🧠 How to Assess the Integrity of an Unpiggable Subsea Pipeline
🔍 What Is an Unpiggable Pipeline?
An unpiggable pipeline is one that cannot accommodate traditional pigs due to design or access constraints. This is common in:
- Deepwater or subsea tiebacks
- Older pipelines without pig launchers
- Systems with small radius bends or diameter changes
⚠️ Key Risk: Without inline inspection, you may be blind to corrosion, deposits, or damage building up inside.
🛠️ How Can You Assess Them Without Pigging?
✅ 1. External Corrosion Direct Assessment (ECDA)
For onshore or nearshore segments: uses indirect inspection methods (e.g., CIPS, DCVG, soil resistivity).
👉 Try the ECDA / ICDA Assessment Tool to get a structured output.
✅ 2. Internal Corrosion Direct Assessment (ICDA)
Identifies where water or corrosive liquids are likely to collect inside a gas pipeline. Requires:
- Flow regime data
- Operating pressure/temperature
- Elevation profile
🛠 Built into our Corrosion Rate & Remaining Life Tool
✅ 3. Subsea ROV or Diver Inspection
Use:
- Ultrasonic wall thickness tools (UT)
- Magnetic flux leakage (MFL)
- Visual surveys of external coating
This is often combined with hydraulic profiling.
✅ 4. Pressure Drop & Hydraulic Behavior
Compare modeled vs. actual pressure losses. Significant deviation may indicate:
- Deposit buildup
- Flow restriction
- Internal damage
🔍 Use our Pipeline Pressure Drop Calculator to simulate expected losses.
🌊 Flow Assurance-Based Inspection Strategies
When pigs aren’t possible, flow assurance tools help assess internal risks. These include:
| Risk Type | Tool |
|---|---|
| Wax Buildup | Wax Deposition Predictor |
| Hydrate Formation | Hydrate Predictor |
| Liquid Holdup | Pipeline Liquid Holdup Calculator |
📈 What If I Can’t Inspect?
You can still manage pipeline risk by using:
🔧 Corrosion Rate Estimator
📉 MAOP Calculator – Reduce operating pressure if integrity is in doubt
🛠️ Fitness-for-Service Screening – Check if the pipeline can still be operated safely
✅ Conclusion
If your pipeline is unpiggable, you’re not without options. By using external assessments, flow modeling, and digital integrity tools, you can maintain confidence in your system without intrusive inspection.
📩 Need Help With an Unpiggable Pipeline?
Our team at Nonlinear Engineering provides both the tools and expert advice to support your integrity decisions.
👉 Contact Us to speak with a specialist.
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