How to Plan and Procure a Cryogenic ISO Tank Container System

A request for “one 40 ft LNG tank” is not a complete project description. It assumes a format before the capacity, operating cycle and receiving-site arrangement are understood. Begin by identifying the intended application. One project may combine several of the applications below.

Application A — Transport and distribution

The tank is filled at one location, transported to another, unloaded and returned for refilling. The decisive inputs are the required quantity, verified payload, route and complete cycle time, not nominal litres alone.

Application B — Transport with temporary storage

The loaded container is delivered to the receiving location and remains there for several hours or days before unloading or exchange. This dwell time changes the number of containers needed in the operating fleet.

Application C — Stationary storage

One or more ISO tank containers remain at the operating site and provide temporary, medium-term or backup cryogenic storage. The site arrangement, connections, withdrawal method and safety systems must be engineered for the intended use.

Application D — Continuous gas supply

One or more containers supply a customer process. The refrigerated liquefied gas is withdrawn, vaporized where required, regulated to the required pressure and delivered to the customer’s equipment. Flow, pressure, operating hours and supply continuity become central project inputs.

Application E — Multi-container or container-bank system

Several containers are connected through an engineered manifold. They may operate simultaneously, sequentially or as duty-and-standby units. The manifold and operating logic form part of a complete system; they are not simply a set of hoses between containers.

Application F — Remote gas or energy supply

Cryogenic ISO tank containers can form part of a supply system for a factory, settlement, mine, power installation or another location without a gas pipeline. In an LNG “virtual pipeline,” LNG is transported to site, stored, vaporized and pressure-regulated before supply as natural gas. An LNG container does not directly generate electricity. If electricity is required, the vaporized gas must supply a suitable engine, turbine, generator or other energy-conversion equipment.

Application G — Temporary, emergency or peak-demand supply

The container system provides supply during maintenance, pipeline interruption, commissioning, construction, seasonal demand or an emergency. Deployment speed, existing site connections and the replacement-container schedule are especially important.

A project may combine several applications. The same LNG containers may transport LNG, remain at the receiving location as temporary storage and then supply vaporized natural gas to an industrial process.

State the exact refrigerated liquefied gas: LNG — Liquefied Natural Gas; LIN — Liquid Nitrogen; LOX — Liquid Oxygen; LAR — Liquid Argon; LH2 — Liquid Hydrogen; LHe — Liquid Helium; or another refrigerated liquefied gas.

When preparing an initial RFQ, estimate the project demand over a clearly defined period. Consider average consumption, peak demand, expected daily or seasonal variations, desired delivery frequency, and any required reserve or autonomy. State every figure with its unit and time basis—for example, tonnes per month or Nm³/h—so the required operating capacity can be assessed.

Quantities may be stated in tonnes, kilograms, litres or cubic metres of cryogenic liquid. Gas demand may be stated in Nm³/h or another clearly defined gas-flow reference. Energy applications may use daily or monthly consumption, kW, MW, kWh or MWh. If only gas flow or energy demand is known, CTT and the project engineers can convert it into an approximate quantity of cryogenic liquid, storage capacity and number of containers.

Every CTT cryogenic ISO tank container is intended as multimodal equipment. Road, rail and sea are not different tank categories that the buyer must choose between. The transport plan is still essential because the complete logistical cycle determines how often one container can deliver and therefore how many containers the operation may require.

To estimate how many tank containers a project will require, take the complete operating cycle into account rather than the journey time alone. Consider the distance between the filling and receiving locations; realistic loaded and empty-return times; border, customs, terminal, ferry and site-access delays; waiting, filling, documentation, release and unloading time; whether each container returns immediately or remains at site; and the actual number of operating days per month. This information will help CTT estimate how many tank containers your project may require.

The complete container cycle

1. Preparation for filling
2. Waiting and filling
3. Documentation and release
4. Loaded journey
5. Waiting at the receiving location
6. Unloading or gradual withdrawal
7. Empty return journey
8. Inspection and preparation for the next filling
9. Allowance for normal delays

Round upward, then assess the need for a reserve container.

