Long Weld Neck Flanges | ASME B16.5 | Heavy Barrel

PM Industries manufactures, supplies, and stocks Long Weld Neck Flanges in a range of materials, pressure classes, and pipe sizes. A long weld neck flange is essentially a weld neck flange with a significantly extended hub, long enough that the hub itself substitutes for a short pipe neck or nozzle. That extended hub is machined to the bore of the connected pipe, making the flange and its integral neck a single forged component that attaches directly to a vessel, drum, or equipment nozzle without requiring a separate pipe nipple between the flange and the equipment wall.

The primary application for long weld neck flanges is pressure vessel and heat exchanger nozzle connections, which is why they're also commonly called nozzle flanges. On a pressure vessel, the nozzle flange connects the vessel shell to the incoming or outgoing piping. A long weld neck flange provides that connection in one piece, with the extended hub acting as the nozzle neck and the flange face providing the bolted pipe connection. That eliminates the weld between a short pipe nipple and a standard weld neck flange that would otherwise be required, reducing the number of pressure-containing welds and inspection points in the connection.

Pressure vessel nozzle service drives most long weld neck flange specifications. ASME Section VIII Division 1 pressure vessel code accepts long weld neck flanges as nozzle connections, and major vessel fabricators use them routinely for that reason. The integral neck meets the code reinforcement requirements for the nozzle opening in the vessel shell, and the flange face provides the standard bolted connection to the process piping. That combination in a single forged component simplifies vessel nozzle fabrication and inspection.

Fatigue resistance at the flange-to-pipe transition is better than with standard weld neck flanges in applications subject to pressure cycling, thermal cycling, or mechanical vibration. The longer hub provides a more gradual section change, reducing the stress concentration factor at the root of the hub where fatigue cracks typically initiate in shorter-hub flanges under cyclic loading. For reactors, pressure vessels, and piping systems that cycle pressure or temperature regularly in service, that reduced stress concentration extends the useful life of the connection.

High-pressure and high-temperature service is a consistent application area. In pressure classes 900, 1500, and 2500, and in elevated temperature service where creep and thermal stress are design considerations, the structural integrity of the flanged nozzle connection is critical. Long weld neck flanges in alloy steel grades F11, F22, and F91 cover the elevated temperature service conditions common in power generation and petrochemical refinery applications.

Long weld neck flanges are available with full material certification to ASTM, ASME, and applicable specifications including NACE MR0175 for sour service. Contact PM Industries for material selection, hub length, bore schedule, pressure class, face type, and pricing.

Specification-Slip On Flange

Standards	ANSI/ASME B16.5, B16.48, GOST, DIN, EN-1092, B16.47 Series A & B, AWWA, BS Flanges
JIS Standard	5K, 10K, 16K, 20K, 30K, 40K, 63K
DIN Flanges	DIN 2527, 2627, 2631, 2656, 2576, 2673, 2629, 2628, 2566

Flanges are Available in Following Materials

Stainless Steel	SS 304, 304L, 310, 316L, 317L, 321, 347, 410, 430, 904L
Duplex Steel	UNS S32205, S31803
Super Duplex	UNS S32750, S32760
Carbon Steel	A105, A36, IS 2062, A350 LF2, A694
Alloy Steel	F1, F5, F9, F11, F22, F91
Copper Alloys	Cu-Ni 70/30, 90/10 and other grades
Nickel Alloys	Nickel 200, 201
Inconel	600, 601, 625, 718, 800, 825
Monel	400, K500
Hastelloy	C-22, C-276, C-4
Titanium	Grade 1, 2, 5, 7, 12
Aluminium	6061, 6063, 5083, 7075
Pressure Rating	Class 150 to 2500 LBS
Types	Threaded, Plate, Screwed, Forged
Size Range	1/2" to 48" (DN10–DN5000)
Production Technique	Forged, Machined, Heat Treated
Origin	India / USA / Europe / Japan
Surface Treatment	Zinc Plated, Anti-rust Paint, Galvanized
Test	Spectrograph, X-ray, Ultrasonic, Hydro Testing

