Basket strainer
The basket strainer in carbon steel or stainless steel is the basic form of industrial filtration: a welded housing, a removable strainer basket and a cover. It retains whatever would damage the pumps, heat exchangers, nozzles and valves downstream – from coarse weld spatter to the finest particles.
Every basket strainer is built to your process data. We design nominal size, pressure rating, material, mesh size and equipment together with you – from DN50 to DN1000.
ISO 9001 · TÜV-approved welding shop AD2000-HP0 · PED 2014/68/EU
Operating principle
The medium enters from the side and flows from the inside to the outside through the strainer basket. The dirt stays in the basket – not on the housing wall. For cleaning, the cover is opened, the basket removed, rinsed and put back.
This design has two practical consequences. The collected dirt is visible and can be assessed. And the basket can be exchanged for a different mesh size without any work on the housing.
When cleaning is due is shown by the differential pressure – not by the calendar. That is why a differential pressure gauge on the basket strainer → belongs in almost every design.
Strainer element
As standard, the basket strainer works with a support basket in 1.4301 with square perforation Qg 10-12 and a fine mesh screen in 1.4401 with a mesh size of 1 mm. The support basket carries the load, the fine mesh sets the filtration grade – two parts with two tasks.
From a mesh size of about 2.5 mm no wire mesh is needed: the perforation of the basket then does the filtering on its own. Below that, the fine mesh screen is fitted. The range goes down to 0.05 mm.
Fine mesh, filter bag or both. The housing stays the same – only the element is changed. A filter bag can be fitted in the same support basket instead of the fine mesh, turning the basket strainer into a bag filter. Both together are possible as well: the bag does the fine filtration, the screen keeps coarse particles away from it.
The bag filters finer than any wire mesh: polypropylene felt from 1 to 300 µm, polyester felt from 1 to 200 µm, nylon on request – in bag sizes 1 to 4. Where the fine mesh ends at 50 µm, the bag goes down to 1 µm. In return it is a replacement part, not a permanent component, and the pressure rating in this design is up to 10 bar.
Designs
On a basket strainer the same task is repeated again and again: cover open, basket out, basket in, cover closed. The three most common options therefore address exactly this task – and with increasing nominal size they turn from convenience into necessity.
Eye bolts with wing or ring nuts, hinged eye bolts or clamps replace the bolt circle. The basket can be reached without a set of spanners – with frequent changes this saves more time per cleaning than the rinsing itself.
From DN200 the cover can no longer reasonably be lifted by hand. Hinge, lifting spindle and swivel arm take the weight: the cover is raised, swung to the side and stays on the housing – it never has to be put down.
The basket strainer stands upright and carries considerable weight when filled. Three-point support legs transfer this load to the foundation instead of the pipeline – important wherever the strainer is not held between two fixed pipe points.
Large nominal sizes
Up to DN250 the basket strainer is a piping component. Above that, the task changes: the housing is made from pipe or plate, and the basket is removed by crane. The cover weighs more than one person can lift. Design, welding sequence and testing therefore come to the fore.
The photo shows a DN700 in carbon steel, painted RAL 5010 blue, with butt-weld ends – without flanges, welded directly into the line. This design is common in district heating, where every flanged joint is a potential leak point.
An example from this class: a start-up strainer with a volume of about 2,600 litres, designed for PN25 and −10 to +120 °C. Shell and heads are made of P265GH to EN 10028-2, with inspection certificate 3.1. It is connected by butt-weld ends and has support legs, vent and drain flanges DN25 and two sockets for differential pressure measurement.
The strainer element there is double-walled: a coarse stage with 0.5 mm and behind it a fine stage with 0.25 mm mesh size. A start-up strainer retains whatever has been left in the line when a new production starts or after maintenance – rust, scale, weld spatter. It runs for only a few hours, but in that time it has to take up everything.
High-pressure design
The standard range ends at PN40. Above that, the high-pressure design takes over: the same design, but with a cover closure for the higher pressure. Instead of a flat gasket, the cover sits in a machined tongue and groove, sealed with a kammprofile gasket. This joint seals reliably again even after many openings.
This has a practical consequence: the quick-opening closure is not possible. At these pressures the cover is bolted, and that takes longer. Where frequent cleaning is needed, it is therefore worth checking whether the operating pressure at the installation point can be kept below PN40 after all.
Strainer element, materials and connection types are the same as in the standard range. Higher pressure ratings and other designs are engineered on request.
Variants
As standard, the basket strainer is a straight-through housing. Three variants differ from it – each for a different reason.
