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GB/T 21447-2018 (GBT 21447-2018)

Chinese standards (related to): 'GB/T 21447-2018'
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GB/T 21447-2018English145 Add to Cart 0-9 seconds. Auto delivery. Specifications for steel pipeline external corrosion control GB/T 21447-2018 Valid GBT 21447-2018
GB/T 21447-2008English869 Add to Cart 5 days Specification for external corrosion control for steel Pipeline GB/T 21447-2008 Obsolete GBT 21447-2008

Standard ID GB/T 21447-2018 (GB/T21447-2018)
Description (Translated English) Specifications for steel pipeline external corrosion control
Sector / Industry National Standard (Recommended)
Classification of Chinese Standard E98
Classification of International Standard 75.200
Word Count Estimation 18,132
Date of Issue 2018-02-06
Date of Implementation 2018-09-01
Drafting Organization Daqing Oilfield Engineering Co., Ltd., China Petroleum Planning Institute, China National Petroleum Pipeline Engineering Co., Ltd., CNOOC Research Institute, CNPC Engineering Technology Research Institute, CNPC Engineering Design Co., Ltd. Southwest Branch, China Petroleum Pipeline Company, PetroChina Southwest Oil and Gas Field Branch Safety and Environmental Protection and Technical Supervision Institute
Administrative Organization National Oil and Gas Standardization Technical Committee (SAC/TC 355)
Proposing organization National Oil and Gas Standardization Technical Committee (SAC / TC 355)
Issuing agency(ies) People's Republic of China General Administration of Quality Supervision, Inspection and Quarantine, China National Standardization Administration

GB/T 21447-2018: PDF in English (GBT 21447-2018)
GB/T 21447-2018
ICS 75.200
E 98
Replacing GB/T 21447-2008
Specifications for steel pipeline
external corrosion control
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 
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
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
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
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
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
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
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
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 pr......