Class 150 Slip On Flange Dimensions In Mm

Normal pipe sizes	Inside Diameter	Outside Diameter	Bolt circle	Raised Face (RF)	Raised Face )RF)	H	RF thickness	T1	Flat Face thickness	Bolt Holes	Number of Bolt Holes
3/4	1.09	3.88	2.75	1.69	.063	1.50	.62	.44	.56	.62	4
1	1.36	4.25	3.12	2.00	.063	1.94	.69	.50	.63	.62	4
1-1/4	1.70	4.62	3.50	2.50	.063	2.31	.81	.56	.75	.62	4
6	6.72	11.00	9.50	8.50	.063	7.56	1.56	.94	1.50	.88	8
1-1/2	1.97	5.00	3.88	2.88	.063	2.56	.88	.62	.82	.62	4
2	2.44	6.00	4.75	3.62	.063	3.06	1.00	.69	.94	.75	4
1/2	0.88	3.50	2.38	1.38	.063	1.19	.62	.38	.56	.62	4
2-1/2	2.94	7.00	5.50	4.12	.063	3.56	1.12	.82	1.06	.75	4
3-1/2	4.07	8.50	7.00	5.50	.063	4.81	1.25	.88	1.19	.75	8
4	4.57	9.00	7.50	6.19	.063	5.31	1.31	.88	1.25	.75	8
5	5.66	10.00	8.50	7.31	.063	6.44	1.44	.88	1.38	.88	8
3	3.57	7.50	6.00	5.00	.063	4.25	1.19	.88	1.13	.75	4
8	8.72	13.50	11.75	10.62	.063	9.69	1.75	1.06	1.69	.88	8
10	10.88	16.00	14.25	12.75	.063	12.00	1.94	1.13	1.88	1.00	12
12	12.88	19.00	17.00	15.00	.063	14.38	2.19	1.19	2.13	1.00	12
16	16.16	23.50	21.25	18.50	.063	18.00	2.50	1.38	2.44	1.12	16
18	18.18	25.00	22.75	21.00	.063	19.88	2.69	1.50	2.63	1.25	16
20	20.20	27.50	25.00	23.00	.063	22.00	2.88	1.63	2.83	1.25	20
22	22.22	29.50	27.25	25.25	.063	24.25	3.13	1.75	3.07	1.38	20
14	14.14	21.00	18.75	16.25	.063	15.75	2.25	1.32	2.19	1.12	12
24	24.25	32.00	29.50	27.25	.063	26.12	3.25	1.82	3.19	1.38	20

Ansi 300 Slip On Flange Dimensions

Normal pipe size	Inside Diameter	Outside Diameter	Bolt Circle	Raised Face	Raised Face	H	Raised Face thickness	T1	Flat Face thickness	Bolt holes	Number of Bolt Holes
1-1/4	1.70	5.25	3.88	2.50	.063	2.50	1.06	0.69	1.00	0.75	4
1/2	0.88	3.75	2.62	1.38	.063	1.50	0.88	0.50	0.82	0.62	4
3/4	1.09	4.62	3.25	1.69	.063	1.88	1.00	.056	0.94	0.75	4
1	1.36	4.88	3.50	2.00	.063	2.12	1.06	0.63	1.00	0.75	4
1-1/2	1.95	6.12	4.50	2.88	.063	2.75	1.19	0.75	1.13	0.88	4
3	3.57	8.25	6.62	5.00	.063	4.62	1.69	1.06	1.63	0.88	8
2	2.44	6.50	5.00	3.62	.063	3.31	1.31	0.82	1.25	0.75	8
2-1/2	2.94	7.50	5.88	4.12	.063	3.94	1.50	0.94	1.44	0.88	8
8	8.72	15.00	13.00	10.62	.063	10.25	2.44	1.56	2.38	1.00	12
3-1/2	4.07	9.00	7.25	5.50	.063	5.25	1.75	1.13	1.69	0.88	8
4	4.57	10.00	7.88	6.19	.063	5.75	1.88	1.19	1.82	0.88	8
5	5.66	11.00	9.25	7.31	.063	7.00	2.00	1.32	1.94	0.88	8
6	6.72	12.50	10.62	8.50	.063	8.12	2.06	1.38	2.00	0.88	12
18	18.18	28.00	24.75	21.00	.063	21.00	3.50	2.32	3.44	1.38	24
10	10.88	17.50	15.25	12.75	.063	12.62	2.62	1.82	2.56	1.12	16
12	12.88	20.50	17.75	15.00	.063	14.75	2.88	1.94	2.82	1.25	16
14	14.14	23.00	20.25	16.25	.063	16.75	3.00	2.06	2.94	1.25	20
24	24.25	36.00	32.00	27.25	.063	27.62	4.19	2.69	4.13	1.62	24
16	16.16	25.50	22.50	18.50	.063	19.00	3.25	2.19	3.19	1.38	20
20	20.20	30.50	27.00	23.00	.063	23.12	3.75	2.44	3.69	1.38	24
22	22.22	33.00	29.25	25.25	.063	25.25	4.00	2.57	3.94	1.63	24

