Home » Products » Stainless Steel Flange » Stainless Steel Socket Weld Flange

Stainless Socket Weld Flange

S&S Stainless International, a trusted stainless steel flange manufacturer, produces high-quality stainless steel socket weld flanges compliant with ASME B16.5 standards. These flanges are designed for smaller-diameter pipes (NPS 2 and below) and are ideal for high-pressure and high-temperature systems. Featuring a recessed socket, they provide a secure, leak-proof connection by allowing pipes to be inserted and welded in place. Socket weld flanges are widely used in critical applications across industries where durability and reliability are essential.

What is a socket weld Flange?

A stainless steel socket weld flange, compliant with ASME B16.5, is a reliable and efficient solution for smaller-diameter, high-pressure piping systems. Its recessed socket design simplifies installation, ensuring a strong, leak-resistant connection. Ideal for high-stress environments, this flange type is particularly suitable for compact systems. While it may not be recommended for larger pipes or systems with frequent temperature or mechanical cycling, the socket weld flange excels in applications where strength and security are essential. Choose S&S Stainless International for superior-quality socket welding flanges.

Product Overview of Stainless Steel Socket Weld Flange

Design of Socket Weld Flange
- The socket weld flange has a socket on its inner bore that matches the outer diameter of the pipe.
- Available Sealing Surface: Raised Face(RF), Tongue and Groove(TG), and Male and Female(MFM).
Material of Socket Weld Flange
- Constructed from premium ASTM A403 stainless steel grades like 304, and 316, the stainless steel socket weld flange resists corrosion, rust, oxidation, and chemical damage, ensuring long-term durability.
Pressure Ratings of Socket Weld Flange
- Available in ASME B16.5 high-pressure classes such as 150, 300, 600, 900, 1500, and 2500, making the socket weld flange suitable for demanding applications.
Weld of Socket Weld Flange
- When the stainless steel pipe is inserted into the socket until it reaches the bottom of the socket, a single fillet weld is applied around the pipe’s outer edge.
Compatibility of Socket Weld Flange
- Compatible with a wide range of gaskets and bolts, they create a dependable seal for flanges, valves, or equipment in various applications.

Stainless Steel Socket Weld Flange Dimensions

ASME B16.5

Nominal Diameter		Pipe Diameter	O.D.of Flange	Diameter of Raised Face	Diameter of Bolt Holes Circle	Diameter of Bolt Holes	Numbers of Bolt Holes	Diameter of Bolt Holes(inch)	Flange Thickness	Hub Diameter	Through Hub Length (H)
DN	NPS	ID	D	G, R	K	L	Numbers of Bolt Holes	Diameter of Bolt Holes(inch)	B1-B4	A	H1	H2	H3
15	½’’	21.3	90	35	60.5	16	4	M14	11.5	30	48	16	16
20	¾’’	26.9	100	43	70	16	4	M14	13	38	52	16	16
25	1’’	33.7	110	51	79.5	16	4	M14	14.5	49	56	17	17
32	1 ¼’’	42.4	120	63.5	89	16	4	M14	16	59	57	21	21
40	1 ½’’	48.3	130	73	98.5	16	4	M14	17.5	65	62	22	22
50	2’’	60.3	150	92	120.5	18	4	M16	19.5	78	64	25	25
65	2 ½’’	76.1	180	105	139.5	18	4	M16	22.5	90	70	29	29
80	3’’	88.9	190	127	152.5	18	4	M16	24	108	70	30	30
90	3 ½’’	101.6	216	140	178	18	8	M20	24	122	71	-	32
100	4’’	114.3	230	157.5	190.5	18	8	M20	24	135	76	33	33
125	5’’	139.7	255	186	216	22	8	M20	24	164	89	36	36
150	6’’	168.3	280	216	241.5	22	8	M20	25.5	192	89	40	40
200	8’’	219.1	345	270	298.5	22	8	M20	29	246	102	44	45
250	10'’	273	405	324	362	26	12	M24	30.5	305	102	49	49
300	12'’	323.9	485	381	432	26	12	M24	32	365	114	56	56
350	14'’	355.6	535	413	476	29.5	12	M27	35	400	127	57	79
400	16'’	406.4	600	470	540	29.5	16	M27	37	457	127	64	87
450	18'’	457	635	533.5	578	32.5	16	M30	40	505	140	68	97
500	20'’	508	700	584	635	32.5	20	M30	43	559	145	73	103
550	22'’	559	750	641	692	35.5	20	M33	46	610	149	-	-
600	24'’	610	816	692	749.5	35.5	20	M33	48	664	152	83	111

