Direct Spring-Loaded Safety Valves
Spring-loaded safety valves engineered from set pressure to final documentation.
For industrial engineers, OEMs, EPC teams and procurement. HHSV spring-loaded products cover low-lift, full-lift, lever, twin-spring, threaded, angle, high-temperature/high-pressure and selected balanced-bellows configurations. Exact suitability is confirmed at model level.
Selection Basis
Mechanism first. Configuration second. Service limits verified last.
How It Works
A calibrated spring supplies the closing force; process pressure supplies the opening force.
The set point is created by spring compression acting through the spindle onto the disc. Pressure at the inlet acts on the seating area. As the protected system reaches the valve’s set condition, opening forces overcome the effective closing force; the disc lifts and relieves capacity. As pressure falls, spring force again dominates and the disc reseats. The exact lift, overpressure and blowdown behavior depends on the model and applicable standard – not on the category name alone.
01
Closed
Spring preload holds the disc on the nozzle/seat during normal operation.
02
Approaching set
Inlet pressure increases the opening force; stable operating margin matters.
03
Relieving
The model-specific disc/nozzle geometry produces the required lift and discharge path.
04
Reseating
Falling process pressure allows spring force to close the valve at its model-specific blowdown condition.
Construction
Common architecture, model-specific details.
Body & inlet nozzle
Pressure boundary and flow entrance; connection and material are series specific.
Disc & seat
Create the pressure seal and control the initial opening interface.
Spindle / stem & guide
Transmit spring force and maintain moving-part alignment.
Spring & spring washers
Provide calibrated closing force; range and material depend on the model.
Adjusting screw / cap
Used to establish spring compression and protect the setting mechanism.
Optional lever, bellows & rings
Lever, balancing bellows and blowdown-adjusting elements appear only on applicable constructions.
Configuration Map
Organize by configuration without turning each feature into a new valve family.
A single spring-loaded model may combine several labels – for example full lift + lever + angle body + high-temperature material. The final model is selected from the combined service and compliance requirements.
Full Lift
For product constructions intended to achieve larger lift/capacity; confirm the exact rated area and discharge basis for the model.
Low Lift
For model families with limited lift; includes threaded, enclosed and lever/spanner configurations in the catalog.
Twin / Duplex Spring
Uses a duplex/twin spring arrangement. Treat spring arrangement as a configuration, not a separate pressure-rating claim.
Lever Operated
Manual lifting lever/spanner is available on applicable spring-loaded constructions for specified service and code requirements.
Angle Type
Angle body/flow arrangements can combine with low/full lift and lever configurations; connection dimensions remain model specific.
Threaded / Compact
Includes HFA21 and HFXY/HFBPXYL compact spring-relief records; exact inlet/outlet connection style remains series-specific.
High Temperature & High Pressure
Includes HFA48SB, HFGS high-temperature and HFGS welded steam records; HFA41, HFA22 and HFYA800 cover high-pressure use cases at their own published ranges.
Leaflet Model & Series Matrix
Keep the family broad; keep the performance claim narrow.
The matrix transcribes Leaflet-confirmed series records and separates them from parameters that must be taken from the exact datasheet, drawing, calculation or certificate. It deliberately avoids assigning one model’s limits to every spring-loaded valve.
