Butt-welded reduced-diameter flange
Thread Content
Everyone, does anyone know how to design butt-welded reduced-diameter flanges? Are there corresponding standards?
I’ve heard of it for the first time – what’s the concept?
The pipe diameters on both sides of a pair of flanges are different
Jacket flanges and reduced-diameter flanges are specified in HG/T20592-20635-2009. . .
It is described in ASME B16.5-2013, Table 6, Note 4: (4) For the method of designating reducing threaded and reducing slip-on flanges, see para. 3.3 and the examples below. EXAMPLES: (1) The size designation is NPS 6 x 2 1/2 — Class 300 reducing threaded flange. This flange has the following dimensions: NPS 2 1/2 for the taper pipe thread tap (ASME B1.20.1); 320 mm for the diameter of a regular NPS 6 Class 300 threaded flange; 35 mm for the thickness of a regular NPS 6 Class 300 threaded flange; 178 mm for the diameter of the hub of a regular NPS 5 Class 300 threaded flange. The hub diameter can be one size smaller to reduce machining requirements; in this example, an NPS 2 1/2 hub diameter would be the smallest acceptable value. The height of the hub for a regular NPS 5 Class 300 threaded flange is 15.5 mm. (2) The size designation is NPS 6 x 2 — Class 300 reducing threaded flange. A regular NPS 6 Class 300 blind flange tapped with an NPS 2 taper pipe thread (ASME B1.20.1) can be used for this purpose.
A standard flange with an unchanged sealing surface; the outer diameter decreases due to welding, and this is what constitutes a reducer flange