Threaded Flanges | ASME B16.5 | NPT/BSP

PM Industries manufactures, supplies, and stocks Threaded Flanges in a range of materials, thread types, pressure classes, and pipe sizes. A threaded flange has an internally threaded bore that screws directly onto an externally threaded pipe end. No welding is involved in the pipe-to-flange connection. The flange face then connects to the mating flange in a standard bolted arrangement with a gasket between the faces, exactly as with any other flange type.

Thread type must be specified at the time of order. NPT (National Pipe Taper) is the standard in North American piping practice. BSPT (British Standard Pipe Taper, also designated Rc) is the standard in European, UK, and much of Asian industrial practice. Parallel thread forms such as BSPF or G are encountered in non-pressure connections. Mixing thread forms at installation creates incompatible joints, so confirming the correct thread standard for the project piping specification before ordering is essential.

Environments where welding is not permitted are the primary driver for threaded flange specifications. Classified hazardous areas where flammable vapors or gases are present require hot work permits that can be difficult to obtain for maintenance work. In those locations, threaded connections allow flanged pipe joints to be made and broken during maintenance without introducing a heat source. Firewater systems, fuel gas distribution, and chemical plant small-bore utility piping in hazardous areas commonly use threaded flanges for that reason.

Pressure limitations deserve attention in design. The pipe thread forms the structural connection, and thread engagement provides a mechanical joint rather than a full-penetration weld. Under cyclic pressure, vibration, or bending loads, threaded connections are less fatigue-resistant than welded ones. Most reputable project piping specifications limit threaded flanges to class 150 maximum, and some exclude them from high-cycle or vibration-sensitive service entirely. Confirming that the project specification permits threaded flanges for the intended service should be done before committing to the design.

Thread sealing practice affects joint integrity. NPT and BSPT tapered threads provide mechanical sealing by thread contact, but thread compound or PTFE tape is standard practice to fill thread surface irregularities and improve the seal. Without sealant, small threaded connections are prone to slow seepage through thread interference paths. The correct sealant material must also be compatible with the process fluid. PTFE tape is incompatible with strong oxidizers, and some thread compounds are not suitable for oxygen service.

Threaded flanges are available with full material certification to ASTM and ASME standards. NPT and BSPT thread forms supplied to applicable thread standards. Contact PM Industries for material selection, thread type, pressure class, face type, pipe size, and pricing.

