Back-up rings

A back-up ring does not seal on its own — it protects the O-ring from extruding into the gap at high pressure. Without it the rubber ring is sheared away within hours. Below are 857 Hansa Flex sizes: the BR and BU series plus MBK and PBK.

Complete size range — 857

The table lists 857 sizes. Start typing a part number or size to filter the list.

857

Part number	Ø, mm
BR
BR 6	6
BR 7	7
BR 8	8
BR 9	9
BR 10	10
BR 11	11
BR 12	12
BR 13	13
BR 14	14
BR 15	15
BR 16	16
BR 17	17
BR 18	18
BR 19	19
BR 20	20
BR 21	21
BR 22	22
BR 24	24
BR 25	25
BR 28	28
BR 110	110
BR 111	111
BR 113	113
BR 114	114
BR 115	115
BR 116	116
BR 117	117
BR 118	118
BR 119	119
BR 120	120
BR 121	121
BR 122	122
BR 123	123
BR 124	124
BR 125	125
BR 126	126
BR 127	127
BR 128	128
BR 129	129
BR 130	130
BR 131	131
BR 133	133
BR 134	134
BR 135	135
BR 136	136
BR 137	137
BR 139	139
BR 140	140
BR 141	141
BR 142	142
BR 143	143
BR 144	144
BR 148	148
BR 151	151
BR 152	152
BR 153	153
BR 154	154
BR 156	156
BR 157	157
BR 210	210
BR 211	211
BR 212	212
BR 213	213
BR 214	214
BR 215	215
BR 216	216
BR 217	217
BR 218	218
BR 219	219
BR 220	220
BR 221	221
BR 222	222
BR 223	223
BR 224	224
BR 226	226
BR 227	227
BR 228	228
BR 229	229
BR 230	230
BR 231	231
BR 233	233
BR 234	234
BR 235	235
BR 236	236
BR 237	237
BR 238	238
BR 239	239
BR 240	240
BR 241	241
BR 242	242
BR 243	243
BR 244	244
BR 245	245
BR 246	246
BR 247	247
BR 248	248
BR 249	249
BR 250	250
BR 252	252
BR 254	254
BR 255	255
BR 256	256
BR 257	257
BR 258	258
BR 260	260
BR 262	262
BR 263	263
BR 264	264
BR 265	265
BR 266	266
BR 272	272
BR 276	276
BR 326	326
BR 327	327
BR 328	328
BR 329	329
BR 330	330
BR 331	331
BR 332	332
BR 333	333
BR 334	334
BR 335	335
BR 336	336
BR 337	337
BR 338	338
BR 339	339
BR 340	340
BR 341	341
BR 342	342
BR 343	343
BR 344	344
BR 345	345
BR 346	346
BR 348	348
BR 349	349
BR 350	350
BR 351	351
BR 352	352
BR 354	354
BR 355	355
BR 356	356
BR 357	357
BR 358	358
BR 359	359
BR 360	360
BR 361	361
BR 362	362
BR 363	363
BR 364	364
BR 365	365
BR 366	366
BR 367	367
BR 368	368
BR 370	370
BR 371	371
BR 373	373
BR 374	374
BR 375	375
BR 376	376
BR 377	377
BR 379	379
BR 380	380
BR 425	425
BR 426	426
BR 427	427
BR 428	428
BR 429	429
BR 430	430
BR 431	431
BR 432	432
BR 433	433
BR 434	434
BR 435	435
BR 436	436
BR 437	437
BR 438	438
BR 439	439
BR 440	440
BR 442	442
BR 443	443
BR 444	444
BR 445	445
BR 446	446
BR 447	447
BR 448	448
BR 449	449
BR 450	450
BR 451	451
BR 452	452
BR 453	453
BR 454	454
BR 455	455
BR 458	458
BR 459	459
BR 460	460
BR 610	610
BR 611	611
BR 613	613
BR 614	614
BR 615	615
BR 616	616
BR 619	619
BR 620	620
BR 621	621
BR 622	622
