GB/T 21447-2018 PDF English (GB/T 21447-2008: Older version)

GB/T21447-2018 (GBT21447-2018): PDF in English

GB/T 21447-2018 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 75.200 E 98 Replacing GB/T 21447-2008 Specifications for steel pipeline external corrosion control ISSUED ON. FEBRUARY 6, 2018 IMPLEMENTED ON. SEPTEMBER 1, 2018 Issued by. General Administration of Quality Supervision, Inspection and Quarantine of the PRC; Standardization Administration of the PRC. Table of Contents Foreword ... 3  1 Scope ... 5  2 Normative references ... 5  3 Terms and definitions ... 6  4 Basic provisions ... 8  5 Anticorrosion coating design ... 10  6 Cathodic protection design ... 13  7 Interference mitigation ... 18  8 Construction and acceptance ... 23  9 Operation and maintenance management ... 27  10 Corrosion control records ... 32  Foreword This Standard is drafted in accordance with the rules given in GB/T 1.1-2009. This Standard replaces GB/T 21447-2008 “Specification for external corrosion control for steel pipeline”. As compared with GB/T 21447-2008, in addition to editorial modifications, the main technical changes are as follows. - MODIFY the scope of application of this Standard (SEE Chapter 1); - ADD 5 terms (SEE 3.1, 3.5, 3.11, 3.12, and 3.13); - REVISE and ADD environmental corrosivity determination methods and grading assessment index (SEE 4.3); - REVISE the general provisions on the design of anticorrosion coatings, and ADD the provisions on overland buried and underwater pipeline anticorrosion coatings, overland above-ground pipeline anticorrosion coatings, and on subsea pipeline anticorrosion coatings (SEE 5.1, 5.2, 5.3, and 5.4); - REVISE the criteria for cathodic protection of overland pipelines, and ADD the cathodic protection content of subsea pipelines (SEE 6.1.2, 6.2); - ADD general provisions on interference control, and REVISE the judgment index for AC and DC interference and the assessment index for mitigation effect (SEE 7.1, 7.2.1, 7.3.1); - REVISE construction and acceptance content (SEE Chapter 8); - ADJUST operation and maintenance management content; and ADD inspection and assessment related content (SEE Chapter 9). This Standard was proposed by and shall be under the jurisdiction of National Technical Committee 355 on Oil and Gas of Standardization Administration of China (SAC/TC 355). Drafting organizations of this Standard. Daqing Oilfield Engineering Co., Ltd., China Petroleum Planning & Engineering Institute, China Petroleum Pipeline Engineering Corporation, CNOOC Research Institute, CNPC Engineering Technology R&D Company Limited, Southwest Branch of CNPC Engineering Design Co., Ltd., PetroChina Natural Gas Pipeline Branch, Institute of Safety, Environment Protection and Technical Supervision of PetroChina Southwest Oil and Gasfield Company. Main drafters of this Standard. Yang Chunming, Zhang Kun, Liu Fang, Huang Specifications for steel pipeline external corrosion control 1 Scope This Standard specifies the minimum requirements for the design, construction, and management, etc. of steel pipeline (hereinafter known as pipeline for short) external corrosion control engineering, including basic provisions, anticorrosion coating design, cathodic protection design, interference mitigation, construction and acceptance, operation and maintenance management, and other contents. This Standard is applicable to the external corrosion control of oil, gas, and water pipelines, which are newly-built, expanded, and re-built overland and subsea, with conveying medium temperature of less than 100 °C. 2 Normative references The following documents are indispensable for the application of this document. For the dated references, only the versions with the dates indicated are applicable to this document. For the undated references, the latest version (including all the amendments) are applicable to this document. GB/T 8923.1 Preparation of steel substrates before application of paints and related products - Visual assessment of surface cleanliness - Part 1. Rust grades and preparation grades of uncoated steel substrates and of steel substrates after overall removal of previous GB/T 19292.1 Corrosion of metals and alloys - Corrosivity of atmospheres - Part 1. Classification GB/T 21246 Measurement method for cathodic protection parameters of buried steel pipelines GB/T 21448 Specification of cathodic protection for underground steel pipelines GB/T 23257 Polyethylene coating for buried steel pipeline GB 32167 Oil and gas pipeline integrity management specification GB/T 50538 Technical standard for anti-corrosion and insulation coating of buried steel pipeline GB/T 50698 Standard for AC interference mitigation of buried steel pipelines GB 50991 Technical standard for DC interference mitigation of buried steel pipeline GB/T 51172 Inspection code for in-service oil & gas pipeline GB/T 35988 Cathodic protection of offshore pipeline in petroleum, natural gas industries SY/T 0029 