Welded connections
Socket Weld Flanges
A recessed socket receives the pipe end, with a fillet weld at the outside of the hub. Socket depth, bore and assembly requirements distinguish it from a slip-on connection.
Mechanical connections
Threaded Flanges
Internal threads connect the flange to a matching threaded pipe end. The thread form, nominal size and mating pipe specification must be stated together.
Threaded and screwed are two names for this connection family. Suitability for vibration, thermal cycling and the process fluid must be evaluated under the applicable piping design requirements. NPT and BSP connections must not be treated as interchangeable.
Compare flange typesDimensions and connection data
Define Threaded 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 Threaded Flanges with the related forms or references below. A related product is not necessarily a permissible substitute.
| Related product / reference | Distinction | Check before selection |
|---|---|---|
| Socket Weld Flanges | A recessed socket receives the pipe end, with a fillet weld at the outside of the hub. Socket depth, bore and assembly requirements distinguish it from a slip-on connection. | Specify socket dimensions and pipe schedule |
| 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 |
| 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 |
Inspection, documents and delivery
Define acceptance requirements for Threaded 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 threaded flanges
Availability, dimensions and pressure-temperature suitability are confirmed against your complete enquiry.
| Item | Requirement |
|---|---|
| Connection | Specify thread standard, size and engagement |
| Sealing | Identify a process-compatible thread sealing method |
| Facing | Match the bolted connection independently of the pipe thread |
| Service | Review temperature cycling, vibration and fluid compatibility |
| Material & quantity | Exact material designation, quantity and required certification or inspection documents |
Application context
Where this form is considered
- Threaded utility connections
- Locations with restricted weld access
- Demountable threaded pipe assemblies
Related connections
Compare other flange forms
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.
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.