Low-Strain Integrity Testing (PIT/SE) Checklist

Definition: Low-strain integrity testing (PIT/SE) guides field engineers through setup, signal quality verification, defect screening, and acceptance of cast-in-place or driven piles, excluding CSL/TIP methods.

What: field-ready process for PIT/SE on cast-in-place and driven piles.
Why: reduce risk of hidden defects and costly rework early.
How: optimize setup, signal-to-noise, screening, and acceptance documentation.
Interactive: tickable, commentable, exportable with QR code security.

Start Interactive
Checklist

Low-strain integrity testing (PIT/SE) verifies pile continuity and length using low-energy impact waves to evaluate cast-in-place and driven piles. Also known as pile integrity test, sonic echo test, or pulse echo test, this checklist focuses on test setup, signal quality, defect screening, and acceptance, while explicitly excluding CSL and TIP methods. You will configure equipment, prepare pile heads, select appropriate time windows from estimated wave speed, and execute consistent impacts to achieve reliable, repeatable traces. Guidance covers SNR improvement, stacking, filtering, and interpretation cues for toe echo timing, early reflections, and damping behavior. Acceptance outcomes are clearly classified with documentary evidence, file naming standards, and sign-off procedures. Use this interactive checklist to reduce rework, catch hidden defects early, and deliver traceable records that meet approved project specifications and authority requirements. Start in interactive mode to tick items, add comments, and export your record as PDF/Excel with a secure QR code.

This checklist streamlines PIT/SE practice from head preparation to acceptance, emphasizing signal quality, repeatability, and defensible interpretations. It reduces ambiguity in wave speed selection, time-window configuration, and gain settings, while standardizing documentary evidence such as photos, screenshots, calibration certificates, GPS timestamps, and reviewer sign-offs for each pile tested.
Technicians gain practical controls for coupling, impact energy, stacking, and filtering so toe echoes and early reflections are readable without saturation. Repeatability across circumferential positions is highlighted, enabling confident screening of necking, voids, bulges, length anomalies, and soft toes, with clear thresholds for retest, remark, or escalation when results remain inconclusive.
Project teams receive a consistent acceptance framework: Accept, Accept with remarks, Inconclusive, or Suspect, tied to measured timing, amplitude, and damping cues. Reporting guidance standardizes file naming, metadata capture, backup verification, and distribution, supporting transparent QA workflows and audit readiness per approved project specifications and authority requirements.
Interactive online checklist with tick, comment, and export features secured by QR code.

Pre-Test Setup

1. Confirm the current test plan, pile list, and any special instructions.
2. Inspect pile head; chip to sound concrete, remove laitance, and create a clean, flat area; unevenness ≤ 2 mm; capture close-up photos.
3. Mark test positions: ≥ 2 positions for small piles; four at 0°, 90°, 180°, 270° for ≥ 600 mm diameter; photo evidence of markings.
4. Estimate wave speed and toe time from design data; set time window ≥ 2.5× predicted two-way travel; record calculation and screenshot device window.

Equipment Verification

5. Verify PIT device calibration certificate (valid ≤ 12 months), firmware version, and serial number; attach certificate and device photo.
6. Check accelerometer/receiver and cables for damage; continuity within manufacturer limits; document resistance reading and photos of connectors.
7. Set sampling rate ≥ 20 kHz with anti-aliasing filter enabled; record filter settings; capture configuration screenshot.
8. Prepare hammer 0.5–1.0 kg with undamaged rubber tip; replace if wear > 2 mm; photograph hammer and tip condition.

Test Execution and Signal Quality

9. Mount or hold sensor firmly with coupling gel/tape; confirm baseline noise within ±0.02 m/s²; take setup photo and baseline screenshot.
10. Perform trial blows to tune gain so peak velocity 0.2–0.8 m/s without clipping; screenshot peak values and gain settings.
11. Record 6–10 consistent impacts per position; standard deviation of peak amplitude ≤ 15%; save stacked trace with GPS time.
12. Confirm time window covers beyond predicted toe arrival by ≥ 50%; verify no saturation; capture full-trace screenshot.
13. If SNR < 6 dB, improve coupling, adjust tip hardness, shield from wind, or reposition; re-test and document achieved SNR or reason.

Defect Screening and Analysis

14. Compare measured toe echo time with predicted; acceptance for known length: within ±10%; annotate deviations and save overlays.
15. Screen for early reflections before 0.7× predicted toe time; if amplitude > 25% of toe, flag potential necking/voids; add annotated screenshot.
16. Assess damping and waveform shape for bulges/soft toes; correlate across filters; record interpretation notes and filtered trace images.
17. Check repeatability across circumferential positions; confirm features recur in ≥ 2 positions; note any position-specific anomalies.

Acceptance and Documentation

18. Classify each pile: Accept, Accept with remarks, Inconclusive, or Suspect; record basis and references to trace images.
19. For inconclusive or suspect results, recommend additional investigation beyond low-strain PIT/SE per approved project specifications and authority requirements.
20. Apply file naming: project-pileID-date-position; back up to two locations; verify checksum match; attach directory screenshot.
21. Compile report: test plan, settings, wave speed assumptions, locations, annotated plots, results table; obtain reviewer signature and date.

Safety and Controls

22. Establish 1 m exclusion zone; brief team on hammer use; record toolbox talk with attendee signatures.
23. Verify safe access and edge protection on pile caps/platforms; no unprotected edges within 2 m; capture access photos.
24. Coordinate with site to pause nearby impact/vibration sources within 20 m during testing; log hold points and times.

