Material selection
Duplex Steel Flanges
Duplex flange selection combines corrosion resistance with a controlled two-phase microstructure. Identify the exact grade rather than requesting duplex alone.
Designation and microstructure
Duplex stainless steels contain ferritic and austenitic phases. Common designations such as UNS S31803 and S32205 must be checked against the actual purchase specification; a dual designation should not be assumed. Product form and heat treatment are part of the ordered material condition.
Corrosion and fabrication review
Service chemistry, chloride exposure and temperature must be evaluated for the selected grade. Welding and thermal processing can affect phase balance and corrosion performance. Specify the required weld procedure and any project limits on ferrite, intermetallic phases or corrosion-test results.
Joint selection remains separate
The material name does not set the bolt pattern, flange class or gasket arrangement. Confirm the dimensional standard and the applicable material-specific design basis. Backing rings, stub ends and mating fasteners may have different materials and must be identified separately.
Selection reference only. Offered scope, technical compliance and availability are confirmed against the complete project enquiry.
Material designations and distinctions
Reference designations for Duplex Steel Flanges. These are not an availability list or an equivalence table. A trade name, UNS number and ASTM product specification have different roles.
| Parameter / designation | Technical information | Selection requirement |
|---|---|---|
| UNS S31803 | Duplex stainless designation | Confirm the product specification, grade/condition, design suitability and required material records. |
| UNS S32205 | Separate composition limits; dual certification is not assumed | Confirm the product specification, grade/condition, design suitability and required material records. |
Compare related options
Compare Duplex Steel Flanges with the related forms or references below. A related product is not necessarily a permissible substitute.
| Related product / reference | Distinction | Check before selection |
|---|---|---|
| Super Duplex Steel Flanges | Super duplex flange enquiries need a grade-specific corrosion and fabrication review. The family name is not a guarantee of suitability for seawater or chemical service. | Exact UNS and material specification |
| Stainless Steel Flanges | Specify stainless steel flanges by grade, product specification and service conditions, not by a bright surface finish or the general name stainless steel. | Material specification, grade and any low-carbon or stabilised variant |
| SMO 254 Flanges | SMO 254 is a high-alloy austenitic stainless material, not a duplex grade. Define the flange using the required alloy designation and product specification. | Required alloy/UNS and product specification |
Inspection, documents and delivery
Define acceptance requirements for Duplex Steel Flanges in the purchase order. Required examinations and documents depend on the material, design and project specification.
| Review stage | Information to confirm | Order requirement |
|---|---|---|
| Material identity and traceability | Specification, grade, heat/lot identification and the required material certificate. | Agree documentation and marking before manufacture; visual appearance cannot verify alloy identity. |
| Dimensional verification | The selected flange form, bore, thickness, bolt pattern and mating geometry. | Identify inspection points, tolerances, units and drawing revision. |
| Surface and end condition | Gasket-contact surface, attachment end, edges and any coating exclusions. | State finish and visual acceptance criteria; agree protection of machined surfaces. |
| Supplementary examinations | Any specified PMI, NDE, hardness, impact, corrosion or other tests. | Define the method, sampling and acceptance criteria; tests are not automatically included. |
| Assembly compatibility | Adjoining components, weld or mechanical interface and project service conditions. | Design approval and correct assembly remain separate from a dimensional inspection report. |
| Packing and order release | Quantity, identification, surface protection, documents and delivery destination. | Agree preservation, packaging and release requirements with the order. |
Enquiry checklist
Details for Duplex Steel
Specify the complete joint and design conditions. This checklist is not a dimensional table or an engineering approval.
| Item | Requirement |
|---|---|
| Identity | UNS designation and applicable product specification |
| Condition | Heat treatment and project microstructure requirements |
| Service | Chlorides, design temperature and corrosion assessment |
| Testing | Required phase-balance, corrosion and mechanical tests |
Continue the specification