Kaifil
Duplex stainless steel for filter mesh and screens
Compare 2205 duplex and 2507 super duplex stainless steel for chloride-bearing filtration service. Grade identity, chromium-molybdenum-nitrogen chemistry and welded construction define the material specification.
| Exact duplex designation | 2205 with UNS S31803 or S32205, or 2507 with UNS S32750. |
|---|---|
| Chloride duty | Chloride concentration, fluid temperature, oxygen exposure and cleaning chemistry. |
| Screen design | Mesh or slot, wire dimensions, support pitch, frame and connections. |
| Fabrication requirements | Material condition, welding specification, surface treatment and dimensional tolerances. |
Austenite and ferrite in one stainless steel
Duplex stainless steel combines austenitic and ferritic phases. This structure provides higher strength than common austenitic stainless grades together with resistance to chloride stress corrosion cracking. In filtration equipment, duplex grades connect corrosion performance with the mechanical requirements of screen wires, supporting members and fabricated assemblies.
2205 and 2507 serve different chloride duties
2205 is the established duplex family for process equipment exposed to chloride-bearing liquids. 2507 is a super duplex grade with higher chromium, molybdenum and nitrogen, supporting increased resistance to pitting and crevice corrosion. Define chloride concentration, temperature, oxygen exposure and stagnant regions when choosing between them. Cleaning chemistry belongs in the same service description.
Preserve the microstructure during fabrication
The welding and thermal cycle form part of a duplex specification. Set heat input, interpass temperature, filler selection and final surface treatment through the fabrication procedure. On a screen assembly, identify both the filtering wire and the support grade. On a framed panel, include the frame and attachment welds in the material schedule.
Compare all filter material families
Connect this grade guide with the complete material comparison and the required filter construction.
Materials and alloys overviewDuplex grade identities
The UNS designation resolves the chemistry within each familiar grade name.
| Grade | UNS | EN reference | Distinction |
|---|---|---|---|
| 2205 | S31803 | 1.4462 | Original 2205 composition range |
| 2205 | S32205 | 1.4462 | Higher minimum chromium, molybdenum and nitrogen within the 2205 family |
| 2507 | S32750 | 1.4410 | Super duplex with higher alloy content |
| Super duplex with copper and tungsten | S32760 | 1.4501 | Separate grade with deliberate copper and tungsten additions |
Write the required UNS designation on the material schedule. S32750 and S32760 are distinct compositions.
Principal alloying elements: mass %
Ranges identify the principal chemical differences among the duplex grades.
| Element | S31803 | S32205 | S32750 |
|---|---|---|---|
| Cr | 21.0–23.0 | 22.0–23.0 | 24.0–26.0 |
| Ni | 4.5–6.5 | 4.5–6.5 | 6.0–8.0 |
| Mo | 2.5–3.5 | 3.0–3.5 | 3.0–5.0 |
| N | 0.08–0.20 | 0.14–0.20 | 0.24–0.32 |
| C | ≤0.030 | ≤0.030 | ≤0.030 |
Values are mass percentages. The ≤ sign denotes a maximum.
Choose the grade and construction together
Translate the process conditions into a complete screen specification.
| Design decision | 2205 | 2507 |
|---|---|---|
| Material priority | Strength and corrosion resistance for chloride-bearing process service | Increased pitting and crevice-corrosion resistance in more demanding chloride service |
| Woven screen | Define count, wire diameter, aperture and wire condition | Define the same geometry using the specified super duplex wire |
| Welded assembly | Control joints, heat input and surface condition | Control the thermal cycle and surface condition for super duplex |
| Procurement identity | State S31803 or S32205 explicitly | State S32750 explicitly |
From material grade to finished filter
- 01
Describe the exposure
Provide process and cleaning compositions, concentration, temperature and flow regime.
- 02
Choose the exact grade
Use the UNS designation to identify the chemistry, including the distinction within 2205.
- 03
Define all wetted parts
Specify wire, support, frame, connections and weld filler as an assembly.
- 04
Control the finished screen
Set dimensional inspection, weld inspection and surface-treatment requirements.
Material selection questions
Are S31803 and S32205 the same specification?
S32205 sets higher minimum chromium, molybdenum and nitrogen than S31803. Both belong to the 2205 family. Order by the required UNS designation and material standard.
What makes 2507 a super duplex grade?
Its higher chromium, molybdenum and nitrogen distinguish it from 2205 and improve resistance to localized corrosion. The grade is identified as UNS S32750.
Does stronger duplex wire change the filtration opening?
Opening size comes from wire diameter, count and weave, or from the welded slot geometry. Strength enters the support and load design; the drawing defines the opening.
What details belong on a duplex screen enquiry?
Include the UNS grade, mesh or slot geometry, wire and support dimensions, finished shape, connections, fluid chemistry, temperatures and differential pressure.
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