The Most Expensive Mistake in Oklahoma Plant Startups
Oklahoma has seen consistent activity in new gas processing plant construction and facility expansions over the past decade, particularly in the STACK and SCOOP plays in the Anadarko Basin. New compression stations, gas treating units, and NGL fractionation facilities have been coming online regularly.
Most of these projects budget carefully for construction, commissioning, and initial operations. A significant number skip or underbudget pre-commissioning chemical cleaning — and pay for it within the first six months of operation.
Pre-commissioning cleaning removes mill scale, construction debris, welding slag, pipe thread compound, hydrotest water residue, and fabrication oils from new piping, vessels, and heat exchangers before process fluids are introduced. None of these contaminants belong in an operating plant. All of them cause problems when they end up in catalysts, fouling heat exchangers at startup, or damaging rotating equipment.
Why Construction Debris Does Not Just Flush Out
A common assumption on new plant projects is that initial flushing with water or process fluid will clear out construction contamination. It does not.
Mill scale — the iron oxide layer that forms on the inside of steel pipe during manufacturing — does not flush out with water. It flakes off in service, travels downstream, and accumulates in heat exchanger tubes, control valve seats, and pump internals. In gas treating plants, it contributes to amine system fouling within weeks of startup.
Welding slag and fabrication residue are not water-soluble. Thread compound and cutting oils coat pipe surfaces and contaminate process fluid at startup. Hydrotest water left in low-point piping causes corrosion during the commissioning period if not properly dried and inhibited.
These are not hypothetical problems. They are documented causes of early heat exchanger fouling, catalyst deactivation, and rotating equipment damage in new Oklahoma plant startups.
The 4-Step Pre-Commissioning Cleaning Sequence
Step 1 — Flush
High-velocity water flushing removes loose construction debris, dirt, and water-soluble contamination. Flow velocity must be sufficient to achieve turbulent flow in all piping circuits — this is not a slow rinse. Flush outlets should be inspected to confirm debris removal before proceeding.
Step 2 — Chemical Cleaning (Pickle)
Inhibited acid circulation dissolves mill scale and iron oxide from piping and vessel internals. The inhibitor protects base metal while the acid attacks scale. Acid concentration, circulation time, and temperature are calculated based on system volume and estimated scale load.
For Oklahoma gas processing plants, this step typically uses inhibited hydrochloric acid or citric acid depending on system metallurgy and environmental considerations. Stainless steel and duplex alloy systems require different chemistry than standard carbon steel piping.
Step 3 — Passivation
After pickling, a passivation solution is circulated to form a protective oxide layer on cleaned metal surfaces. This layer prevents flash rusting and reduces the rate of corrosion during the commissioning period before process fluids are introduced.
Skipping passivation after pickling leaves freshly cleaned steel vulnerable to rapid surface rust formation. In Oklahoma’s humidity levels during summer commissioning windows, flash rusting can begin within hours on unpasivated surfaces.
Step 4 — Dry-Out or Nitrogen Purge
After passivation, systems that will not be immediately commissioned need to be dried and either nitrogen-blanketed or properly preserved. Residual moisture in passivated piping causes corrosion under preservation conditions and creates water contamination issues at startup.
Equipment Covered in Oklahoma Pre-Commissioning Programs
| Equipment Type | Primary Contaminants | Cleaning Method |
| Carbon steel process piping | Mill scale, welding slag, fabrication oils | Flush + inhibited acid pickle + passivation |
| Stainless / duplex piping | Mill scale, weld discoloration | Flush + citric acid + passivation |
| Shell-and-tube heat exchangers | Mill scale, thread compound, hydrotest residue | Chemical circulation through tube side and shell side separately |
| Pressure vessels | Welding slag, sand blast media, construction debris | Water flush + chemical circulation |
| Amine contactors and regenerators | Construction contamination + iron | Flush + light acid + passivation before amine charge |
How to Plan Pre-Commissioning Cleaning Into Your Project Schedule
Pre-commissioning cleaning is not a one-day activity. For a mid-size Oklahoma gas processing plant, a complete pre-commissioning program typically requires five to ten days depending on system volume, metallurgy mix, and number of isolated circuits.
It needs to be scheduled after hydrotest is complete and before any process fluids are introduced. On projects where schedule pressure pushes commissioning dates earlier, pre-commissioning cleaning is often the activity that gets compressed or skipped. That decision transfers contamination risk directly into the operating plant.
The contractor doing pre-commissioning work needs to be involved in planning early enough to review P&IDs, identify circuit isolation points, and calculate chemical volumes. Bringing in a cleaning contractor two weeks before startup and asking them to develop a pre-commissioning program on the fly produces poor results.
Rock Hill Industrial provides pre-commissioning chemical cleaning for new plant startups and facility expansions across Oklahoma. Contact us during the project planning phase, not the week before commissioning.
Related: Best Practices for Industrial Chemical Circulation System Maintenance
FAQ
What happens if pre-commissioning cleaning is skipped on a new Oklahoma plant?
The most common outcomes are early heat exchanger fouling within the first operating cycle, amine system contamination in gas treating units, control valve and instrument failures from debris, and pump seal damage from particulate. These issues show up within weeks to months of startup and require taking equipment offline to address.
Is pre-commissioning cleaning required by any Oklahoma regulation?
There is no single Oklahoma DEQ or state regulation that mandates pre-commissioning cleaning as a standalone requirement. However, API and ASME standards referenced in many project specifications include cleaning requirements, and process licensor warranties for catalytic units often require documentation of pre-commissioning cleaning as a condition of warranty coverage.
Can pre-commissioning cleaning be done system by system as construction completes?
Yes, and this is often the better approach on large projects. Cleaning individual piping circuits and equipment systems as they are mechanically complete allows construction and cleaning to run in parallel rather than sequentially, which reduces the total commissioning schedule. It requires more coordination but avoids the compressed schedule problem at project end.
What documentation should a pre-commissioning cleaning contractor provide?
As-completed cleaning records for each circuit or system, chemical volumes used, flush water discharge documentation for Oklahoma DEQ compliance, passivation verification, and waste disposal manifests. This documentation supports process licensor requirements and provides a baseline for future maintenance planning.
Written by the Rock Hill Industrial field team. Internal links: Chemical Circulation System Maintenance | Texas Chemical Cleaning Service | Contact RHI