Specification of application for underground steel coupons SY/T 0087.1 Standard of steel pipeline and tank corrosion assessment - Steel pipeline external corrosion direct assessment SY/T 0315 Technological specification of external fusion bonded epoxy coating for steel pipeline SY/T 0407 Specification of Steel Surface Preparation Before Application of Paint SY/T 0414 Specification of polyolefin tape coating for steel pipeline SY/T 0447 Standard of coal tar epoxy coating for buried steel pipeline SY/T 5918 Technical specification for thermal insulation repair of buried steel pipeline exterior coating SY/T 6854 Technical standard of liquid epoxy external coating for buried steel pipeline SY/T 6878 Cathodic protection of submarine pipelines by galvanic anodes SY/T 6964 Specification of cathodic protection for petroleum and gas station SY/T 7036 Specification of external coating for piping and equipment in petroleum and gas stations SY/T 7041 Specification of polypropylene coating for steel pipeline SY/T 7347 Standard of coating and insulation for aboveground oil and gas pipelines 3 Terms and definitions The following terms and definitions apply to this document. 3.11 Direct assessment; DA An integrity assessment method which uses a structured process. That is, by integrating the physical characteristics of pipeline, the operational record of the system, or the test, inspection, and assessment results, and other information of pipeline, a predictive conclusion of pipeline integrity assessment is given. 3.12 Fault The mechanical damage, uncoated dot on the anticorrosion coating and other defects of anticorrosion coating. 3.13 Subsea pipeline INCLUDE risers and pipelines below the water level at the highest tidal level. 4 Basic provisions 4.1 It shall, according to factors such as the expected service life of pipeline, engineering safety requirements, and economy, carry out pipeline external corrosion control. a) Newly-built pipeline. External anticorrosion coating (hereinafter known as anticorrosion coating) or anticorrosion coating combined with cathodic protection shall be used. If the investigation indicates that corrosion control is not required, it may not be used. b) Buried or underwater pipelines which have been built with anticorrosion coating and no cathodic protection. If the investigation indicates that corrosion control needs to be strengthened, cathodic protection shall be added. c) Pipelines which have been built without external corrosion control. Corrosion conditions of the pipeline system shall be detected and evaluated. The corrosion control measures taken, based on the assessment results, shall be determined. 4.2 The selection of corrosion control method shall consider the following factors. a) Environmental corrosivity; b) Pipeline characteristics; c) Operating conditions; anticorrosion coating, in addition to the factors of 5.1.2, the following factors shall also be considered. a) Compatibility with cathodic protection; b) Soil stress, including the stress caused by thermal-cold cycling; c) Resistance to mechanical damage in rocky area, trenchless crossing construction, or under the influence of other external forces; d) Resistance to impact damage; e) The effects of the interface between the atmosphere and the soil; f) Matching with the weight coating of pipeline. 5.2 Anticorrosion coating of buried and underwater pipelines 5.2.1 The anticorrosion coating of buried and underwater pipelines shall have good resistance to soil stress in addition to the basic properties specified in 5.1.1; and shall be matched with cathodic protection. 5.2.2 When the pipeline is constructed in a low temperature environment, the anticorrosion coating shall also have good low-temperature construction property. 5.2.3 For rocky segment pipelines and the pipe sections where the construction process is likely to cause damage to the anticorrosion coating, it shall take protective measures. The protective measures include but are not limited to fine soil backfilling, thickening anticorrosion coating, protective layer of anticorrosion coating, etc. When choosing a protective layer, the following factors shall be considered. a) It shall match the chemical and physical properties of the pipeline anticorrosion coating; b) The protective layer shall not adversely affect the effectiveness of cathodic protection. 5.2.4 For buried and underwater pipeline anticorrosion coating, when selecting the following external anticorrosion coatings of pipeline, the following standards shall be implemented. a) The extruded polyethylene anticorrosion coating shall comply with the provisions of GB/T 23257; b) The extruded polypropylene anticorrosion coating shall comply with the 6 Cathodic protection design 6.1 Overland pipeline 6.1.1 General provisions 6.1.1.1 Cathodic protection shall be adopted for buried oil and gas long- distance pipelines, oil and gas field outward-transmi.......
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