H44X swing check valve dimensions cannot be confirmed from DN and PN alone. Before ordering, match the face-to-face length, flange standard, flange drilling, valve height, body width, shaft projection, accessory clearance, and weight to one approved drawing.
For one published PN16 H44X reference series, a DN50 check valve has a 203 mm face-to-face length, while the DN600 check valve is 1295 mm long. These values help with preliminary layout work. They do not prove that a PN10, PN25, or another manufacturer’s H44X uses the same body pattern.
| Buyer question | Working answer |
|---|---|
| Does DN50-DN600 define the complete valve size? | No. DN identifies nominal bore. It does not define face-to-face length, flange geometry, height, width, or weight. |
| Can one H44X dimensions table cover PN10, PN16, and PN25? | Only if the manufacturer confirms that the same table applies to all three ratings. Do not assume it. |
| Is a PN16 swing check valve the normal choice for water lines? | It is common, but selection must cover operating pressure, static pressure, pump shut-off pressure, surge, and field test conditions. |
| Can a PN25 valve replace a PN16 valve directly? | Sometimes, but only after checking both flanges, face-to-face length, supports, weight, and the rating of every connected component. |
| Which document controls fabrication? | The approved general arrangement drawing for the exact DN, PN, flange standard, material, and accessory arrangement. |
For valve construction, resilient-seat materials, and free-shaft operation, read the separate guide to H44X free shaft structure and pump-station use. This page deals with dimensional fit, pressure-rating selection, and purchase-document checks.
Why the H44X model code is not a dimension standard
H44X is a Chinese valve model designation commonly used for a flanged, resilient-seated swing check valve. It identifies a construction family, but it does not assign one universal body length or flange pattern.
The model may appear in forms such as H44X-10Q, H44X-16Q, or H44X-25Q. The number usually identifies the nominal pressure family, while Q often identifies a ductile iron body. The purchase specification still needs the full material grade, flange standard, face-to-face series, sealing material, coating, test requirements, and installation arrangement.
Two valves can both be called H44X-16Q and still have different face-to-face lengths. One supplier may use an EN or ISO dimensional series. Another may use a GB series or a manufacturer’s own body pattern. The model code does not settle that difference.
Norite lists the H44X swing check valve with free shaft in sizes DN50-DN600 and pressure configurations including PN10, PN16, and PN25. The quotation must state which configuration and drawing revision apply to the order.
Which H44X dimensions control pipeline fit?
A catalog often shows only L and H. That is enough for a rough envelope, but it is not enough to release a spool drawing or plan a replacement shutdown.
| Drawing field | Common meaning | What it controls on site |
|---|---|---|
| DN | Nominal size | Line-list and pipe-size match |
| L or A | Face-to-face length | Installed flange gap and replacement fit |
| D | Flange outside diameter | External flange envelope |
| K, D1, or PCD | Bolt pitch circle diameter | Alignment with the mating flange |
| n x d | Number and diameter of bolt holes | Bolt pattern compatibility |
| b | Flange thickness | Bolt or stud length |
| H or B | Valve height shown on the drawing | Overhead clearance |
| W | Maximum body width | Clearance from walls, pipes, and cable trays |
| Shaft projection | Distance from body to shaft end | Space for a free shaft, seal, and coupling |
| Accessory envelope | Lever, weight, spring, switch, and guard dimensions | Full moving and maintenance clearance |
| Weight and center of gravity | Mass and balance point | Support design, lifting, and removal planning |
Drawing letters vary between manufacturers. Compare the dimension legend, not the letter alone. A value marked B on one sheet may describe body height, while another sheet may use B for flange thickness.
Face-to-face length comes first
The face-to-face dimension is the distance between the two flange faces. It decides whether a valve fits an existing gap and where a new pipe spool ends.
A few millimetres may be manageable during new fabrication if the designer revises the spool before production. A large difference can stop a replacement job. Bolts must not be used to pull fixed pipework toward a valve that is too long or too short.
EN 558 and ISO 5752 provide face-to-face series for flanged metal valves. Referring only to either standard is incomplete because both contain several dimensional series. State the series or list the required L value for every DN.
Flange drilling is a separate check
Matching face-to-face length does not prove that the valve will bolt into the line. Confirm the flange outside diameter, pitch circle, hole count, hole diameter, facing, gasket seating area, and flange thickness.