| Series | Leaflet product description | Medium | Standard shown | Size | Pressure | Temperature | Configuration / service note |
|---|---|---|---|---|---|---|---|
| HFA38 | Duplex spring safety valve | Steam | GB/T 12243 | DN50-150 | PN16-40 | -29 to 350 C | Duplex / twin spring |
| HFA48SB | High temperature and high pressure spring safety valve | Steam | GB/T 12243 | DN40-250 | PN16-160 | -29 to 540 C | High temperature / pressure |
| HFA44 | Spring full lift safety valve | Gas, steam | GB/T 12243 | DN25-400 | PN16-100 | -196 to 300 C | Full lift |
| HFA42 | Spring full lift safety valve | Gas, liquid | GB/T 12243 | DN25-400 | PN16-100 | -196 to 300 C | Full lift |
| HFA41 | Spring low lift closed high pressure safety valve | Gas, liquid | GB/T 12243 | DN15-80 | PN160-420 | -196 to 300 C | Low lift / high pressure |
| HFA40 | Spring full lift safety valve with radiator | Gas, liquid, steam | GB/T 12243 | DN40-400 | PN16-100 | -196 to 540 C | Full lift / radiator |
| HFO | Spring safety relief valve | Gas, liquid | ASME VIII / API 526 | 3/4-16 in | Class 150-2500 | -196 to 300 C | Conventional HF architecture |
| HFB | Spring safety relief valve | Gas, liquid | ASME VIII / API 526 | 3/4-16 in | Class 150-2500 | -196 to 300 C | Balanced-bellows HF architecture; confirm allowable backpressure by model |
| HFGS | High temperature spring safety valve | Steam | ASME I | 1 1/2-16 in | Class 150-2500 | -29 to 565 C | High-temperature steam; marking/certification requires separate verification |
| HFA900 | Spring safety valve | Gas, liquid, steam | Not stated in Leaflet row | 3/4-8 in | Class 150-300 | -196 to 300 C | Series-specific construction |
| HFA28 | Spring safety valve | Gas, steam | Not stated in Leaflet row | 1/2-2 in | Class 150-300 | -196 to 300 C | Compact spring-loaded |
| HFSVL488 | Stainless-steel safety valve for cleaning system | Gas, liquid | Not stated in Leaflet row | 1-2 in | Class 150 | -196 to 200 C | Clean-service record; confirm exact mechanism/configuration before blanket claim |
| HFA22 | Spring high pressure safety relief valve | Gas, liquid | Not stated in Leaflet row | 1/2-1 in | Class 150-2500 | -196 to 200 C | Compact high-pressure spring relief |
| HFXY / HFBPXYL | Spring safety relief valve | Gas, liquid | ASME VIII / API 526 | 1/4-1 in | Class 150-600 | -196 to 200 C | Compact / connection-specific spring relief |
| HFNJ | Heating-jacket bellows safety relief valve | Gas, liquid | ASME VIII / API 526 | 1-10 in | Class 150-600 | -196 to 427 C | Jacketed / bellows; verify backpressure and jacket details by model |
| HFA21 | Spring safety valve | Gas, liquid | Not stated in Leaflet row | 1/2-1 in | Class 150-300 | -196 to 200 C | Compact spring-loaded |
| HFYA800 | High pressure relief valve | Liquid | Not stated in Leaflet row | 1/4-1 in | Class 600-2500 | <200 C | Confirm direct-spring mechanism before final taxonomy/certification claim |
| HFGS welded | Welded-type spring loading safety valve | Steam | ASME I | 2-10 in | Class 600-2500 | 300-540 C | Welded / high-temperature steam; certification and marking verified separately |
Values above are transcribed from the HHSV Leaflet at series-record level. The Leaflet does not publish one universal rated capacity, discharge coefficient, allowable backpressure or dimensional table for the entire Spring-Loaded family. Use the selected model datasheet, sizing calculation and approved GA drawing for contractual values.
Procurement rule: quote the exact model code and approved data sheet whenever a pressure, temperature, capacity, backpressure, connection or certification limit becomes contractual.
Published Manufacturing Envelope
These are company-level limits - not a blanket Spring-Loaded rating.
The HHSV Leaflet states the overall manufacturing envelope below. A particular spring-loaded series can cover only a subset. Use the exact model row, datasheet and engineering calculation for contract selection.
Overall HHSV size envelope
DN10-600
1/2-24 in
Overall HHSV pressure envelope
0.6-42 MPa
ASME Class 150-2500
Overall HHSV temperature envelope
-196 to 570 C
Model/material dependent
Media
Steam · Gas · Liquid
Corrosive/toxic service by review
Body-material options
WCB · LCB/LC2 · WC6/WC9 · CF grades
Duplex · Monel · Hastelloy options
Connections
Flanged · Threaded · project-specific
Series/drawing dependent
Conventional vs Balanced Bellows
Backpressure behavior depends on the selected construction.
Superimposed and built-up backpressure must be quantified during selection. A conventional design can be affected by outlet pressure. Where the specific design allows it, a Balanced Bellows construction is used to reduce the effect of backpressure on set behavior and can also isolate bonnet internals from process media. Allowable backpressure is model specific.
Conventional spring-loaded
Use only within the model’s stated backpressure and discharge-system limits. Confirm outlet pressure before sizing and configuration.
