings ................................................................................................................................... 25 4.2.1 Visual Examination During Excavations...................................................................... 25 4.2.2 Above Ground Surveys ............................................................................................... 26 4.3 Cathodic Protection