Gasket India

NON-ASBESTOS GASKETS

Non-asbestos gaskets are the simplest type of gasket for flanges and are produced by cutting graphite, organic or inorganic non asbestos sheets into shape (generally, with water jet cutting machines). This type of gaskets for flanges suits low pressure, low temperature, and non-critical piping and plumbing applications.
The two main types of non-asbestos gaskets are the “full face” (FF) for FF flanges and the “flat ring” type for raised face flanges (RF).

Non-asbestos gaskets have fully replaced asbestos gaskets for decades as studies demonstrated the risks (for human health) associated with the production, use, and disposal of asbestos materials. The ASME B16.21 specification covers non-asbestos sheet gaskets (types, sheet materials, dimensions, dimensional tolerances, and marking requirements).

The terms, “flat-cut gaskets”, “die-cut gaskets”, “compressed sheet gaskets” and “asbestos-free gaskets” are synonyms to define this low-end family of flange gaskets. To select the right material for non-asbestos gaskets, multiple factors shall be considered: fluid, temperature, pressure, fugitive emissions laws, and mechanical issues. The most common materials used to manufacture compressed fiber gaskets are aramid fibers (Kevlar), glass fibers, elastomers, Teflon (PTFE), graphite, neoprene mixed with various binder materials (the most common binder is NBR, i.e. Buna-N):

Aramid NBR binder
carbon graphite reinforced
glass reinforced (steam service gasket)
PTFE bi-axially oriented (silica filler)
SBR (styrene-butadiene)
CR-chloroprene (Neoprene)
EPDM gasket (ethylene propylene)
fluorocarbon (Viton)
graphite
BUNA-n-rubber (nitrile, NBR gasket)
chlorosulfonated polyethylene (Hypalon gasket)
aramid + SBR binder (premium type gasket)

graphite + ss316/316l insert
PTFE biaxially oriented (with hollow glass microsphere) blue
PTFE biaxially oriented (pigment-free)-gray
expanded PTFE gasket
PTFE joint sealant
PTFE envelope slit type
PTFE envelope milled type
PTFE envelope formed type
MICA sheet
ceramic fiber

Non-asbestos gaskets can also be coated with graphite, for non-stick and steam resistance, mixed with PTFE for excellent chemical resistance, or with EPDM for potable water applications.

NON-ASBESTOS GASKET DIMENSIONS

Soft Gaskets for ASME B16.5 Flanges

Non-asbestos gaskets dimensions (for ASME B16.5 flanges), in millimeters

NPS	d1 (ID)	d2 (GASKET OUTSIDE DIAMETER)
NPS	d1 (ID)	Class 150	Class 300	Class 400	Class 600	Class 900
1/2	21	48	54	54	54	64
3/4	27	57	67	67	67	70
1	33	67	73	73	73	79
1¼	42	76	83	83	83	89
1½	48	86	95	95	95	98
2	60	105	111	111	111	143
2½	73	124	130	130	130.2	165
3	89	137	149	149	149	168
3½	102	162	165	162	162	…
4	114	175	181	178	194	206
5	141	197	216	213	241	248
6	168	222	251	248	267	289
8	219	279	308	305	321	359
10	273	340	362	359	400	435
12	324	410	422	419	457	498
14	356	451	486	483	492	521
16	406	514	540	537	565	575
18	457	549	597	594	613	638
20	508	606	654	648	683	699
24	610	718	775	768	791	838

Soft Gaskets for ASME B16.47 – Series A Flanges

Non-asbestos gaskets dimensions (for ASME B16.47 series A flanges), in millimeters

NPS	d1 (ID)	d2 (GASKET OUTSIDE DIAMETER)
NPS	d1 (ID)	Class 150	Class 300	Class 400	Class 600
26	660	775	835	832	867
28	711	832	899	892	914
30	762	883	953	946	972
32	813	940	1006	1003	1022
34	864	991	1057	1054	1073
36	914	1048	1118	1118	1130
38	965	1111	1054	1073	1105
40	1016	1162	1114	1127	1156
42	1067	1219	1165	1178	1219
44	1118	1276	1219	1232	1270
46	1168	1327	1273	1289	1327
48	1219	1384	1324	1346	1391
50	1270	1435	1378	1403	1448
52	1321	1492	1429	1454	1499
54	1372	1549	1492	1518	1556
56	1422	1607	1543	1568	1613
58	1473	1664	1594	1619	1664
60	1524	1715	1645	1683	1721

Soft Gaskets for ASME B16.47 – Series B Flanges

Non-asbestos gaskets dimensions (for ASME B16.47 series B flanges), in millimeters

NPS	d1 (ID)	d2 (GASKET OUTSIDE DIAMETER)
NPS	d1 (ID)	Class 150	Class 300	Class 400	Class 600
26	660	725	772	746	765
28	711	776	826	800	819
30	762	827	886	857	879
32	813	881	940	911	933
34	864	935	994	962	997
36	914	987	1048	1022	1048
38	965	1045	1099	…	…
40	1016	1095	1149	…	…
42	1067	1146	1200	…	…
44	1118	1197	1251	…	…
46	1168	1256	1318	…	…
48	1219	1307	1368	…	…
50	1270	1357	1419	…	…
52	1321	1408	1470	…	…
54	1372	1464	1530	…	…
56	1422	1514	1594	…	…
58	1473	1580	1656	…	…
60	1524	1630	1705	…	…

All values in millimeters. Dimensional tolerances:
For outside diameter NPS 12 and smaller: +0 / -1.5 mm.; NPS 14 and larger: +0 / -3.0 mm.
For inside diameter NPS 12 and smaller: ± 1.5 mm; NPS 14 and larger: ± 3.0 mm

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Non-asbestos Gaskets