Overview of the Planning and Pre-engineering Phase for Hot Nitrogen Plant Dry-Out Operations

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The plant dry-out operation is done in two phases. Planning and pre-engineering are completed during the first phase, while the use of hot nitrogen gas to complete the plant dry-out forms the second phase. A brief overview of the first phase of the processis sketched below to give an indication as to the scope, necessary safety regulations, communication processes, and equipment involved in a project of this nature.

Planning and Pre-engineering

In this example, we provide the nitrogen and handle the dry-out of a specific section of a chemical plant before the re-commissioning. During the pre-engineering phase, we divide the relevant systems into so-called “drying packs”. This enables us to streamline the plant dry-out process and to minimise time wastage on the parts that don’t require drying out. This process is completed in close collaboration with the plant personnel team. During this phase, we mark each pack to indicate the relevant vent, valve, and nitrogen injection positions among other important points.

Creating an Inert Environment with Hot Nitrogen

Once done, the operational part of the first phase commences for the purpose of system purging with hot nitrogen gas for moisture removal and to create an inert environment for the recommissioning of theplant. The process entails the introduction of hot nitrogen gas into the system through the usage of specialised vaporisation machinery. We, for instance, use a high-velocity diesel driven pump for the trust blowing and related processes. To ensure sufficient nitrogen liquid is available at all times, we have our portable liquid nitrogen storage tanks at the site. Our team ensures the availability and supply of the liquid nitrogen.

Safety is Always a Priority

Safety is always a priority, and we thus coordinate with the client team to ensure all regulatory requirements are met. We man the equipment 24/7, with the relevant operations’ technicians and shift supervision in place. To minimise the risk of misunderstandings, we communicate with the client personnel throughout and provide constant updates on the progress of the plant dry-out operations.

The Oleum Process & Pipeline Services (OPPS) personnel are properly trained in all safety aspects. We adhere to the safety regulations of the client, including undergoing inductions for such at the client site.  Our technicians are qualified to work with nitrogen gas and erect the necessary warning signs to inform the client personnel of the hazardous work in progress.

Auditing the Process

An audit trail is available because we measure the progress at predetermined end-points, using well-maintained and calibrated dew-point measuring devices. The client is given an estimate of how long the process takes. This estimate is based on our previous projects at similar plants. The client stays in overall control while our team provides the maximum assistance with tasks such as the control of valves, etc.


Machinery and equipment used during this phase include, amongst others, steam hoses, dew point meters, nitrogen gas pumps, vaporisation equipment, storage tanks, and appropriate site vehicles. We provide the client with a budget proposal that also details site requirements needed to perform the dry-out of the plant.

Experts You Can Trust

Years of experience, the usage of sophisticated equipment, trained and qualified personnel, and the strict adherence to industry accepted standards for plant dry-outs, make it possible for us to complete the project quickly and safely. View our services and get in touch for a quote or more information.

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