CATHODIC PROTECTION

Pre-Design Surveys

We conduct pre-design surveys to be used in the design, including:

  • Soil resistivity survey
  • Current drain tests
  • Complete CP trials.
Design of CP Systems

Our services include providing complete design packages including scope of work, specifications, drawings and bill of quantities for sacrificial and impressed current systems for all types of reinforced concrete and steel structures including:

  • Existing reinforced concrete structures
  • New reinforced concrete structures
  • Pipelines
  • Internal and bottoms of above ground steel tanks
  • Offshore structures
  • Oil well casings
Materials Supply

We offer services in materials selection and supply of materials from all standard international and local suppliers, including transformer rectifiers, dc power supplies, sacrificial anodes (magnesium, zinc and aluminum), high silicon iron anodes, mixed metal oxide anodes, reference electrodes, junction boxes, cables and all other CP materials.

Installation and Commissioning

We offer services for independent installation and commissioning of all types of CP systems for steel and reinforced concrete structures. We also offer supervision services only for the installation works to be carried out by the construction contractor.

  • Installation of CP hardware (transformer rectifiers, anodes, reference electrodes, junction boxes, cabling etc.)
  • Quality control during installation
  • Testing and commissioning
  • Provision of operation and maintenance manuals
Monitoring

Periodic monitoring of the CP systems is important to provide the desired protection against corrosion. The monitoring is generally carried out at time intervals of monthly, six-monthly and annually.

  • Periodic monitoring
  • Assessment of malfunctioning systems
  • Rehabilitation and upgrading existing systems.

REPRESENTATIVE PROJECTS IN CATHODIC PROTECTION


Project # 1: Condition Survey and Performance Assessment of CP Systems of Concrete Structures and Seawater Pipes

The existing CP system for the partially reinforced concrete chambers protected the portions of the structures below the groundwater table as the anodes were installed below the water table. It was suspected that the buried portions of the structures above the water table were not receiving protection. CONTEC was commissioned to make a study and prepare detailed design for upgrading the CP systems to protect the entire structure.

The project scope included condition assessment, performance evaluation and recommendations for upgrading the existing impressed current CP systems of reinforced concrete structures and 2000 mm diameter buried prestressed concrete seawater pipelines as well as condition assessment of the unprotected concrete structures above grade level. The study included checking the CP systems performance by measuring the potentials using existing permanent reference electrodes located below water table and reference electrodes above water table installed during the study, condition assessment of the concrete structures at and above grade and the buried pipes.

It was recommended to install additional CP system to protect reinforcement for concrete at and above ground level and to improve the monitoring of the pipes by installing new monitoring system in order to effectively monitor the prestressing steel to avoid over- protection.


Project # 2: Installation & Commissioning of ICCP System for Bottoms of Aboveground Steel Tanks

The bottoms of the aboveground steel tanks were not protected cathodically. The client suspected that the ongoing corrosion may lead to metal loss and holes in the tank bottom plates and lead to leakage of the products. CONTEC was assigned the contract to design, install and commission the CP systems for 17 tank bottoms.

The project scope included design, material supply, installation, commissioning and monitoring of impressed current CP (ICCP) system to protect tank bottoms of 17 existing aboveground steel tanks.

As the tanks were existing, distributed high silicon iron anodes were installed in 6 m deep drilled holes around the tank. The anodes were fed with an oil- cooled transformer rectifier. Monitoring system was installed including reference electrodes under the tanks, instrument negative cables and monitoring junction boxes. The system was commissioned simultaneously for all the tanks using GPS controlled current interrupters. The current interrupters were installed at all the tanks and the CP systems were interrupted simultaneously. The CP systems were monitored for one year before handing over to the client.


Project # 4: Installation & Commissioning of SACP System for Pipelines and Tank Internal

The scope of work included material supply, installation and commissioning of sacrificial anode CP (SACP) system to protect gas pipeline at road crossings and internal of tanks. High potential magnesium anodes were installed horizontally at depths corresponding to the invert level of the pipes and hanged inside the tanks. Potentials were measured and the system commissioned.


Project # 5: Monitoring of CP Systems for Steel Tanks, Pipeline, Reinforced Concrete Building Foundations

As part of the 5-year CP monitoring contract, the existing CP systems for concrete pipeline, bottom of steel tanks, foundations of reinforced concrete buildings and tanks and seawater retaining structures were monitored and maintained. The monitoring included monthly monitoring to check the condition of the transformer rectifiers, six- monthly monitoring to measure potentials and adjust the systems and system analysis every three years. The scope also includes troubleshooting and rectification of the systems including replacement of anodes, repair of transformer rectifiers and other repairs as required.


Project # 6: Preparing Scope of Work and Supervision of CP Installation Contracts

CONTEC also carried out supervision of contracts on behalf of clients. The scope of such contracts includes preparing scope of work, answering technical queries raised by bidders during the bidding process, technical evaluation of bids, review of technical submittals, design change notices, change orders, inspection and release of hold points, witnessing commissioning, reviewing commissioning report and other documentation and project close- out.