Vacuum-jacketed piping is not governed by one universal standard. For many industrial projects, ASME B31.3 defines the design and fabrication basis for the process piping, while the European Pressure Equipment Directive 2014/68/EU establishes legal conformity requirements for pressure equipment placed on the EU market. At HL Cryogenics, we therefore begin every Vacuum Insulated Pipe project by identifying the governing code, design pressure, design temperature, fluid, piping category, inspection level, and certification scope before detailed engineering starts. ASME B31.3 addresses matters such as allowable stresses, material suitability, pressure design, fabrication, welding, examination, and pressure testing for process piping. PED takes a different approach: pressure equipment is classified according to parameters such as maximum allowable pressure, nominal diameter or volume, and fluid group, after which the appropriate conformity assessment route is determined. For a cryogenic transfer system, the pressure-retaining inner pipe is normally the principal process boundary, while the vacuum jacket serves a thermal-insulation function. Nevertheless, its mechanical design, fabrication, venting, and credible pressure conditions must also be evaluated as part of the complete assembly.
Phase Separator
Vacuum Insulated Pipe
Vacuum Insulated Flexible Hose
Vacuum Insulated Shut-off Valve
Table of Contents
1. Material Selection, Welding, and Examination Under Cryogenic Service
2. Vacuum Insulation Performance Must Be Engineered Separately from Pressure Code Compliance
3. International Requirements Vary by Region and Cryogenic Application
4. Procurement Should Confirm Code Scope Before the First Drawing Is Released
● Material Selection, Welding, and Examination Under Cryogenic Service
Compliance becomes more demanding when the process temperature falls to liquid nitrogen, oxygen, argon, LNG, hydrogen, or helium conditions. Materials must retain adequate toughness at the minimum design temperature, and weld procedures must be suitable for both the selected stainless-steel grade and the required code. We commonly use austenitic stainless steels in cryogenic pipe construction because they maintain useful ductility at very low temperature, but material selection cannot be reduced to temperature alone. Pressure, corrosion allowance, cleanliness, cyclic operation, customer specification, and connection design must also be considered. Under ASME B31.3, the required examination depends on the piping service and project specification; radiographic testing, liquid penetrant testing, visual examination, and pressure testing may all form part of the inspection plan. PED projects additionally require traceability, material documentation, qualified joining procedures, and conformity assessment appropriate to the equipment category. At HL Cryogenics, we coordinate material certificates, welding documentation, NDE records, helium leak testing, and final inspection as one package. This is particularly important for Vacuum Insulated Valve assemblies and Vacuum Insulated Flexible Hose connections, where several pressure boundaries and welded interfaces may be concentrated within a small installation envelope.
● Vacuum Insulation Performance Must Be Engineered Separately from Pressure Code Compliance
Meeting a pressure code does not automatically guarantee good cryogenic performance. A Vacuum Insulated Pipe can be mechanically compliant yet still perform poorly if heat leak, vacuum stability, thermal contraction, or joint design is not properly controlled. We therefore evaluate the cryogenic and mechanical design together. Heat enters the inner pipe through conduction across supports and connections, radiation across the annular space, and residual-gas conduction if the vacuum deteriorates. High-vacuum insulation and multilayer insulation are used to reduce these loads, while supports must restrain the inner pipe without creating excessive thermal bridges. Long cryogenic pipe runs also require consideration of contraction from ambient temperature to cryogenic service, together with anchor loads, flexibility, and equipment nozzle limits. Where a distributed network requires centralized vacuum maintenance, a Dynamic Vacuum Pump System can connect selected vacuum chambers to pumps, gauges, valves, and monitoring points to support long-term vacuum integrity. This does not replace sound vacuum-jacket construction; it is an additional system solution for applications where access, network size, or maintenance philosophy justifies it. The same engineering principle applies to a cryogenic hose or Mini Tank: pressure compliance and thermal performance must both be verified.
