SPECIFICATION FOR SACRIFICIAL BRACELET ANODE MATERIAL

Transcription

1 SPECIFICATION FOR SACRIFICIAL BRACELET ANODE MATERIAL Specification for Sacrificial Bracelet Anode Materials.doc 3 of 8

2 TABLE OF CONTENTS 1.0 SCOPE REFERENCE DOCUMENTS MATERIALS DESIGN REQUIREMENTS FABRICATION INSPECTION AND TESTING STORAGE, HANDLING AND SHIPPING PERFORMANCE OF WORK...8 Specification for Sacrificial Bracelet Anode Materials.doc 4 of 8

3 1.0 SCOPE This specification shall govern the design requirements, material selection, inspection, and other requirements for use in the fabrication of bracelet type aluminum anodes which are to be used for the cathodic protection of offshore pipelines. The work includes the furnishing of all labor, materials, tools and equipment and the performance of all operations and incidentals necessary for the fabrication, handling, storing and shipping of the cathodic protection anodes. Furthermore, the work shall meet any additional requirements stated elsewhere in the CONTRACT. As used in this specification, the following definitions shall apply: COMPANY: CONTRACTOR: The firm responsible by contract for the supply/manufacture of the anodes CONTRACT: Signed work agreement between COMPANY and CONTRACTOR. CONTRACTOR shall obtain COMPANY's written approval for any deviations from the requirements of this specification or specifications, standards and drawings referenced herein or elsewhere in the CONTRACT. In case of conflict between documents, the order of precedence given in the CONTRACT shall govern. This document is not intended to be all inclusive, and the use of the requirements set forth does not relieve the CONTRACTOR of his responsibility to supply a product capable of performing its intended service. 2.0 REFERENCE DOCUMENTS 2.1 Codes and Standards The anodes shall be manufactured in accordance with the latest editions and addenda of the following codes and standards. Steel Structures Painting Council SSPC SP 10 Near White Blast Cleaning American Society of Testing and Materials ASTM A36Specification for Structural Steel Specification for Sacrificial Bracelet Anode Materials.doc 5 of 8

4 2.2 Project Drawings DRWG # Anode Drawing D e t a il s 3.0 MATERIALS The CONTRACTOR shall supply all anode materials required by this specification. 3.1 Alloys The aluminum alloy bracelets shall be manufactured of an aluminumzinc indium alloy such as Galvalum III or COMPANY approved equivalent. 3.2 Steel Core All steel used for the anode steel core shall be ASTM A36 plate. 4.0 DESIGN REQUIREMENTS Anodes are based on the following design considerations, and are presented for CONTRACTOR information: (i) Service Life, years 20 * (ii) Current Density, ma/sq. ft. (unburied) 5 * (iii) Current Density, ma/sq. ft. (buried) 2 (iv) Exposed Bare Metal, % 10 (v) Seawater Resistivity, ohm cm 30 (vi) Soil Resistivity, ohm cm 100 (vii) Seawater Temperature, F 46 (viii) Pipeline Temperature, F 70 * (ix) Anode Output, amp hr./lb. (unburied) 900 * (x) Anode Output, amp hr./lb. (buried) 800 (xi) Utilization Factor 0.90 * (xii) Anode Potential, Volts (Ag/AgCl) 1.08 (xiii) Pipeline Protective Potential, (Ag/AgCl) 0.90 * Based on 70 F operating temperature. Any material not meeting these minimum requirements is not acceptable. Specification for Sacrificial Bracelet Anode Materials.doc 4 of 8

