GB/T 21246-2020 in English
VALIDMeasurement method for cathodic protection parameters of buried steel pipelines
- Issued on:2020-11-19
- Implemented on:2021-06-01
- File Format:PDF
- Delivery:Via email within 5 business days
$418.00
《GB/T 21246-2020埋地钢质管道阴极保护参数测量方法》由TC355（全国石油天然气标准化技术委员会）归口，主管部门为国家标准化管理委员会。
Introduction
Technical evolution and core changes of standards
| Technical elements | 2007 version | 2020 version | Description of changes |
|---|---|---|---|
| Reference electrode | Only copper sulfate electrode is specified | New silver oxide electrode parameters | Expand applicability in high saline and alkaline environments |
| Off-power potential measurement | Basic requirements | Refine synchronization verification | Improve data accuracy |
| New methods | - | Soil tube method/current loop method | Solving stray current interference |
Key measurement technical specifications
1. Potential measurement system
The standard constructs a complete potential measurement matrix:
- Natural potential: measurement must be made after complete power failure for 24 hours
- Power-on potential: comprehensive value including IR drop
- Power-off potential: synchronization error of <0.1s is required
Key points for implementing the close interval potential method (CIPS):
A pulse oscilloscope is used to verify synchronization, with a measurement interval of 1-3m, and GPS coordinate data needs to be recorded. Typical problems include:
- Current asynchrony caused by multiple sets of sacrificial anodes
- Capacitive decoupling devices require extended power-off time
Innovation in insulation performance testing
| Method | Applicable scenarios | Accuracy | Limitations |
|---|---|---|---|
| Voltage method | Ground pipe section | ±5% | Required feeding current>2A |
| Current loop method | Overhead pipe section | ±1mA | Not applicable current<1A |
Breakthrough in Corrosion Monitoring Technology
The new Chapter 11 stipulates two monitoring methods:
- Weightlessness inspection piece method: annual cycle measurement, requiring 3 parallel specimens
- Resistance probe method: trenchless continuous monitoring, accuracy of 0.01μm
Typical application scenarios:
For pipelines near high-voltage substations, the polarization probe method combined with the resistance probe should be used to solve the problem of corrosion rate measurement under DC stray current interference.
Implementation suggestions
1. Measurement scheme design
- In strong interference areas, the soil pipe method
- Pipelines above DN800 need to verify the applicability of the current loop
2. Data quality control
- Reference electrode calibration every month
- Magometer regular verification according to JJG622
- Establish measurement environment records (temperature/humidity/soil status)
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