BR 623	623
BR 624	624
BR 628	628
BR 674	674
BR 676	676
BR 678	678
BR 680	680
BR 682	682
BR 684	684
BR 686	686
BR 688	688
BR 809	809
BR 812	812
BR 824	824
BR 825	825
BR 826	826
BR 828	828
BR 829	829
BR 830	830
BR 832	832
BR 834	834
BR 836	836
BR 838	838
BR 842	842
BR 843	843
BR 844	844
BR 846	846
BR 860	860
BR 865	865
BR 867	867
BR 872	872
BR 874	874
BR 876	876
BR 878	878
BR 882	882
BR 884	884
BU
BU 4	4
BU 5	5
BU 6	6
BU 7	7
BU 8	8
BU 9	9
BU 10	10
BU 11	11
BU 12	12
BU 13	13
BU 14	14
BU 15	15
BU 16	16
BU 17	17
BU 18	18
BU 19	19
BU 20	20
BU 21	21
BU 22	22
BU 23	23
BU 24	24
BU 25	25
BU 26	26
BU 27	27
BU 28	28
BU 29	29
BU 30	30
BU 31	31
BU 32	32
BU 33	33
BU 34	34
BU 35	35
BU 36	36
BU 37	37
BU 38	38
BU 39	39
BU 40	40
BU 41	41
BU 42	42
BU 43	43
BU 44	44
BU 45	45
BU 46	46
BU 47	47
BU 48	48
BU 49	49
BU 50	50
BU 103	103
BU 104	104
BU 105	105
BU 106	106
BU 107	107
BU 108	108
BU 109	109
BU 110	110
BU 111	111
BU 112	112
BU 113	113
BU 114	114
BU 115	115
BU 116	116
BU 117	117
BU 118	118
BU 119	119
BU 120	120
BU 121	121
BU 122	122
BU 123	123
BU 124	124
BU 125	125
BU 126	126
BU 127	127
BU 128	128
BU 129	129
BU 130	130
BU 131	131
BU 132	132
BU 133	133
BU 134	134
BU 135	135
BU 136	136
BU 137	137
BU 138	138
BU 139	139
BU 140	140
BU 141	141
BU 142	142
BU 143	143
BU 144	144
BU 145	145
BU 146	146
BU 147	147
BU 148	148
BU 149	149
BU 150	150
BU 151	151
BU 152	152
BU 153	153
BU 154	154
BU 155	155
BU 156	156
BU 157	157
BU 158	158
BU 159	159
BU 160	160
BU 161	161
BU 162	162
BU 163	163
BU 164	164
BU 165	165
BU 166	166
BU 167	167
BU 168	168
BU 169	169
BU 170	170
BU 171	171
BU 172	172
BU 173	173
BU 174	174
BU 175	175
BU 176	176
BU 177	177
BU 178	178
BU 201	201
BU 202	202
BU 203	203
BU 204	204
BU 205	205
BU 206	206
BU 207	207
BU 208	208
BU 209	209
BU 210	210
BU 211	211
BU 212	212
BU 213	213
BU 214	214
BU 215	215
BU 216	216
BU 217	217
BU 218	218
BU 219	219
BU 220	220
BU 221	221
BU 222	222
BU 223	223
BU 224	224
BU 225	225
BU 226	226
BU 227	227
BU 228	228
BU 229	229
BU 230	230
BU 231	231
BU 232	232
BU 233	233
BU 234	234
BU 235	235
BU 236	236
BU 237	237
BU 238	238
BU 239	239
BU 240	240
BU 241	241
BU 242	242
BU 243	243
BU 244	244
BU 245	245
BU 246	246
BU 247	247
BU 248	248
BU 249	249
BU 250	250
BU 251	251
BU 252	252
BU 253	253
BU 254	254
BU 255	255
BU 256	256
BU 257	257
BU 258	258
BU 259	259
BU 260	260
BU 261	261
BU 262	262
BU 263	263
BU 264	264
BU 265	265
BU 266	266
BU 267	267
BU 268	268
BU 269	269
BU 270	270
BU 271	271
BU 272	272
BU 273	273
BU 274	274
BU 275	275
BU 276	276
BU 277	277
BU 278	278
BU 279	279
BU 280	280
BU 281	281
BU 282	282
BU 283	283
BU 284	284
BU 309	309
BU 310	310
BU 311	311
