MAXWELL PECT U11 | Corrosion Detection and Mapping Through Insulation

Removing insulation and protective cladding to inspect industrial equipment for corrosion can be costly, time-consuming and disruptive. MAXWELL PECT U11 is a portable Pulsed Eddy Current Testing system designed to screen carbon steel pipes, storage tanks, pressure vessels and process equipment without removing insulation or protective coatings. The system is particularly suitable for Corrosion Under Insulation — CUI inspections. It measures changes in the average remaining steel wall thickness through insulation and helps identify areas that may require further investigation. The integrated Durabook U11i touchscreen computer, portable data acquisition unit and application-specific probes allow the system to be transported and operated in demanding field environments. When used with the optional position encoder, measurement results can be linked to their location for colour-coded corrosion mapping and reporting.

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Corrosion Detection Through Insulation

MAXWELL PECT U11 uses Pulsed Eddy Current technology to inspect ferromagnetic steel without requiring direct contact with the steel surface.

The probe generates a magnetic field that induces eddy currents within the steel component. The decay of these eddy currents is analysed to estimate the average remaining steel thickness within the probe footprint.

This allows inspectors to screen equipment through insulation, coatings and other suitable materials without removing the complete insulation system.

Key benefits

Inspection without removing the complete insulation system
No direct contact with the steel surface
No liquid couplant required
Rapid screening of large areas
Identification of general wall thinning
Prioritisation of areas for follow-up inspection
Reduced insulation removal and reinstatement costs
Improved maintenance and inspection planning

PECT is primarily a screening and corrosion-mapping method. It measures the average steel thickness within the probe footprint and is not intended to replace local ultrasonic testing for the precise sizing of small pits or highly localised corrosion.

Corrosion Under Insulation — CUI Inspection

Corrosion Under Insulation is a major integrity concern in refineries, petrochemical plants, power stations, offshore facilities and other process industries.

MAXWELL PECT U11 can be used to screen:

Insulated carbon steel pipework
Process piping
Pressure vessels
Storage tanks
Columns and similar equipment
Fireproofed or coated steel components
Areas where insulation removal is difficult or expensive

The system helps detect general metal loss and changes in average wall thickness while allowing inspection teams to focus additional testing on the most critical areas.

Encoder-Assisted Corrosion Mapping

An optional single-axis position encoder can be attached to the standard S, M, L and XL probes.

The encoder links each measurement to the probe position, enabling structured data collection and colour-coded thickness mapping.

The system supports three data-collection methods:

Point-by-point measurements using manual triggering
Dynamic scanning while the probe is moving
Stop-and-Go measurements triggered when the probe becomes stationary

Collected data can be displayed using colour coding and exported to customisable Microsoft Excel reports. This makes changes in average wall thickness easier to evaluate across the inspected area.

Measurement Performance

Steel wall thickness range

The system is designed for steel wall thicknesses from:

2 mm to 65 mm

Maximum lift-off range

The maximum distance between the probe and steel surface depends on the steel wall thickness.

Steel wall thickness	Maximum lift-off
Up to 15 mm	250 mm
More than 15 mm up to 30 mm	200 mm
More than 30 mm up to 65 mm	100 mm

The maximum 250 mm lift-off should therefore not be presented as applicable to every wall thickness.

Typical measurement accuracy

MAXWELL PECT measures the average steel thickness within the probe footprint with a typical accuracy of:

±10%

Probe footprint

The footprint diameter is approximately:

1.5 times the insulation thickness, with a minimum diameter of 25 mm

As the distance between the probe and steel increases, the area represented by each measurement also becomes larger.

Typical Data-Collection Speed

Measurement time depends on steel thickness, vibration, inspection conditions and selected parameters.

Steel wall thickness	Typical time per reading
More than 3 mm up to 12 mm	0.5 seconds
More than 12 mm up to 25 mm	1 second
More than 25 mm up to 50 mm	2 seconds

Four Standard PECT Probes

The standard system includes four probes designed for different lift-off ranges.