Class 600 SORF Flange Dimensions

Normal pipe size	Inside Diameter	Outside Diameter	Bolt circle	Raised Face	Raised Face	H	Raised Face thickness	T1	Flat face thickness	Bolt Hole	Number of Bolt holes
1	1.36	4.88	3.50	2.00	.250	2.12	1.31	0.69	1.06	0.75	4
1/2	0.88	3.75	2.62	1.38	.250	1.50	1.13	0.56	0.88	0.62	4
3/4	1.09	4.62	3.25	1.69	.250	1.88	1.25	0.62	1.00	0.75	4
1-1/4	1.7	5.25	3.88	2.50	.250	2.50	1.37	0.81	1.12	0.75	4
3	3.57	8.25	6.62	5.00	.250	4.62	2.06	1.25	1.81	0.88	8
1-1/2	1.95	6.12	4.50	2.88	.250	2.75	1.50	0.88	1.25	0.88	4
2	2.44	6.50	5.00	3.62	.250	3.31	1.69	1.00	1.44	0.75	8
2-1/2	2.94	7.50	5.88	4.12	.250	3.94	1.87	1.12	1.62	0.88	8
3-1/2	4.07	9.00	7.25	5.50	.250	5.25	2.19	1.38	1.94	1.00	8
8	8.72	16.50	13.75	10.62	.250	10.75	3.25	2.19	3.00	1.25	12
4	4.57	10.75	8.50	6.19	.250	6.00	2.37	1.5	2.12	1.00	8
5	5.66	13.00	10.50	7.31	.250	7.44	2.63	1.75	2.38	1.12	8
6	6.72	14.00	11.50	8.50	.250	8.75	2.87	1.88	2.62	1.12	12
10	10.88	20.00	17.00	12.75	.250	13.5	3.63	2.50	3.38	1.38	16
12	12.88	22.00	19.25	15.00	.250	15.75	3.87	2.62	3.62	1.38	20
14	14.14	23.75	20.75	16.25	.250	17.00	3.94	2.75	3.69	1.50	20
22	22.22	34.25	30.63	25.25	.250	26.25	5.50	3.75	5.25	1.75	24
16	16.16	27.00	23.75	18.50	.250	19.50	4.44	3.00	4.19	1.62	20
24	24.25	37.00	33.00	27.25	.250	28.25	5.75	4.00	5.50	2.00	24
18	18.18	29.25	25.75	21.00	.250	21.50	4.87	3.25	4.62	1.75	20
20	20.20	32.00	28.50	23.00	.250	24.00	5.25	3.50	5.00	1.75	24

ASME B16.5 Class 900 Slip On Flange Dimensions

Normal pipe size	Inside diameter	Outside diameter	Bolt circle	Raised Face	Raised Face	H	Raised Face thickness	T1	Face flat thickness	Bolt hole	Number of bolt holes
6	6.72	15.00	12.50	8.50	.250	9.25	3.63	2.19	3.38	1.25	12
3	3.57	9.50	7.50	5.00	.250	5.00	2.38	1.50	2.13	1.00	8
5	5.66	13.75	11.00	7.31	.250	7.50	3.38	3.00	3.13	1.38	8
16	16.16	27.75	24.25	18.50	.250	20.00	5.50	3.50	5.25	1.75	20
8	8.72	18.50	15.50	10.63	.250	11.75	4.25	2.50	4.00	1.50	12
10	10.88	21.50	18.50	12.75	.250	14.50	4.50	2.75	4.25	1.50	16
4	4.57	11.50	9.25	6.19	.250	6.25	3.00	1.75	2.75	1.25	8
24	24.25	41.00	35.50	27.25	.250	29.50	8.25	5.50	8.00	2.63	20
12	12.88	24.00	21.00	15.00	.250	16.50	4.88	3.13	4.63	1.50	20
14	14.14	25.25	22.00	16.25	.250	17.75	5.38	3.38	5.13	1.63	20
18	18.18	31.00	27.00	21.00	.250	22.25	6.25	4.00	6.00	2.00	20
20	20.20	33.75	29.50	23.00	.250	24.50	6.50	4.25	6.25	2.13	20