The flange standard must be named in full. An EN 1092-2 PN16 flange should not be treated as interchangeable with a Class 125 or Class 150 flange because both are used on a valve with a similar nominal bore.
Free-shaft clearance is part of the installed size
An H44X with a plain external shaft needs less side space than the same valve fitted with a lever and weight. A spring, damper, limit switch, or safety guard changes the envelope again.
The drawing should show the selected shaft side and the complete accessory sweep. Check the movement against handrails, structural columns, nearby actuators, walkways, and removable floor panels. The lever and weight must also remain accessible for inspection without creating an unguarded strike point.
PN16 H44X reference dimensions from DN50 to DN600
The table below gives one published W-H44X-16Q PN16 dimensional series for water service. A is the face-to-face reference and B is the height reference used on that source drawing. All values are in millimetres.
Use this table for early comparison and quotation review. Do not release pipe fabrication from it unless the offered valve uses the same dimensional series and the supplier confirms the values on an approved drawing.
| Nominal size | Inch reference | A, face-to-face (mm) | B, drawing height (mm) |
|---|---|---|---|
| DN50 | 2 | 203 | 86 |
| DN65 | 2 1/2 | 216 | 100 |
| DN80 | 3 | 241 | 110 |
| DN100 | 4 | 292 | 120 |
| DN125 | 5 | 330 | 140 |
| DN150 | 6 | 356 | 150 |
| DN200 | 8 | 495 | 180 |
| DN250 | 10 | 622 | 251 |
| DN300 | 12 | 698 | 310 |
| DN350 | 14 | 787 | 350 |
| DN400 | 16 | 914 | 380 |
| DN450 | 18 | 978 | 400 |
| DN500 | 20 | 978 | 450 |
| DN600 | 24 | 1295 | 520 |
The published series assigns the same 978 mm A dimension to DN450 and DN500. That is a specific catalog detail worth checking on the signed drawing instead of silently “correcting” it or replacing it with a value from another table.
What the table proves
The table identifies one complete DN50-DN600 length series for a PN16 H44X product. It also shows why the nominal size is not the installed length. DN600 refers to nominal bore, while the reference body length is 1295 mm.
What the table does not prove
It does not provide flange drilling, body width, service height, shaft projection, accessory sweep, valve weight, or lifting data. It also does not establish dimensions for Norite’s PN10 and PN25 configurations unless the quotation drawing adopts the same series.
Do not combine the A and B values above with flange dimensions copied from another manufacturer. Body length and flange geometry must come from one coordinated product drawing.
DN50 check valve compared with a DN600 check valve
The selection principle is the same at both ends of the size range, but the site work is not.
| Project check | DN50 check valve | DN600 check valve |
|---|---|---|
| PN16 reference face-to-face length | 203 mm | 1295 mm |
| PN16 reference height field | 86 mm | 520 mm |
| Layout review | Spool gap, flange match, and access to bonnet fasteners | Full body and accessory envelope, support loads, lifting route, and component-removal space |
| Handling data | Confirm weight and approved lifting method | Obtain assembly weight, center of gravity, lifting points, and the weight of removable parts |
| Support | Control loads from connected pipework | Provide support based on the issued weight and allowable nozzle or flange loads |
| Hydraulic review | Check stable opening at minimum duty | Review disc response and transient consequences with the pump and rising main data |
| Shutdown planning | Confirm isolation and drainage | Plan rigging, temporary support, dismantling space, access, isolation, drainage, and removal route |
A DN50 valve can still fail to fit because of the wrong flange drilling or body length. A DN600 mismatch is harder to correct after delivery because the valve, supports, access route, and lifting equipment may all depend on the approved dimensions.
Never lift a valve by its free shaft, lever, counterweight, spring, or bonnet bolts unless the manufacturer has identified that point for lifting. Use the marked lifting points and the supplier’s handling instructions.
Choosing PN10, PN16, or PN25
PN selection starts with the pressure envelope at the valve location. Normal operating pressure is only one input.
| Pressure family | Nominal reference | Common water-system starting point | Main purchasing check |
|---|---|---|---|
| PN10 | 10 bar | Gravity mains, low-head distribution, drainage, and low-pressure irrigation | Confirm that static, shut-off, surge, and test conditions remain within the declared limits |
| PN16 | 16 bar | Municipal water, treatment plants, utility water, and many pump stations | Confirm pressure margin, flange standard, and the exact dimensional series |
| PN25 | 25 bar | High-head pumping, elevated pressure zones, and transmission pipelines | Confirm actual need, size availability, flange geometry, body weight, and support impact |
These are screening categories, not automatic approvals. Norite’s PN10 vs PN16 vs PN25 valve guide covers the pressure terms and broader system checks in more detail.
