Modernizing Subsea ACFM


ACFM Subsea Inspection System for the Detection and Sizing of Surface-breaking Cracks

For the last 30 years, ACFM® technology has been used globally as the method of choice for the detection and sizing of subsea surface-breaking cracks. Recognized and approved by many certification bodies, including DNV, ABS and Loylds, the technique has been used successfully against traditional uncomputerized and more user dependent methods, such as MPI.

As today’s industry is looking to scale the use of auditable NDT methods to all their assets, faster, more flexible, easier to deploy inspections and better reporting capabilities are required. Who else but Eddyfi Technologies to redefine and modernize subsea crack inspection with its new TSC U41™.

The U41 is supported by a global network of calibration and training centres, located in Milton Keynes (UK), Québec (Canada), Houston (USA) and Dubai (UAE).

Want to see U41 in action? Book a demo!

Deployment Method

Diver from fixed platform, vessel or from saturation bell (U41D / U41DA)

The subsea bottle is lowered to the diver and the diver uses probes connected to the bottle through a 5 m (16.4 ft) cable. There is an umbilical cable from the bottle to a topside unit that provides power to the bottle and communication protocol conversion between the VDSL used down to the bottle and Ethernet which is connected to a controlling laptop. The umbilical is 150 m (492 ft) standard with subsea connectors at both ends. Three umbilicals may be connected together for a total length of 450 m (1476.4 ft). A 15 m (49.2 ft) whip is provided between the top umbilical and the topside unit so that this can be temporarily fixed-routed to the dive shack (normal ACFM operator location). The diver uses simple Bx/Bz pair probes or the mini (8 channel) array (requires the DA version).

Exclusive Content

Modernizing subsea ACFM inspection with U41

The webinar features a demonstration where Dr. Michael Smith shows you how the U41 true ACFM subsea inspection system delivers accurate subsea crack detection and sizing, better data quality with new electronics, faster inspection with easier deployment, array probed and reporting.

The webinar will include:

  • An introduction to the U41
  • An overview of the main features and applications
  • A demonstration of system
  • Q&A





  • 3 × SENSU® 2 UW

Max umbilical length

  • U41D/DA: 450 m (1476 ft) (Extended Ethernet)
  • Standard length 150 m, up to 3 can be connected in series


  • U41D: no
  • U41DA: 4 × rows mini


  • U41D/DA: VDSL only

Depth rating

  • U41D/DA: 300 m (984 ft)

Topside units type

  • U41D/DA: Topside unit D

Bottle dimension

  • U41D/DA: 156 × 156 × 430 mm (6.2 × 6.2 × 17 in)
  • U41D/DA: 156 × 156 × 292 mm (6.2 × 6.2 × 11.5 in) (without lifting cage)

Bottle weight (in air)

  • U41D/DA: 9.2 kg (20.3 lb)


  • U41D: Single
  • U41DA: Dual

Operating temperature range

  • 0–45°C (32–113°F)

Probe cable length

  • 5 m (16 ft)

Power requirements

  • Topside: 110 V AC/400 mA U41: 48 Vdc/1A