Slip On Flange Weight Chart In Kg

Nominal Pipe Size		Dimension		Weight in Kg
Normal Pipe Size (Inche)	Diameter Nominal	Flange Outer Diameter in MM	Flange Thickness in MM	Socket Weld	Weld Neck	Blind
8	200	342.9	28.4	12.1	17.6	19.6
3/4	20	98.6	12.7	0.6	0.7	0.6
1	25	108	14.2	0.8	1	0.9
1 1/4	32	117.3	15.7	1	1.3	1.2
1 1/2	40	127	17.5	1.3	1.7	1.5
2	50	152.4	19.1	2.1	2.6	2.4
2 1/2	65	177.8	22.4	3.3	4.1	3.9
1/2	15	88.9	11.2	0.4	0.5	0.4
3	80	190.5	23.9	3.9	4.9	4.9
24	600	812.8	47.8	86.9	115	185.0
3 1/2	90	215.9	23.9	4.8	6.1	6.2
4	100	228.6	23.9	5.3	6.8	7.0
5	125	254	23.9	6.1	8.6	8.6
6	150	279.4	25.4	7.5	10.6	11.3
10	250	406.4	30.2	16.5	24	28.6
14	350	533.4	35.1	34.6	48.4	58.1
12	300	482.6	31.8	26.2	36.5	43.2
16	400	596.9	36.6	44.8	60.6	76.1
18	450	635	39.6	48.9	68.3	93.7
20	500	698.5	42.9	61.9	84.5	122.0

SS SORF Flange Pressure Rating

Nominal Pipe Size	Class #150			Class #300			Class #600			Class #900			Class #1500			Class #2500
	Weld Neck	Slip on	Blind	Weld Neck	Slip on	Blind	Weld Neck	Slip on	Blind	Weld Neck	Slip on	Blind	Weld Neck	Slip on	Blind	Weld Neck	Slip on	Blind
1/2"	2	1	1	2	1	1	2	2	2	1500# WEIGHTS			5	4	4	7	7	7
3/4"	2	2	2	3	3	3	4	3	3	1500# WEIGHTS			6	5	6	8	8	8
1"	3	2	2	4	3	3	4	4	4	1500# WEIGHTS			9	8	8	12	11	11
1 1/2"	4	3	3	7	6	6	8	7	8	1500# WEIGHTS			13	12	13	25	22	23
2"	6	5	5	9	7	8	12	9	10	1500# WEIGHTS			25	25	25	42	37	39
2 1/2"	8	7	7	12	10	12	18	13	15	1500# WEIGHTS			36	36	35	52	55	56
3"	10	8	9	15	13	16	23	16	20	31	26	29	48	48	48	94	83	86
4"	15	13	17	25	22	27	42	37	41	53	53	54	73	73	73	145	125	130
5"	19	15	20	32	28	35	68	63	68	86	83	87	130	130	140	245	210	225
8"	39	30	45	67	58	81	120	115	140	175	170	200	275	260	300	580	485	530
6"	24	19	26	42	39	50	81	80	86	110	110	115	165	165	160	380	325	345
10"	52	43	70	91	81	124	190	170	230	260	245	290	455	435	510	1075	930	1025
18"	150	130	220	320	250	395	475	400	630	680	600	850	1625	NA	1750	NA	NA	NA
12"	80	64	110	140	115	185	225	200	295	325	325	415	690	580	690	1525	1100	1300
24"	260	220	430	580	475	790	830	730	1250	1500	1400	2025	3325	NA	3625	NA	NA	NA
14"	110	90	140	180	165	250	280	230	355	400	400	520	940	NA	975	NA	NA	NA
16"	140	98	180	250	190	295	390	330	495	495	425	600	1250	NA	1300	NA	NA	NA
20"	180	165	285	400	315	505	590	510	810	830	730	1075	2050	NA	2225	NA	NA	NA
22"	225	185	355	465	370	640	720	590	1000	NA	NA	NA	NA	NA	NA	NA	NA	NA