Foreword

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This document was prepared by Technical Committee ISO/TC156, Corrosion of metals and alloys.

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Introduction

Microbiologically influenced corrosion (MIC) refers to corrosion caused by the presence and activities of microorganisms (e.g. bacteria, archaea and fungi). Although microorganisms do not produce unique types of corrosion, they can accelerate corrosion reactions and increase the susceptibility of materials to corrosion processes such as pitting, embrittlement and under deposit corrosion (UDC). MIC has been identified as a contributor to rapid corrosion of metals and alloys exposed to seawater, crude oil, hydrocarbon fuels, soils and sewage. In recent years, the oil and gas industry, especially pipelines, are suffering from severe MIC threats. It is estimated that approximately 20 % of pipeline incidents are related to MIC.

This document establishes a microbiological corrosion test method applicable to oil and gas transmission pipelines to facilitate microbiological corrosion test evaluation by oil and gas industry users and product suppliers. In this document, the total immersion corrosion test is used to determine the corrosion rate (including uniform corrosion rate and pitting corrosion) of metals and alloys. In particular, the test conditions (e.g. strain source, test solution and corrosive gas), procedures and results are regulated in detail. This document focuses on the internal microbial corrosion environment of oil and gas transmission pipelines, but it also applies to environments involving microbial corrosion risks such as water injection and downhole in the oil and gas industry.

1 Scope

This document specifies a laboratory test method for microbiologically influenced corrosion (MIC) of oil and gas transmission pipelines, including the principle, apparatus, sources of strains, solutions, specimens, sterilization, procedure, results and report.

This document applies to the MIC test of metals and alloys for internal surfaces of oil and gas transmission pipelines.

2 Normative references

3 Terms and definitions

4 Principle

5 Apparatus

5.1 Vessel

5.2 Biological equipment

5.3 Other equipment

6 Strain source

6.1 General

6.2 Strains from on-site pipelines

6.3 Commercial standard strains

6.4 Microbial culture for test

7 Test solutions

7.1 General

7.2 Natural solutions

7.3 Artificial solutions

7.4 Introduction of target microorganisms

8 Test specimens

8.1 General

8.2 Shape and size of specimens

8.3 Preparation of specimens

9 Sterilization

9.1 Sterilization of glassware

9.2 Sterilization of aqueous solution

9.3 Sterilization of other devices

10 Procedure

10.1 General

10.2 Specimen assembly

10.3 Introduction of solution

10.4 Deaeration

10.5 Test conditions

10.6 Detection of planktonic and sessile microorganisms

10.7 Cleaning specimens after test

10.8 Pitting evaluation

10.9 Calculating corrosion rates

10.10 Quantitative comparison of abiotic and biotic tests

11 Test results

12 Test report

Bibliography