Nitrogen Drying Services
Dew Points Below -40°F. Coast to Coast.
Moisture in pipelines causes corrosion, hydrate plugs, instrument failures, and failed commissioning. NitroTech deploys high-flow nitrogen drying units with real-time dew point monitoring to dry your pipeline, vessel, or process system to specification — fast, documented, and done right.
The Science
What Is Dew Point — and Why Does It
Determine Your Commissioning Timeline?
Dew point is the temperature at which water vapor in a gas stream begins to condense into liquid. In pipelines and process equipment, moisture above specification is not a minor issue — it is a project-stopper.
Internal Corrosion
Even a thin film of condensed water on carbon steel pipe wall initiates electrochemical corrosion within hours. On new construction, moisture trapped during commissioning accelerates wall thinning before the line ever carries product. Nitrogen drying eliminates moisture before it can cause damage.
Hydrate Formation
Natural gas pipelines are highly susceptible to hydrate plug formation when free water is present at operating pressures. Hydrates can block a line completely within minutes and take days to remediate. Achieving a certified dew point before introducing gas eliminates this risk entirely.
Instrument & Valve Damage
Control valves, instrumentation, and pressure transmitters exposed to moist commissioning gas suffer premature wear, calibration drift, and seal degradation. Drying the system to spec before instrument commissioning protects capital equipment and extends service life.
Failed Pressure Tests
Hydrostatic pressure tests leave residual water throughout a pipeline system. If that water is not removed before gas commissioning, it contaminates the product stream and violates pipeline quality specs. Nitrogen drying after hydrotest is standard practice on every midstream and gathering system.
Why Nitrogen — Not Compressed Air?
Compressed air contains 78% nitrogen but also 21% oxygen and ambient moisture. Oxygen promotes oxidation and creates combustion risk in hydrocarbon systems. Nitrogen is inert, oxygen-free, and can be generated at dew points far below what any compressed air dryer can achieve — making it the only choice for sensitive pipeline commissioning.
Real-Time Dew Point Monitoring
NitroTech uses calibrated dew point analyzers at the outlet end of every drying operation. You receive continuous data throughout the job and a final dew point certificate when specification is confirmed — documentation your pipeline operator, owner, or regulatory agency requires.
Process
NitroTech Nitrogen Drying Process:
6 Steps to a Certified Dew Point
Every nitrogen drying job follows a disciplined process. Here is exactly how NitroTech executes it.
System Review & Connection Plan
NitroTech reviews P&IDs, pipeline dimensions, and elevation profiles to calculate nitrogen volume requirements, expected drying time, and connection points. Inlet connections are typically made at pig launcher, valve inlets, or flanged taps. Outlet connections are established at the far-end pig receiver or drain valves. A pre-job safety review covers all isolation and venting requirements.
Initial Sweep & Liquid Removal
Before drying can begin, bulk liquids must be removed. NitroTech initiates a high-velocity nitrogen sweep to push standing water, hydrotest fluid, or process residuals through the system to outlet drains or collection points. Foam pigs or gel pigs may be used on large-diameter lines to maximize liquid displacement efficiency. This phase continues until outlet flow shows no visible liquid carry-over.
Continuous Nitrogen Drying Flow
With bulk liquids displaced, NitroTech transitions to sustained drying flow. Dry nitrogen — generated at a dew point of -40°F to -60°F at the unit — flows continuously through the system, picking up residual moisture from pipe walls, low spots, welds, and fittings. Flow rate is calibrated to the pipeline volume and target dew point to optimize nitrogen consumption and drying time. Our field supervisors monitor inlet pressure, flow rate, and outlet dew point throughout this phase.
Dew Point Trending & Hold Confirmation
As drying progresses, the outlet dew point reading drops steadily. NitroTech tracks this trend in real time using calibrated dew point analyzers. When the outlet dew point approaches the target specification (typically -40°F or as specified in the commissioning plan), we hold the system at low positive nitrogen pressure and monitor for dew point stability. A stable dew point reading confirms that residual moisture has been fully displaced from the system.
Nitrogen Blanket & Positive Pressure Hold
Once dew point spec is confirmed, NitroTech pressurizes the system to a low positive pressure (typically 5–15 psig) with dry nitrogen. This nitrogen blanket prevents atmospheric moisture re-entry and protects the system during the transition from drying completion to mechanical tie-in, final inspection, or gas introduction. We coordinate directly with your commissioning team on hold pressure and handoff timing.
Final Verification & Handoff
Every NitroTech drying job concludes with verified specification achievement and an operator-led handoff to your project team. It is delivered digitally the same day the job is complete.
Applications
When Is Nitrogen Drying
Required?
Nitrogen drying is a code requirement on many pipeline systems and a best-practice standard on virtually all others. These are the most common scenarios where NitroTech is mobilized.
