Valve End Connections: Flanged, Butt-Weld, Socket-Weld, Threaded and Wafer
A valve end connection controls installation geometry, joint integrity, maintainability and often the applicable pressure-temperature route. “Flanged” does not identify standard, series, facing or drilling; “butt-weld” does not identify pipe schedule, bore or preparation; threaded and socket-weld ends need material, size and service limitations. Wafer and lug bodies add bolt, gasket and pipeline-load considerations. Every quote should define the complete mating interface and verify it on an approved drawing.
Choose the connection around installation and lifecycle duty
The connection standard, material, class/PN and joint components must suit every design case.
Toxic, flammable, vacuum, emissions or cyclic service may influence joint type and inspection needs.
Bolting clearance, welding space, heat treatment, NDE and valve removal must be feasible.
Weight, thermal movement, nozzle loads and misalignment should not be forced through the valve body.
Flanged joints support removal; welded joints reduce detachable leak paths but complicate replacement.
Crevices, pockets, internal mismatch, weld penetration and full-bore/piggable needs can govern.
Compare valve end connections by complete interface requirements
| Connection | Advantages | Critical specification fields | Common risk |
|---|---|---|---|
| Flanged | Detachable joint, familiar installation and broad size/rating availability. | Exact flange standard/series, size, class/PN, facing, finish, gasket, bolting and face-to-face. | Non-mating drilling/facing or treating the flange designation as the valve-length standard. |
| Butt-weld | Permanent compact joint with no detachable flange gasket at the valve ends. | Pipe OD, schedule/wall, material, end-preparation standard, bore transition, welding/PWHT and NDE. | Ordering before mating pipe dimensions and heat-treatment restrictions are known. |
| Socket-weld | Compact connection commonly used in limited smaller-bore applications within governing scope. | Size/class, socket dimensions, gap/workmanship, material, welding procedure and examination. | Crevice/fit-up concerns or use outside project service and size restrictions. |
| Threaded | Simple compact assembly for selected services without field welding. | Thread standard, form, size, direction where relevant, sealant and engagement. | Mixing NPT/BSP or other thread forms and ignoring leakage/fatigue/fire-service limitations. |
| Wafer | Short, light valve body installed between mating flanges. | Compatible flange standard, bolt pattern, centering, gasket/seat arrangement, face-to-face and dead-end limits. | Interference with flange bore/bolt geometry or unsuitable gasket selection. |
| Lugged | Flange-lug bolting can support selected isolation or dead-end arrangements when designed and rated for them. | Thread/bolt engagement, flange compatibility, directional/dead-end rating and installation sequence. | Assuming every lug valve has full bidirectional dead-end capability. |
Interface details to show on the approved valve drawing
Document number, edition, flange series or weld/thread form.
Face-to-face, end thickness, facing, drilling, bore and transition.
Gasket, bolting, weld consumables and any insulating kit.
Flow arrow, shaft/stem position, eccentricity and access.
Allowable piping loads, valve weight, supports and lifting points.
Welding, PWHT, NDE, coating repair, alignment and commissioning steps.
Claims and shortcuts this page does not support
Nominal size does not guarantee a mating connection
Standards, classes, series, facings, schedules and thread forms must match.
The valve must not be used to pull piping into alignment
Installation strain can distort bodies, increase torque and damage seats or joints.
A welded end is not maintenance-free
Weld quality, heat treatment, NDE, corrosion and future cut-out/replacement planning remain necessary.
From requirement to auditable evidence
Information and records to define
How this resource should be used
Selection and specification guidance for engineers comparing flanged, welded, threaded, wafer and lug valve connections and preventing mating-interface errors.
Raymon Valve technical content team. Final project decisions require the controlled documents and responsible engineer or quality reviewer.
Connection suitability and dimensions come from the controlled end-connection, valve product, piping and project standards. This page omits dimensional tables; verify the exact standard, edition, size, rating, material and mating components.
Technical scope reviewed 27 July 2026. Editions, procedures, acceptance criteria and product evidence must be reconfirmed before order.
Valve End Connection Types and Selection FAQ
What information is needed to specify a flanged valve?
State flange standard and series, nominal size, class or PN, material, facing and finish, gasket/bolting requirements and valve face-to-face dimensional route.
When is a butt-weld valve preferred?
It may be chosen for permanent high-integrity joints or weight/space reasons, but pipe dimensions, welding, heat treatment, NDE and future maintenance must be planned.
Can NPT and BSP threads connect directly?
They are different thread systems and should not be treated as interchangeable. Specify the exact form and use compatible fittings and sealing practice.
Can every lug butterfly valve be used for dead-end service?
No. Dead-end direction and rating depend on the valve design, lug/bolt engagement and manufacturer qualification. Require explicit approved capability for the actual condition.
Send the requirement and the evidence you need to verify
We will identify the applicable scope, missing records and approval path without inventing compliance claims.
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