Specification Threaded 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 201, SS 202, SS 301, SS 304, SS 304L, SS 310, SS 310S, SS 316L, SS 316TI, SS 317, SS 317L, SS 321, SS 347, SS 409, SS 409M, SS 409L, SS 410, SS 410S, SS 420, SS 430, SS 431, SS 441, SS 444, SS 446, SS 17-4PH, SS 904L.
Duplex Steel	UNS S32205, UNS S31803 Flange
Super Duplex Steel	UNS S32750, UNS S32760 Flanges
Carbon Steel	Carbon steel A105 Flanges, A36 Flanges, IS 2062 Flanges, A350 LF2 Flanges, F42 Flanges, F52 Flanges, F56 Flanges, F60 Flanges, F65 Flanges, F70 Flanges, F80 Flanges, IBR flanges, A694 Flanges, SS400, SF440, ST37-2 Flanges, S235JrG2 Flanges, P250GH Flanges, C22.8 Flanges, etc.
Alloys Steel	Alloy 20, F1, F5, F9, F11, F22, F91 Flanges
Copper Alloys	Cu-Ni 70/30, Cu-Ni 90/10, C 24000, C 75700, C 51100, C 22000, C 27200, C 21000, C 26800, C 52100, C 77000, C 52000, C 11000, C 74500, C 23000, C 28000, C 12200, C 76400, C 51900, C 75400, C 26000, C 51000, C 10200, C 27000
Nickel Alloys	Nickel 200, 201
Inconel	Inconel 600, 601, 625, 718, 800, 825, X-750
Monel	Monel 400, k500
Hastelloy	Hastelloy C-22, C-276, C-4, X
Titanium	Grade 1, 4, 5(Ti 6Al-4V), 6(Ti 5Al-2.5Sn), 7, 11, 6Al-2Sn-4Zr-2Mo, Grade 12, 6Al-6V-25n, Grade 23(Ti 6AL-4V ELI), 8Ai-1Mo-1V, Grade 5 ELI, Grade 9(3Al-2.5V), 6Al-7Nb.
Aluminium	6063, 1100, 6082 A96082, 1050, 2017, 2024 A92024, 7050 A97050, 5083 A95083, 2014A A92014, 2011 A92011, 6061 A96061 A86061, 5754, 7085, 2050, 7071 7020, 7178, 5052 A95052, 7150, 7075 A97075 A87075, 7575, 2219, 7175
Pressure Rating	Class 150 LBS, 300 LBS, 600 LBS, 900 LBS, 1500 LBS, 2500 LBS
Types	Threaded, Plate, Screwed, Forged.
Supporting material	Gasket, Ring Joint, Flange Bolts
Size range	1/2" (15 NB) to 48" (1200NB) DN10~DN5000
High Temperature	Above 200°C (400°F) For Class 150 Or Above 400°C (750°F)
Low Temperature	Above -29 Degree C (−20°F)
Production technique	Forged, machined and Heat treated
Custom design	As per your drawing
Origin	Indian / USA / Korean / West Europe / Japan
Pressure Class	PN 6 TO PN 100
Coating/Surface Treatment:	Zinc Plated, Anti-rust Paint, Oil Black Paint, Yellow Transparent, Cold and Hot Dip Galvanized.
European/African/Russian Standard Flanges	Available
Test	Direct-reading Spectrograph, X-ray detector, UItrasonic flaw detector, Magnetic particle detector, Hydrostatic testing machine.
Marking Standard	Name of Manufacturer
	Schedule
	Type of Flange Facing
	Pressure Class
	Nominal Pipe Size, etc
Test Certificates	EN 10204/3.1B, NACE MR0103, NACE MR0175
	Raw Materials Certificate
	100% Radiography Test Report
	Third Party Inspection Report, etc

Threaded Flange Pressure Rating

Temperature (oF)	Pressure Class
	150 LBS	300 LBS	400 LBS	600 LBS	900 LBS	1500 LBS	2500 LBS
	Hydrostatic Test Pressure (psig)
	450	1125	1500	2225	3350	5575	9275
200	260	750	1000	1500	2250	3750	6250
-20 to 100	290	750	1000	1500	2250	3750	6250
300	230	730	970	1455	2185	3640	6070
500	170	665	885	1330	1995	3325	5540
600	140	605	805	1210	1815	3025	5040
1000	20	85	115	170	255	430	715
650	125	590	785	1175	1765	2940	4905
400	200	705	940	1405	2110	3520	5865
700	110	555	740	1110	1665	2775	4630
750	95	505	675	1015	1520	2535	4230
800	80	410	550	825	1235	2055	3430
850	65	320	425	640	955	1595	2655
900	50	225	295	445	670	1115	1855
950	35	135	185	275	410	685	1145

