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CP & FMD Inspection Services 

PMAC Inspection is a division of the PMAC Group of companies who specialise in subsea integrity services to the Oil, Gas, Renewables and related Offshore Industries. 


​​PMAC Inspection is a leading provider of a range of specialist corrosion underwater inspection services to the Offshore Oil and Gas Industry on a worldwide basis. The service offerings include; subsea Cathodic Potential monitoring (C.P) surveys utilising PMAC’s proprietary system as well as Gamma Flooded Member Detection (FMD) surveys with combined skilled engineers able to perform both practices. With numerous skill sets under one roof, PMAC can offer multitasking engineers, helping reduce costs and bed space requirements.

PMAC offer a complete Offshore CP Inspection service to ensure the integrity of pipelines and structures. This service is based on proven technology with further developed hardware and software to meet industry and legislative requirements with experienced engineers who hold external certification in Cathodic Protection.

With Offices in Aberdeen and Singapore PMAC are licensed to operate radioactive Sources for FMD in various territories. PMAC Inspection leverages advanced equipment and techniques to provide innovative inspection solutions that deliver low cost, high quality solutions for our clients. With many years experience working with the leading underwater inspection companies, PMAC is well placed to offer our clients the benefit of this proven track record.

We strive at all times to meet and exceed our client's expectations to deliver their projects within budget and help them to manage their asset inspections. PMAC has a wealth of knowledge and experience that is available to our clients to assist with their project requirements. Our personnel hold CSWIP Cathodic Protection certification at levels 2 and 3, as well as being Radiation Protection Supervisors/Officers.

The management of PMAC has many years experience in working with the Offshore Oil and Gas Industry and leads a team of dedicated professionals. With extensive specialist training and a commitment to safety, quality and customer satisfaction, PMAC are ideally placed to deliver cost effective solutions to our clients with their projects no matter how large or small. PMAC conform to ISO 14001:2015 / ISO 9001:2015 / ISO 45001:2018 as well as being Corporate Members of NACE and the Institute of Corrosion.

PMAC work with their clients and partners to understand the challenges and objectives and make appropriate technical and business recommendations for a solution that fits their needs. The experience that PMAC Inspection has with inspection technology, procedures and staff, we not only get the right technology in place, but also make sure that the client is getting the quality information they require to make decisions regarding the maintenance of their assets. PMAC Inspection takes a very active role in managing the data collected during the project including pre-project preparation, project execution, reporting and archiving of the data using the latest in software and hardware technologies.

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Cathodic Potential Surveys (CP)

Regulatory authorities require constant evaluation/auditing of CP systems to ensure structural integrity. CP Surveys allow a system’s ability to resist/avoid corrosion to be monitored, and any corrosion issues to be remedied before the onset of major failure.


PMAC Inspection offer a complete Offshore Cathodic Protection Survey & Monitoring service to ensure the integrity of pipelines and structures. This service is based on proven technology with further developed hardware and software to meet industry and legislative requirements and experienced engineers.

Ensuring the integrity of oil and gas pipelines and structures requires specialist monitoring with sophisticated hardware and software. This is an area where PMAC have invested heavily, offering the industry proprietary technology with enhanced data acquisition and management software to meet these demands.

The system is controlled by a proprietary Software system allowing the user to measure, store and report in an integrated package. Advanced connectivity options allow configurable real-time gathered data to be freely passed from the PMAC Systems PC to any other onboard system, such as the survey package or video overlay.

The PMAC CPROS acquisition, processing and reporting software, used in conjunction with PMAC’s experience, offers a choice of data reporting and interpretation methods, to meet the specific requirements of the client. The reporting package uses innovative methods to reduce processing times and hence reduce reporting delivery times, making onboard data processing a real alternative to onshore reporting. PMAC also manage an extensive database of historical data which can be used to monitor CP trends to identify areas of interest throughout the design life of CP systems.


Based on the use of the Twin Cells (TC) probe technique, the system gives real time data measurement for both subsea pipelines and structures. Continuous Cathodic Potential (CP) can be measured by either 'cell to cell' or 'trailing ('earth') wire' methodologies as well as electrical Field Gradient (FG) readings and contact spot CP readings are all logged simultaneously. Anode current outputs, estimated remaining life of installed anodes as well as pipelien current density profiles can all be calculated.

