GB/T 19285-2026 Inspection of corrosion protection for buried steel pipelines English, Anglais, Englisch, Inglés, えいご
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ICS 13.220.10
CCS H 57
National Standard of the People's Republic of China
GB/T 19285-2026
Replaces GB/T 19285-2014
Inspection of corrosion protection for buried steel pipelines
埋地钢质管道腐蚀防护工程检验
Issue date: 2026-01-28 Implementation date: 2027-02-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative References
3 Terms, Definitions, and Abbreviations
4 General Provisions
5 Inspection during Construction
6 Operational Inspection
7 Periodic Inspection
Annex A (Normative) Test Method for Soil Corrosivity
Annex B (Normative) Test Method for Corrosion Rate
Annex C (Normative) Test Method for Stray Current Interference
Annex D (Normative) Test Method for Physical Properties of External Anti-corrosion Coating
Annex E (Normative) Non-excavation Detection Method for Coating Defects
Annex F (Normative) Detection Method for Overall Condition of External Anti-corrosion Coating
Annex G (Normative) Test Method for Insulation Performance of Insulating Flanges (Joints)
Annex H (Normative) Test Method for Grounding Resistance
Annex I (Normative) Test Method for Cathodic Protection Effectiveness
Annex J (Normative) Test Method for Sacrificial Anode Parameters
Annex K (Normative) Quality Grade Evaluation Method for Corrosion Protection Systems of Buried Steel Pipelines
Annex L (Informative) Calculation Example for Quality Grade Evaluation of Corrosion Protection Systems for Buried Steel Pipelines
Inspection of Corrosion Protection Engineering for Buried Steel Pipelines
1 Scope
This document specifies the basic requirements for the inspection of the quality and effectiveness of external corrosion protection engineering for onshore buried steel pipelines.
This document applies to construction period inspection, operational inspection, and periodic inspection of external corrosion protection engineering for onshore buried steel pipelines.
2 Normative References
The following documents contain provisions which, through normative reference in this text, constitute essential provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 11032 AC Metal Oxide Surge Arresters Without Gaps
GB/T 21447 Specification for External Corrosion Control for Steel Pipelines
GB/T 30582 Risk-Based External Damage Inspection and Assessment of Buried Steel Pipelines
GB 50423 Code for Design of Oil and Gas Transmission Pipeline Crossing Engineering
GB/T 50538 Technical Standard for Anti-corrosion and Thermal Insulation Coating of Buried Steel Pipeline
GB/T 51241 Technical Code for External Anti-corrosion Field Joint Coating of Pipelines
SY/T 0029 Technical Specification for Application of Coupons for Buried Steel Pipelines
3 Terms, Definitions, and Abbreviations
3.1 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
reference electrode
An electrode having a stable and reproducible potential in moist soil, used as a reference when measuring the potential of other electrodes.
3.1.2
analytic hierarchy process (AHP)
A systematic analysis and decision-making method that decomposes a complex problem into multiple levels and factors, determines the relative importance of each factor, and constructs a hierarchical model to provide a scientific basis for decision-making, applicable to complex multi-objective, multi-criteria decision problems.
3.1.3
off potential
The potential of a pipeline relative to the electrolyte (soil) measured instantaneously after a short time delay following the interruption of current in the circuit, intended to measure the pipe-to-soil potential without IR drop.
3.1.4
corrosion activity area
Locations on a pipeline where external corrosion is prone to occur, occurs frequently, or is ongoing.
3.1.5
pipe-to-soil potential
The potential difference between a pipeline and its adjacent electrolyte (soil).
3.1.6
coupon
A general term for steel test pieces prepared from materials similar or identical to the pipeline under investigation, simulating a defect point in the external anti-corrosion coating of a buried pipeline.
NOTE: Used for testing corrosion rate, cathodic protection parameters, AC/DC interference parameters, etc. Includes cathodic protection coupons, free corrosion coupons, AC/DC interference coupons, weight loss coupons, etc.
3.1.7
alternating current attenuation survey (ACAS)
A surface survey method that applies the principle of electromagnetic induction, using specialized instruments to test the electromagnetic signal generated by the signal current flowing within a buried steel pipeline, and evaluating the overall condition of the pipeline coating through the signal current attenuation rate.
3.1.8
alternating current voltage gradient (ACVG)
A surface survey method to locate coating defect points by testing the changes in AC voltage gradient in the soil caused by the leakage of AC current from a defect point in the external anti-corrosion coating.
3.1.9
AC interference
The phenomenon where AC voltage and current are induced on a pipeline by AC stray currents.
NOTE: Sources of AC stray current interference include AC power transmission systems, AC traction systems, or other AC electrical systems.
3.1.10
close interval potential survey (CIPS)
A method of surveying the pipe-to-soil potential distribution along a pipeline by moving a reference electrode at close intervals (1 m to 3 m) along the ground surface above the pipeline.
3.1.11
on potential
The potential of a pipeline relative to the electrolyte (soil) measured while the cathodic protection system is operating continuously.
3.1.12
soil resistivity
The resistance of soil per unit cross-sectional area and unit length in the direction of measurement.
NOTE: Soil resistivity is an indicator of the soil's electrical conductivity, with the unit Ω·m.
3.1.13
working potential of sacrificial anodes
The pipe-to-soil potential at the point where a sacrificial anode is connected when protective current is flowing.
3.1.14
open potential of sacrificial anodes
The potential of a sacrificial anode relative to a reference electrode when no current is flowing.
3.1.15
redox potential
The potential established when an inert electrode is placed in moist soil containing oxidizing or reducing agents, upon reaching equilibrium between the oxidized and reduced states.
3.1.16
stray current
Current flowing in an unintended path.
NOTE: Stray currents include DC stray currents and AC stray currents.
3.1.17
direct current voltage gradient (DCVG)
A surface survey method to locate coating defect points and assess their severity and characterize corrosion activity by testing the changes in DC voltage gradient in the soil caused by the leakage of DC current from a defect point in the external anti-corrosion coating.
3.1.18
DC interference
Disturbance of pipeline potential/current caused by DC stray currents.
NOTE: DC interference includes steady-state and dynamic DC interference. Sources of DC interference include DC traction systems, HVDC ground electrodes, DC electrolysis devices, welding machines, cathodic protection systems of other structures, and other DC electrical facilities.
3.1.19
free corrosion potential
The corrosion potential when no external net current flows onto or off the pipeline surface.
3.1.20
IR drop
The voltage drop occurring in the electrolyte between the reference electrode and the metallic pipeline due to the flow of current. According to Ohm's law, the IR drop is the product of the total current in the cathodic protection circuit and the circuit resistance.
3.2 Abbreviations
The following abbreviations apply to this document.
CSE Copper/Copper Sulfate Electrode
SCE Saturated Calomel Electrode
SRB Sulfate-Reducing Bacteria
SHE Standard Hydrogen Electrode
Vs relative to
