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CATHODIC PROTECTION

REMEDIATION

By Lance Godfrey, Network Supervisor for North West Pipelines pipeline from the effects of corrosion
at Cadent and YPPC finalist 2019 is the utilisation of a good coating.
However, no coating will contain zero
IN 2015, National Grid Gas was issued shapes and possesses the strength to deficiencies and at locations of coating
an improvement notice from HSE as a withstand high stress loading. Around defects the corrosion process will be
result of not adequately identifying and 60 years ago, it was considered to be highly focused. Therefore, a secondary
carrying out remedial work required on the ideal replacement material for method, known as cathodic protection,
cathodic protection systems installed an ageing gas distribution network is required to ensure all areas of the
on both its low and medium pressure consisting of iron and asbestos mains. pipeline are protected from corrosion.
gas networks. The introduction of natural gas
This shortcoming could lead to subsequently became a reality with Requisites of corrosion
corrosion failure of steel pipelines and the development of a high pressure There are four components required to
subsequent uncontrolled escapes of transmission network constructed form a corrosion cell:
gas. In recent years, the gas distribution using steel pipelines. Anode: This is the area where
business has been sold off and is now However, one major drawback with oxidation and metal loss occurs
known as Cadent. steel is the inevitable susceptibility to Cathode: This is the area where a
My role as a Cadent Pipelines corrosion if inadequately protected reduction in electrons occurs and is
Network Supervisor is to oversee the from environmental conditions. The protected from metal loss
cathodic protection remediation project manufacturing process begins with iron Electrolyte: This is a solution in which
in the North West for all pressure ore. This raw material is processed within electric current can pass between the
ranges. During the last two years, I foundry mills and blast furnaces, utilising anodic and cathodic areas
have been responsible for identifying oxidation reactions to remove carbon and Metallic connection: The anode
cathodic protection schemes that increase toughness and ductility. and cathode must be connected to
require remediation and then creating The end product is steel. When steel complete the corrosion circuit
or modifying existing designs. encounters an electrically charged
I have then progressed to the electrolyte, the iron atoms within its Electrochemical reaction
planning and supervision of the composition react with hydrogen and When all components are present, the
remediation and post-construction oxygen atoms to form iron hydroxide, electrochemical reaction will commence.
survey work followed by updating the which is more commonly known as Negatively charged electrons will
records. The project presents constant rust. The formation of rust is at the migrate from the anode through the
challenges, predominantly due to the expense of the steel and ultimately the metallic connection to the cathode.
nature of buried services and varying integrity of the pipeline. Positively charged iron atoms remain at
degrees of accuracy in terms of legacy The primary method of protecting a the anode and combine with negatively
records and modifications to roads.
Historically, the North West gas
transmission and distribution network FIGURE 1 FACTORY APPLICATION OF COATING TO STEEL PIPE
consisted of multiple areas working
independently of each other and hence
processes were not consistent across the
network, leading to cathodic protection
design variation and therefore varying
degrees of effectiveness.
There has been a significant
investment and allocation of new
resources by Cadent, with the intention
of delivering the productivity required
to achieve compliance and ensure
additional improvement notices are not
issued by HSE.

Introduction
Steel is characteristically durable, can
be manufactured in the form of various

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