​The PMAC Subsea Digitiser utilises the latest technology adding increased reliability. With selectable outputs of RS232 and RS485, the bottle allows multiple configurations for various operational requirements. The electronic housing mounting allow the electronics package to be mounted on almost all ROVs from Observation to full Work Class, or even on deck (topside) if necessary for use with Micro/Mini vehicles.

Data is measured by the subsea digitser at a rate of 3Hz allowing for 'fast' surveys upto a theoretical speed of 5.8 knots.


System electronics are calibrated to record at a resolution of;

Contact and Proximity CP to 0.1mV,

Contact and Proximity FG to 0.1μV/cm

Calibrations on the electronics have an uncertainties confidence level of 95% and are all traceable to UKAS ISO/IEC 17025 certified testing and calibration laboratories.

In addition to 'Cell to Cell' methodology PMAC also offers Trailing Wire surveys for instances where pipelines are buried or lack contact points as well as and Single Cell contact only surveys and equipment. For pipeline land falls PMAC also offer CIPS/DCVG onshore surveys to complete surveys across beach areas up to test posts or where the pipeline connects to an onshore based protection system.

Our CP technicians hold specialist CSWIP and/or NACE qualifications in Cathodic Protection to assure quality of service and may hold other qualifications such as FMD Radiation Protection Supervisors enabling them to fulfill multiple roles on a vessel saving cost and bed space.

Please do not hesitate to contact us for more extensive information or individual CP consulting.

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Cathodic Potential Surveys

Gamma Flooded Member Detection (FMD)

Flooded Member Detection by gamma source allows for offshore platform members to be inspected for flooding as a result of cracking, damage, corrosion or weld defect, without the need for high levels of cleaning required by other methodologies. As such, a more tailored inspection plan can be prepared for more detailed investigation as well as other inspection tasks and techniques.

Flooded Member Detection is designed to indicate whether through-thickness cracking has occurred to a structure, resulting in member flooding, without the need for the member to be cleaned down to bare metal. This allows detailed crack inspection to be carried out on a limited number of high-risk members, saving both time and cost.


The use of radioactive sources for the inspection for flooded members on offshore steel structures is a well-proven technique. The PMAC Gamma FMD system has operated with radioactive sources offshore for more than 25 years and was developed from this extensive experience to address the specific needs of repair and maintenance programs in conjunction with subsea inspection requirements.

The PMAC ROV-mounted FMD system uses a small radioactive source to cover member sizes from 150mm up to 3m diameter. A radioactive source and robust detector unit are mounted on opposite forks of a variable yoke positioned across the diameter of the member under inspection. The ROV Mounting frame can be configured to operate at any angle from horizontal to vertical to suit measurements on horizontal, diagonal or vertical members. Our proprietary software package analyses and records the data quickly and efficiently allowing for production of a report within hours of completing a work scope and single member results within minutes.


​The ROV-mounted FMD system operates on the principle that a collimated beam of radiation is transmitted through the member and received by the detector at the other side. The strength of the received beam is compared with computer predictions for a dry, flooded or partially flooded member.

The advantages of the system include, but are not restricted to, the following:-


  • ​Survey is fast and can exceed 30 components per hour with the resulting assessment instant and clear.

  • ​Prior removal of marine growth and cleaning is unnecessary saving time and cost

  • ​May be safely and effectively deployed by ROV

  • ​A proven system with an impressive track record since 1991

  • Configured for survey of horizontal or vertical components

  • ​Detection of water ingress to structural steel jacket members.

  • ​Pipeline inspection providing flooded or dry status and the location of 'pigs' or other blockage.

  • ​​Location and monitoring of gamma emitting equipment or materials 'lost' in a subsea environment.

  • ​Detection and level measurement of fluids in small vessels and pipes in a subsea environment.

Our FMD technicians hold Radiation Protection Supervisor qualifications as well as other regulatory requirements for the region of operation to assure safety. FMD Technicians may also hold other qualifications such as CP or CSWIP, enabling them to fulfill multiple roles on a vessel, saving on time, bed space and ultimately, cost.

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