Cryogenic test

Conditions under which gases are liquid at very low temperatures, usually below −150 °C.

A test that verifies whether a test object (e.g., valves or swivels) continues to function correctly at low temperatures and meets requirements for operability and internal/external leak tightness, both during cooling and afterwards, and often also after returning to room temperature.

Low temperatures cause shrinkage, stresses, and brittle behavior, and reduce the elasticity of elastomers; without verification, this can lead to higher operating forces, seizing parts, and leaks.

Depending on the standard and application. Often −196 °C (LN₂); other setpoints may apply for LNG, LOX, or LH₂.

Yes. Usually a pre-test at ambient, then the cryophase and a short final test at room temperature.

ISO 28921‑1 (production testing), ISO 28921‑2 (type approval), BS 6364 and Shell MESC SPE 77/200 and 77/306.

Custom procedures are possible if they are documented in advance.

Often the end user determines the standard. Deviating or additional requirements can be recorded in a project-specific test procedure, including setpoint, cooling rate, number of cycles, and leakage limits.

Generally yes. ITIS is an ISO 17025 accredited testing laboratory and thus a conformity assessment body (CAB).

As an independent organization, we assess whether products, processes, persons, or services comply with legislation, standards, or specifications. Accreditation increases trust and international acceptance; the final acceptance lies with the customer/authority.

Datasheet (DN/NPS, Class/PN, materials), drawing/BoM, sealing materials, standard/criteria, operation method (manual/gear/actuator), test medium, and any project specifications (purity, O₂ compatibility).

Yes. Test objects that need to be tested under cryogenic conditions must be completely free of: dirt, grease, oil, moisture. For (liquid) oxygen applications, additional cleaning and inspection requirements often apply.

Not always. With screw or clamp adapters, testing can sometimes be done without welding. Whether this is safe mainly depends on the test pressure (and additionally on size/weight and temperature).

Note: adapters bring additional risks (dislodging, leaks). For higher pressures or heavier/cryogenic tests, we therefore recommend welded test flanges as the safest and most reliable solution. It remains a customized approach; contact us for the conditions per test.

Depending on the product, standard, and test objective.

Often: thermocouples at fixed measuring points with data logging, pressure sensors, helium mass spectrometer for external leakage, flow meters for seat leakage, and torque/force sensors for operation.

Standards can specify the number of measuring points, stabilization criteria, and accuracies; all instruments are calibrated and traceable.

Yes, provided the method falls within our scope. The current scope is available at the RvA; upon request, we will send the link or the certificate. Tests outside the scope are conducted according to the same procedures; the reporting is then not accredited.

Setpoint according to standard/customer requirement; controlled cooling with cold, evaporated nitrogen gas or LN₂; continuous temperature monitoring at measuring points to start as soon as all points have stabilized within tolerance.

Until all prescribed measurement points reach the target temperature and fall within the stabilization criteria; duration depends, among other things, on the setpoint, standard, but especially the weight of the test object.

Any setpoint below room temperature down to −196 °C (LN₂). Examples: −162 °C (LNG) and −183 °C (LOX).

External: helium (pure or mixture) with mass spectrometer. Internal: usually dry nitrogen (N₂); around −196 °C we use helium as a medium because nitrogen can condense. Other media upon consultation.

At a fixed pressure difference and flow direction, with a calibrated flow meter. Comparison with standard limit or pre-agreed limit.

Yes, often prescribed. We measure torque or force under specified conditions and check against standard or customer limits.

Depending on the standard and configuration; usually multiple cycles.

Specification for low-temperature/cryoservice, including requirements for extended bonnet below −50 °C (vapour space), production and FE testing with leak limits, and reporting/marking.

British standard for cryogenic valves (−50 °C to −196 °C), including requirements for extended bonnet/gland, orientation requirements for the spindle, cycles and leak criteria for metal/soft seats, with reporting and marking.

Pre-test at ambient, controlled cooling and stabilizing, low-pressure seat at low T, external leakage check with helium, functional cycles and torque measurement, then high-pressure seat in steps up to CWP and a short final test at ambient.

Type approval between −50 °C and −196 °C with LN₂ or cooled gas; representative valve from the size range, fixed cycles and measurements on operating torque, seat and external leakage, plus full reporting.

Thresholds for internal/external leakage and requirements for operability/operating moment; exact values are stated in the standard or project specification.

This is recorded as ‘non-compliant’ in the test report according to the applicable customer requirements and/or standard. The valve has thereby proven functional for the intended operating or design conditions. A retest is often only possible after corrective measures, for example a technical modification such as adjusting tolerances, followed by a full retest according to the same test procedure.

