Material selection
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.
Grade and product form
Austenitic grades such as 304L and 316L are common enquiry designations, but they are not interchangeable for every service. Low-carbon, stabilised and other grade variants have distinct requirements. State the complete flange material specification and grade, and identify whether the component is forged or made by another approved route.
Corrosion and fabrication
Chloride concentration, temperature, crevices, cleaning chemicals and shutdown conditions can change material suitability. A generic stainless designation does not establish resistance to pitting or stress-corrosion cracking. Welding, heat treatment, surface cleaning and contamination controls should be reviewed with the piping specification.
Joint and documentation
Material selection does not select the flange class or facing. Confirm the dimensional standard, pressure-temperature rating and gasket separately. Request traceability to the ordered material designation and specify any corrosion, intergranular or other supplementary testing in the enquiry rather than assuming it is included.
Selection reference only. Offered scope, technical compliance and availability are confirmed against the complete project enquiry.
Material designations and distinctions
Reference designations for Stainless 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 |
|---|---|---|
| 304 / 304L | Austenitic grades with different carbon requirements | Confirm the product specification, grade/condition, design suitability and required material records. |
| 316 / 316L | Molybdenum-bearing austenitic grades | Confirm the product specification, grade/condition, design suitability and required material records. |
| 321 / 347 | Stabilised austenitic grades | Confirm the product specification, grade/condition, design suitability and required material records. |
| 904L | High-alloy austenitic designation | Confirm the product specification, grade/condition, design suitability and required material records. |
Compare related options
Compare Stainless 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 |
|---|---|---|
| Duplex Steel Flanges | Duplex flange selection combines corrosion resistance with a controlled two-phase microstructure. Identify the exact grade rather than requesting duplex alone. | UNS designation and applicable product specification |
| 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 |
| Flange Material Selection | Choose a flange material from the service and fabrication requirements, then define the exact grade and product specification. A photograph or broad alloy family cannot establish suitability. | Fluid chemistry, temperatures, pressure and external exposure |
Inspection, documents and delivery
Define acceptance requirements for Stainless 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 Stainless Steel
Specify the complete joint and design conditions. This checklist is not a dimensional table or an engineering approval.
| Item | Requirement |
|---|---|
| Designation | Material specification, grade and any low-carbon or stabilised variant |
| Service | Fluid composition, chloride exposure and design temperatures |
| Fabrication | Weld procedure, heat treatment and surface-cleanliness requirements |
| Documents | Material traceability and project-specific inspection or test requirements |
Continue the specification