Balanced-bellows spring-loaded
HFB and HFNJ are Leaflet-listed bellows-related Spring-Loaded records. Confirm allowable backpressure, bellows material, jacket details and failure considerations for the exact model.
Sizing & Selection
Required area comes from the relieving case, not from nominal pipe size.
HHSV can size/select to API 520 or ISO 4126 where applicable to the project and product. Calculations state the input data, assumptions and correction factors used. Two-phase or unusual fluids require an agreed method rather than a generic shortcut.
Relieving case & capacity
Required mass/volumetric flow and the credible scenario used to establish it.
Medium & phase
Steam, gas, liquid or multiphase plus density, molecular weight, k/Cp/Cv, viscosity or other needed properties.
Pressure basis
Operating pressure, set pressure, allowable overpressure/accumulation and atmospheric reference where relevant.
Temperature
Normal and relieving temperature; material/rating must be checked at the applicable condition.
Backpressure
Superimposed + built-up, constant or variable; include outlet-system assumptions.
Mechanical / compliance
Inlet/outlet connection, material, owner standard, inspection, certification and documentation requirements.
Standards & Compliance
State what was designed, what was tested and what is actually certified.
A referenced standard does not automatically mean every Spring-Loaded model carries that certification. Quote documentation should connect the selected model and legal entity to the actual approval scope.
API 520
Sizing/selection methodology where applicable; calculation assumptions must match the relieving case.
API 526 / ASME B16.5
API flanged product dimensions/orifice conventions and flange requirements only where the actual series uses them.
API 527
Seat-leakage test method/acceptance basis where specified; this is a test statement, not a product certification.
ISO 4126
Design/sizing/testing basis where specified for the applicable product and project.
ASME BPVC
Section VIII UV authorization and Section I V authorization are different scopes; UV must never be represented as V.
GB/T 12241 / 12243
Leaflet-listed design/performance and test basis for applicable series; verify the exact series and project-required edition.
Designed to
The stated code/standard is used as the design, sizing or dimensional basis for the selected model.
Tested in accordance with
The supplied valve is tested using the stated method and acceptance criteria for the agreed scope.
Certified to
Only use when the legal entity, factory, model, pressure range and marking are within the actual certificate/authorization scope.
Testing & Quality Evidence
The test report must identify the valve it represents.
Material identity, set pressure, leakage result, serial number and inspection status are controlled as deliverable evidence. The exact test medium, acceptance and witnessing requirement are defined by the applicable valve, standard and purchase specification.
Incoming material control
Material certificates, heat/lot identity and specified PMI/NDT are controlled before release to manufacture.
Pressure-boundary test
Applicable shell/pressure-boundary testing is performed to the approved product/project requirement.
Set-pressure verification
The assembled valve is adjusted and verified at its specified set pressure using the applicable test basis.
Reseating / blowdown
Reseating behavior is checked where required; acceptance limits remain standard/model specific.
Seat leakage
API 527 testing is available where applicable to the selected product/project; acceptance depends on valve type and test basis.
Witness / traceability
Third-party witness points, serial number, test records and final release documents can be agreed before manufacture.
Certification Scope
Company certifications are evidence; model coverage is the decision point.
HHSV maintains CE, ASME UV and National Board authorization together with relevant Chinese safety-valve manufacturing licensing and ISO management-system certifications. For a Spring-Loaded quotation, HHSV should map the selected valve to the applicable current certificate/authorization, nameplate and pressure/model scope before the product is described as certified.
ASME UV / National Board
Use only for products within the actual Section VIII authorization and National Board/NB-18 scope; do not imply Section I V coverage.
CE / PED
State CE/PED only when the supplied pressure accessory falls inside the applicable conformity-assessment scope and supporting documentation.
China manufacturing license
Map the valve category/range to the applicable manufacturing-license scope used for the supplied product.
ISO management systems
ISO 9001 / 14001 / 45001 describe management systems; they are not product-performance certificates.
Typical Applications
Application narrows the construction; service data still selects the model.
Do not treat an industry label as proof that every Spring-Loaded valve is suitable. The selected product still requires an approved relieving case, materials, pressure-temperature rating and compliance basis.
Boilers & steam systems
Full-lift / lever / high-temperature constructions may be relevant; verify the exact code section and authorization.
