LNG Vent Nozzle Selection Guide: Specifications and Application Considerations

Select an LNG vent nozzle by matching its material, connection, geometry, and pressure-temperature limits to the equipment and venting duty it will serve. Start with the process conditions and the approved vent-system design—not with a preferred nozzle size or a supplier’s standard configuration. A vent nozzle provides an outlet or connection for gas release, but it does not by itself determine whether the complete vent route is safe or adequately sized.

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This guide explains the specifications to prepare, the application questions to resolve, and the supplier details to verify before purchasing. LNG is commonly stored near its boiling point of approximately -162°C at near-atmospheric pressure, but actual conditions vary with pressure, composition, and process design. Treat that figure as context, not as a universal nozzle design temperature.

Key Takeaways

• Specify the nozzle for its actual service, including operating and design pressure, temperature, fluid phase, and connection requirements.
• Choose materials and fabrication details for the full temperature range, environmental exposure, and applicable project requirements.
• Confirm that the nozzle is compatible with the vent piping and the system’s approved dispersion, backpressure, and safety design.
• Give suppliers a defined technical data package so that quotations, drawings, and delivery estimates can be compared fairly.

Who This Guide Is For

This guide is intended for LNG station designers, EPC contractors, equipment manufacturers, maintenance teams, and procurement professionals evaluating a vent nozzle or nozzle assembly. It is relevant when specifying outlets on LNG storage and process equipment, or when replacing a component in an existing installation. The exact scope depends on the equipment design and the intended venting function.

Use this information for early selection and supplier discussions, then verify the final design through the responsible engineering team. A nozzle selection should not replace a relief-device assessment, vent-stack calculation, hazardous-area review, or project code check. Those tasks require the complete system context.

What an LNG Vent Nozzle Does

Basic function and system boundary

An LNG vent nozzle is a connection or outlet that allows gas or vapor to leave equipment and enter a defined vent route. Depending on the installation, it may connect to piping, a vent header, or a vertical vent arrangement. Its shape and orientation affect how it interfaces with surrounding equipment, but the nozzle alone does not establish the capacity or safe discharge location of the overall system.

Before specifying one, identify whether the service is routine venting, equipment depressurization, maintenance, or another defined operating condition. Do not assume that a process vent nozzle can also serve as a pressure-relief outlet. The system designer must determine the applicable function, flow case, and required safeguards.

Types, Materials, and Specification Options

Configuration and connection

Nozzles may differ in outlet direction, overall length, end preparation, flange or other connection, and integration with a vessel or piping spool. Selection depends on the mating component, available installation space, access for inspection, and the route required by the vent-system design. A drawing with interface dimensions is more useful than a product name alone.

Define the connection standard and size according to the project documents, and state whether the item is a standalone nozzle or part of an assembly. Where a flange is required, specify the relevant standard, pressure class, facing, and material requirements. Avoid mixing nominal pipe size, outside diameter, and actual bore in a purchase description.

Material and fabrication

Material selection must account for minimum design temperature, pressure, fluid exposure, environmental conditions, and the requirements applicable to the equipment. Stainless steel grades are often considered for cryogenic service, but no grade should be selected solely because it is commonly used elsewhere. Confirm suitability, material documentation, weld details, and any impact-testing or traceability requirements with the project engineer.

Also define fabrication and inspection expectations, such as weld configuration, surface condition, dimensional tolerances, and required inspection records. These details can affect compatibility and acceptance, but the requirements should come from the project specification rather than assumptions about a supplier’s standard product. Dongzhao can review the requested configuration and clarify which details are needed to assess manufacturability and quotation scope.

Application Matching and Key Specifications

Build a complete duty description

Start by recording the equipment served, the nozzle’s intended function, and the upstream and downstream interfaces. Provide normal operating conditions as well as design limits, including pressure and temperature, and identify whether the stream is expected to be gas, vapor, or potentially contain liquid. If conditions change during startup, shutdown, or an upset case, have the engineering team identify which cases govern the nozzle and connected system.