Five pressure values to send with the RFQ
- Highest continuous operating pressure at the valve location
- Maximum static pressure when flow stops or downstream isolation is closed
- Pump shut-off pressure from the approved pump curve
- Highest and lowest transient pressure from the surge assessment
- Pipeline field test pressure and the proposed test arrangement
Temperature, fluid composition, solids, and chemical exposure must accompany those values. The allowable pressure of the complete valve can depend on its body material, seat, bonnet gasket, shaft seals, coating, and governing standard.
Does a higher PN rating change H44X dimensions?
It can. A higher rating may require a thicker flange, different drilling, heavier wall sections, a stronger shaft, or another body pattern. The exact changes depend on the selected product and flange standard.
Face-to-face length is controlled separately. A PN10 and PN16 valve may share L within one product family, while their flange drilling differs at some sizes. A PN25 valve may keep the same L or use another body. The supplier must state which dimensions change.
Why PN25 is not a water-hammer fix
PN25 provides a higher nominal pressure class, but it does not change an unsuitable closing response by itself. Check valve slam develops from the interaction between disc travel, flow deceleration, reverse velocity, pump behavior, and the pipeline system.
If the surge study shows that the selected H44X closes too late, compare the design with another closing arrangement. Norite’s check valve guide for pump stations discusses closure behavior, while the swing check valve versus wafer check valve comparison covers the trade-off between body length and valve dynamics.
Survey an existing valve before ordering a replacement
A readable nameplate helps, but it is not a dimensional survey. Record the installed condition while the line is safely isolated and the measurement can be taken without disturbing the joint.
- Photograph the complete valve, flow arrow, nameplate, bonnet, shaft side, supports, and nearby obstructions.
- Record DN, pressure marking, body material marking, manufacturer, model, and serial number.
- Measure the clear face-to-face gap between the mating flange faces.
- Measure or verify flange outside diameter, pitch circle, hole count, and hole diameter.
- Record the flange facing and gasket arrangement.
- Measure maximum body width, installed height, and available maintenance height.
- Record shaft projection and the complete lever, weight, spring, or guard envelope.
- Check the pipe centerline, support condition, drainage, and access for lifting equipment.
- Confirm the required flow direction and whether the line is horizontal or vertical with upward flow.
- Compare every field value with the proposed GA drawing before approval.
If removal space is limited, a correctly specified dismantling joint may provide controlled axial adjustment and make future maintenance easier. Its DN, PN, flange drilling, restraint, and available movement must suit the same pipeline. It should not be used to force misaligned flanges together.
Drawing review for a new installation
The valve drawing should pass three separate reviews before purchase.
| Review | Information to verify | Release decision |
|---|---|---|
| Piping fit | L, flange standard, drilling, facing, gasket, flow direction, and pipe centerline | Release the connected spool only after all interfaces match |
| Civil and structural fit | Weight, center of gravity, supports, lifting points, floor loading, access, and removal route | Release supports and access structures after receiving verified loads |
| Operation and maintenance | Bonnet-removal height, shaft side, lever sweep, guard, inspection space, and replaceable-part route | Accept only when the full operating and service envelope is clear |
For large valves, add hold points for the lifting plan and shipment dimensions. A DN600 valve can fit the pipe model and still fail the installation plan if it cannot pass through the plant doorway or be rotated into position.
Common dimension and pressure mistakes
| Mistake | Result | Better requirement |
|---|---|---|
| Treating DN as the valve’s physical diameter | Body or flange clashes with nearby equipment | Use the complete GA envelope |
| Copying an online H44X table without its pressure and series | Wrong spool length or flange joint | Tie every table to a model, PN, standard, and drawing revision |
| Assuming all PN16 swing check valves are interchangeable | Matching rating but different L or drilling | Compare both valve drawings line by line |
| Ordering PN25 because it appears safer | Higher cost and weight without fixing surge or interface problems | Select against the verified pressure envelope and transient study |
| Checking body length but ignoring the free shaft | Lever, weight, or guard hits nearby structure | Approve the full accessory sweep and selected shaft side |
| Releasing DN600 supports before weight data arrive | Incorrect foundation, hanger, or lifting design | Obtain weight and center-of-gravity data before structural release |
| Using flange bolts to correct pipe misalignment | Joint stress, gasket leakage, or body distortion | Align and support the pipe independently |
Generic bolt torque, minimum velocity, or straight-pipe distance should not be copied into the order from an unrelated valve guide. Bolt torque depends on the joint design, fastener, gasket, flange, lubrication, and thread condition. Stable disc position and installation distance depend on the valve geometry and actual flow profile.
