ANSI B16.5 1500LB American Standard Slip-on Welding Neck Flange/Stainless Steel Flange Disk

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Nominal Size		Outer Diameter	Central circle diameter	Bolt Hole Diameter	Number of Bolt Holes	Inner Diameter	Flange Ring Height	Weld Groove Diameter	Flange Overall Height	Sealing Face Diameter	Sealing Face Height
DN	NPS	A	J	I		B	C	F	D	G
15	1/2	120.6	82.6	22.4	4	22.4	22.4	38.1	31.7	35.1	6.4
20	3/4	130	88.9	22.4	4	27.7	25.4	44.4	35	42.9	6.4
25	1	149.3	101.6	25.4	4	34.5	28.4	52.3	41	50.8	6.4
32	1-1/4	158.7	111.3	25.4	4	43.2	28.4	63.5	41	63.5	6.4
40	1-1/2	177.8	124	28.4	4	49.5	31.7	69.85	44.5	73.15	6.4
50	2	215.9	165.1	25.4	8	62	38.1	104.6	57.15	91.9	6.4
65	2-1/2	244.3	190.5	28.4	8	74.7	41.1	123.9	63.5	104.6	6.4

Design Structural Features

Neck Enhancement Design:
With Short Neck (Hub): Compared with ordinary SO flanges, the short neck structure is added, which improves the rigidity and bending resistance of the flange and is suitable for higher pressures (such as Class 600 - 1500).
Transition Groove: A 30° - 45° groove is adopted at the butt joint of the neck and the pipeline, which is convenient for complete joint penetration (CJP) welding and reduces stress concentration.
  Installation Method:
Slip-on + Fillet Weld: After the pipeline is inserted into the inner hole of the flange, fillet welding is carried out on both the inner and outer sides (the inner weld throat height should be ≥ 1.4 times the pipe wall thickness).
It is installed faster than WN flanges, but has higher welding quality than ordinary SO flanges.
  Types of Sealing Surfaces:
Raised Face (RF): Suitable for medium and high-pressure liquids or non-corrosive gases (Class 150 - 600).

Ring-Type Joint (RTJ): Used for high-pressure gases (such as natural gas, hydrogen) of Class 900 - 1500, with more reliable sealing.

Material Selection

Operating Conditions Recommended Materials Applicable Standards
Conventional High Pressure ASTM A105 (Carbon Steel) ASME B16.5
High Temperature (≤600°C) ASTM A182 F11/F22 (Chromium-Molybdenum Steel) API 6A
Corrosive Medium A182 F316L/Hastelloy C276 NACE MR0175 (Sulfur-Resistant)
Ultra-Low Temperature (-196°C) A350 LF3 (Low-Temperature Carbon Steel) ASME B31.3