Joining, flanges and sealing
Weld neck flange
Creating a detachable joint between piping, valves and equipment
Specialist selection guide
What should be reviewed before selecting this product?
A weld-neck flange is butt welded to pipe through a tapered hub and provides a smooth stress transition for demanding process service. Class, facing, hub bore and pipe schedule must be selected together.
Technical selection path
- 1
Define standard, size and pressure class
- 2
Specify raised face, flat face or ring-type joint
- 3
Match hub bore to pipe schedule
- 4
Check forging grade and design-temperature compatibility
- 5
Treat gasket, bolting and tightening sequence as one joint
Key strengths
- Good stress distribution at the joint
- Suitable for higher pressure-temperature duties
- Full butt-weld examination can be specified
Selection limitations
- Higher cost and installation time than slip-on
- Requires exact bore-to-pipe-wall matching
- Alignment and weld preparation are critical
Typical applications
Where can this option be considered?
- Critical process piping
- High pressure or temperature service
- Connections to major valves and equipment
Reference standards
A standard does not replace the project specification
Common technical questions
Concise answers before enquiry
Why does pipe schedule matter for a weld-neck flange?
The hub bore should align with the pipe bore to control internal mismatch, stress concentration and flow disturbance.
Does Class 150 always have one pressure rating?
No. Allowable pressure depends on material group and design temperature and must be taken from the applicable edition's pressure-temperature tables.
Locations requiring assembly, inspection or periodic maintenance
Standard, class, material group, facing, gasket and bolting
Initial review sheet
Technical attributes to review
Final values must come from project specifications, calculations and manufacturer data. This table defines the information scope.
FamilyIndustrial flanges
Main groupJoining, flanges and sealing
Materials to evaluateCarbon steel, Stainless steel, Alloy steel, Low-temperature steel
Connections to evaluateWelded, Threaded, Socket, Loose/lap
Typical mediaAll piping services
Relevant industriesOil and gas, Refining, Petrochemical, Power generation, Water and utilities
Reference standardsASME B16.5 · ASME B16.47 · ASME B16.36 · API 6A · EN 1092-1 · BS 10
Enquiry checklist
Include this information with your request
Standard and class
Nominal size
Facing
Material and grade
Pipe schedule
Drilling and dimensions
Before substitution
A matching name does not guarantee interchangeability
Installation dimensions, pressure rating, wetted materials, sealing design, construction standard, testing and documentation must be checked independently.
Adjacent types
Other options in this family
Final technical approval is required
This page is educational and intended for initial screening. Final selection must be approved against project requirements, actual service conditions and manufacturer documentation.
Send request for review