ASME B16.47 covers large-diameter steel flanges in nominal pipe sizes (NPS) 26 through 60 inches. Its two dimensional series, Series A and Series B, differ in flange geometry and bolting, so buyers should not assume that a flange from one series will fit a mating flange from the other. Before requesting a quote, confirm the required series, NPS, pressure class, flange type, material, facing, and applicable standard edition against the project documents.
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This guide is for engineers, procurement teams, project contractors, and distributors sourcing large-diameter flanges for industrial piping systems. It is particularly useful when specifications refer to ASME B16.47 but do not make the required series or mating dimensions immediately clear. Use it as a purchasing aid, then verify the final selection against the applicable standard and project engineering documents.
Longrun supplies stainless steel pipes, industrial pipe fittings, and flanges for B2B projects. We can review the information in your inquiry and help clarify which details are needed for a technically aligned quotation. Final product selection should remain consistent with the project’s design conditions and approved specifications.
ASME B16.47 is a dimensional standard for large-diameter steel flanges, covering NPS 26–60. The standard includes pressure class designations from Class 75 through Class 900, with the applicable size and flange configuration determined by its tables. A class designation is not, by itself, a universal pressure rating: allowable pressure depends on factors such as material and temperature, so consult the governing design code and material requirements.
Buyers commonly encounter weld-neck and blind flanges in this size range. The exact configurations available and their dimensional requirements must be checked against the specified edition of the standard. Do not infer flange type from a product description that only states “B16.47”; ask the supplier to identify the type and confirm it against the purchase specification.
Series A and Series B define different dimensional patterns for the same nominal size and pressure class. In general, Series A flanges are larger and heavier, while Series B designs are typically more compact and use a different bolt arrangement. These are useful general distinctions, not a substitute for checking the exact dimensions for a particular NPS, class, and flange type.
| Buyer consideration | Series A | Series B |
|---|---|---|
| Dimensional pattern | Uses Series A dimensions in the applicable standard tables. | Uses a separate Series B dimensional pattern. |
| General design tendency | Often larger and heavier for a comparable size and class. | Often more compact, with a different bolting arrangement. |
| Compatibility check | Confirm series and mating flange dimensions. | Confirm series and mating flange dimensions. |
Do not treat the two series as interchangeable simply because their NPS and class match. Differences in outside diameter, bolt circle, bolt-hole count, bolt-hole size, and other dimensions can prevent proper alignment or assembly. Verify the full mating connection before ordering replacement flanges or combining components from different sources.
Flange dimensions determine fit-up, bolting, and connection geometry. For each item, check the dimension in the applicable ASME B16.47 table rather than relying on a generic online description. The standard’s tabulated dimensions are expressed in inches; for reference, 1 inch equals 25.4 millimeters, but conversions should not replace the specified standard values.
A frequent mistake is specifying only “ASME B16.47, NPS 36,” without stating Series A or Series B, class, and flange type. Another is assuming that flanges with the same nominal size and class will mate even when their series differ. Buyers can also overlook material, facing, or document requirements until after the quotation stage, which may affect availability and project coordination.
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Reduce these risks by sending the supplier the full callout and, where possible, a drawing or approved material specification. If a replacement flange is involved, confirm the existing flange’s actual series and connection details instead of relying on a partial marking or old purchase record. Where dimensions conflict with project documents, request clarification before manufacturing or release.
ASME B16.47 flanges are used in large-diameter piping where the connection must match the specified size, class, and dimensional series. Application suitability depends on the complete piping design, including pressure and temperature conditions, material compatibility, loading, gasket selection, and assembly requirements. A standard dimensional match does not by itself establish that a component is suitable for a particular process.
Material selection should follow the project’s piping specification and service conditions. Stainless steel may be specified for some applications, but grade selection should be reviewed for the fluid, temperature, corrosion considerations, and applicable design requirements. Ask the supplier to identify the offered material clearly and state what material documentation can be provided for the order.
Large-diameter flange quotations depend on more than nominal size. Series, pressure class, material, flange type, quantity, manufacturing route, inspection scope, and documentation requirements can all affect the commercial offer. Because requirements and availability vary, buyers should request a project-specific quotation rather than assume a standard price or minimum order quantity.
Lead time should be confirmed against the exact specification and order scope. Ask whether the quoted schedule includes manufacturing, inspection, documentation, packing, and shipment, and clarify any approval steps that could affect release. For urgent projects, provide the required delivery location and target date early so the supplier can assess feasibility without making an unsupported schedule commitment.
At Longrun, we work with B2B buyers sourcing stainless steel pipes, industrial pipe fittings, and flanges. Share your technical specification, quantity, destination, and delivery target so our team can review the requirements and respond with a quotation scope. Where a requirement is unclear, include the relevant drawing or project note so it can be clarified before order confirmation.
To choose an ASME B16.47 flange correctly, identify the required Series A or Series B pattern, then confirm NPS, pressure class, flange type, material, facing, and the applicable standard edition. Series A and Series B have distinct dimensions and bolting arrangements, so matching nominal size alone is not enough to establish compatibility. Verify the mating connection and project design requirements before purchase.
Your next step is to prepare a complete flange callout and send it with any relevant drawings, quantity, and delivery information to your supplier. Longrun can review your inquiry and support the sourcing process for stainless steel pipes, fittings, and flanges. A clear specification helps both sides align the quotation with your project needs.
For more information, please visit ASME B16.47 Flanges.