H42H vertical lift check valve
Gaoshan H42H is a vertical lift check valve for upward-flow vertical pipelines — the disc lifts on forward flow and closes by gravity, so there is no spring to fatigue and no actuator to power.
•Gravity-loaded disc on a guided stem — automatic non-return protection for pump risers that must not drain back
•No spring, no hinge pin, no external power — nothing to fatigue in continuous service
•Two bodies cover temperature: H42H-25Q ductile iron to 300°C, H42H-25 WCB cast steel to 425°C
•2Cr13 stainless steel disc and seat, lappable in service — PN25 rating
•DN40 – DN200; flanged ends (GB / ANSI / EN on request)
•Install on vertical pipe with upward flow only — for horizontal lines use H41H lift or H42F silent check valve
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Product Details
The H42H vertical lift check valve — the pattern buyers also search as a vertical check valve or non-return valve for vertical pipelines — is the automatic non-return valve for upward-flow risers. The guided disc lifts open when forward flow pressure overcomes its weight and drops shut by gravity the moment flow stops or reverses, so a vertical line draining back through a pump is cut off without any spring or actuator. PN25, DN40–DN200, in ductile iron to 300°C or WCB cast steel to 425°C.
- Vertical lift (gravity) check valve for upward-flow vertical pipelines
- Guided disc on a stem: short, positive travel, immediate closure on flow reversal
- No spring or external power — closure is gravity-driven and self-acting
- H42H-25Q ductile iron body to 300°C; H42H-25 WCB cast steel to 425°C
- 2Cr13 stainless steel disc and seat, PN25 (2.5 MPa), shell tested 3.8 MPa
- DN40–DN200, flanged, protects pumps, motors and risers from backflow
Product Overview
The H42H is an automatic non-return valve for vertical pipelines with upward flow. The disc travels vertically on a guided stem: forward flow lifts it off the seat, and when flow stops or reverses it drops closed by gravity. Because the closure is gravity-driven there is no spring to fatigue and no actuator to power, which is why the pattern is trusted on risers that must not drain back through a stopped pump.
Body material follows temperature. The H42H-25Q ductile iron body suits water and steam to 300°C; the H42H-25 WCB cast steel body extends that to 425°C for steam and petroleum duty. Both carry a 2Cr13 stainless disc and seat at PN25.
The H42H is the vertical-line specialist of the check valve family. On a horizontal run the gravity disc has nothing to fall against, so the pattern is not used there — the lift-pattern H41H or the spring-assisted H42F silent check valve take horizontal and slam-sensitive duty. Decode the model code on the Valve Model Decoder.
Core Strengths
Gravity Closure, Nothing to Fatigue
Closure comes from the disc’s own weight, not a spring. There is no spring to lose preload, no actuator to power, and nothing to maintain except the sealing surfaces. On a riser that cycles with every pump start/stop, that simplicity is reliability.
Guided, Positive Disc Travel
The disc moves on a guided stem square onto the seat, so it cannot hinge, flutter or seat half-open the way an unguided disc can on a vertical line. Closure is immediate when flow reverses.
Built for the Riser
Vertical pipelines are where backflow drains a column of water back through the pump. The H42H is designed exactly for that orientation, with the flow arrow cast for upward flow.
Two Bodies Cover 300 and 425 degC
Ductile iron to 300°C for water and low steam; WCB cast steel to 425°C for steam and petroleum. The same 2Cr13 trim serves both, so spares stay simple.
PN25 With Real Test Margins
Rated 2.5 MPa with shell test at 3.8 MPa and seat test at 2.8 MPa, giving the headroom a vertical column and pump surge demand.
Serviceable Sealing Surfaces
The 2Cr13 disc and seat can be inspected, lapped or replaced in line; sediment that collects on a vertical seat is cleaned during routine maintenance rather than becoming a permanent leak.
Performance Specifications
| Parameter | H42H-25Q | H42H-25 |
|---|---|---|
| Nominal Pressure PN (MPa) | 2.5 | 2.5 |
| Shell Test Pressure (MPa) | 3.8 | 3.8 |
| Seal Test Pressure (MPa) | 2.8 | 2.8 |
| Max. Working Temperature | ≤300°C | ≤425°C |
| Applicable Medium | Water, Steam, Petroleum, etc. | Water, Steam, Petroleum, etc. |
| Installation Orientation | Vertical pipelines only (upward flow) | Vertical pipelines only (upward flow) |
Main Component Materials
| Model | Valve Body / Bonnet | Disc / Seat Ring |
|---|---|---|
| H42H-25Q | Ductile Cast Iron | 2Cr13 Stainless Steel |
| H42H-25 | WCB Cast Steel | 2Cr13 Stainless Steel |
Main Dimensions & Weights (PN25)
PNPN25
| Nominal size | L (face-to-face) | Weight (kg) |
|---|---|---|
| DN40 | 200 | 9.5 |
| DN50 | 230 | 14 |
| DN65 | 290 | 17 |
| DN80 | 310 | 26 |
| DN100 | 350 | 37 |
| DN125 | 400 | 60 |
| DN150 | 480 | 90 |
| DN200 | 495 | 150 |
Dimensions are for the PN25 series; certified drawings are issued with the quotation. DN150 and above should be given independent pipe support so the valve carries no line weight.
