OEM manufacturer ASME B16.5
Reducing Flanges — ASME B16.5
A reducing flange has the outside diameter and bolt pattern of a larger pipe size but is bored for a smaller pipe. Teshi Group manufactures reducing weld neck, slip-on and threaded flanges to ASME B16.5 in carbon, stainless and alloy steels.
Also called: reducer flange, reduced bore flange, reducing weld neck flange, reducing slip-on flange
What is a Reducing Flange?
A reducing flange changes line size at a flanged joint without a separate reducer. The flange ring takes the OD, thickness and drilling of the larger NPS, while the bore and hub suit the smaller pipe, for example a 6″ × 4″ flange that mates a 6″ flange and welds to 4″ pipe. It saves a weld and a fitting where space is limited. Reductions should be modest; for large size changes or where flow disturbance matters, a concentric reducer with standard flanges is usually preferred.
Key features
- Flange end of the larger NPS; bore and hub for the smaller pipe
- Weld neck, slip-on and threaded types
- Removes a reducer and one weld from the spool
- RF, FF or RTJ facing
- Bore matched to smaller pipe schedule on weld neck types
Specification
| Supply | OEM manufacturer — Teshi Group, India |
|---|---|
| Standard | ASME B16.5 (flange dimensions per the larger NPS) |
| Types | Reducing weld neck, reducing slip-on, reducing threaded |
| Pressure class | Class 150, 300, 600, 900, 1500, 2500 |
| Facing | RF, FF, RTJ |
| Materials — carbon steel | ASTM A105 / A105N; ASTM A181 Cl 60, Cl 70; ASTM A266 Gr 2, Gr 4 (large forgings) |
| Materials — high-yield carbon steel | ASTM A694 F42, F46, F48, F50, F52, F56, F60, F65, F70 (MSS SP-44 grades F52–F70) |
| Materials — low-temperature carbon steel | ASTM A350 LF1, LF2 Cl 1, LF2 Cl 2, LF3, LF6, LF9 |
| Materials — alloy steel (Cr-Mo) | ASTM A182 F1, F2, F5, F5a, F9, F11 Cl 1 / 2 / 3, F12 Cl 1 / 2, F21, F22 Cl 1 / 3, F22V, F91, F92, F911; ASTM A336 F11, F22 (large forgings) |
| Materials — stainless steel | ASTM A182 F304, F304L, F304H, F304LN, F309H, F310, F316, F316L, F316H, F316LN, F316Ti, F317, F317L, F321, F321H, F347, F347H, F348 |
| Materials — 904L and 6Mo | 904L (ASTM A182 F904L, UNS N08904); 254 SMO / 6Mo (ASTM A182 F44, UNS S31254); AL-6XN (ASTM A182 F62, UNS N08367) |
| Materials — duplex stainless steel | ASTM A182 F51 (UNS S31803), F60 (UNS S32205, 2205) |
| Materials — super duplex stainless steel | ASTM A182 F53 (UNS S32750, 2507), F55 (UNS S32760), F61 (UNS S32550) |
| Materials — nickel alloys | ASTM B564 / B160 / B462: Nickel 200 / 201 (N02200 / N02201), Monel 400 (N04400), Monel K-500 (N05500), Inconel 600 (N06600), Inconel 625 (N06625), Inconel 718 (N07718), Incoloy 800 / 800H / 800HT (N08800 / N08810 / N08811), Incoloy 825 (N08825), Hastelloy C276 (N10276), Hastelloy C22 (N06022), Hastelloy B2 / B3 (N10665 / N10675), Alloy 20 (N08020) |
| Materials — titanium | ASTM B381 Grade F1, F2, F5 (Ti-6Al-4V), F7, F12 |
| Materials — copper-nickel | Cu-Ni 90/10 (UNS C70600) and 70/30 (UNS C71500), ASTM B151 bar; flanges to ASME B16.5 or EEMUA 145 |
| Grade availability | Every grade listed is made or supplied against order, with EN 10204 3.1 certificates (3.2 / third-party inspection when specified) and PMI on alloy, stainless, duplex and nickel grades. |
| Testing | Visual and dimensional inspection, PMI on alloy and stainless grades, hardness; UT, MPI/DPI as specified |
| Documents | EN 10204 3.1 mill test certificate; 3.2 / third-party inspection when the order specifies; dimensional inspection report; IBR certification when specified |
Applications
- Pump suction and discharge connections
- Equipment nozzles smaller than the connected line
- Compact skids and packages
- Instrument and control valve stations
- Tank connections
Technical data sheets
Dimensions & weights
FAQ
Reducing Flange: common questions
How is a reducing flange specified?
Give the larger NPS first, then the smaller, plus class, type, facing and bore, for example 'Reducing WNRF 6″ × 4″ Class 300, bore Sch 40, A105'.
Does a reducing flange have the same rating as a standard flange?
Yes. Its pressure-temperature rating follows the ASME B16.5 class and material group, because the flange ring has the dimensions of the larger nominal size. The hub and weld must still suit the smaller pipe.
When should I use a reducer instead?
For large size changes, high-velocity or erosive service, or where a gradual transition is needed for flow measurement, a concentric or eccentric reducer with standard flanges is better than a reducing flange.
Can you make reducing blind flanges?
A blind flange tapped or bored for a smaller outlet is often called a reducing blind. It can be made to drawing, with the tapping or bore specified.
Need a size or grade not listed here?
Our engineering team manufactures against your drawing or datasheet, with dimensional sign-off before dispatch.
Send us your specificationTraceability
From mill heat to your site
- 01
Approved mill material
Received against the mill certificate; heat number registered.
- 02
Forging & machining
Heat number carried through every stage in our Indian works.
- 03
PMI, dimensional & NDT
Every lot inspected to the governing standard; TPI witness on request.
- 04
Stamped & certified dispatch
Hard-stamped pieces with EN 10204 3.1 / 3.2 certificates.
Quick RFQ
Quote for Reducing Flange in 24–48 hours
More industrial flanges
All industrial flangesSquare Flange
Manufacturer standard / client drawing
View productIndustrial FlangesAnchor Flange
ASME B31.4 / B31.8 / B31.3 (design) · Manufacturer standard / client drawing
View productIndustrial FlangesExpander Flange
ASME B16.5 (flange end) · Manufacturer standard (body)
View productIndustrial FlangesFlat Face Flange
ASME B16.5 · EN 1092-1 (Type A facing)
View productIndustrial FlangesTongue and Groove Flange
ASME B16.5 · EN 1092-1 (facing Type C / Type D)
View productIndustrial FlangesMale and Female Flange
ASME B16.5 · EN 1092-1 (facing Type E / Type F)
View product