A cryogenic ISO tank container can serve as relocatable on-site storage where a pipeline or permanent storage tank is unavailable, uneconomic, not yet installed or needed only for a limited period. Instead of transferring the cryogenic medium into another storage vessel, the delivered container can remain at the prepared site and supply the local operation directly through its approved connection points and suitable external equipment.

Practical uses

• Supplying remote industrial sites, mines, farms, communities or energy projects that do not have access to a gas pipeline.
• Providing LNG to an external vaporizer and then to a generator, boiler, burner, industrial process or local gas network.
• Supplying cryogenic industrial gases to production facilities, laboratories or other users without permanent bulk storage.
• Temporary supply for construction projects, commissioning, pilot plants, seasonal operations or facilities waiting for permanent infrastructure.
• Backup or emergency inventory during pipeline interruptions, maintenance, repairs or unusually high demand.
• A relocatable supply solution for projects that may later move to another site.

In a simple exchange arrangement, a filled container is delivered, connected at the prepared position and used until it reaches the agreed replacement level. It is then exchanged for a filled unit. Where the site and operating arrangement permit, a container may instead remain in position and be refilled. Two or more containers can be arranged so that one continues supplying the site while another is being exchanged or refilled.

For initial planning, consider the cryogenic medium, average and peak consumption, required operating time without another delivery, liquid or vapour withdrawal, required outlet pressure and flow, available site space, vehicle access and whether the service is continuous, temporary or backup. These inputs help determine the number of operating and reserve containers, exchange frequency and the external vaporization, pressure-regulation, manifold, monitoring or safety equipment required for the project.

The certified tank container itself remains unchanged. Supports, connections and all external equipment must be designed for the specific site and must use the container's approved connection points and operating limits. Transport approval does not by itself approve the complete stationary installation.

A bank of cryogenic ISO tank containers is not simply additional storage. Once several units are connected to a common system, they become a coupled pressure-and-flow network. The operating philosophy may use balanced parallel withdrawal, lead-and-lag sequencing or completely separate duty-and-standby trains. It must define which source is active, when another source joins, how pressure is controlled and how one container can be isolated without disturbing the rest of the system.

Technical facts that matter

• Parallel containers do not automatically empty evenly. Small differences in vessel pressure, liquid level, hose length, valve position or piping resistance can make one unit carry most of the flow while another contributes very little.
• More containers do not automatically mean more gas flow. The common header, vaporizer, pressure regulator or downstream connection may remain the limiting component.
• Ambient vaporizers lose capacity as ice accumulates. Their duty must be checked at the lowest design ambient temperature and for the longest expected peak withdrawal, not only at favourable daytime conditions.
• Trapped cryogenic liquid requires pressure relief. Liquid isolated between two closed valves can warm, expand and create a rapid pressure rise. Every blockable liquid section must have an engineered relief route.
• Automatic changeover needs stable control logic. Level, pressure and flow signals require validated setpoints, time delays and hysteresis so the system does not repeatedly switch between containers when demand fluctuates.
• Cross-flow must be prevented. A higher-pressure container must not unintentionally feed a lower-pressure unit. Header design, valve sequencing and non-return protection must be considered together.

System architecture and operating logic

Each container position should be treated as an independently controllable source, with appropriate isolation, connection, pressure and level indication, back-flow protection where required, and a safe method for depressurizing or purging the external connection before disconnection. The common liquid or vapour header must be sized for peak flow and acceptable pressure drop. Vaporizers and regulators may be arranged as duty, assist and standby trains so maintenance or icing does not remove the entire supply capacity.

The control sequence should define lead-container rotation, low-level changeover, pressure support, peak-demand assistance, isolation of a container being exchanged, alarm priorities and the safe state after loss of power or instrument air. Emergency shutdown should isolate the affected part of the external system without defeating pressure relief. Operators also need unambiguous valve identification and a controlled connection, leak-test, purge, cooldown, start-up and shutdown procedure.