Which Check Valve for a Vertical or Horizontal Line
| Line / duty | Correct valve | Why |
|---|---|---|
| Vertical pipe, upward flow | H42H vertical lift (this page) | Gravity disc closes on reversal; made for risers |
| Horizontal pipe | H41H lift or H44H swing | A gravity vertical disc has nothing to fall against horizontally |
| Pump discharge with slam / noise | H42F silent | Spring returns the disc before reverse flow builds |
| Large horizontal main | H76H dual plate | Slim wafer, low loss, big sizes |
| Boiler return, overflow risk | H7B41X | Normally closed, opens on pump pressure |
Structure Drawing
Design, Testing and Reference Standards
- Design Standard: GB/T 12235; face-to-face to GB/T 12221; flanges to GB/T 9113, JB/T 79, HG/T 20596
- Testing & Inspection: GB/T 13927, JB/T 9092
International Standards & Certification
- Also referenced to international equivalents on request: design to EN 13709, face-to-face EN 558 / ASME B16.10, flanges EN 1092-1 / ASME B16.5, testing ISO 5208 / API 598.
- Material certificates to EN 10204 3.1 are supplied with delivery.
- Flow coefficient Cv / Kv is available on request for sizing.
Installation & Maintenance Guidelines
- Body Material : Ductile iron (H42H-25Q) / WCB cast steel (H42H-25)
- Applicable Media : Water, steam, oil products and weak corrosive fluids
- Working Temperature : ≤300℃ (ductile iron) / ≤425℃ (cast steel)
- Installation Options : Vertical (without spring) or horizontal (with spring) mounting
- Core Function : Automatically prevents medium backflow to protect pumps, motors and pipelines
- Application Scenarios : Petroleum, chemical, pharmaceutical, power, water treatment and industrial pipeline systems
- Applicable International Standards: EN 13709, EN 558 (optional)
- Vertical Installation Only: H42H must be installed on vertical pipelines with upward medium flow. Do NOT install on horizontal lines — the disc will not function correctly without the gravity-assisted closure mechanism.
- Flow Direction: Ensure the medium flows upward through the valve, matching the direction arrow on the valve body. Reverse installation will cause valve failure.
- Pipeline Support: Do not let the valve bear pipeline weight. Large-diameter valves (DN150 and above) require independent support brackets to prevent flange stress.
- Maintenance: Periodically inspect the disc, guided stem, and seat ring for wear or sediment buildup. Clean and replace sealing surfaces as needed to maintain reliable anti-backflow performance.
- Confirm orientation before ordering: the catalogued H42H is a gravity, vertical-up valve. If your line is horizontal or you need spring-assisted closure, specify the H41H or H42F instead — do not fit a gravity vertical valve on a horizontal run.
Application Fields
The H42H protects vertical risers across petroleum and chemical plants; power stations; pharmaceutical and water treatment works; boiler feed and steam risers; pump discharge columns; general industrial vertical pipelines. Wherever a stopped pump must not see its column drain back, the gravity vertical lift valve is the simple, maintenance-light answer.
What We Need to Quote Your H42H Check Valves
- Size and quantity: DN40–DN200, PN25.
- Medium and temperature: decides the body — ductile iron to 300°C or WCB to 425°C.
- Orientation: confirm vertical with upward flow; if horizontal, we will redirect to H41H/H42F.
- Flange standard: GB/T 9113 as standard; EN 1092 or ASME on request.
- Support: tell us if DN150+ so we can note independent brackets.
- Documentation: EN 10204 3.1 certificates and test records for tenders.
Send the riser data or P&ID and we will confirm the body and size. Drawings are in the download center and qualifications on the certifications page.
Frequently Asked Questions
Why must the H42H be installed vertically with upward flow?
The disc closes by gravity. On a vertical pipe with upward flow, when the pump stops the disc drops onto its seat and cuts off the draining column. On a horizontal run there is no gravity component to seat the disc, so it would not close reliably – use a lift or swing pattern there instead.
Does the H42H have a spring?
As catalogued it is gravity-driven – no spring. Some listings mention a spring-supported variant for horizontal mounting, but that is a different configuration; the standard H42H is a gravity vertical valve. If you need spring-assisted or horizontal duty, specify the H42F silent or H41H lift check valve and we will confirm.
How is it different from the H42F silent check valve?
Both suit vertical pump discharge, but the H42F adds a spring that returns the disc as forward flow decelerates, so it closes before reverse flow builds and without slam – the choice where noise and water hammer matter. The H42H is the simpler gravity valve where slam is not the concern.
Which body for steam at 425 degC?
The H42H-25 WCB cast steel body, rated to 425 degC. The ductile iron H42H-25Q stops at 300 degC. Give us the saturation pressure so the PN25 class is checked at temperature.
How is it different from the H41H lift check valve?
The H41H is the horizontal/vertical-capable lift pattern with a broader size and pressure range; the H42H is the dedicated vertical-up, gravity valve at PN25. If your line is vertical and you want the simplest reliable non-return, the H42H; if horizontal or higher class, the H41H.
Do large sizes need pipe support?
Yes – DN150 and above should be given independent support brackets so the valve body carries no pipeline weight, protecting the flanges from stress. Note it on the installation drawing.
Get a Quote & Technical Support
Gaoshan Valve has manufactured industrial valves since 1975 and holds ISO 9001/14001/45001 with CE, API 6D and PED product certification. It is an approved supplier to Sinopec, CNPC and State Grid and exports to more than 30 countries. Contact us for dimension sheets, CAD drawings and an H42H selection matched to your riser. Reply within 24 hours.