Nominal Diameter		Pipe Diameter	O.D. of Flange	Diameter ofRaised Face	Diameter of Bolt Holes Circle	Diameter ofBolt Holes	Numbers ofBoltHoles	Diameter of Bolt Holes(inch)	Flange Thickness	Hub Diameter	Through Hub Length
DN	NPS	ID	D	G, R	K	L	Numbers ofBoltHoles	Diameter of Bolt Holes(inch)	B1-B4	A	H1	H2	H3
15	½’’	21.3	95	35	66.5	16	4	M14	14.5	38	52	22	22
20	¾’’	26.9	120	43	82.5	18	4	M16	16	48	57	25	25
25	1’’	33.7	125	51	89	18	4	M16	17.5	54	62	27	27
32	1 ¼’’	42.4	135	63.5	98.5	18	4	M16	19.5	64	65	27	27
40	1 ½’’	48.3	155	73	114.5	22	4	M20	21	70	68	30	30
50	2’’	60.3	165	92	127	18	8	M16	22.5	84	70	33	33
65	2 ½’’	76.1	190	105	149	22	8	M20	25.5	100	76	38	38
80	3’’	88.9	210	127	168.5	22	8	M20	29	118	79	43	43
90	3 ½’’	101.6	229	140	184	22	8	M20	30	140	81	45	45
100	4’’	114.3	255	157.5	200	22	8	M20	32	146	86	48	48
125	5’’	139.7	280	186	235	22	8	M20	35	178	98	51	51
150	6’’	168.3	320	216	270	22	12	M20	37	206	98	52	52
200	8’’	219.1	380	270	330	26	12	M24	41.5	260	111	62	62
250	10'’	273	445	324	387.5	29.5	16	M27	48	321	117	67	95
300	12'’	323.9	520	381	451	32.5	16	M30	51	275	130	73	102
350	14'’	355.6	585	413	514.5	32.5	20	M30	54	426	143	76	111
400	16'’	406.4	650	470	571.5	32.5	20	M33	57.5	483	146	83	121
450	18'’	457	710	533.5	628.5	32.5	24	M33	60.5	533	159	89	130
500	20'’	508	775	584	686	32.5	24	M33	63.5	587	162	95	140
550	22'’	559	840	641	743	42	24	M39	66.5	640	165	-	-
600	24'’	610	915	692	813	42	24	M39	70	702	168	104	152

Nominal Diameter		Pipe Diameter	O.D. of Flange	Diameter of Raised Face	Diameter of Bolt Holes Circle	Diameter of Bolt Holes	Numbers of Bolt Holes	Diameter of Bolt Holes(inch)	Flange Thickness	Hub Diameter	Through Hub Length
DN	NPS	ID	D	G, R	K	L	Numbers of Bolt Holes	Diameter of Bolt Holes(inch)	B1-B4	A	H1	H2	H3
15	½’’	21.3	95	35	66.5	16	4	M14	14.5	38	52	22	22
20	¾’’	26.9	120	43	82.5	18	4	M16	16	48	57	25	25
25	1’’	33.7	125	51	89	18	4	M16	17.5	54	62	27	27
32	1 ¼’’	42.4	135	63.5	98.5	18	4	M16	21	64	67	29	29
40	1 ½’’	48.3	155	73	114.5	22	4	M20	22.5	70	70	32	32
50	2’’	60.3	165	92	127	18	8	M16	22.5	84	73	37	37
65	2 ½’’	76.1	190	105	149	22	8	M20	29	100	79	41	41
80	3’’	88.9	210	127	168.5	22	8	M20	32	117	83	46	46
90	3 ½’’	101.6	229	140	184	26	8	M24	35	133	86	49	49
100	4’’	114.3	275	157.5	216	26	8	M24	38.5	152	102	54	54
125	5’’	139.7	330	186	267	29.5	8	M27	44.5	189	114	60	60
150	6’’	168.3	355	216	292	29.5	12	M27	48	222	117	67	67
200	8’’	219.1	420	270	349	32.5	12	M30	55.5	273	133	76	76
250	10'’	273	510	324	432	35.5	16	M33	63.5	343	152	86	111
300	12'’	323.9	560	381	489	35.5	20	M33	67	400	156	92	117
350	14'’	355.6	605	413	527	39	20	M36	70	432	165	94	127
400	16'’	406.4	685	470	603	42	20	M39	76.5	495	178	106	140
450	18'’	457	745	533.5	654	45	20	M42	83	546	184	117	152
500	20'’	508	815	584	724	45	24	M42	89	610	190	127	165
550	22'’	559	870	641	778	48	24	M45	95	665	197	-	-
600	24'’	610	940	692	838	51	24	M48	102	718	203	140	184

