GB/T 23258-2020Standard practice controlling internal corrosion in steel pipelines and piping systems (English PDF)

3.4 Glass lining

A layer of vitreous enamel formed on the inner surface of the metal substrate by high-temperature cladding.

5.2 Treatment of pipeline transportation medium

5.2.3 For systems containing acidic media such as hydrogen sulfide and carbon dioxide, separation measures should be taken, to remove hydrogen sulfide and carbon dioxide from the pipeline transportation media.

5.2.4 For severely-corroded produced water and water injection pipelines, measures, such as airtight oxygen isolation, water quality modification, and pre-oxidation processes, can be used to slow down the corrosion. If dissolved oxygen is the main corrosion factor, a closed treatment process should be adopted. If acid gas is the main corrosion factor, pre-oxidation and water quality modification process should be adopted. If the low pH value causes severe corrosion, the pH value should be adjusted.

5.3 Pigging

5.3.1 For pipelines with deposits which can easily cause corrosion, pigging measures should be adopted, to remove deposits.

5.3.2 Based on the corrosion of deposits and bacteria on the pipeline, it shall establish a reasonable pigging cycle.

5.3.3 Pigging measures should be used in conjunction with other corrosion control measures, such as adding corrosion inhibitors and dehydration. When pigging, it shall avoid adversely affecting the inner coating.

5.4 Sand erosion control

5.4.1 For oil and gas transportation pipelines containing sand, it is advisable to install a desander at the front end.

5.4.2 For pipelines conveying liquid media containing sand, the liquid flow rate should be controlled.

5.4.3 For pipe sections and fittings that are prone to erosion corrosion, one or more of the following measures to control erosion corrosion should be adopted:

a) Long-radius pipe fittings such as elbows, blind tees;

b) Erosion corrosion-resistant metal materials;

c) Apply anti-erosion coating.

6.1 General

6.1.1 Material selection shall be determined through technical and economic […]

6.3 Seawater pipelines

6.3.4 The connection of the pipelines and fittings of corrosion-resistant alloy material should not use threaded connection.

6.3.5 Graphite-containing gaskets shall not be used in metal seawater piping systems. […]

7.1 General

7.1.1 Chemicals agents used for corrosion control, such as corrosion inhibitors, bactericides, deoxidizers, and scale inhibitors, shall be selected according to the working conditions and the corrosiveness of the medium.

7.1.2 The type and filling volume of chemical agents shall be determined through screening, laboratory evaluation, and field verification, etc.

7.1.3 Before filling the chemical agent, the compatibility of the various agents in the system shall be evaluated.

7.2 Corrosion inhibitor

7.2.1 The corrosion inhibitor shall be selected based on the following factors:

a) Corrosion type and corrosion factor;

b) Compatibility with pipeline transportation media and other chemical agents;

c) Corrosion inhibition performance, physical and chemical properties and use conditions of corrosion inhibitor;

d) Operability of storage, transportation, use and filling;

e) Influence on the subsequent process.

7.2.2 The performance evaluation of corrosion inhibitors for oil and gas pipelines should meet the requirements of SY/T 7025. The performance evaluation of corrosion inhibitors for produced water should meet the requirements of SY/T 5273.

7.2.3 The filling method and technical requirements of corrosion inhibitor for oil and gas pipelines shall meet the requirements of SY/T 7408.

7.2.4 The material of the corrosion inhibitor filling device shall be adapted to the working conditions of continuous contact with the corrosion inhibitor. Carbon steel or stainless steel should be used. Small-diameter pipelines should be […]

8.1 Coating

8.1.1 The inner coating shall be selected based on the following factors:

a) Corrosiveness of pipeline transportation medium;

b) Aggressiveness of dirt, impurities, additives, etc.;

c) Adhesion, toughness and ductility to the pipe wall;

d) Influence on the pipeline transportation medium.

8.1.2 According to the degree of corrosion of the transportation medium, the type, structure and thickness of the inner coating shall be determined.

8.1.3 The inner coating pipe should be prefabricated in the factory. When liquid epoxy coating is used for the inner coating, the material properties, construction coating, and quality test shall meet the requirements of SY/T 0457. When epoxy powder coating is used for the inner coating, the material properties, construction coating, and quality test shall meet the requirements of SY/T 0442.

8.1.4 When the inner coating adopts the overall extrusion coating process at the construction site, it shall meet the requirements of SY/T 4076.

8.1.5 When the pipeline transportation temperature is higher than 80 °C, high-temperature-resistant coatings shall be selected. The long-term use temperature shall be determined through tests in conjunction with the on-site conditions.

8.1.6 The inner corrosion-resistant coating of high-pressure transportation pipelines higher than 12 MPa shall be subjected to high-pressure resistance tests under simulated working conditions. After the test, the permeability and adhesion of the coating shall meet the requirements of working conditions.

8.2 Lining corrosion-resistant alloy material

8.2.1 Corrosion-resistant alloy composite pipe includes two forms: inner cladding or lining. The process pipeline of the station should be the inner-cladded composite pipe. The line pipeline should be the lining composite pipe or the inner-cladded composite pipe. Pipe fittings, perforated pipelines, bends, and pipelines for cutting should adopt inner-cladded composite pipes.

8.2.2 Corrosion-resistant alloy composite pipes shall be inspected in the factory for chemical composition, bonding strength, and corrosion resistance, etc. […]

8.4 Patching and jointing process

8.4.3 During the construction of the on-site inner coating patch, the selected patching materials and construction methods shall be subject to process evaluation. The corresponding inner coating patch construction plan and quality control measures shall be prepared. The quality of the inner coating patch shall not be lower than the inner coating of the pipe body.

8.4.4 For small-caliber pipelines and golden openings with inner anticorrosion layer of liquid/solid paint, it is advisable to adopt the method of pipe end corrosion-resistant alloy surfacing and lining joint patching. The surfacing material shall be selected according to the corrosiveness of the medium. 316 L, duplex stainless steel, nickel-based alloy, etc. should be selected. Lining joints should select anticorrosion steel short-joint, FRP, polytetrafluoroethylene and other materials. […]

9.1 Corrosion control management plan

9.1.1 When pipelines are prone to internal corrosion, internal corrosion control management plans should be prepared.

9.1.2 The internal corrosion control management plan should include the following:

a) Overview of the pipelines;

b) Corrosion control objectives and indexes;

c) Measurement and analysis of internal corrosion and related parameters;

d) Corrosion mechanism and corrosion characteristics;

e) Corrosion risk assessment;

f) Current status and plan of internal corrosion control measures;

g) Corrosion control engineering construction quality and design modification;

h) Testing/monitoring plan;

i) Evaluation and countermeasures of corrosion control effect;

j) Feedback and continuous improvement;

k) Data recording and storage. […]

9.2 Corrosion monitoring and testing

9.2.10 Internal corrosion testing methods include ultrasonic thickness measurement, electromagnetic ultrasonic thickness measurement, ultrasonic C-scan, X-ray, ultrasonic guided-wave, magnetic flux leakage testing, ultrasonic testing, etc. They shall be selected according to the specific conditions of the pipeline.

9.3 Effect evaluation

9.3.1 Based on the results of corrosion monitoring, internal testing, internal corrosion direct evaluation, etc., combined with production and operation conditions and changes in media properties, the effect of internal corrosion control of the pipelines shall be evaluated.

9.3.2 The evaluation of the effect of corrosion control in the pipeline shall be carried out periodically. The effect evaluation shall be based on the evaluation results of the previous cycle; the evaluation plan for the next cycle shall be formulated.