How to Run a PIT Test with PET: Step‑by‑Step Guide

Pile Integrity Testing (PIT) using Pile Echo Testing (PET) is a non-destructive method to evaluate the quality and structure of foundation piles. It helps detect internal flaws, confirm pile length, and verify compliance with design standards. Conducting PIT properly ensures reliable results, avoiding structural risks and costly remediation.

Understanding PIT with PET

PET works by generating a stress wave at the top of the pile and analyzing the reflected signals. Variations in the reflections can indicate voids, cracks, changes in pile diameter, or other anomalies. The method is suitable for concrete, steel, and timber piles. Using PET correctly provides a detailed picture of the pile’s condition and ensures construction integrity and safety.

Step 1: Pile Head Preparation

Proper pile head preparation is essential. The surface must be clean, free of dust, debris, and loose concrete. Uneven or rough surfaces can distort wave signals, leading to inaccurate results. Any protruding reinforcement or debris should be removed, and the pile head should be flat. This ensures proper contact between the impact device and the pile.

Step 2: Equipment Setup

We recommend using the wireless PIT PET Bluetooth, as it is fast and easy, and can also connect to your Android phone using the PET App. If you are using a PIT device with a cable, ;ike the PET USB, make sure the cable is in good shape, and that the connectors are secures on the sensor side and the computer side.

Set the software parameters (wave speed, amplification etc) according to the pile age, length, and ground SPT value. Proper setup is crucial for reliable data.

Step 3: Applying Putty and Impact Testing

A thin layer of putty on the pile head improves contact between the sensor and the pile. It ensures good acoustic coupling which helps reduce signal noise and consistent wave transmission. Hold the sensor firmly on the pile head with one head, while striking the pile at the chosen location, avoiding edges to prevent false reflections. Multiple strikes (10-20) at the same spot help confirm consistency and allows choosing the best impacts for averaging a clear average impact reflectogram for the spot.

This step is important for producing accurate, repeatable results. The putty acts as a coupling agent, preventing air gaps that could distort the waveform.

Step 4: Trigger setting Impact Sampling

Use the PET SamrtTrigger to reduce the chance of sampling noisy impacts. Sampling multiple strikes allows choosing only the good and clean impacts for the averaging function of the PET. Inconsistent waveforms may indicate issues with pile preparation, sensor placement, or pile top material. For difficult cases use proper filtering level, which smoothes noisy impacts, and use proper sharpening for better impact signal contrast. Do not over do it which can impair interpretation. If there is repetitive impact signal, the repetition marks tool can be used to identify it, The FFT standard function of the PET, can be used to analyse the location of the flaw causing it.

Step 5: Interpreting the Waveforms

After testing, analyze the waveforms for anomalies. Reflected signals reveal important information about the pile’s integrity, including:

• Bulges and cavities

• Cracks or fractures

• True pile length

Comparing these readings with expected pile profiles helps identify areas requiring further investigation or remediation. Understanding the waveforms is key to ensuring accurate assessment and maintaining safety standards.PET also support signal match function, which draws the pile profile. This can help to better understand the flaws of the pile. One also must understand the limitation of the Low Strain impact test, which can not see much beyond the first flaw, like a second flaw or a clear pile bottom reflection and length assessment. See this webinar on PET Analysis

Step 6: Documentation and Reporting

A thorough report should be compiled for each tested pile. Include details on pile preparation, sensor placement, equipment settings, and observed anomalies. Annotated waveforms should highlight any irregularities. Proper documentation supports regulatory compliance and provides a reference for future inspections. Use of the PileWave simulator from Piletest can also help demonstrate to the client, the flaw that been observed in the pile reflectogram. PileWave is available here.

Practical Considerations

Field engineers should focus on several practical considerations during PIT with PET. Consistent pile preparation, correct sensor setup, and uniform strikes are crucial for accurate results.. Attention to these details reduces errors and improves reliability.

Benefits of PIT with PET

PET offers significant advantages over traditional testing methods. It is non-destructive, allowing pile evaluation without excavation or removal. It provides real-time data and works with multiple pile materials. The method can detect internal voids, cracks, and diameter variations early, reducing the risk of structural failures. PET AIM for AI Measurement can help in supporting pile length assessment, which is a key parameter being requested by PIT clients.

Field Tips for Engineers

Field engineers can improve testing efficiency by following a structured approach. Maintain detailed logs for each pile, including software settings, sensor placement, and observations. Ensure pile heads are clean and flat before testing. Monitor strikes and waveforms for repeatability. These practices improve accuracy and confidence in the results.

Conclusion

PIT testing with PET is a reliable, non-destructive method for evaluating pile integrity. By following a structured process—pile preparation, equipment setup, impact testing, waveform analysis, and documentation—engineers can detect internal flaws early, reduce risk, and maintain compliance with design standards. With proper technique, PET provides valuable insights into pile conditions, ensuring safe and long-lasting foundation structures.

Frequently asked questions

How many strikes per pile are needed for accurate results?

10 to 20 strikes at the same location are generally sufficient to ensure enough repeatable clean waveforms.

Can PET be used on all pile types?

Yes, PET works with concrete, , and timber piles, though equipment settings may differ.

How important is pile head preparation?

Very important. A clean, flat surface ensures accurate contact and reduces signal distortion.

What defects can PET detect?

PET identifies voids, bulges, cracks, and changes in pile diameter.

Which software settings are most critical for PET?

Wave speed, gain, and filtering should be adjusted for the specific pile material and length.