Pressure vessels
Direct spring-loaded relief for gas, steam or liquid service with model-level sizing and certificate checks.
Refining & petrochemical
Conventional or balanced constructions selected from backpressure, medium, temperature and material compatibility.
Compressors & packaged equipment
Threaded or flanged spring-loaded valves for repeat OEM/skid supply after the service basis is standardized.
Chemical service
Material, corrosion, toxicity and bonnet isolation requirements can drive stainless/duplex/special alloys and balanced construction.
Power & high-temperature steam
HFA48SB and HFGS high-temperature records require project-specific temperature, pressure, material, testing and code review.
Dimensions & Technical Documentation
Dimensions belong to the exact inlet / outlet / orifice combination.
The Leaflet does not publish one complete model-level dimension set for this family. Use the dedicated datasheet or approved GA drawing for the selected series; never reuse one model’s dimensions across the family.
Product datasheet
Selected model, service basis, set pressure, materials and configuration.
Sizing calculation
Relieving-case inputs, assumptions, correction factors and required area/capacity basis.
GA / dimensional drawing
Inlet/outlet sizes, face-to-face/center dimensions, overall height, orientation and connection standard.
Material records
MTC and specified PMI/NDT/heat-lot traceability for the agreed scope.
Test reports
Set, pressure-boundary, reseating/blowdown and leakage records as applicable.
Certificate matrix
Maps the quoted valve/model to the claimed product authorization or conformity scope.
QAP / ITP
Inspection stages, hold/witness points and third-party requirements where contractually required.
MDR / final dossier
Controlled document index, approved revisions, certificates and shipment-release records.
Project Evidence
Project evidence is released only when the supplied product and scope can be verified.
Customer confidentiality and owner-approval restrictions can limit what is public. Where a Spring-Loaded reference is publishable, HHSV records the application, selected model, service condition, testing and document scope instead of presenting an industry logo as proof.
Process-service evidence
Published records identify the actual medium, set pressure, material and Spring-Loaded series where disclosure is permitted.
OEM repeat-supply evidence
Relevant records can show approved model baseline, dimensional control, repeat quantity and document consistency.
Inspection & delivery evidence
Project records can document sizing basis, witness scope, test package, MDR and delivery outcome when releasable.
FAQ
Questions engineering and procurement teams usually need answered before approval.
How do I choose between full lift and low lift?
Start from the required relieving capacity, service medium, set pressure, applicable standard and the actual product-series data. Do not select only from nominal line size or the words "full lift" / "low lift".
When should a balanced-bellows spring-loaded valve be considered?
When backpressure or bonnet-media isolation makes it relevant. Superimposed and built-up backpressure must be quantified, then checked against the model's stated limits and bellows design.
Does API 527 mean the valve is API certified?
No. API 527 is a seat-leakage testing standard. A valve may be tested in accordance with API 527 without that statement representing a product certification.
Does ASME UV cover power-boiler Section I valves?
No. UV and V are different authorization marks. Section VIII UV coverage must not be presented as Section I V coverage.
Can the tank-page DN, pressure and temperature envelope be used as a model rating?
No. Those are HHSV's overall published manufacturing limits. The selected Spring-Loaded model may cover only a subset.
What information is needed for sizing?
At minimum provide the relieving case, required capacity, medium/phase, operating and set pressure, relieving temperature, backpressure and mechanical/compliance requirements. Additional fluid properties may be required by the sizing method.
Can HHSV provide custom materials, connections or witness testing?
These can be reviewed against the selected model, manufacturing feasibility, certificate scope and project requirement. They should be defined in the quotation and approved document/inspection scope.
Related Product Paths
If the service does not fit a direct spring-loaded configuration, change the architecture - not the assumptions.
Pilot-Operated Safety Valves
Review when the system or pressure behavior points to a pilot-controlled architecture.
Back-Flow Safety Valves
Use the dedicated family where the primary system requirement is back-flow protection.
Custom Safety-Valve Solution
Special material, temperature, pressure, connection, inspection and document requirements can be reviewed as an engineered configuration.
Request a Technical Selection
Send the relieving case, datasheet or existing valve nameplate.
HHSV can identify missing inputs, size the required capacity, select the exact Spring-Loaded series, confirm materials/connection/compliance scope and return the technical quotation package.