What are ASME B16.5 flanges
ASME B16.5 is the standard specification for pipe flanges and flanged fittings from NPS 1/2 (1/2″) through NPS 24 (24″) covering materials, pressure-temperature ratings, dimensions, tolerances, marking & packaging, and testing methods. ASME B16.5 flanges are designated into seven pressure ratings including Class 150, 300, 400, 600, 900 and 1500 in sizes NPS 1/2 (1/2″) through NPS 24 (24″) and Class 2500 in sizes NPS 1/2 (1/2″) through NPS (12″). The pipe flanges can also be categorized according to its type as: welding neck (WN), slip on (SO), socket welding (SW), threaded (TH), blind (BL), long weld neck (LWN), and lapped joint (LJ). NPS, followed by a dimensionless number, is the designation for nominal flange size. It is related to the reference nominal diameter, DN, which is used in international standards. Their relationship is shown in following table:
The Relationship between NPS and DN
| NPS | DN |
|---|---|
| 1/2 | 15 |
| 3/4 | 20 |
| 1 | 25 |
| 1-1/4 | 32 |
| 1-1/2 | 40 |
| 2 | 50 |
| 2-1/2 | 65 |
| 3 | 80 |
| 3-1/2 | 90 |
| 4 | 100 |
| 5 | 125 |
| 6 | 150 |
| 8 | 200 |
| 10 | 250 |
| 12 | 300 |
| 14 | 350 |
| 16 | 400 |
| 18 | 450 |
| 20 | 500 |
| 24 | 600 |
Material selection for ASME B16.5 flanges
The pipe flanges can be made from either cast or forged materials. Especially, plate material are only allowed for some certain unhubbed flanges such as blind, slip on plate or reducing plate flanges due to the consideration of plate-lamination flaws. HBMetals manufactures pipe flanges from a comprehensive range of materials covering carbon steel, alloy steel, stainless steel and special alloys:
(1) Carbon Steel: ASTM A105(N), ASTM A515, ASTM A516, ASTM A694, ASTM A350;
(2) Alloy Steel: ASTM A182 F1, F2, F5, F5a, F9, F91, F92, F11, F12, F21, F22;
(3) Stainless Steel: ASTM A182 F304(L), F316(L), F317(L), F321, F347, F348,
F51, F44, F904L, 254SMO;
(4) Special Alloys: Inconel 600, Inconel 625, Inconel 601, Inconel 718;
Hastelloy B, C-276, C-22; Incoloy 800 / 825;
Monel K-500, Monel 400, Monel 401, Monel 404;
Titanium; Aluminium, Cobalt, Niobium.