Design parameters
Values for the standard design. The final design is based on your process data – higher pressure ratings, further temperature ranges and different face-to-face lengths are available on request.
Dimensions
Dimensions of the standard design in PN10 and PN16: H1 is the overall height, L the face-to-face length to EN 558-1 series 1, ∅D the housing pipe. The weight applies to the empty carbon steel design without attachments. A dimensioned drawing for your nominal size is included with the design proposal.
| Nominal size | H1 [mm] | L [mm] | ∅D [mm] | Screen area [cm²] | Volume [l] | Weight [kg] |
|---|---|---|---|---|---|---|
| DN50 | 255 | 230 | 114.3 | 290 | 2.2 | 20 |
| DN65 | 300 | 290 | 139.7 | 420 | 4.0 | 27 |
| DN80 | 330 | 310 | 168.3 | 650 | 6.5 | 36 |
| DN100 | 415 | 350 | 219.1 | 1,270 | 14 | 55 |
| DN125 | 415 | 400 | 273 | 1,270 | 15 | 57 |
| DN150 | 505 | 480 | 323.9 | 2,025 | 36 | 106 |
| DN200 | 610 | 600 | 355.6 | 3,350 | 58 | 157 |
| DN250 | 700 | 730 | 457 | 4,560 | 108 | 305 |
| DN300 | 830 | 850 | 508 | 5,815 | 163 | 412 |
| DN350 | 970 | 980 | 610 | 9,285 | 268 | 625 |
| DN400 | 1,095 | 1,100 | 711 | 11,690 | 408 | 819 |
| DN450 | 1,095 | 1,200 | 711 | 11,690 | 436 | 856 |
| DN500 | 1,145 | 1,250 | 711 | 12,020 | 480 | 925 |
| DN500 | 1,170 | 1,400 | 813 | 13,190 | 620 | 1,125 |
The two DN500 rows differ in the housing pipe and therefore in screen area and volume. Nominal sizes up to DN1000 and different face-to-face lengths are built to your piping layout. Dimension sheets and STEP models are available on request.
Applications
Wherever a component has to be protected and the strainer can be isolated briefly for cleaning. It covers the largest part of our strainer production – and is the first choice as long as no switchover operation is required.
Manufacturing and documentation
Cutting, welding, turning, surface finishing and testing are done in our own workshop. A different face-to-face length, a special material or an additional socket is therefore not a surcharge on a catalogue part but part of the design.
Enquiry
Tell us the medium, flow rate, operating pressure and operating temperature. From this we design nominal size, screen area and material. Only nominal size and pressure rating are mandatory – if you do not know them yet, select “please advise” or “not sure”. Add further strainers with “+ further item”.
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You can reach us by email at info@industriefabrik.com.
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As long as the line may be isolated briefly for cleaning, the basket strainer is the simpler and more economical solution. As soon as downtime costs more than a second housing – or the dirt load is so high that frequent cleaning is needed – the duplex strainer with changeover unit pays off.
The filtration grade depends on the component downstream of the strainer, not on the medium. A centrifugal pump tolerates coarser particles than a nozzle or a plate heat exchanger. The finer the screen, the more often it has to be cleaned – too fine is therefore just as wrong as too coarse. The selection is explained under Mesh size and filtration grade.
By the differential pressure between inlet and outlet. It is the only reliable indicator of the degree of fouling; the service life cannot be planned by the calendar. The permissible differential pressure is 2 bar; operation up to a maximum of 0.5 bar is recommended. The options, from the gauge to a contact for the control system, are explained under Differential pressure on the strainer.
We manufacture up to DN1000 in pressure ratings PN6 to PN40. The table above shows the common sizes up to DN500; above that, the housing is designed to your piping layout.
Yes, also for housings from other manufacturers. The quickest way is with the dimensions of the old part: outside diameter, height, handle or bottom design and the mesh size. A photo also helps. On request we make the basket in several parts or fit it with magnetic rods.
Yes – housing and flanges in 1.4571, pickled and passivated, are the second standard variant alongside the painted carbon steel design. Support basket and fine mesh are always made of stainless steel anyway. For aggressive media, Monel, Hastelloy or duplex can be used – see Materials for strainers.
All basic types compared: Industrial strainers
Replacement strainer elements for basket strainers are made to size or to sample. When a strainer element is worn, we replace it – for our own ranges as well as for other manufacturers’ strainers. To the spare part →
Tell us the medium, flow rate, pressure and temperature as well as the component to be protected. You will receive a design proposal with nominal size, mesh size, material and equipment.
