CC004 External corrosion failure mechanisms

Competency ID
and title

CC004 External corrosion failure mechanisms

Competency area

Corrosion control

Stream/s

Design, Operations

Level

Elective

Knowledge

Understanding of different types and sources of external corrosion, including:

·         general corrosion

·         pitting and crevice corrosion

·         galvanic corrosion

·         stress corrosion cracking (SCC)

·         microbiologically influenced corrosion

·         stray currents

·         tellurics

·         hydrogen induced cracking.

Understanding of the range of corrosion mechanisms applicable to pipelines and facilities, including:

·         coating damage including holidays, wrinkles and disbondment

·         coating degradation

·         corrosion on longitudinal and girth welds

·         shielding of cathodic protection

·         conditions for SCC: soil conditions, coating disbondment, susceptible line pipe steel, CP levels, temperature and pressure

·         dissimilar metals.

Detailed understanding of factors contributing to corrosion mechanisms including:

·         construction damage

·         excess temperature (high and low temp implications)

·         soil stress on coating

·         rock damage

·         poor joint coating

·         concrete weight blocks, weight coating rock shield damage

·         cased and uncased crossings

·         termite damage

·         soil to air interface (risers)

·         UV damaged coating

·         insufficient cathodic protection

·         cathodic interference

·         excess cathodic protection

·         soil and/or environment

·         reversed cathodic protection

·         corrosive atmospheres

·         proximity to potential corrosive compounds

·         piping dead legs/low point

·         gas impurities.

Methods for preventing and mitigating each corrosion type and mechanism, including:

·         coating and joint specification and application

·         correct cathodic protection design and settings and regulatory requirements

·         management of interference

·         addressing problem locations such as bores and crossings.

Requirements of AS 2885.3 Section 5 – Pipeline Integrity Management.

Regulatory requirements.

Requirements for data management of corrosion defect information from a range of sources.

Experience

At least 18 months working in the pipeline industry that involves a proportion of time working with corrosion specialists who are identifying, preventing and mitigating corrosion on pipelines and related facilities.

Expertise

Identifies existing and potential sources of external corrosion on a pipeline/facility as part of corrosion management process.

Determines when corrosion specialists must be commissioned to undertake design work or undertake inspection and assessments for operating pipelines.

Briefs and scopes work to be undertaken by corrosion specialists in respect of design requirements to minimise external corrosion and investigations on operating pipelines.

Understands and applies reports and recommendations by corrosion specialists.

Oversees detection of corrosion on pipelines and facilities and development plans to mitigate further corrosion once detected, including use of in-line inspection, CP surveys and coating defect surveys.