
Problem: Failure to fully understand the P&ID (Piping and Instrumentation Diagram)
Solution: Thoroughly review and confirm the P&ID before starting pre-commissioning. Cross-check valve locations, instrument points, and system connections with as-built drawings to ensure correct interpretation.
Problem: Incorrect assessment of pigability (Bend Radius, Full-Bore Valves & Restrictions)
Solution: Ensure the pipeline design includes adequate bend radii and full-bore valves for pig passage. Perform pigging simulations to verify that pigs can traverse without blockage or damage.
Problem: Failure to verify and document internal pipeline dimensions (Gauging)
Solution: Perform detailed gauging of the pipeline after cleaning to verify internal dimensions and detect any deformations. Use appropriately sized gauging plates to ensure no obstructions remain that could restrict flow.
Problem: Inadequate flow rate control during Hydrotesting
Solution: Carefully control and monitor flow rates and pressure during hydrotesting. Follow established industry standards i.e. Design & Engineering Practice, API and or ASME for test pressure, duration, and flow rates based on the pipeline’s specifications.
Problem: Improper pipeline coating and insulation inspection
Solution: Inspect coatings and insulation before pre-commissioning. Use soft or coated pigs that minimize internal damage and avoid aggressive cleaning methods that could damage protective coatings.
Problem: Overlooking the impact of Valves
Solution: Ensure all valves in the pipeline, if any, are full-bore and installed according to specifications. Verify valve sizes and configurations to ensure smooth pig passage without restrictions.
Problem: Inadequate selection of pigging medium
Solution: Select the correct pigging medium i.e. water or air based on the pipeline’s design, cleaning requirements, and material compatibility. Perform trials if necessary to ensure effective medium choice.
Problem: Failure to consider pipeline profile (elevation changes ΔZ)
Solution: Map out the pipeline’s elevation changes and plan pigging, cleaning, and hydrotesting accordingly. Use air vents and low-point drains to prevent air pockets or water accumulation at high or low points where possible.
Problem: Ineffective dewatering and swabbing operations
Solution: Use efficient dewatering and swabbing techniques to remove all water post-hydrotest. Perform multiple swabbing runs to ensure that the pipeline is free of moisture and debris.
Problem: Inadequate drying of the pipeline
Solution: Use appropriate drying methods, such as nitrogen purging or drying pigs, to remove residual moisture. Monitor the pipeline’s dryness levels i.e. dew point temperature, to ensure it is fully prepared for operational use and free from corrosion risk. In most cases, the pipeline may have to be preserved with an inert gas i.e. N2 to maintain its dryness and prevent moisture ingress prior to the pipeline being made operational.
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