H44X RFQ and drawing checklist
| RFQ field | Information to provide or request |
|---|---|
| Valve schedule | Quantity and DN for each line |
| Pressure conditions | Required PN, continuous pressure, static pressure, pump shut-off pressure, transient limits, and field test pressure |
| Service | Fluid, solids, oil or chemical exposure, operating temperature, and design temperature |
| Flanges | Standard, part, PN, type, facing, drilling, gasket, and mating-flange material |
| Face-to-face | Named series or required L for every DN |
| Envelope | Maximum width and height, service height, shaft projection, and accessory clearance |
| Construction | Body, bonnet, disc, shaft, seat, bushings, fasteners, and coating |
| Accessory | Plain shaft, lever and weight, spring, guard, indicator, or limit switch, including the required side |
| Hydraulic data | Minimum, normal, and maximum flow, pump curve, static head, pump sequence, and surge-study output |
| Installation | Horizontal or approved vertical-upward orientation, indoor or outdoor location, support arrangement, and lifting access |
| Documents | GA drawing, bill of materials, pressure and leakage test procedure, head-loss data, weight, center of gravity, lifting instructions, certificates, and spare-parts list |
A purchase description can be written as follows:
H44X resilient-seated swing check valve, DN300, PN16, ductile iron body and bonnet, EPDM-covered disc, stainless steel shaft, flanged to EN 1092-2 PN16, face-to-face length as shown on the approved GA drawing, free shaft on the specified side with lever and weight, horizontal pump-discharge installation, coating and pressure testing to the project specification.
Require the supplier to list deviations next to the affected specification clause. A general statement of compliance does not resolve a missing dimensional series or an unidentified flange pattern.
Frequently asked questions
What is the face-to-face dimension of an H44X DN50 check valve?
One published PN16 H44X series lists 203 mm. Another H44X body pattern may use a different length, so the signed drawing for the offered valve must control the order.
What is the face-to-face dimension of an H44X DN600 check valve?
The PN16 reference series in this guide lists 1295 mm. Confirm the PN rating, flange standard, body width, total installed height, weight, and accessory envelope before using that value for layout.
Are H44X dimensions the same for every manufacturer?
No. H44X describes the general valve type. It does not assign one universal face-to-face series, flange pattern, height, shaft projection, or weight.
Are PN10 and PN16 H44X valves the same size?
They may share some body dimensions within a manufacturer’s product family, but that does not prove complete interchangeability. Check L, flange drilling, thickness, facing, weight, and the exact drawing revision.
Can a PN25 H44X replace a PN16 swing check valve?
Only after the designer confirms the pressure requirement, mating flanges, face-to-face length, supports, connected-component ratings, and hydraulic behavior. A higher PN marking does not guarantee a direct fit.
Can the dimension table be used for pipe spool fabrication?
Use it for preliminary planning only. Fabricate the spool from the approved GA drawing for the purchased valve, with the drawing number and revision recorded in the project documents.
Which standards should be stated for H44X dimensions?
State one standard for face-to-face dimensions and one for flange geometry. For example, a project may specify a particular EN 558 series for L and EN 1092-2 for ductile iron PN flanges. Name the required editions and any project deviations.
What should be checked first for a replacement valve?
Start with the installed face-to-face gap and the complete flange pattern. Then check the body and accessory envelope, weight, supports, flow direction, and removal route.
Approve one coordinated drawing before purchase
Use the DN50-DN600 table for preliminary comparison, then replace the reference values with the supplier’s confirmed data. The final drawing must identify the exact DN, PN rating, flange standard, face-to-face series, body material, shaft arrangement, accessory envelope, weight, and revision.
Send the line schedule, pressure data, flange details, available space, pump duty, and document requirements through Norite’s contact page. Request one coordinated offer so the valve, spool, supports, lifting plan, and maintenance access are reviewed against the same drawing.