Threaded Flange Dimensions In Mm

Nominal Pipe Size	Outside Diameter of Flange (A)	Diameter of Raised Face (B)	Thickness of Flange (C)	Diameter of Hub at Base (J)	Length of Hub (L)	Minimum Thread Length (N)	Number of Bolt Holes	Approx. Weight (Lbs)
1/2	3 1/2	1 3/8	7/16	1 3/16	5/8	5/8	4	2
3/4	3 7/8	1 11/16	1/2	1 1/2	5/8	5/8	4	2
1	4 1/4	2	9/16	1 15/16	11/16	11/16	4	2
1 1/4	4 5/8	2 1/2	5/8	2 5/16	13/16	13/16	4	3
1 1/2	5	2 7/8	11/16	2 9/16	7/8	7/8	4	3
2	6	3 5/8	3/4	3 7/16	1	1	4	5
2 1/2	7	4 1/8	7/8	3 9/16	1 1/8	1 1/8	4	7
3	7 1/2	5	15/16	4 1/4	1 3/16	1 3/16	4	8
3 1/2	8 1/2	5 1/2	15/16	4 13/16	1 1/4	1 1/4	8	11
4	9	6 3/16	15/16	5 5/16	1 5/16	1 5/16	8	13
5	10	7 5/16	15/16	6 7/16	1 7/16	1 7/16	8	15
6	11	8 1/2	1	7 9/16	1 9/16	1 9/16	8	19
8	13 1/2	10 5/8	1 1/8	9 11/16	1 3/4	1 3/4	8	30
10	16	12 3/4	1 3/16	12	1 15/16	1 15/16	12	43
12	19	15	1 1/4	14 3/8	2 3/16	2 3/16	12	64
14	21	16 1/4	1 3/8	15 3/4	2 1/4	2 1/4	12	85
16	23 1/2	18 1/2	1 7/16	18	2 1/2	2 1/2	16	93
18	25	21	1 9/16	19 7/8	2 11/16	2 11/16	16	120
20	27 1/2	23	1 11/16	22	2 7/8	2 7/8	20	155
22	29 1/2	25 1/4	1 13/16	24	3 1/8	3 1/8	20	159
24	32	27 1/4	1 7/8	26 1/8	3 1/4	3 1/4	20	210

Class 150 Threaded Flange Dimension Table

Nominal Bore Threaded Flanges in inches	Diameter (D)	Thickness (E)	Diameter (F)	Diameter (B)	Height 1 (H)	NBR	Holes	Diameter(C)
1/2	90	9.6	35.05	30	14	4	15.87	60.3
3/4	100	11.2	42.92	38	14	4	15.87	69.9
1	110	12.7	50.80	49	16	4	15.87	79.4
1 1/4	115	14.3	63.50	59	19	4	15.87	88.9
1 1/2	125	15.9	73.15	65	21	4	15.87	98.4
2	150	17.5	91.94	78	24	4	19.05	120.7
2 1/2	180	20.7	104.65	90	27	4	19.05	139.7
3	190	22.3	127.00	108	29	4	19.05	152.4
3 1/2	215	22.3	139.70	122	30	8	19.05	177.8
4	230	22.3	157.22	135	32	8	19.05	190.5
5	255	22.3	185.67	164	35	8	22.22	215.9
6	280	23.9	215.90	192	38	8	22.22	241.3
8	345	27.0	269.75	246	43	8	22.22	298.5
10	405	28.6	323.85	305	48	12	25.40	362.0
12	485	30.2	381.00	365	54	12	25.40	431.8
14	535	33.4	412.75	400	56	12	28.57	476.3
16	595	35.0	469.90	457	62	16	28.57	539.8
18	635	38.1	533.40	505	67	16	31.75	577.9
20	700	41.3	584.20	559	71	20	31.75	635.0
24	815	46.1	692.15	663	81	20	34.92	749.3

