Cathodic protection – vital for oil and gas pipelines

Underground pipelines, transporting liquid petroleum products and natural gas are critical components of civil infrastructure, making corrosion prevention an essential part of asset-protection strategy.

For all the major oil and gas terminals around the world, protection of pipelines is vital. The Ormen Lange terminal at Nyhamna is not an exception. Norway’s second largest gas field is one of the most complex and technological challenging field development. No other fields produce as deep, under such rough conditions, and with such advanced equipment.

Ormen Lange covers up to 20 % of the United Kingdom’s gas requirement.

Pipelines at Nyhamna terminal

Two major pipelines are carrying gas from the Ormen Lange offshore field, and one pipeline, called Polarled (the first pipeline crossing the polar circle) carrying gas from the Åsta Hansten offshore field to the onshore terminal at Nyhamna. The incoming gas is processed in the Nyhamna onshore terminal, where it spends 10 minutes before being exported 1200 km through the world’s second longest pipeline, Langeled, to United Kingdom.

Corrosion protection system

The landfall sections of these pipelines stretch from the lowest astronomical tide (LAT) until the pipelines get above ground just a few meters above the highest astronomical tide (HAT). These pipeline sections are protected against corrosion with an advanced impressed current cathodic protection system above HAT, combined with sacrificial anode protection from HAT to LAT.

The ICCP system for the pipeline sections above HAT consist of:

• Continuous cable-like anodes parallel with the pipelines
• Reference cells and monitoring coupons installed in customised housing at 25 different location
• One CathFlow® control panel for energising 7 active anodes
• Two CathFlow® control panels as back-up system

Additionally, 11 zinc sacrificial anodes are installed for corrosion protection below HAT.

Full control of the corrosion protection is obtained by an excessive measurement system with continuous monitoring, and a data logging system saving historical data.