Often yes, to determine lasting effects (e.g. cold deformation).

Austenitic stainless steels and nickel alloys generally perform well. Ferritic/duplex steel grades and certain cast qualities require extra attention; check impact toughness and minimum design temperature.

Seats: PTFE/filled PTFE low moments; PCTFE dimensionally stable to very low temperatures and suitable at higher pressures; PEEK limited.

Hard seats: graphite or metal. Elastomers lose elasticity at low temperatures and are often unsuitable as a primary seal.

A P-T diagram is a chart or table that shows the maximum allowable pressure (P) a valve or the used material can have at a certain temperature (T). It is the basis for assessing whether a valve is suitable for your design and operating conditions.

Briefly explained

• Purpose: determining the pressure rating at the operating temperature (derating at higher T, brittleness risk at low T).
• Source: manufacturer data or standards (including ASME B16.34, EN 12516) per material (e.g. WCB, CF8M), pressure class (Class/PN) and connection.
• Components: separate limits can apply for body/bonnet, bolts/flanges, seals and seats (PTFE, elastomer, graphite). The lowest limit determines the overall rating.
• Media influence: some tables distinguish media(groups) and corrosion/impact allowances.

How do you use it?

1. Select the material, pressure class and connection type of the valve.
2. Locate the operating temperature on the T-axis and read the corresponding pressure.
3. Check additional limits for seat/packing (soft seats often have lower T limits).
4. Include safety margins and standard/customer requirements; the lowest of all subcomponents is decisive.
5. If in doubt: always follow the manufacturer table for the specific type/serial number.

Important notes

• Values are material- and standard-specific; do not use generic numbers.
• High temperature ⇒ pressure rating decreases (derating).
• Low temperature ⇒ watch toughness and impact requirements (brittle fracture).
• Test pressure ≠ operating pressure: hydrotest/pneumatic tests follow separate rules and often temporarily exceed the operating rating under controlled conditions.

To keep the packing out of the cold zone. This reduces the risk of brittleness of a stem seal, ice formation, and higher operating torques, while allowing space for insulation and good operability. Length and design follow the applicable standard or customer requirement, such as ISO 28921, BS 6364, or Shell SPE 77/200.

Guideline: the extension must be long enough to keep the spindle packing at a temperature within the range of the packing material.

Yes. Main risks: O₂ displacement by evaporated LN₂, frostbite, brittleness of materials, and pressure build-up due to freezing.

We limit this with bunkers, ventilation and O₂ monitoring, shielding/interlocks, PPE, work instructions, and emergency procedures; only trained personnel conduct testing.

Yes, via the ITIS Cloud Portal (secure livestream). On-site witnessing by arrangement.

That is difficult to predict without additional information. The duration largely depends on the mass and internal volume of the test object, test temperature and temperature profile, standard or procedure, the number of thermal cycles, and the test pressure(s). Heating up and controlled cooling usually take the most time.

That depends on the same factors. For a targeted quote, we would like to receive: product type, weight and dimensions, setpoint(s), standard or procedure, number of cycles, test pressure(s) and the internal volume.

Preferred order where allowed: first cryo, then hydro. If hydro is required beforehand, then strictly follow: draining and operating, long-term vacuum drying (possibly with dry N₂ purge), visual cleaning/inspection, where practical reassemble seals dry, verify dew point and only then cryo. Hydrostatic pressure can force water into capillaries; complete removal is difficult.

Yes. Due to shrinkage, increased friction, and material behavior, design faults and contaminants become apparent quickly; rejection rates are therefore relatively high.

Causes: residual water/oil/grease, non-qualified components (soft seats, gaskets, stem seals, bearings), unsuitable “low-temp” lubricants, tolerance/alignment issues, and insufficient conditioning.

Approach: test clean, dry, oil-free; dry/purge to low dew point; choose demonstrably cryo-suitable materials and lubricants with datasheet; ensure gentle cooling strategy and sufficient soaking time; component or mock-up prequalification.

Type test: a design qualification at low or cryogenic temperature of one representative sample from a design family; the approval applies to sizes and pressure classes within that family, examples: ISO 28921-2, BS6364.

Production test: a sample of a valve from a batch to check whether the delivered production meets the specified requirements, examples: ISO 28921-1, Shell 77/200.

A type test is often prescribed for a new or modified design, new size or pressure class, new materials, or changed sealing materials. Purpose: to qualify the design for the entire design family.

Choose a production test for series or project deliveries to verify batch conformity (sample or 100%, depending on standard/customer requirement) and for pre-shipment inspections.