Probe	Description	Nominal lift-off range
S	Small	0–20 mm
M	Medium	25–75 mm
L	Large	40–125 mm
XL	Extra Large	75–250 mm

During inspection setup, the software uses test measurements to assist with probe selection and automatically configure suitable measurement parameters.

Insulation and Cladding Materials

The system can be used through suitable insulation materials and non-magnetic materials between the probe and the carbon steel surface.

The technical documentation identifies aluminium and stainless steel insulation sheeting as supported applications.

Performance through galvanised or other magnetic sheeting depends on the specific magnetic properties of the cladding and should be assessed for each application.

Portable Field Design

The data acquisition system is permanently connected to a Durabook U11i touchscreen computer.

Portable system features

Integrated touchscreen operation
Sunlight-readable display
8 GB memory
250 GB SSD
Wi-Fi connectivity
Bluetooth connectivity
USB 3.0
Remote control through VNC
Instrument weight with batteries: approximately 7.5 kg
Field transport by a single operator
Backpack and instrument carrier belt
Protective transport cases for road and air transport

The backpack and carrier belt support hands-free transportation. The inspection itself still requires the operator to handle and position the probe.

Battery Performance

The main batteries provide a typical operating time of approximately:

8 hours

The batteries are hot-swappable, allowing replacement without shutting down the instrument. External chargers help reduce downtime during extended field operations.

The tablet battery is automatically recharged from the main system battery when its charge level becomes low.

Reporting and Analysis Software

MAXWELL PECT U11 provides comprehensive software functions for data collection, analysis and reporting.

Software capabilities

Graphical user interface
Automatic analysis option
Automatic probe and parameter selection
Storage of complete PECT signals
Export of raw signals to Microsoft Excel
Direct Microsoft Excel reporting
Customisable report layouts
Colour-coded measurement results
Multilingual software menus
PC-based analysis software
Windows 10 and Windows 11 compatibility
Unlimited licence-free copies of the analysis software
Password-protected advanced parameter settings

Reports can be generated from both the instrument software and the PC-based analysis software.

Environmental and Field Specifications

MAXWELL PECT U11 is designed for industrial field use.

Specification	Value
Protection rating	IP65
Environmental resistance	Salt and fog resistant
Operating temperature	-20°C to +40°C
Relative humidity	Below 93%
Atmospheric pressure	70–105 kPa
Compliance	CE, RoHS and FCC Part 15B

These characteristics make the system suitable for use in refineries, petrochemical plants, power-generation facilities and offshore environments.

Standard System Configuration

A standard MAXWELL PECT U11 system includes:

PECT data acquisition and pulse-generation unit
Integrated Durabook U11i touchscreen computer
S, M, L and XL standard probes
Probe protection shoes and wear pieces
Two vibration-suppression shims
Two 8-metre signal cables
Two main PECT batteries
External battery charger
Reference plate for functional checks and calibration support
Transport and field-carrying equipment

Optional accessories

Single-axis position encoder
Flat probe for annular ring inspection of atmospheric storage tanks
Splash-zone probe rated to 50 metres water depth
Underwater probe rated to 2,500 metres
Extended signal cables
Underwater umbilical cables
Telescopic extension pole
Custom-designed probes

Main Applications

Corrosion Under Insulation inspection
CUI screening
Corrosion mapping through insulation
Insulated pipeline inspection
Carbon steel wall-thickness screening
Process piping inspection
Pressure-vessel inspection
Storage-tank inspection
Annular ring inspection
Corrosion Under Fireproofing inspection
Splash-zone inspection
Offshore inspection
Refinery inspection
Petrochemical plant inspection
Power-generation facility inspection

Please contact with us to receive quotation for PEC solutions

Learn More About Pulsed Eddy Current Technology

For detailed information about how Pulsed Eddy Current works, its use in Corrosion Under Insulation (CUI) inspections, encoder-assisted corrosion mapping, and the technical advantages of the method, read our blog article.

Pulsed Eddy Current Corrosion Mapping Through Insulation