What Is a Flangeolet?

A flangeolet is a forged branch connection fitting that provides a flanged outlet directly from a pipe header. The header end has a contoured base that welds to the pipe OD, and the branch end terminates in an integral raised-face flange per ASME B16.5. This eliminates the need for a separate weldolet-to-pipe-to-flange assembly. Flangeolets are manufactured per MSS SP-97 and ASME B16.5 (for the flange face dimensions).

Property	Detail
Standard	MSS SP-97 (body), ASME B16.5 (flange dimensions)
Branch angle	90° to header
Branch end	Integral RF flange (raised face)
Header end	Contoured to match header OD
Size range	Header: NPS 4 to NPS 36; Branch: NPS 1 to NPS 12
Flange ratings	Class 150, 300, 600, 900, 1500
Materials	ASTM A105 (CS), A182 F304/F316 (SS), A182 F11/F22 (alloy)

When to Use a Flangeolet

Flangeolets are specified when a flanged branch connection is required but the branch-to-header ratio is too small for a reducing tee:

Scenario	Preferred Fitting
Branch/header ratio > 0.5, flanged branch	Reducing tee + welding neck flange
Branch/header ratio < 0.5, flanged branch	Flangeolet
Branch/header ratio < 0.5, butt weld branch	Weldolet
Branch/header ratio < 0.5, threaded branch	Threadolet or nipolet

Flangeolet vs Weldolet + Flange Assembly

The conventional approach for a flanged branch uses a weldolet, a short spool piece, and a welding neck flange. The flangeolet replaces all three components with a single fitting:

Factor	Flangeolet	Weldolet + Spool + WN Flange
Components	1	3
Welds	1 (header weld)	3 (header + 2 butt welds)
Bolted joint	1 (at branch flange face)	1 (at WN flange face)
NDE scope	1 weld	3 welds
Installation time	Faster	Longer
Total cost	Lower (fewer parts, less welding)	Higher
Availability	Limited (specialty item)	Components widely stocked
Lead time	6-12 weeks	Shorter (standard items)

Flange Face and Gasket

The integral flange face of a flangeolet matches ASME B16.5 dimensions for the specified class. The raised face, bolt hole pattern, and bolt circle diameter are identical to a standard welding neck flange in the same size and class. Standard gaskets and stud bolts for the matching flange size and class are used.

Applications

Flangeolets are commonly specified for:

• Valve stations on headers: Direct flanged connection for branch valves without additional spool fabrication
• Instrument flanged connections: Orifice taps, flow meter branches requiring flanged interfaces
• Equipment nozzle connections: Branching from pipe headers to flanged equipment nozzles
• Maintenance access points: Flanged branches that allow equipment removal without cutting pipe

Ordering Information

When specifying a flangeolet, provide:

Parameter	Example
Header size and schedule	NPS 16, SCH 40
Branch size	NPS 4
Flange class	Class 300
Flange face type	Raised Face (RF)
Material	ASTM A105

The manufacturer matches the contoured base to the header OD and the flange dimensions to ASME B16.5 for the specified class.

Read the full guide to pipe fittings