Overview
ASME B16.47 covers large-diameter steel pipe flanges in sizes NPS 26 through NPS 60 within the scope stated by ASME. It includes pressure-temperature ratings, materials, dimensions, tolerances, marking, and testing. The standard contains Series A and Series B dimensional systems, which must be identified in every RFQ and drawing.
A B16.47 flange description is incomplete without the series. Series A and Series B can differ in outside diameter, thickness, bolt-hole count, bolt size, and bolt-circle diameter. They are not intended to be mixed by visual similarity.
Why It Matters for Pipe Components
Large flanges carry high pressure thrust and can weigh hundreds or thousands of kilograms depending on size, class, material, and construction. A drilling mismatch is expensive to discover during site installation. It can delay spool completion, crane work, testing, and commissioning.
The size scope also matters. ASME B16.5 covers a different nominal-size range. Using a B16.5 table for a B16.47 item, or omitting the series, is a major procurement error.
Large-diameter manufacturing introduces additional controls for forging or plate route, heat treatment, flatness, machining capacity, lifting, packaging, and dimensional survey. Project specifications may impose requirements beyond the base product standard.
Methods, Parameters, or Process
Build the purchase description in a fixed sequence so the series and rating cannot be overlooked.
| RFQ field | Required entry | Inspection focus |
|---|---|---|
| Standard and edition | ASME B16.47 and agreed edition | Correct dimensional table and marking |
| Series | Series A or Series B | OD, thickness, drilling, bolt circle |
| Size and class | NPS and pressure class | Rating and dimensions |
| Flange type and facing | Weld neck, blind, and specified facing | Hub, bore, face finish, groove |
| Material route | Forged or permitted construction route | Specification, heat treatment, traceability |
| Bore and weld end | Pipe OD, wall, bevel, transition | Fit-up and internal mismatch |
| Handling | Weight, lifting points, packing | Safe movement and face protection |
Supplier and Inspection Checklist
- State Series A or Series B in the first line of the description.
- Confirm the project-required standard edition.
- Verify OD, thickness, hole count, hole diameter, and bolt circle.
- Measure flange flatness and facing condition using an approved method.
- Check weld-neck bore and bevel against the connected pipe.
- Maintain material and heat-number traceability after machining.
- Review heat treatment, mechanical tests, NDE, and supplementary requirements.
- Confirm actual unit weight and lifting method before shipment.
- Protect gasket faces, RTJ grooves, bevels, and markings during packing.
Application to Pipe Fittings, Valves, and Flanges
B16.47 flanges are used on large process lines, pipelines, water systems, terminals, vessels, and rotating-equipment connections when the project standard specifies them. The connected valve or equipment nozzle must use the same series and compatible facing.
Custom large flanges can resemble B16.47 products but use project-specific drilling or thickness. Such items should be marked and documented as drawing-based components rather than represented as standard flanges.
FAQ
What sizes does ASME B16.47 cover?
The current ASME product description states NPS 26 through NPS 60. Verify the edition required by the project.
What is the difference between Series A and Series B?
They use different dimensional systems, including drilling and flange geometry. The exact differences depend on size and class.
Can Series A connect to Series B?
Do not assume so. The drilling and dimensions can differ and require engineered transition arrangements.
Is B16.47 the same as B16.5?
No. They have different size scopes and dimensional tables.
Can a large flange be made from plate?
The permitted material and construction route depend on flange type, standard provisions, material specification, and project requirements. Verify before ordering.
Next Steps
For every B16.47 enquiry, request size, class, Series A or B, type, facing, material, bore, pipe wall, quantity, testing, and drawing approval requirements.
Request a Quote
