Threaded Piston Valves
A threaded piston valve is a shut-off valve that screws directly into small-bore lines from 1/2″ to 2″ through its female-threaded ends and carries the piston closing mechanism in a compact body. As no flange set is needed, it saves space in tight spots such as boiler fittings, sampling and drain points.
The standard series has a grey iron body in pressure class PN16; end threads are BSP (EN 10226-1 or EN ISO 228-1) or NPT on request. In sizes 1/2″–1 1/4″ the body length follows the DIN 3202-M9 series; for lines needing higher pressure, threaded or socket-weld types with cast steel and forged steel bodies are also available.
Main Applications
- Steam boiler sampling and drain points
- Steam trap and strainer bypass lines
- Small-bore steam and superheated water branches
- Compressed air points of use
- Equipment inlet isolation in heating circuits
Technical Data
| Connection | Female thread BSP (EN 10226-1 / EN ISO 228-1), NPT (ASME B1.20.1) on request |
|---|---|
| Sizes | 1/2″, 3/4″, 1″, 1 1/4″, 1 1/2″, 2″ |
| Pressure class | PN16 |
| Body | Grey iron EN-GJL-250 (5.1301) |
| Temperature | −10 / +300 °C |
| Pressure–temperature | 16 bar / 120 °C · 12.8 bar / 200 °C · 9.6 bar / 300 °C |
| Body length (A) | 100 mm (1/2″) · 120 mm (3/4″) · 135 mm (1″) · 160 mm (1 1/4″) · 175 mm (1 1/2″) · 195 mm (2″) |
| Length standard | DIN 3202-M9 (except 1 1/2″ and 2″) |
| Kv value | 4.5 (1/2″) · 8.5 (3/4″) · 14 (1″) · 20.5 (1 1/4″) · 32 (1 1/2″) · 50 m³/h (2″) |
| Weight | 1.7 kg (1/2″) … 11.9 kg (2″) |
| Sealing | Metal-reinforced laminated graphite, lower and upper ring |
| High-pressure option | Cast steel PN63 (1/2″–1″) and forged steel 800 lb types depending on model |
Material Options
| Part | PN16 · grey iron, threaded | PN63 · cast steel, threaded / socket weld | 800 lb · forged steel, threaded / socket / butt weld |
|---|---|---|---|
| Body | Grey iron EN-GJL-250 (5.1301) | Cast steel 1.0619 | Forged steel ASTM A105 |
| Bonnet | Grey iron EN-GJL-250 (5.1301) | Cast steel 1.0619 | Forged steel ASTM A105 |
| Piston | Stainless 1.4301 (1/2″–3/4″) · 1.4104 (1″ and above) | Stainless 1.4301 (1/2″–3/4″) · 1.4104 (1″) | Stainless ASTM A582 XM34 |
| Stem | Steel 1.0718 | Stainless 1.4305 (AISI 303) | Stainless ASTM A479 Type 410 |
| Lower / upper ring | Graphite T1 / graphite T4 | Graphite T1 / graphite T1 | Graphite T1 / graphite T1 |
| Lantern (intermediate piece) | Carbon steel (1/2″–3/4″) · grey iron 5.1301 (1″ and above) | Carbon steel (1/2″–3/4″) · grey iron 5.1301 (1″) | Carbon steel or grey iron 5.1301 (by size) |
| Stud / nut | Steel 5.6 / 5.2 | Steel 5.6 / 5.2 | ASTM A193 B7 / A194 2H |
| Handwheel | Grey iron 5.1301 | Grey iron 5.1301 | Cast iron |
Which type? On steam and water lines not exceeding 16 bar and 300 °C, the grey iron PN16 threaded type is sufficient. On small-bore steam lines reaching 400 °C or above 16 bar, consider cast steel PN63; where welded connections are required and temperatures approach 425 °C, consider the forged steel 800 lb type. Use suitable thread sealants for the threads.
Advantages
Compact Body
- No flanges, short body length.
- Saves space in tight boiler rooms and fitting groups.
Direct Screwing
- Female-threaded ends connect straight to the pipe.
- No flange, gasket or bolt set needed.
In-Line Ring Renewal
- Graphite rings are replaced by opening the bonnet.
- Maintenance without removing the valve from the pipe.
Thread Choice
- BSP as standard, NPT on request.
- Fits installations built to different standards.
High-Pressure Alternative
- Steel-bodied types in the same sizes.
- Switch with the same body length when pressure rises.
Construction and Design Features
- Compact globe body with female threads at both ends
- Lower and upper graphite rings separated by a lantern
- Stainless piston sliding between the rings
- Two-piece piston nut and stop plate on 1″ and above
- Disc-spring bonnet and handwheel operation
Send the thread size, thread standard (BSP or NPT), pressure and temperature through the Request a Quote form; we will prepare the right threaded piston valve right away.
How to Choose?
- Identify the thread standardCheck whether the line thread is BSP or NPT.
- Choose the sizeSelect between 1/2″ and 2″ according to the pipe size.
- Check pressure and temperatureMove to a steel-bodied type above 16 bar and 300 °C.
- Calculate the flow lossFind the pressure drop for the flow using the Kv value.
- Mark the flow directionInstall so that flow follows the arrow on the body.
Complementary Products
Why ORFA?
Other Piston Valves
Our Threaded Piston Valves
ORFA supplies threaded piston valves in a range of pressure classes, sizes and connection types to suit your application. Descriptions, technical specifications, materials and dimension tables are available on each detail page.
Threaded Piston Valve
Threaded piston valve: cast iron body, stainless steel piston, stainless-reinforced pure graphite seal rings, 1/2"–2", PN16, high temperature. For steam, hot water and thermal oil.
Details →Pneumatic Piston Valve
Pneumatic piston valve: AISI 316 stainless steel body, PTFE seat, single acting normally closed, 1/2"–2", PN16, max 180 °C, control air 3–8 bar.
Details →Get a quote for your project
Our sales team will prepare the best solution for your needs.