5 5.0 FABRICATION Anodes shall be sized and fabricated in accordance with Project Drawings. 5.1 Anode Types The bracelet anodes shall be of the segmented type. 5.2 Dimensional Characteristics The aluminum anode bracelets shall be internally sized to fit the outside diameter of the pipe plus its corrosion coating system. For pipe which is concrete weight coated, the bracelets shall be sized such that the outside diameter of the anode is the same as the outside diameter of the concrete weight coating. The minimum anode thickness, however, shall be 1½ inches. If the pipe is not concrete weight coated, the anode thickness shall be 1½ inches with a 2:1 taper slope on the anode ends. The anodes shall be of sufficient length to provide the required net weight of the anode material. 5.3 Anode Core The steel core shall be cleaned to a "Near White" finish in accordance with SSPC SP10 at the time of casting. 5.4 Coatings Each anode assembly shall be coated on the inside surface and on the edges with coal tar epoxy. Minimum coating thickness shall be 12 mils. 5.5 Anode Identification All anodes will have their heat number and alloy identification placed such that they are clearly visible. If more than one anode is produced from a heat, the casting sequence number shall also be stamped on the anode. 6.0 INSPECTION AND TESTING 6.1 COMPANY Access for Inspection COMPANY representative(s) shall be given ready access to inspect the CONTRACTOR's quality control procedures, methods and results of the anode materials, equipment, and the CONTRACTOR's work. All stages of the work shall be subject to full time inspection by the COMPANY. Such inspection shall not relieve the CONTRACTOR of his responsibility to provide materials and workmanship to this specification. Specification for Sacrificial Bracelet Anode Materials.doc 5 of 8

6 6.2 Visual Inspection All anodes shall be subject to visual inspection before accepting them. Anode surfaces shall be free from dirt or any foreign materials. 6.3 Radiographic Inspection CONTRACTOR shall carryout 100% radiographic examination on the first five anodes of each size in order to establish the adherence between the steel core and the body of the anode. CONTRACTOR shall submit proof of the examination for COMPANY review and approval. 6.4 Anode to Core Resistance Anode to steel core resistance shall be measured to confirm electrical continuity. 6.5 Anode Potential A performance test shall be carried out to confirm that the closed circuit potential is achieved at the design temperature. A potential measurement for each batch of anodes is to be carried out at the pipeline temperature given in Section 4.0 with reference to a Ag/AgCl electrode. 6.6 Alloy Composition Quality control samples shall be taken at the start and finish of each melt which produces more than four bracelets. Otherwise, one sample shall be taken for each melt. 6.7 Rejection of Anodes COMPANY shall have the right to reject any anodes that do not meet the requirements of this specification, included but not limited to the following and associated referenced material. Rejected anodes shall be replaced by the CONTRACTOR without expense to the COMPANY. Anodes shall be rejected under the following conditions: (i) The net weight of one half of the bracelet is less than or exceeds five percent of half of the specified net weight of the bracelet. The net weight of the bracelet shall be defined as the weight of anode alloy material. (ii) The diameter tolerances of the anode bracelet exceed: External diameter, inches Internal diameter, inches (iii) An anode has face cracks (internal Specification for Sacrificial Bracelet Anode Materials.doc 6 of 8

7 or external) where the length of the crack exceeds 4 inches and the crack depth exceeds 0.2 inches. (iv) An anode has a face crack frequency exceeding 3 per anode segment or if any two cracks are separated by less than 8 inches. (v) Judgement of the COMPANY that the cracks in the internal face are detrimental to the integrity of the anode. (vi) The depth of shrinkage cavities exceed 10 percent of the anode thickness. (vii) Inclusions of slag or casting are apparent in an anode. (viii) Mechanical repairs of partial fusion. 6.8 Mill Certificate Mill certificates shall be provided by the CONTRACTOR on each melt of alloy used in the manufacture of the bracelets. These certificates shall indicate: (vii) (viii) (xi) Performance test data Net and gross weight of each anode Dimensions of each anode (length, ID and OD) 7.0 STORAGE, HANDLING AND SHIPPING CONTRACTOR shall pack and ship the anode bracelets to the COMPANY's designated delivery point as per instructions on the CONTRACT. Shipping and handling shall be in accordance with acceptable industrial practice. All anode bracelets damaged during shipment or handling shall be replaced by CONTRACTOR at no cost to COMPANY. Anodes shall be stored above ground and shall be electrically isolated from the earth, steel structures and any other object that could sacrifice the anode. (i) Manufacturer (ii) Heat number (iii) Anode Specification (iv) Metallurgical composition of the alloy (v) Method of analysis for the metallurgical composition of alloy (vi) Electromechanical properties of the alloy Specification for Sacrificial Bracelet Anode Materials.doc 7 of 8

8 8.0 PERFORMANCE OF WORK CONTRACTOR shall guarantee that work performed when fabricating the anodes shall be in accordance with this specification. The COMPANY's representative shall have proper access rights to CONTRACTOR's plant and property to assure the COMPANY that the foregoing specifications are being followed. Specification for Sacrificial Bracelet Anode Materials.doc 8 of 8