Closure & measurement
Blind Flanges
A solid flange closes a flanged opening without a through bore. Its bolted connection allows the closure to be removed for access when the system is safely isolated.
Closure & measurement
High Hub Blind Flanges
A high hub blind flange combines a closed centre with a projecting hub on its rear side. The hub profile distinguishes it from an ordinary flat-backed blind flange.
Specify the hub diameter and projection as well as the pressure-retaining section and mating face. A raised hub does not itself establish a higher allowable pressure. Any drilled, tapped or machined modification must be assessed as part of the agreed design rather than assumed acceptable.
Compare flange typesHub versus gasket facing
The high hub is a body feature and must not be confused with a raised gasket face. Identify which side carries the hub and specify the mating face independently.
Modifications need a drawing
Include any required ports, recesses or attachment features on a controlled drawing. Specify inspection and acceptance requirements for the actual modified component.
Dimensions and connection data
Define High Hub Blind Flanges as part of the complete joint. These fields identify required engineering data; they are not universal dimensions or a declaration of available sizes.
| Parameter / designation | Technical information | Selection requirement |
|---|---|---|
| Nominal size and bore | State the nominal connection size separately from the actual bore or pipe outside diameter. | A matching size label does not establish matching internal geometry. |
| Outside diameter and thickness | Identify the finished flange diameter, minimum thickness and any hub or collar projection. | Include the drawing datum and units for replacement measurements. |
| Bolt circle and holes | Record pitch-circle diameter, hole quantity, hole diameter and any special orientation. | Check against the mating flange; do not infer a bolt pattern from pressure class alone. |
| Gasket-contact surfaces | Specify face form, seating dimensions and surface finish on the assembled joint. | Include gasket designation; a visually similar surface is not evidence of compatibility. |
| Pipe-side interface | Identify weld preparation, socket, thread, collar or other attachment geometry as applicable. | Provide pipe schedule/wall thickness and the connection-specific standard. |
| Design conditions | State design pressure, minimum/maximum temperature, fluid and mechanical loads. | Pressure class is not a pressure value in bar or psi. Use the material-specific rating basis. |
Compare related options
Compare High Hub Blind Flanges with the related forms or references below. A related product is not necessarily a permissible substitute.
| Related product / reference | Distinction | Check before selection |
|---|---|---|
| Blind Flanges | A solid flange closes a flanged opening without a through bore. Its bolted connection allows the closure to be removed for access when the system is safely isolated. | Solid centre; identify any required drilling separately |
| Forged Flanges | Forged flanges describe a manufacturing route spanning several connection forms, including weld neck, slip-on and blind. The flange type must still be specified. | Weld neck, slip-on, blind or other specified form |
| Companion Flanges | A companion flange is selected to mate with a particular flanged connection. The term describes its role in an assembly, so the actual connection form and dimensions must be identified. | Provide equipment drawing or flange designation |
Inspection, documents and delivery
Define acceptance requirements for High Hub Blind 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 | Critical dimensions from the selected standard or controlled drawing. | 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. |
Specification checklist
Define your high hub blind flanges
Availability, dimensions and pressure-temperature suitability are confirmed against your complete enquiry.
| Item | Requirement |
|---|---|
| Hub profile | Diameter, height, transition and orientation |
| Closure | Minimum section and any separately specified modifications |
| Mating face | Bolt pattern, facing and gasket requirements |
| Design basis | Approved standard or drawing and pressure-temperature assessment |
| Material & quantity | Exact material designation, quantity and required certification or inspection documents |
Application context
Where this form is considered
- Equipment closures requiring a defined rear hub
- Drawing-specified blind-flange variants
- Replacement closures with a verified profile
Related connections
Compare other flange forms
Construction & special designs
Forged Flanges
Forged flanges describe a manufacturing route spanning several connection forms, including weld neck, slip-on and blind. The flange type must still be specified.
Mechanical connections
Companion Flanges
A companion flange is selected to mate with a particular flanged connection. The term describes its role in an assembly, so the actual connection form and dimensions must be identified.