SY/T 6151-2009Assessment of corroded steel pipelines (English PDF)

Foreword

Pipeline corrosion damage causes the pipe body to form various shape and

size defects. Serious defects can lead to pressure pipeline leak or rupture

accident, which impacts the safe and smooth operation of pipeline. Therefore,

as for the damaged pipeline, proposing a scientific assessment method has

become a pressing need for the pipeline industry.

This Standard replaces SY/T 6151-1995 "Assessment of corroded steel

pipelines".

Compared with SY/T 6151-1995, the main changes are as follows.

- MODIFY the corrosion damage assessment category content (Chapter 6 of

this edition);

- USE Rstreng's yield strength calculation equation to replace the yield

strength calculation equation under ASME B31G-1991 which is referenced

in SY/T 6151-1995 (Clause 8.1 of this edition);

- MODIFY the assessment threshold of corrosion damage category (Clause 8.2

of this edition).

The Appendix A and B of this Standard are normative.

This Standard was proposed by and shall be under the jurisdiction of Gas

Storage and Transportation Standardization Technical Committee.

The drafting organizations of this Standard. China National Petroleum Pipeline

Company Limited (including the original Northeast Oil Transportation Authority),

Chinese Academy of Sciences Institute of Metal Research.

Main drafters of this Standard. Chen Jianfeng, Han Enhou, Zhang Huabing,

Feng Qingshan, Yu Jingchun, Li Shaozhong, Zhang Bo, Ke Wei, Wang Xueli,

Song Hancheng, Wang Fuxiang.

This Standard replaces the previous standard as follows.

- SY/T 6151-1995.

Assessment of corroded steel pipelines

1 Scope

This Standard specifies the method for assessment of corrosion damage of in

service pipeline.

This Standard applies to the assessment of blunt, low stress concentration

corrosion damage carbon steel and low alloy steel pipeline. The assessment of

pipeline's blunt mechanical damage can be conducted in accordance with this

Standard.

This Standard does not apply to the assessment of the steel pipeline which is

before installation or in installation process, or the assessment of the steel

pipelines which have serious defects in weld and heat affected zone.

This Standard applies only to the internal pressure bearing pipeline; when the

pipeline is withstanding a big additional stress, it shall be considered separately.

2 Normative references

The provisions in following documents become the provisions of this Standard

through reference in this Standard. For dated references, the subsequent

amendments (excluding corrigendum) or revisions do not apply to this Standard,

however, parties who reach an agreement based on this Standard are

encouraged to study if the latest versions of these documents are applicable.

For undated references, the latest edition of the referenced document applies.

GB/T 228 Metallic materials - Tensile testing at ambient temperature

GB/T 21143 Metallic materials - Unified method of test for determination of

quasi-static fracture toughness

SY/T 6597 Technical standard of intelligent pigging on steel pipeline

3 Requirements for assessment personnel

Assessment personnel shall have the following basic knowledge and abilities.

a) Pipeline work principles and safe operation precautions.

b) Basic knowledge on material corrosion and mechanical properties.

c) Identification and measurement of field corrosion state.

4 Raw data preparation before assessment

Raw data shall include the following.

a) Pipeline diameter, wall thickness, material, mechanical properties AND

manufacturers.

b) Transmission medium, working pressure, temperature, AND the latest

pressure test conditions.

c) Corrosion environment and corrosion protection conditions.

d) Pipeline operating history, such as pipe age, leak history, AND larger

maintenance and repair works, etc.

5 Corrosion area measurement