Loose Flanges | EN 1092-1 Type 02 | DIN 2642

PM Industries manufactures, supplies, and stocks Loose Flanges in a range of materials, pressure ratings, and pipe sizes. A loose flange, also called a backing ring flange or loose ring flange, works on the same principle as a lap joint flange assembly. It consists of a stub end, which is welded to the pipe and provides the sealing face, and a loose backing ring that slides over the pipe and rotates freely around the stub end. The loose ring is never welded to the pipe. It bears against the back of the stub end at the joint and carries the bolt load, but it's free to rotate at any time before the bolts are tightened.

That free rotation is the practical value of the design. In a fixed flange, getting bolt holes aligned between two mating flanges requires rotating the pipe or spool. On large-diameter or heavy pipe runs where rotating the assembly isn't practical, misaligned bolt holes force delays while the piping is repositioned. With a loose flange, the backing ring simply turns to line up the holes regardless of pipe position.

Lined piping systems are one of the most consistent applications for loose flanges. In rubber-lined, PTFE-lined, or glass-lined piping where the lining material provides the corrosion resistance and the lining also covers the stub end face, a loose backing ring provides the bolted connection without requiring the ring to contact the aggressive process fluid. The ring can be carbon steel, which keeps cost low, while the stub end and lining handle the corrosion requirement.

Mixed-material economy is the same principle applied to unlined corrosion-resistant piping. In a system where the process requires stainless or nickel alloy at all wetted surfaces, using a loose flange limits the expensive alloy material to the stub end only. The backing ring, which doesn't contact the process, is specified in carbon steel. On systems with many flange connections in expensive alloy materials, that difference across the backing ring population reduces total flange material cost meaningfully.

Frequent disassembly service suits loose flanges well. In chemical plant, food processing, and pharmaceutical piping where sections are regularly removed for cleaning, inspection, or process modification, reassembly is faster with loose backing rings that rotate to meet the mating flange bolt pattern without repositioning the spool.

Loose flanges are available with full material certification to applicable ASTM and ASME standards. Stub ends supplied to ASME B16.9. Contact PM Industries for material selection, stub end pattern (short or long), pipe size, pressure rating, 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 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

ANSI B16.5 Loose Flanges – Class 150 Lbs

Drilling
Nominal Bore Loose Flanges	Dia. (D)	Thick. (E)	Dia. (B)	Dia. (A)	Height (H)	Nbr	Holes	Dia. (C)
1/2″	90	11.2	30	22.9	16	4	15.87	60.3
3/4″	100	12.7	38	28.2	16	4	15.87	69.9
1″	110	14.3	49	34.9	17	4	15.87	79.4
1 1/4″	115	15.9	59	43.7	21	4	15.87	88.9
1 1/2″	125	17.5	65	50.0	22	4	15.87	98.4
2″	150	20.7	78	62.5	25	4	19.05	120.7
2 1/2″	180	22.3	90	75.4	29	4	19.05	139.7
3″	190	23.9	108	91.4	30	4	19.05	152.4
3 1/2″	215	23.9	122	104.1	32	8	19.05	177.8
4″	230	23.9	135	116.8	33	8	19.05	190.5
5″	255	23.9	164	144.4	36	8	22.22	215.9
6″	280	25.4	192	171.4	40	8	22.22	241.3
8″	345	28.6	246	222.2	44	8	22.22	298.5
10″	405	30.2	305	277.4	49	12	25.40	362.0
12″	485	31.8	365	328.2	56	12	25.40	431.8
14″	535	35.0	400	360.2	79	12	28.57	476.3
16″	595	36.6	457	411.2	87	16	28.57	539.8
18″	635	39.7	505	462.3	97	16	31.75	577.9
20″	700	42.9	559	514.4	103	20	31.75	635.0
24″	815	47.7	663	616.0	111	20	34.92	749.3

ANSI B16.5 Loose Flanges – Class 300 Lbs

Drilling
Nominal Bore Loose Flanges	Dia. (D)	Thick. (E)	Dia. (B)	Dia. (A)	Height (H)	Nbr	Holes	Dia. (C)
1/2″	95	14.3	38	22.9	22	4	15.87	66.7
3/4″	115	15.9	48	28.2	25	4	19.05	82.6
1″	125	17.5	54	34.9	27	4	19.05	88.9
1 1/4″	135	19.1	64	43.7	27	4	19.05	98.4
1 1/2″	155	20.7	70	50.0	30	4	22.22	114.3
2″	165	22.3	84	62.5	33	8	19.05	127.0
2 1/2″	190	25.4	100	75.4	38	8	22.22	149.2
3″	210	28.6	117	91.4	43	8	22.22	168.3
3 1/2″	230	30.2	133	104.1	44	8	22.22	184.2
4″	255	31.8	146	116.8	48	8	22.22	200.0
5″	280	35.0	178	144.4	51	8	22.22	235.0
6″	320	36.6	206	171.4	52	12	22.22	269.9
8″	380	41.3	260	222.2	62	12	25.40	330.2
10″	445	47.7	321	277.4	95	16	28.57	387.4
12″	520	50.8	375	328.2	102	16	31.75	450.8
14″	585	54.0	425	360.2	111	20	31.75	514.4
16″	650	57.2	483	411.2	121	20	34.29	571.5
18″	710	60.4	533	462.3	130	24	34.29	628.6
20″	775	63.5	587	514.4	140	24	34.29	685.8
24″	915	69.9	702	616.0	152	24	41.27	812.8

ANSI B16.5 Loose Flanges – Class 600 Lbs

Drilling
Nominal Bore Loose Flanges	Dia. (D)	Thick. (E)	Dia. (B)	Dia. (A)	Height (H)	Nbr	Holes	Dia. (C)
1/2″	95	14.3	38	23.6	22	4	15.87	66.7
3/4″	115	15.9	48	29.0	25	4	19.05	82.6
1″	125	17.5	54	35.8	27	4	19.05	88.9
1 1/4″	135	20.7	64	44.4	29	4	19.05	98.4
1 1/2″	155	22.3	70	50.6	32	4	22.22	114.3
2″	165	25.4	84	63.5	37	8	19.05	127.0
2 1/2″	190	28.6	100	76.2	41	8	22.22	149.2
3″	210	31.8	117	92.2	46	8	22.22	168.3
3 1/2″	230	35.0	133	104.9	49	8	25.40	184.2
4″	275	38.1	152	117.6	54	8	25.40	215.9
5″	330	44.5	189	144.4	60	8	28.57	266.7
6″	355	47.7	222	171.4	67	12	28.57	292.1
8″	420	55.6	273	222.2	76	12	31.75	349.2
10″	510	63.5	343	276.2	111	16	34.92	431.8
12″	560	66.7	400	328.6	117	20	34.92	489.0
14″	605	69.9	432	360.4	127	20	38.10	527.0
16″	685	76.2	495	411.2	140	20	41.27	603.2
18″	745	82.6	546	462.0	152	20	44.45	6654.0
20″	815	88.9	610	512.8	165	24	44.45	723.9
24″	940	101.6	718	614.4	184	24	50.80	838.2