Nominal Diameter		Pipe Diameter	O.D. of Flange	Diameter of Raised Face	Diameter of Bolt Holes Circle	Diameter ofBolt Holes	Numbers ofBolt Holes	Diameter of Bolt Holes(inch)	Flange Thickness	Hub Diameter	Through Hub Length
DN	NPS	ID	D	G, R	K	L	Numbers ofBolt Holes	Diameter of Bolt Holes(inch)	B1, B2, B4	A	H1	H2
15	½’’	21.3	120	35	82.5	22	4	M20	22.5	38	60	32
20	¾’’	26.9	130	43	89	22	4	M20	25.5	44	70	35
25	1’’	33.7	150	51	101.5	26	4	M24	29	52	73	41
32	1 ¼’’	42.4	160	63.5	111	26	4	M24	29	64	73	41
40	1 ½’’	48.3	180	73	124	29.5	4	M27	32	70	83	44
50	2’’	60.3	215	92	165	26	8	M24	38.5	105	102	57
65	2 ½’’	76.1	245	105	190.5	29.5	8	M27	41.5	124	105	64
80	3’’	88.9	240	127	190.5	26	8	M24	38.6	127	102	54
100	4’’	114.3	290	157.5	235	32.5	8	M30	44.5	159	114	-
125	5’’	139.7	350	186	279.5	35.5	8	M33	51	190	127	-
150	6’’	168.3	380	216	317.5	32.5	12	M30	56	235	140	-
200	8’’	219.1	470	270	393.5	39	12	M36	63.5	298	162	-
250	10'’	273	545	324	470	39	16	M36	70	368	184	-
300	12'’	323.9	610	381	533.5	39	20	M36	79.5	419	200	-
350	14'’	355.6	640	413	559	42	20	M39	86	451	213	-
400	16'’	406.4	705	470	616	45	20	M42	89	508	216	-
450	18'’	457	785	533.5	686	51	20	M48	102	565	229	-
500	20'’	508	855	584	749.5	55	20	M52	108	672	248	-
600	24'’	610	1040	692	901.5	68	20	M64	140	749	267	-

Navigating Our Socket Weld Flange Dimension Table

The weld neck flange dimension tables provide detailed measurements for selecting the correct stainless steel weld neck flange. You will find dimensions for:

Nominal Pipe Size (NPS): The standard pipe size for which the flange is designed.
Outside Diameter (OD) of Flanges: The total diameter of the flange itself.
Raised Face (RF) Height: The height of the raised portion of the flange sealing surface (if applicable).
Bolt Circle Diameter (BCD): The diameter on which the centers of the bolt holes lie.
Number of Bolts & Bolt Hole Diameter: Specifies the quantity and size of bolts required for connection.
Flange Thickness (T): The overall thickness of the flange.
Hub Diameter: The diameter of the cylindrical or tapered projection from the flange.
Through Hub Length: The length of the hub from the flange face to its end, indicating how far the pipe will extend into the flange.

Carefully match these dimensions to your project’s requirements to ensure a secure and leak-proof connection.

Custom Stainless Steel Flange by S&S Stainless International

S&S Stainless International specializes in precision-engineered custom stainless steel flanges tailored strictly to customer-provided technical drawings and unique operational specifications. Designed to solve complex cross-standard alignment challenges, our advanced forging and machining capabilities allow us to seamlessly combine ASME/ANSI, JIS, and EN 1092-1 standards—such as blending ASME bolt circles with EN sealing faces or JIS pressure dimensions—to deliver a 100% exact match for hybrid or legacy pipeline systems.

FAQs

1. How does a socket weld flange connect to a pipe, and for what line sizes is it recommended?

A socket weld flange features a recessed socket drive where the pipe is inserted until it hits an internal shoulder, then pulled back approximately 1/16 inch (1.6 mm) before applying a single fillet weld around the outer hub. Socket weld flanges are specifically designed for small-bore piping systems (typically 2 inches and smaller) operating under high pressure, as they provide smooth internal flow without restricting velocity or causing turbulent pressure drops.

2. Why is the 1/16-inch expansion gap required during installation of socket weld flanges?

The 1/16-inch (1.6 mm) gap between the pipe end and the bottom of the flange socket allows for thermal expansion of the pipe during welding and thermal cycling. Leaving this expansion space prevents thermal stress accumulation, which could otherwise crack the fillet weld or deform the flange face under high-temperature service conditions.

3. What pressure ratings, face types, and material grades are available for socket weld flanges?

We supply forged stainless steel socket weld flanges in ASME Class 150, 300, 600, and 1500 pressure ratings per ASME B16.5 standards. Available in dual-certified ASTM A182 F304/304L and F316/316L material grades, they can be configured with Raised Face (RF), Flat Face (FF), or Ring-Type Joint (RTJ) sealing surfaces to match your pressure vessel and valve specifications.

4. How do you verify socket depth accuracy, hub concentricity, and material chemistry during QC?

Our quality control team inspects 100% of socket bore diameters and socket depths using precision depth calipers to guarantee slip-free pipe insertion. Every production batch undergoes Positive Material Identification (PMI) chemical verification, ultrasonic testing (UT) for internal forging flaws, and full solution annealing heat treatment, supported by EN 10204 3.1 Material Test Reports (MTRs) and Third-Party Inspection (TPI) options.

5. What export packaging protection is used for socket weld flanges during international transit?

To protect the internal socket bore and gasket sealing face from rust and impacts during ocean freight, all flange faces are coated with anti-rust oil and covered with plastic protective end caps. Flanges are stacked with cardboard separators inside ISPM-15 heat-treated, seaworthy wooden cases lined with waterproof plastic film to ensure safe delivery to your warehouse or job site.