Set up for reliable low-strain testing

Successful PIT/SE starts with head preparation and correct assumptions. A clean, flat, sound pile head reduces coupling losses and spurious reflections. Estimate wave speed from mix data, prior calibration piles, or back-analysis; then set a time window that comfortably captures the toe echo and any early reflections. Choose a hammer and tip that deliver repeatable, low-strain impacts without damaging the head or saturating the sensor. Configure sampling rate and filters to preserve phase and amplitude fidelity. Mark circumferential positions to cross-check repeatability. On congested sites, plan brief pauses in adjacent operations to limit vibration contamination. Document everything: serial numbers, settings, pile IDs, GPS timestamps, and photos of the setup. This discipline shortens troubleshooting and improves confidence in your interpretations, especially on variable soil profiles or mixed pile geometries, where damping and wave speed can change from location to location.

Ensure head flatness within 2 mm and remove loose material.
Set time window at least 2.5× predicted two-way travel.
Use hammer 0.5–1.0 kg with undamaged rubber tip.
Record device settings and capture configuration screenshots.
Plan testing when site vibration sources are paused.

Maximize signal quality and interpret with intent

Signal quality drives interpretation. Target consistent impacts and stack multiple traces to suppress random noise. If signal-to-noise is low, improve coupling, adjust gain, or change tip hardness. Confirm that toe arrival lies within the window without clipping, then scan for early reflections suggesting necking, voids, or construction anomalies. Compare traces around the circumference; genuine features tend to repeat, while local coupling issues do not. Use filtering judiciously—confirm any interpretation across at least two filter settings to avoid creating artifacts. For length-known piles, compare measured toe time to predicted values; large deviations merit caution. For unknown lengths, use consistent, high-quality toe echoes to estimate length, noting the assumed wave speed. When results remain ambiguous, classify as inconclusive and recommend further investigation beyond low-strain PIT/SE per approved project specifications and authority requirements.

Stack 6–10 consistent blows per position.
Aim for SNR ≥ 6 dB without signal clipping.
Confirm interpretations across multiple filter settings.
Look for features repeating at multiple positions.
Flag early reflections with annotated screenshots.

Acceptance, reporting, and traceable QA

Acceptance rests on repeatability, timing consistency, and the absence of strong early reflections. Classify each pile as Accept, Accept with remarks, Inconclusive, or Suspect. Tie every judgment to trace evidence: annotated plots, timing tables, and photos of the setup. Standardize file naming and maintain redundant backups to preserve chain-of-custody. Include assumptions for wave speed, filter settings, impact counts, and positions tested. Obtain reviewer sign-off and distribute to stakeholders per project protocols. If suspect or inconclusive, outline the reason and recommended next steps consistent with project specifications and authority requirements. Close out by exporting records to PDF/Excel and embedding a QR code for authentication so field and office teams can verify that published reports match the captured datasets.

Classify results with clear, evidence-based rationale.
Adopt consistent file naming and backup verification.
Include settings, assumptions, and positions in reports.
Secure reviewer sign-off and distribution logs.
Embed QR for authenticity and easy retrieval.

How to Use This PIT/SE Checklist On Site

Preparation: gather PIT device, accelerometer, cables, 0.5–1.0 kg hammer with rubber tip, coupling gel/tape, PPE, cleaning tools, and a tablet/phone for the interactive checklist.
Review the test plan, pile IDs, drawings, and any constraints. Estimate wave speed and initial time window from design data or previous calibration piles.
Open the interactive checklist, start a new session, and select the project and pile ID. Enable GPS timestamp and camera permissions for evidence capture.
Tick items as you prepare the head and equipment. Add comments on site conditions, instrument settings, and planned circumferential positions.
During testing, attach photos and screenshots of traces directly to the relevant checklist items. Flag anomalies for later review.
After each pile, review classification (Accept, Accept with remarks, Inconclusive, Suspect). Request internal review in-app if needed.
Export the completed record as PDF/Excel, including images and metadata. Share the file link and QR code with stakeholders.
Sign-off: obtain digital signatures, archive to the project drive with standardized naming, and verify backup integrity.

Call to Action

Aisha Khan AquaEngineerAisha

Jan 11, 2026

FAQ

Question: How many test locations and blows should I record per pile for PIT/SE?

For small-diameter piles, test at least two positions; for piles about 600 mm or larger, test four positions at 0°, 90°, 180°, and 270°. At each position, record a stack of 6–10 consistent impacts. This combination improves signal-to-noise, confirms repeatability, and helps distinguish genuine reflections from local coupling issues.

Question: What indicates a good PIT/SE signal, and how can I improve SNR?

A good signal has clear head motion, no clipping, and a toe echo within the capture window. Aim for peak velocity between roughly 0.2–0.8 m/s and SNR ≥ 6 dB. Improve SNR by ensuring firm sensor coupling, using an appropriate rubber tip, adjusting gain, shielding from wind, and pausing nearby impact activities.

Question: Which defects can low-strain PIT/SE detect, and what are its limits?

Low-strain PIT/SE is effective for detecting length anomalies, significant necking, voids, bulges, and soft toes when echoes are interpretable. It is less reliable for very small defects, complex geometry transitions, or highly damped piles in soft soils. When results are inconclusive, recommend further investigation per approved project specifications and authority requirements.

Question: How do I set the time window and wave speed assumptions?

Estimate wave speed from mix design, prior calibration piles, or literature ranges, then set a capture window at least 2.5 times the predicted two-way travel time to include the toe echo and early reflections. Document the assumed speed, any calibration basis, and screenshots of the configured window for traceability.

Question: What acceptance criteria should I apply to PIT/SE results?

Use evidence-based acceptance: consistent toe timing across positions, no strong early reflections, and repeatable waveforms. For known lengths, measured toe time should be close to the prediction. Classify results as Accept, Accept with remarks, Inconclusive, or Suspect, and document the basis per approved project specifications and authority requirements.