Flanges matching pipe sizes
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Hello, teachers and guys. The flanges I have chosen are from the GB/T9124 PN series. The stainless steel pipes selected by the installer have an outer diameter of 51 mm. 1. For the GB/T9124 PN series of plate-type butt weld flanges for DN50 pipes, there are two different outer diameter options: one is 60.3 mm and the other is 57 mm; neither of these matches the pipe’s outer diameter of 51 mm. 2. Is it possible to use flanges according to this standard for pipes with an outer diameter of 51 mm?
Based on the information you provided, the GB/T9124 PN series flat welding flanges are typically suitable for pipes with an outer diameter of 60.3 mm or 57 mm. Flanges with an outer pipe diameter of 51 mm may not meet the size requirements of this standard. It is recommended that you consult with the installer to confirm whether there are any other flange specifications suitable for a pipe outer diameter of 51 mm. .
D51 has a non-standard outer diameter, and there is no flange that fits perfectly. Welding flanges, DN50 II series outer diameter, in accordance with GB/T 9124.1-2019. The outer diameter of D51 can be welded on.
I checked – the welded flange of Series II also has a diameter of 57. There’s a difference of 6 mm, and even when it’s inserted into the flange, there’s still a 3 mm difference; therefore, welding is not possible
I see. A pipe with an outer diameter of 51 should be made of pharmaceutical-food-grade stainless steel, and it needs to be connected using chucks and clamps. But aren’t there any standards for such chucks and clamps in China?
I don’t know where to start at all; it seems like you really have no experience on the ground at all. Inconsistent outer diameters can be addressed by adjusting the groove welding; refer to GB 50236-2011 \"Code for Construction of Welding Works of Field Equipment and Industrial Pipelines\" for more details. I recommended using butt-weld flanges because I figured your project had stringent requirements; for my part, I’d simply install the lap-joint flanges directly.
Thank you for the advice. I indeed lack experience and need to improve. Thank you
Mismatch. It is best to use the standard sizes of 60.3 and 57; in addition to the outer diameter of the steel pipe, the outer diameter dimensions of other pipe fittings may also be relevant for proper connection.
I checked, and there are no flange standards, either domestic or international, around DN50 that are suitable for pipes with an outer diameter of 51. The outer diameters of pipes suitable for use in various countries and industries within a country are four types: 60.3, 60.5, 60, and 57. Logically, it should be to first understand the owner’s requirements before selecting the flange standard; then the designer should prepare a plan for the pipeline materials, and subsequently an procurement plan should be developed in accordance with the design specifications. The standard for seamless stainless steel pipelines used for fluid transport is generally GB17395, and pipes with an outer diameter of 51 belong to the second series.
Sanitary-grade stainless steel pipes with an outer diameter of 51 come with matching flanges