Engineering design basis

A technical design should establish the required continuous and peak flow, peak duration, minimum delivery pressure, operating pressure band, turndown, redundancy target, permitted interruption, ambient design conditions, changeover criteria, instrumentation and communication signals, metering requirements, hazardous-area classification, relief and vent philosophy, maintenance bypasses and the intended operator. The complete manifold and control system is external to the certified tank containers and must use only their approved connections and operating limits. No modification of a certified CTT tank container is permitted.

A cryogenic container system can provide a practical supply route for remote industrial sites, communities, mines, construction projects, agricultural installations, power-generation sites and other locations without pipeline access. For LNG, the general flow is straightforward: certified containers are filled; transported to site; used as on-site LNG inventory; connected for withdrawal; and the LNG is vaporized, temperature- and pressure-regulated, then supplied to a process, boiler, burner, local network or generator. Empty containers are exchanged or refilled.

Provide the final gas use, average and peak hourly consumption, delivery pressure and temperature, operating hours, seasonal variation, required autonomy, permitted interruption, distance from the LNG source, available utilities and site area, staffing model, final connection and desired commissioning date.

CTT can use this information to assess whether its existing certified LNG tank container model is suitable and to advise on the indicative number of operating and reserve containers, on-site LNG inventory and exchange frequency. Vaporization, pressure regulation, manifold, monitoring and other auxiliary systems are separate from the certified tank container and must be defined as external project equipment. A quotation must clearly identify equipment supplied by CTT, equipment from another system integrator, customer-supplied equipment, civil works, installation, commissioning, permits and local approvals.

ISO tank containers may support planned maintenance, a pipeline shutdown, commissioning, seasonal peak demand, emergency interruption, temporary construction or industrial activity, or a trial operation before a permanent installation is complete.

State the cryogenic medium, normal and maximum flow, the time available for deployment, required operating duration, existing site connection and vaporization equipment, whether automatic operation and uninterrupted changeover are required, and how often replacement containers can arrive. The practical solution depends as much on site readiness and delivery planning as on container capacity.

Holding time and residence time are related, but they are not the same measurement. Holding time is a thermal-performance value determined from defined initial filling, temperature and pressure conditions. It describes the period before normal heat ingress raises the internal pressure to a specified limit under the stated calculation or test conditions. Residence time is the actual period for which the cryogenic medium remains inside the container during a particular transport, storage or supply operation.

Main influences

• The cryogenic medium. Each liquid has different thermodynamic properties, boiling behaviour and pressure response.
• Initial filling conditions. Starting liquid temperature, tank pressure, permitted filling level and available vapour space affect the pressure-rise margin.
• Heat ingress. Thermal performance depends on the insulation system, vacuum condition, internal supports, piping, valves and other potential heat-transfer paths.
• Ambient exposure. High or low ambient temperature, prolonged direct solar radiation, wind and changing weather can influence the external heat load, although they do not act directly on the cryogenic liquid through a properly insulated inner vessel.
• Operating activity. Filling, liquid or vapour withdrawal, pressure-building operation, connection of external equipment and repeated start-stop cycles change the actual pressure and inventory history.
• Real project dwell time. Transport delays, waiting, stationary storage, partial use and the exchange schedule determine actual residence time even when the container's technical holding-time capability is much longer.

How CTT reduces environmental influence

CTT cryogenic ISO tank containers are engineered to reduce heat ingress to a minimum through product-specific vacuum insulation, thermal barriers and carefully designed supports, piping and connections. The inner vessel is protected from direct weather exposure by the insulated double-wall construction. These measures reduce the effect of normal ambient changes and help preserve the cryogenic medium during long transport and storage periods. The exact insulation arrangement and approved operating envelope remain fixed for each certified CTT model.