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For example, a project may identify an LNG-side design temperature of -196°C, but that number should be treated as a project-specific input—not as a standard requirement for every LNG vent nozzle. Likewise, the commonly cited LNG boiling point of approximately -162°C applies near atmospheric pressure and does not define the full design envelope. Always use the design basis approved for the specific installation.

Check interfaces and vent-system effects

Compare the nozzle’s bore and connection details with the mating pipe or equipment drawing, and check orientation, projection, clearance, and support needs. Ask the system designer to confirm the allowable pressure drop and any backpressure constraints for the complete vent path. Also review whether rain, debris, icing, or other site conditions need to be addressed through the system design without obstructing the required discharge path.

Do not select a nozzle diameter based only on the connected pipe’s nominal size or a visual comparison with an existing installation. Flow capacity depends on the complete system, including the flow case, fittings, piping length, and outlet arrangement. Where flow sizing is required, provide the governing data to the qualified engineer responsible for the vent calculation.

Buyer Selection Framework

Step-by-step review

1. Define the duty: Identify the equipment, service purpose, operating cases, and whether the requested item is a nozzle only or a larger assembly.
2. Confirm design conditions: Record operating and design pressure and temperature, fluid phase, and any relevant composition or environmental constraints.
3. Freeze the interfaces: Supply connection standards, dimensions, orientation, and current equipment or piping drawings.
4. Set quality requirements: State material, traceability, inspection, documentation, and project-code requirements explicitly.
5. Review the supplier’s documents: Check the quotation, datasheet, drawing, exceptions, and delivery scope before approval.

This sequence helps separate technical suitability from commercial comparison. A low price is difficult to evaluate if one quotation excludes documentation, special material requirements, or drawing approval. Ask suppliers to list assumptions and deviations so that the same scope is being compared.

Pricing, MOQ, and Lead Time

The price and delivery period for an LNG vent nozzle depend on the specified material, dimensions, connection, fabrication scope, inspection requirements, and order quantity. Custom geometry or project-specific documentation may require additional engineering and review. Minimum order quantity and lead time should therefore be confirmed against the actual configuration rather than assumed from a general product category.

For a useful quotation, submit a datasheet or marked-up drawing, target quantity, destination, requested delivery schedule, and documentation requirements. Ask whether the quoted lead time begins after technical approval, drawing approval, or order confirmation. This makes it easier to identify schedule assumptions before placing an order.

Supplier Evaluation Checklist

Evaluate a supplier on its ability to understand the service, respond to technical questions, and document the offered configuration—not simply on whether it lists a vent nozzle. Confirm that the supplier can review the specified material and interfaces, provide a controlled drawing for approval where required, and identify any exclusions. Request only the certifications and inspection records required by the project, and verify that they are included in the quotation.

• Can the supplier confirm the quoted scope and identify all technical assumptions?
• Are material, connection, dimensions, and design conditions clearly stated?
• Are inspection, traceability, and documentation requirements addressed?
• Are deviations, exclusions, MOQ, and lead-time conditions disclosed?
• Is there a clear process for resolving drawing comments before manufacture?

As a supplier, Dongzhao can support LNG station accessory sourcing by reviewing the requested nozzle configuration, interface information, and documentation scope for quotation. Provide the project requirements early so we can identify missing inputs and clarify whether the request is for a component or a broader assembly. Final suitability remains subject to the approved project design and applicable requirements.

Conclusion: How to Choose the Right LNG Vent Nozzle

The right LNG vent nozzle is the one that matches the approved duty, design conditions, materials, and equipment interfaces while fitting into a properly engineered vent system. Begin with the service and design basis, verify dimensions and connection standards, and document inspection and supply requirements before comparing quotations. Do not treat a nozzle as a substitute for system-level vent sizing or safety review.

Your next step is to prepare a datasheet or drawing package with the operating and design conditions, quantity, connection details, material requirements, and requested records. Send it to Dongzhao for a configuration and quotation review, and resolve technical comments before order approval. This process gives your engineering and procurement teams a clearer basis for selecting and sourcing the nozzle.

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