Temperature control
Media that become viscous or solidify when they cool down block any strainer. A welded heating jacket around the housing keeps the medium at operating temperature – heated with thermal oil, steam or hot water. We design steam jacketed strainers and heated Y strainers, also as a retrofit.
Thermal oil · Steam · Hot water
welded stainless steel
up to 200 °C at 40 bar
Leak detection sensor
Liquid sulphur is filtered at 145 °C, chocolate at 50 to 70 °C; bitumen and heavy fuel oil need constant heat. If the medium cools down in the strainer housing, its viscosity rises, the differential pressure increases and, in the worst case, the contents solidify in the screen. After that, cleaning no longer helps – only removal and melting out.
The jacket prevents this: it holds the temperature at which the plant is running anyway. It is not a heater that heats up the medium; it compensates for the heat loss at the housing. The housing is particularly vulnerable because it has more surface area than the pipeline and holds a large, slowly flowing volume in the screen. The jacket is designed to the Pressure Equipment Directive 2014/68/EU.
How much jacket surface is needed depends on the medium, the temperature and the surroundings.
A second shell is placed around the strainer housing and seal-welded; the heating medium flows in between. If it encloses the entire shell surface, it is called a double jacket. This gives the most uniform temperature and is the choice for media that drop out even with slight heat loss. An example: 1.4571 on a basket strainer DN50 PN16 for hot water at 95 °C and 5 bar.
The angled housing of a Y strainer cannot be enclosed by a straight jacket – we shape the jacket to follow the housing. An example: Y strainer in stainless steel with female thread Rp 1¼″, heating connection as a ¼″ socket, designed for steam at 10 bar and 200 °C. Also possible for flanged designs.
Not every point needs a jacket all the way round. As a partial heating jacket, it encloses only one section: a valve, a pipe section or part of the strainer. Many partial heating jackets can also be retrofitted.
We can also design and weld a heating jacket onto units that were not made by us – for example Y strainers and customer-supplied ball valves. Send us the unit or a drawing, and we will check whether the material and wall thickness allow a jacket.
Where the issue is safety rather than heat, the second jacket becomes a leakage jacket. A sensor on the jacket space signals when medium escapes from the process side or heating medium enters. For toxic and hazardous substances with high safety requirements, this is often the actual reason for the double jacket, not the temperature. Heating jacket and leakage jacket can be combined on the same housing.
Simplex strainer DN80 · heating and leakage jacket
Basket strainer DN50 · stainless steel with heating jacket
Basket strainer DN100 PN10 · carbon steel with heating jacket
Y strainer · flange and thread, with heating jacket
Every jacket is designed for the individual strainer. The following data are examples and show the available range.
| Feature | Value | Note |
|---|---|---|
| Basic data | ||
| Designs | Heating jacket · Double jacket | welded, in stainless steel |
| Further designs | Partial heating jacket · Partial heating | where a full surrounding jacket does not fit |
| Heating medium | Thermal oil · Steam · Hot water | to suit your existing circuit |
| Material | 1.4571 | carbon steel also possible |
| Code | PED 2014/68/EU | design of the pressure chamber |
| Optional | Sensor for escaping leaks | monitoring of the jacket space |
| Connection of the heating circuit | ||
| Socket | 1/4" · 1/2" · 3/4" | usual for low heating capacities |
| Flange | DN15 PN16 | e.g. on the duplex strainer |
| Pipe | 21.3 × 2 | with 45° bend and corrugated hose |
| Butt-weld end | to drawing | for fixed piping |
| Design examples | ||
| Hot water | 95 °C · 5 bar | Basket strainer DN50 PN16, 1.4571 |
| Hot water | 120 °C · 5 bar | DN50, carbon steel, 2 × socket 1/2″ |
| Water | 60 °C · 6 bar | Basket strainer DN50, socket 3/4″ |
| Steam | 5 bar | Carbon steel, 2 × socket 1/4″ |
| Partial heating jacket | 200 °C · 40 bar | 1.4571, example shown above |
| Available for | ||
| Basket strainer | yes | welded heating jacket / double jacket |
| Simplex strainer | yes | heated design |
| Duplex strainer | yes | also the side sections only |
| T-type strainer | yes | together with butt-weld ends |
| Y strainer | yes | also on other manufacturers’ strainers |
| Pot type strainer | possible | subject to design |
This is regularly overlooked when ordering: the jacket and insulation cover the housing and with it everything on it that has to be operated. Hand levers and actuators of ball valves suddenly sit too deep to be reached – which is why stem or shaft extensions belong to the heated strainer. They are usual for DN50 in 1.4301 with lengths of 100 and 250 mm. Likewise, the cover still has to open: closure, swivel device and the insulation over them must fit together. We take this into account in the design proposal and show it in the drawing.
Yes. Before production starts, you receive the design drawing for approval – with jacket geometry, position and type of the heating connections and the design data. The order goes into production only after you have approved the drawing.
Certainly. Drawings, specifications, data sheets of the heating circuit or details of the previous unit are the best basis. Our design engineers adopt your requirements and adapt them where production or the applicable code requires – we agree any deviations with you in advance.
Both are a welded second shell through which the heating medium flows. It is called a double jacket when it encloses the entire shell surface; a heating jacket can also cover just one section. The surface needed depends on the heat loss at your installation site.
Thermal oil, steam and hot water are the common heating media. What matters is which circuit you already have in the plant – this determines the design pressure, the temperature and the type of connection. Tell us the medium, flow temperature and pressure.
This is not a catalogue value but the result of the design: it depends on the heating surface, temperature difference, heating medium and surroundings. Tell us the operating temperature of the process medium, the ambient conditions and the data of your heating circuit – we then calculate the required surface and define it in the drawing.
Yes. Jackets that enclose only the side sections of a duplex strainer or only the middle section of a valve are possible. If one particular point cools down and the rest is not critical, this is the more economical solution.
Yes, also on units that were not made by us. Designing heating jackets for strainers supplied by others is part of our services, as is welding them onto customer-supplied valves. We check beforehand whether the material and wall thickness of the existing housing allow this.
It monitors the space between housing and jacket and signals when medium appears there. For toxic and hazardous substances subject to strict safety regulations, this is often required – the leak is detected before medium reaches the outside.
As a rule, yes. The jacket supplies heat, the insulation keeps it in the unit – without it you are heating against the surroundings. Removable insulation jackets are suitable for strainers because the cover has to be free for changing the screen. More details are on the insulation page.
Only with extensions. The jacket and insulation add thickness, so stem or shaft extensions belong on heated valves – usual for DN50 in 1.4301 with 100 and 250 mm. We include them in the design proposal.
All topics at a glance: Strainer options
Tell us the process medium with its operating temperature, the data of your heating circuit and the installation site – these determine the jacket shape, heating surface and connections.
