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.
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.
Weld-neck construction is used where the joint must accommodate demanding mechanical loading or thermal cycling. Selection depends on the piping design, weld preparation, material and pressure-temperature requirements, not the flange shape alone.
Compare flange typesDimensions and connection data
Define Weld Neck 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 Weld Neck Flanges with the related forms or references below. A related product is not necessarily a permissible substitute.
| Related product / reference | Distinction | Check before selection |
|---|---|---|
| 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 |
| Long Weld Neck Flanges | An extended neck combines a flanged connection with a longer nozzle section. Neck length, bore and end preparation must be specified for the intended equipment connection. | Provide required projection, wall and bore |
| 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 Weld Neck 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 weld neck flanges
Availability, dimensions and pressure-temperature suitability are confirmed against your complete enquiry.
| Item | Requirement |
|---|---|
| Pipe connection | Butt-weld end; specify pipe schedule and bore |
| Facing | Specify RF, FF or RTJ as required by the mating joint |
| Design basis | ASME B16.5 or another project-specified flange standard |
| Inspection | State weld preparation, dimensional inspection and document requirements |
| Material & quantity | Exact material designation, quantity and required certification or inspection documents |
Application context
Where this form is considered
- Process piping and plant connections
- Lines subject to thermal cycling
- Butt-welded piping assemblies
Related connections
Compare other flange forms
Welded connections
Long Weld Neck Flanges
An extended neck combines a flanged connection with a longer nozzle section. Neck length, bore and end preparation must be specified for the intended equipment connection.
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.