Screwed Flange Class 300 Dimension

Nominal Bore Threaded Flanges in inches	Diameter (D)	Thick.(E)	Diameter (F)	Diameter (B)	Diameter (A)	Height1(H)	Nbr	Holes	Diameter (C)
1/2	95	12.7	35.05	38	23.6	21	4	15.87	66.7
3/4	115	14.3	42.92	48	29.0	24	4	19.05	82.6
1	125	15.9	50.80	54	35.8	25	4	19.05	88.9
1 1/4	135	17.5	63.50	64	44.4	25	4	19.05	98.4
1 1/2	155	19.1	73.15	70	50.3	29	8	22.22	114.3
2	165	20.7	91.94	84	63.5	32	8	19.05	127.0
2 1/2	190	23.9	104.65	100	76.2	37	8	22.22	149.2
3	210	27.0	127.00	117	92.2	41	8	22.22	168.3
3 1/2	230	28.6	139.70	133	104.9	43	8	22.22	184.2
4	255	30.2	157.22	146	117.6	46	8	22.22	200.0
5	280	33.4	185.67	178	144.4	49	8	22.22	235.0
6	320	35.0	215.90	206	171.4	51	12	22.22	269.9
8	380	39.7	269.75	260	222.2	60	12	25.40	330.2
10	445	46.1	323.85	321	276.2	65	16	28.57	387.4
12	520	49.3	381.00	375	328.6	71	16	31.75	450.8
14	585	52.4	412.75	425	360.4	75	20	31.75	514.4
16	650	55.6	469.90	483	411.2	81	20	34.92	571.5
18	710	58.8	533.40	533	462.0	87	24	34.92	628.6
20	775	62.0	584.20	587	512.8	94	24	34.92	685.8
24	915	68.3	692.15	702	614.4	105	24	41.27	812.8

T2 Inch Screwed Pipe Flange #600 Dimension Chart

Nominal Bore Threaded Flanges in Inches	Diameter (D)	Thickness (E)	Diameter(F)	Diameter(B)	Diameter(A)	Height1(H)	Nbr	Holes	Diameter (C)
1/2	95	14.3	35.05	38	23.6	22	4	15.87	66.7
3/4	115	15.9	42.92	48	29.0	25	4	19.05	82.6
1	125	17.5	50.80	54	35.8	27	4	19.05	88.9
1 1/4	135	20.7	63.50	64	44.4	29	4	19.05	98.4
1 1/2	155	22.3	73.15	70	50.6	32	4	22.22	114.3
2	165	25.4	91.94	84	63.5	37	8	19.05	127.0
2 1/2	190	28.6	104.65	100	76.2	41	8	22.22	149.2
3	210	31.8	127.00	117	92.2	46	8	22.22	168.3
3 1/2	230	35.0	139.70	133	104.9	49	8	25.40	184.2
4	275	38.1	157.22	152	117.6	54	8	25.40	215.9
5	330	44.5	185.67	189	144.4	60	8	28.57	266.7
6	355	47.7	215.90	222	171.4	67	12	31.75	292.1
8	420	55.6	269.75	273	222.2	76	12	31.75	349.2
10	510	63.5	323.85	343	276.2	86	16	34.92	431.8
12	560	66.7	381.00	400	328.6	92	20	34.92	489.0
14	605	69.9	412.75	432	360.4	94	20	38.10	527.0
16	685	76.2	469.90	495	411.2	106	20	41.27	603.2
18	745	82.6	533.40	546	462.0	117	20	44.45	654.0
20	815	88.9	584.20	610	512.8	127	24	44.45	723.9
24	940	101.6	692.15	718	614.4	140	24	47.62	838.2

NPT Threaded Floor Flange Dimensions

Class	150 LBS	300 LBS	600 LBS	900 LBS	1500 LBS	2500 LBS
Diameter A	30	38	38	38	38	43
Diameter D	90	95	95	120	120	135
THK B	9.6	12.7	14.3	22.3	22.3	30.2
	11.2	14.3	20.7	28.7	28.7	36.6
Diameter G	35.1	35.1	35.1	35.1	35.1	35.1
Diameter K	60.3	66.7	66.7	82.6	82.6	88.9
H	14	21	22	32	32	40
	15.6	22.6	28.4	38.4	38.4	46.4
NO. L	4	4	4	4	4	4
Diameter L	15.9	15.9	15.9	22.2	22.2	22.2
Stud Bolts Diameter x Length
Diameter (in)	1/2	1/2	1/2	3/4	3/4	3/4
Length mm	55	65	75	110	110	120