Post-Hydrotest Drying
The most common application. After a hydrostatic pressure test, thousands of gallons of water must be removed from the pipeline before gas introduction. Nitrogen drying after hydrotest is required by most pipeline operators and is standard practice on all FERC-regulated and DOT-regulated systems.
New Pipeline Commissioning
New construction pipelines accumulate moisture from mill scale, fabrication, and exposure during construction. Drying to spec before first gas introduction prevents contamination of the initial product stream and protects new pipeline infrastructure from day one.
Vessel & Heat Exchanger Turnarounds
Pressure vessels and heat exchangers opened during turnaround maintenance are exposed to atmospheric moisture. Before restart, nitrogen drying returns the vessel to a moisture-free condition, protecting catalyst beds, heat transfer surfaces, and downstream instrumentation from damage during startup.
Gathering System Tie-Ins
When new well laterals or gathering lines are tied into an existing system, the new segment must be dried before opening the tie-in valve. Introducing a wet lateral into a dry operating system contaminates the entire header and can trigger hydrate events downstream.
LNG and High-Pressure Gas Systems
LNG facilities, CNG compression stations, and high-pressure transmission lines require ultra-low dew points — sometimes below -60°F (-51°C). NitroTech has the high-flow, high-purity nitrogen generation equipment to meet these demanding specifications.
Offshore and Subsea Systems
Offshore pipelines and subsea flowlines operating at high pressures and low ambient temperatures are especially vulnerable to hydrate formation. Nitrogen drying before commissioning is standard procedure and is typically specified in the pipeline operating agreement.
Capabilities
NitroTech Drying Equipment Specifications
FAQ
Nitrogen Drying Common Questions
What dew point can nitrogen drying achieve?
Nitrogen drying can achieve dew points below -40°F (-40°C) and in demanding applications as low as -60°F (-51°C). This is far beyond what compressed air dryers can achieve and meets the most stringent pipeline commissioning specifications including ASME B31.8 and operator-specific requirements.
How long does nitrogen drying take for a pipeline?
Drying time depends on pipeline length, diameter, initial moisture content, ambient temperature, and target dew point. A typical 2-mile, 8-inch pipeline section can be dried to -40°F in 4–8 hours. Larger systems (20+ miles, 16–24" diameter) may require 16–36 hours. NitroTech provides time estimates based on your specific pipeline geometry and target specification before mobilization.
Can you dry pipelines and vessels at the same time?
Yes. NitroTech routinely performs integrated drying campaigns covering multiple segments, connected vessels, pig launchers, receivers, and process skids in a single mobilization. We coordinate the drying sequence to maximize efficiency and minimize your overall commissioning timeline.
What documentation do I receive after nitrogen drying?
Every job includes: verified specification achievement confirmed by the field supervisor and handed off to your project team for the dew point analyzer, and a job completion report. Documentation is delivered digitally the same day.
Does NitroTech perform pigging before or after nitrogen drying?
Both. NitroTech uses nitrogen to propel foam pigs or gel pigs to displace bulk liquids as the first step in the drying process. In some cases, multiple pig passes are performed before transitioning to continuous drying flow. We coordinate pig selection, launcher/receiver setup, and pig tracking as part of the integrated service.
Need a Pipeline Dried to Spec?
NitroTech Mobilizes Fast.
Tell us your pipeline dimensions, target dew point, and project location. We'll give you an estimated timeline and quote within hours — not days.
Related Resources
Part of the HydroTech Family
Need Hydrostatic Testing Too?
NitroTech Rentals is part of the HydroTech Testing family of companies. If your project also requires hydrostatic pressure testing services, our sister company specializes in exactly that — with the same documentation standards and field experience you get from NitroTech.
hydrotechtesting.com
Configured for Each Project — Not a One-Size Rating
NitroTech systems are configured for high-pressure nitrogen applications, with project-specific operating pressures determined by the service type, equipment package, and jobsite requirements. Select systems may support up to 6,500 PSI capability, while many drying, purging, and commissioning applications operate at lower project-specific pressure ranges. Final pressure, flow, and volume requirements should be confirmed during project planning.
Standards & References Commonly Used in Pipeline Projects
Project requirements vary by system, operator, jurisdiction, and application. NitroTech recommends confirming all project-specific requirements with the operator, engineer of record, applicable authority, and relevant project specifications. Commonly referenced standards and regulatory frameworks include:
- PHMSA pipeline safety regulations ↗
- 49 CFR Part 192 for gas pipeline systems ↗
- 49 CFR Part 195 for hazardous liquid pipeline systems ↗
- ASME B31.4 — pipeline transportation systems for liquids and slurries ↗
- ASME B31.8 — gas transmission and distribution piping systems ↗
- OSHA jobsite safety requirements ↗
- Operator-specific procedures and project specifications
Linked references go to the official regulator or standards body. Always confirm the current edition with the relevant authority.