ASME B16.5 Class 900 Socket Weld Flange Dimensions
Socket Weld flange dimensions to ASME B16.5 Class 900 in millimetres: outside diameter, thickness, raised face, hub, length through hub, bolt circle and drilling, NPS ½" to 2½". A socket weld flange has a socket the pipe sits in, with a single fillet weld outside. It suits small-bore, high-pressure lines up to NPS 3 (NPS 2½ in Classes 900 and 1500).
Key to dimensions
- O
- Outside diameter of flange
- tf
- Minimum flange thickness
- R
- Diameter of raised face
- X
- Diameter of hub at base
- Y
- Length through hub (socket weld)
- W
- Bolt circle diameter
Socket weld flanges are made in ASME B16.5 Classes 150 to 1500, NPS ½ to 3 (to 2½ in Classes 900 and 1500).
ASME B16.5 Class 900 socket weld flange dimensions (mm)
| NPSin | DN | OOutside dia | tfMin thickness | RRaised face dia | XHub dia | YThis type | WBolt circle | HolesNo. | Hole diamm | Boltin |
|---|---|---|---|---|---|---|---|---|---|---|
| ½" | 15 | 120 | 22.3 | 34.9 | 38 | 32 | 82.6 | 4 | 22.2 | ¾" |
| ¾" | 20 | 130 | 25.4 | 42.9 | 44 | 35 | 88.9 | 4 | 22.2 | ¾" |
| 1" | 25 | 150 | 28.6 | 50.8 | 52 | 41 | 101.6 | 4 | 25.4 | ⅞" |
| 1¼" | 32 | 160 | 28.6 | 63.5 | 64 | 41 | 111.1 | 4 | 25.4 | ⅞" |
| 1½" | 40 | 180 | 31.8 | 73.0 | 70 | 44 | 123.8 | 4 | 28.6 | 1" |
| 2" | 50 | 215 | 38.1 | 92.1 | 105 | 57 | 165.1 | 8 | 25.4 | ⅞" |
| 2½" | 65 | 245 | 41.3 | 104.8 | 124 | 64 | 190.5 | 8 | 28.6 | 1" |
Notes
- Dimensions are in millimetres unless stated otherwise.
- Flange thickness tf and length through hub Y do not include the 7 mm raised face.
- Blind flanges have the same outside diameter, thickness tf and drilling as the other flange types of the same size and class.
- In ASME B16.5, Class 900 flanges NPS ½" to 2½" use Class 1500 dimensions.
- The bore of a weld neck or socket weld flange is machined to match the inside diameter of the pipe schedule stated in the order.
- Bolt holes are tabulated in inches in ASME B16.5; the millimetre values shown are direct conversions (bolt diameter plus ⅛").
- Stud bolt lengths do not include the height of the points. Weights are approximate catalogue values and vary with bore and manufacturer.
Reference information compiled from the published standard for convenience. It does not replace the current edition of the governing standard, which takes precedence. Verify critical dimensions and properties before design, purchase or fabrication. Teshi Engineers & Sales Promoters (P) Ltd accepts no liability for errors or omissions.
Other Class 900 flange types
Socket Weld flange dimensions in other classes
FAQ
Class 900 socket weld flange: common questions
What is the outside diameter of a 1¼" Class 900 socket weld flange?
160 mm, with a minimum thickness tf of 28.6 mm, bolt circle 111.1 mm and 4 bolt holes of 25.4 mm.
Which sizes are covered?
This chart covers NPS ½" to 2½" (DN 15 to 65). Socket weld flanges are made in ASME B16.5 Classes 150 to 1500, NPS ½ to 3 (to 2½ in Classes 900 and 1500).
Are dimensions the same for all flange types of one class?
Outside diameter, thickness and drilling are the same for every flange type of the same size and class; the hub length Y, hub and bore differ by type.
Does Teshi Group manufacture Class 900 socket weld flanges?
Yes. Teshi Group is an OEM manufacturer of ASME B16.5 flanges in India, in carbon, low-temperature, chrome-moly, stainless, duplex, super duplex and nickel alloys, with EN 10204 3.1 certificates and IBR certification on request.

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