● International Requirements Vary by Region and Cryogenic Application
The applicable compliance route depends strongly on where the system will be installed and how it will be used. A liquid nitrogen system for a semiconductor facility in East Asia may focus heavily on cleanliness, phase stability, terminal pressure, and installation interfaces, while an industrial gas plant in Europe may require CE marking under PED together with detailed technical documentation and conformity assessment. LNG infrastructure in Southeast Asia can combine ASME-based piping requirements with owner specifications, local statutory rules, and project-specific inspection plans. Hydrogen projects in the Middle East may introduce additional requirements for material compatibility, hazardous-area interfaces, leak control, and owner-approved specifications. At HL Cryogenics, we manufacture within our applicable ASME, CE/PED, and ISO certification and compliance capabilities, with the precise scope confirmed for each project. A realistic example is a long LN2 distribution line where the pressure design satisfies the governing code, but the calculated terminal pressure approaches the saturation condition after frictional and elevation losses. The engineering response is not simply to increase wall thickness; it may require a larger pipe size, revised routing, a Vacuum Insulated Phase Separator near the point of use, or a different operating-pressure strategy to maintain stable liquid delivery.
● Procurement Should Confirm Code Scope Before the First Drawing Is Released
For EPC contractors and procurement teams, the most expensive compliance problems usually begin with an incomplete specification rather than with fabrication. Before we release a Vacuum Insulated Pipe system for production, we need the cryogenic medium, operating and design pressure, operating and design temperature, required flow, line sizes, routing, connection standard, applicable code, cleaning requirement, NDE requirement, documentation package, and certification expectations. The same applies to Vacuum Insulated Valves, flexible connections, phase-management equipment, and supporting accessories. It is also important to distinguish between a code requirement, a legal requirement, and an owner specification. ASME B31.3 may define the piping design basis, PED may establish the legal route for EU pressure equipment, and the customer may add stricter welding, oxygen-cleaning, documentation, or inspection requirements. At HL Cryogenics, we prefer to resolve these interfaces during quotation and design review rather than after manufacturing has started. That approach reduces technical changes, avoids unnecessary cost, and gives the owner a clearer compliance path. If your project involves a cryogenic transfer system, liquid nitrogen system, LNG line, or other vacuum-insulated network, our engineering team can review the applicable requirements and help define an appropriate manufacturing and documentation scope.
● FAQS
Since 1992, HL Cryogenics has specialized in the design and manufacturing of high-vacuum insulated cryogenic piping systems and related support equipment, tailored to meet diverse customer needs. We hold ASME, CE, and ISO 9001 certifications, and have provided products and services to many well-known international enterprises. Our team is sincere, responsible, and committed to excellence in every project we undertake.
Vacuum Insulated/Jacketed Pipe
Vacuum Insulated/Jacketed Flexible Hose
Phase Separator / Vapor Vent
Vacuum Insulated (Pneumatic) Shut-off Valve
Vacuum Insulated Check Valve
Vacuum Insulated Regulating Valve
Vacuum Insulated Connectors for Cold Boxes & Containers
MBE Liquid Nitrogen Cooling Systems
Other cryogenic support equipment related to VI piping — including but not limited to safety relief valve groups, liquid level gauges, thermometers, pressure gauges, vacuum gauges, and electric control boxes.
We are happy to accommodate orders of any size — from single units to large-scale projects.
HL Cryogenics' Vacuum Insulated Pipe (VIP) is manufactured in accordance with the ASME B31.3 Pressure Piping Code as our standard.
HL Cryogenics is a specialized vacuum equipment manufacturer, sourcing all raw materials exclusively from qualified suppliers. We can procure materials that meet specific standards and requirements as requested by customers. Our typical material selection includes ASTM/ASME 300 Stainless Steel with surface treatments such as acid pickling, mechanical polishing, bright annealing, and electro polishing.
The size and design pressure of the inner pipe are determined according to the customer's requirements. The size of the outer pipe follows HL Cryogenics' standard specifications, unless otherwise specified by the customer.
Compared with conventional piping insulation, the static vacuum system provides superior thermal insulation, reducing gasification losses for customers. It is also more cost-effective than a dynamic VI system, lowering the initial investment required for projects.
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Post time: Oct-16-2026