Normal heat entering a closed cryogenic tank causes a small portion of the liquid to form vapour and gradually increases internal pressure. It does not mean that the refrigerated liquefied gas is immediately released. The medium remains contained until it is withdrawn or the pressure reaches the safety system's defined operating point.

These terms help a buyer read and compare proposals. The buyer does not need to calculate them.

Nominal capacity

The internal water volume of the tank.

Usable liquid capacity

The quantity that can be loaded after the permitted filling level for the selected cryogenic medium is applied.

Net payload

The actual mass of cryogenic medium transported after filling limits, density, tank tare and maximum gross mass are considered.

Tare mass

The mass of the empty tank container and permanently installed equipment.

Maximum gross mass

The maximum permitted combined mass of tank, equipment and loaded cryogenic medium.

Working pressure

The pressure range under which the tank normally operates.

Design pressure

The pressure basis used for vessel design and approval; it is not necessarily the normal operating pressure.

Heat influx

The heat entering the tank through the insulation system.

Holding time

The time from an established filling condition until heat influx raises pressure to a defined limit under stated conditions.

Residence time

The actual period for which the cryogenic medium remains inside the container during a specific transport, storage or supply operation.

Withdrawal rate

The rate at which liquid or vapour is removed from the container.

Vaporization capacity

The quantity of cryogenic liquid that can be converted into gas per unit of time.

Autonomy

The period during which available inventory can support demand without another delivery.

A clear quotation allows the buyer to understand what is being supplied, what assumptions were used and which work remains with others. At minimum, it should state the following.

• Selected cryogenic medium and intended application
• Specific existing certified CTT model offered
• Approved nominal capacity and verified net payload
• Certified tare and maximum gross mass
• Fixed working pressure and design pressure
• Approved insulation and thermal-performance data
• Holding-time conditions and stated assumptions
• Approved filling and withdrawal arrangement
• Fixed valve, piping and instrument configuration
• Type approval and third-party inspection basis
• Documentation, factory inspection and testing
• Warranty, spare parts and maintenance support
• Delivery schedule and any included services
• Exclusions, deviations and buyer-supplied work

For stationary or multi-container systems, the quotation should additionally identify the suggested number of operating and reserve units. Any manifold, vaporization, pressure regulation, metering, monitoring, emergency shutdown, civil works, site installation and commissioning must be shown as separate external system scope. None of that scope changes the certified tank container.

Compare like with like. Price and nominal litres do not reveal the number of units required, the operating capability or the work that has been excluded.

A lower tank price may not mean a lower project cost. Lower payload, slower turnaround, insufficient vaporization, missing equipment or unclear site responsibilities can increase the total number of containers and final operating cost.

Example 1 — LNG transport project

A company needs approximately 100 tonnes of LNG per month moved between locations 300 kilometres apart. CTT would use the verified LNG payload of its existing certified model together with average and peak demand, filling and unloading time, loaded and return journeys, customer storage, container dwell time, ambient conditions, delivery frequency and operational reserve. Only then can an indicative fleet be calculated; the example does not justify inventing a final number of containers.

Example 2 — Remote factory without a gas pipeline

A factory needs continuous natural-gas supply and provides average consumption, peak hourly flow, delivery pressure, operating hours, autonomy, site area, distance from the LNG source and commissioning date. CTT checks whether its existing certified LNG model is suitable and advises on operating and reserve units and exchange frequency. Storage connections, manifold, vaporization, pressure regulation, monitoring and control remain separate external system scope.

Example 3 — Stationary industrial-gas supply

An industrial site requires LIN, LOX or LAR and plans to use several exchangeable ISO tank containers. The site provides the exact cryogenic medium, average and peak consumption, liquid or gaseous withdrawal, pressure and flow, existing vaporizer, desired autonomy, connection arrangement and site layout. CTT confirms which existing certified model is suitable and advises on the number of containers and operating sequence. Connections and supporting equipment are engineered outside the tank container; the certified container remains unchanged.