GUL Scanning – Frequently Asked Questions

GUL Scanning – Frequently Asked Question

QSR is the abbreviation of Quantitative Short Range, which is a patented GUL Guided Wave Scanning technology that with limited access can quantitatively size remaining wall thickness of a relatively short section of pipe.


The QSR1® is a scanner that accurately measures remaining pipe wall thickness across a short pipe section, using guided waves and advanced frequency analysis.


The QSR1® is mainly used for the sizing of remaining pipe wall thickness at locations where corrosion under pipe supports - CUPS - or touch point corrosion are usually present.


The most important information the QSR1® provides is the minimum remaining wall thickness plotted against axial position, accompanied by the average wall thickness in that same location.

These values can be used to perform fitness-for-service (FFS) assessments (e.g. ASME B31G) of a corroded pipe section.

QSR1® Results - Graphic

The QSR1® can accommodate standard pipe sizes from NPS 6 to NPS 24 (DN 150 to 600), with nominal pipe wall thicknesses ranging from 6 mm to 13 mm (¼" to ½").

The diameter of the pipe to be inspected determines the frame size required. For example, to scan an NPS 10 pipe, the 10‑inch frames must be used.

Non‑standard pipe sizes between NPS 6 and NPS 24 can be made to order.

QSR1® Frames - 10in

The QSR1® can be used to evaluate simple resting pipe supports, providing there are no features that hinder the movement of the scanner along the pipe section.

QSR1® - Simple Support

QSR1® - Rod Support

The QSR1® is designed to work exclusively on Carbon Steel pipes.

Other materials, such as aluminium, or composite materials cannot be inspected with this equipment.

The QSR1® can scan pipes with coating or paint that is up to 1 mm thick.

The QSR1® when setup with the Circumferential Sensors is designed to move along the top of the pipe while it collects wall thickness measurements at fixed scanning intervals.

At each interval the QSR1® transmits shear-horizontal guided waves into the pipe – in the low frequency ultrasound range (hundreds of kHz) – that propagate circumferentially at that axial position.

QSR1® SH Waves
Both the reflection and transmission of the waves are measured by the receiver sensor and are analysed using the patented GUL Scanning Frequency‑Based Algorithm to provide the wall thickness measurements. See our Demo video for more information.


The frequency-based method used by QSR1® directly relates the frequency properties of the waves to the pipe wall thickness.

In contrast, conventional NDT techniques - such as MRUT - use amplitude‑based methods, which only estimate defect sizes based on the amplitude of the signals.

Many external factors affect the amplitude of guided waves, therefore curtail the accuracy of a sizing estimate. Clear examples of these variables are: Corrosion Profile, Signal Energy Loss, and Energy Leakage. However, the frequency content or signature of the signals is not affected by these variables.

Analysis - Amplitude vs. Frequency
By using frequency‑based analysis, the QSR1® provides a truly quantitative and more accurate sizing capability than instruments using amplitude‑based methods.

For more detailed information, watch on GUL's YouTube Channel the video: "Accurate Corrosion under Pipe Support Sizing (CUPS) using the QSR1® and Frequency Analysis".

The smallest defect that GUL inspectors have reliably detected and validated is a 25 mm x 25 mm real corrosion patch on a 10” pipe.

It is important to keep in mind that sensitivity will always depend on the existing pipe condition.

The resolution for pipe wall thicknees measurement is ±0.01 mm.

The accuracy is typically ±0.5 mm for <50% wall thickness, and ±1 mm for >50% wall thickness; based on rigorous lab tests conducted on a NPS10 Schedule 40 pipe.

The minimum scanning step size is ±0.5 cm.

The QSR1® is designed to operate within -20°C to +70°C (0 to 160°F).

Circumferential girth welds – Generally, no. However, it depends on the height of the weld cap; if the welds have been ground flush with the pipe and the QSR1® can move across it without restrictions the answer is yes.
Long Seam welds or spiral welds - Either types of seams do not matter for results; but the sensor carts have problems driving over the hump of the weld cap.

The QSR1® is designed to operate within -20°C to +70°C (0 to 160°F).

The QSR1® can scan pipes with coatings or paint thickness of up to 1 mm.

The smallest defect size that our GUL inspectors have reliably detected and validated, is a 25 mm x 25 mm real corrosion patch on a 10” pipe. It is important to keep in mind that sensitivity of an inspection will always depend on existing pipe condition.

This application is currently not possible with the QSR1® but we are looking to develop a solution for this application in the near future.

The QSR1® is designed to inspect pipe sections at supports, which typically involves scanning 0.5-meter pipe sections. The speed of the scanner on a pipe depends on the Collection and Scan configuration settings that the user has selected. For 1 cm scanning steps using the “Default” protocol on a NPS 10 Schedule 40 pipe, the scanning rate is approximately 17 minutes per meter. Therefore, a typical QSR1® scan is approximately 9 minutes per support location.

Yes, we are proposing to charge a year fee for access to the Trunk and the software that will be on this platform. The purpose is to keep up-dated with software, firmware and WaveProQSR. There will be a major upgrade for QSR processing using an advanced and innovative AI (artificial Intelligence) approach called machine learning. This will allow us to move towards the goal of fully automated analysis and providing advanced tools and capabilities.

The calibration certificate is valid for 1 year. The QSR1® must be shipped back to GUL annually for calibration.

The QSR1® battery can be found in the electronics pod. It does not matter if the sensors are connected. Plug in the charger (you can check its charging by turning on the unit and look to see the symbol for charging on the battery icon). The MSDS for the battery can be found here.

The larger the pipe diameter, the lower the radial clearance. The following lists the nominal pipe diameter and their respective radial clearance: - NPS 6 (60 mm), NPS 8 (53 mm), NPS 10 (51 mm) and NPS 12 (17 mm).


The access to the software will be provided to you once you have purchased a QSR1®.


A trained and qualified Level 2:QT inspector is required to operate and analyse the results from the QSR1®. For more information, please see GUL Training webpage.

Training for the QSR1® is currently offered as a combined Level 1:Q and Level 2:QT course.

The length of the course is 32 hours: 8 hours a day, over 4 days.

An additional day for examination must be allocated.

For further information, please visit the GUL Training website.

GULT - GUL Training - QSR

Suitable for Level 2 NDT inspectors new to the field of Guided Wave Testing (GWT).

Recommended Qualifications:

  • Experienced NDT technician (1 year), or
  • Experienced Level 2 NDT technician, or
  • Degree or HNC in a technical subject

Level 2:QT

Application specific training course for the inspection of touchpoint supports.


  • Level 1:Q qualification, and
  • Degree or HNC in a technical subject, or
  • Valid Level 2 or 3 UT qualification
GULT - GUL Training

For further information, please visit the GUL Training website.

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