Quick answer
What is the difference between rising and non-rising stem gate valves?
A rising stem moves axially as the gate travels, so the installation must allow its full movement. A non-rising stem rotates without that external axial travel while the gate moves inside the body. Compare the available space, required position indication and maintenance access, then verify the complete valve against the service specification.
KEHUA VALVE procurement guidance for the existing rising-stem and non-rising-stem gate valve series. Public references support general principles; confirm the offered construction, service limits and maintenance instructions in the model documents.
Updated: — Added a cast steel wedge gate valve reference alongside the stem-selection checks; model specifications unchanged.
| Procurement check | Rising stem | Non-rising stem |
|---|---|---|
| Operating movement | Allow the external axial stem travel. | Confirm the internal gate travel and rotating stem arrangement. |
| Installed envelope | Request open and closed heights plus any stem guard. | Request the complete operator and indicator envelope. |
| Position indication | Review how visible travel shows position. | Specify how the offered indicator shows position. |
| Thread and nut location | Identify the drive and exposed components on a section drawing. | Identify the internal drive and any contact with the process fluid. |
| Maintenance access | Check access for inspection, protection and lubrication. | Check the procedure and access for inspecting internal components. |
| Manual or powered operation | Confirm handwheel or actuator clearance and operating requirements. | Confirm gearbox or actuator clearance and indication requirements. |
| Service acceptance | Check materials, rating, seats and tests independently. | Use the same service specification and acceptance requirements. |
Start with the installation and operating requirement
Record why the stem arrangement matters to the project: a low overhead beam, visibility from an operating platform, actuator access or planned maintenance. Treat these as separate requirements instead of choosing a design from a photograph.
KEHUA lists rising-stem and non-rising-stem gate valve series. Use those entries to identify candidates, then request the offered model drawing. A series name alone does not establish the dimensions or indicate which accessories are included.
Check the complete operating and maintenance envelope
Ask for dimensions in both fully open and fully closed positions, measured from an agreed datum such as the pipe centreline. Include any stem cover, handwheel, gearbox, actuator and position indicator. Overlay the drawing on the pipe layout to check nearby steelwork, insulation and access routes.
For example, a valve may fit beneath a beam when closed but lack space for its full operating movement. A more compact operating envelope may still need additional room for component removal. Confirm operating clearance and maintenance clearance separately; do not estimate either from nominal pipe size.
Specify how operators will confirm position
State where the operator needs to read valve position and whether local indication, remote feedback or both are required. Request the actual indicator arrangement and its open/closed references. Do not assume a non-rising-stem offer includes an indicator unless it is listed.
For powered operation, define required feedback signals and ask how the indication is set and checked. Visible stem travel or a position signal describes mechanism position; agreed seat-leakage testing remains a separate acceptance item.
Review the stem, nut and maintenance requirements
Request a section drawing showing the stem, drive nut, packing and any protective cover. Establish which components contact the fluid and which are exposed to the surrounding environment. Ask for the specified lubrication, inspection access and replacement procedure for that construction.
For dusty, corrosive or restricted-access locations, include the environment in the enquiry. Compare the actual maintenance provisions rather than assigning a universal service life or maintenance interval to either stem type. The manufacturer’s model-specific instructions should govern the work.
Select rating, materials and end connections separately
Keep the operating and design pressure, temperature, fluid composition, required shutoff and maximum operating differential pressure on the same duty sheet for both candidates. Review body, trim, stem and sealing materials together with the offered end connections. For a cast steel body proposal, review the cast steel wedge gate valve series separately and confirm the offered stem arrangement on its drawing.
ASME B16.34 addresses rating, materials, testing and other requirements within its stated scope. A rising or non-rising stem designation does not replace the applicable valve standard, contract edition or approved datasheet. Confirm required tests and records for the offered configuration.
Compare quotations using the same drawing requirements
Ask suppliers to return the same clearance and indication schedule with the drawing revision, operator configuration and included accessories identified. Record missing dimensions or unconfirmed features as open technical items before approving the order.
If a proposed substitution changes the stem arrangement, review the layout, indication and maintenance plan again. Matching nominal size and pressure class does not establish that the replacement fits. Retain the accepted drawing and resolved deviations with the purchase order.
Copy this stem-selection checklist into the RFQ
Complete the known fields and request confirmation of open items. Use the full RFQ guide for the remaining project and commercial information.
- Valve tag, quantity, nominal size and proposed series: ___.
- Fluid, operating/design pressure and temperature, maximum operating differential pressure: ___.
- Stem arrangement; drawing and revision; open/closed height datum: ___.
- Available operating envelope and separate maintenance/removal clearance: ___.
- Handwheel, gearbox or actuator configuration and access: ___.
- Local indication, remote feedback and included accessories: ___.
- Stem/nut materials, fluid exposure, protection and maintenance documents: ___.
- Applicable standards, end connections, tests, records and unresolved deviations: ___.
Compare valve families
Use this guide together with the relevant valve family and project operating data.
Primary technical references
Confirm the edition required by the contract. The project specification and purchased standard remain controlling.
More technical notes