Welded connections
Weld Neck Flanges
A tapered hub carries the connection from the flange body to a butt-welded pipe end. The pipe bore and wall thickness are important parts of the flange specification.
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.
Blind flanges are used at pipe ends, equipment nozzles and other openings requiring a bolted closure. A drilled or tapped blind is a modified design and must be specified separately rather than assumed equivalent to a standard blind.
Compare flange typesDimensions and connection data
Define 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 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 |
|---|---|---|
| Weld Neck Flanges | A tapered hub carries the connection from the flange body to a butt-welded pipe end. The pipe bore and wall thickness are important parts of the flange specification. | Butt-weld end; specify pipe schedule and bore |
| Slip-On Flanges | The flange bore slips over the pipe before the connection is secured with fillet welds. Pipe outside diameter and installation clearance govern the fit. | Slip-over bore with project-specified fillet welds |
| Orifice Flanges | Pressure-tapping connections distinguish an orifice flange from a general pipe flange. A matched assembly supports the differential-pressure measurement arrangement around an orifice plate. | Specify the matched flange pair and plate arrangement |
Inspection, documents and delivery
Define acceptance requirements for 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 blind flanges
Availability, dimensions and pressure-temperature suitability are confirmed against your complete enquiry.
| Item | Requirement |
|---|---|
| Construction | Solid centre; identify any required drilling separately |
| Joint | Match mating flange dimensions and facing |
| Design basis | Specify class, material and design temperature |
| Modifications | Provide an approved drawing for non-standard openings |
| Material & quantity | Exact material designation, quantity and required certification or inspection documents |
Application context
Where this form is considered
- Flanged pipe-end closures
- Equipment opening isolation
- Maintenance and inspection access
Related connections
Compare other flange forms
Welded connections
Slip-On Flanges
The flange bore slips over the pipe before the connection is secured with fillet welds. Pipe outside diameter and installation clearance govern the fit.
Closure & measurement
Orifice Flanges
Pressure-tapping connections distinguish an orifice flange from a general pipe flange. A matched assembly supports the differential-pressure measurement arrangement around an orifice plate.