BU 312	312
BU 313	313
BU 314	314
BU 315	315
BU 316	316
BU 317	317
BU 318	318
BU 319	319
BU 320	320
BU 321	321
BU 322	322
BU 323	323
BU 324	324
BU 325	325
BU 326	326
BU 327	327
BU 328	328
BU 329	329
BU 330	330
BU 331	331
BU 332	332
BU 333	333
BU 334	334
BU 335	335
BU 336	336
BU 337	337
BU 338	338
BU 339	339
BU 340	340
BU 341	341
BU 342	342
BU 343	343
BU 344	344
BU 345	345
BU 346	346
BU 347	347
BU 348	348
BU 349	349
BU 350	350
BU 351	351
BU 352	352
BU 353	353
BU 354	354
BU 355	355
BU 356	356
BU 357	357
BU 358	358
BU 359	359
BU 360	360
BU 361	361
BU 362	362
BU 363	363
BU 364	364
BU 365	365
BU 366	366
BU 367	367
BU 368	368
BU 369	369
BU 370	370
BU 371	371
BU 372	372
BU 373	373
BU 374	374
BU 375	375
BU 376	376
BU 377	377
BU 378	378
BU 379	379
BU 380	380
BU 381	381
BU 382	382
BU 383	383
BU 425	425
BU 426	426
BU 427	427
BU 428	428
BU 429	429
BU 430	430
BU 431	431
BU 432	432
BU 433	433
BU 434	434
BU 435	435
BU 436	436
BU 437	437
BU 438	438
BU 439	439
BU 440	440
BU 441	441
BU 442	442
BU 443	443
BU 444	444
BU 445	445
BU 446	446
BU 447	447
BU 448	448
BU 449	449
BU 450	450
BU 451	451
BU 452	452
BU 453	453
BU 454	454
BU 455	455
BU 456	456
BU 457	457
BU 458	458
BU 459	459
BU 460	460
BU 461	461
BU 462	462
BU 463	463
BU 464	464
BU 465	465
BU 466	466
BU 467	467
MBK
MBK 4 8	4
MBK 6 10	6
MBK 7 11	7
MBK 10 14	10
MBK 11 15	11
MBK 12 16	12
MBK 13 17	13
MBK 14 18	14
MBK 15 19	15
MBK 16 20	16
MBK 17 21	17
MBK 18 22	18
MBK 20 25	20
MBK 23 28	23
MBK 25 30	25
MBK 27 32	27
MBK 30 35	30
MBK 35 40	35
MBK 37 42	37
MBK 40 45	40
MBK 40 50	40
MBK 45 50	45
MBK 45 55	45
MBK 50 55	50
MBK 50 60	50
MBK 53 63	53
MBK 55 60	55
MBK 55 65	55
MBK 58 63	58
MBK 60 65	60
MBK 60 67	60
MBK 60 70	60
MBK 63 68	63
MBK 65 70	65
MBK 65 75	65
MBK 69 74	69
MBK 70 75	70
MBK 70 77	70
MBK 70 80	70
MBK 72 77	72
MBK 72 82	72
MBK 75 80	75
MBK 75 85	75
MBK 78 88	78
MBK 79 84	79
MBK 80 85	80
MBK 80 87	80
MBK 80 90	80
MBK 85 90	85
MBK 85 95	85
MBK 90 100	90
MBK 90 95	90
MBK 92 99	92
MBK 94 99	94
MBK 95 100	95
MBK 95 105	95
MBK 100 105	100
MBK 100 110	100
MBK 105 110	105
MBK 105 115	105
MBK 110 115	110
MBK 110 120	110
MBK 113 118	113
MBK 115 120	115
MBK 115 125	115
MBK 120 125	120
MBK 120 130	120
MBK 125 130	125
MBK 125 135	125
MBK 130 135	130
MBK 130 140	130
MBK 135 140	135
MBK 135 145	135
MBK 140 145	140
MBK 140 150	140
MBK 142 151	142
MBK 145 150	145
MBK 145 155	145
MBK 150 160	150
MBK 152 161	152
MBK 155 165	155
MBK 160 170	160
MBK 165 175	165
MBK 170 180	170
MBK 175 185	175
MBK 180 190	180
MBK 185 195	185
MBK 190 200	190
MBK 195 205	195
MBK 200 210	200
MBK 210 220	210
MBK 220 230	220
MBK 230 240	230
MBK 240 250	240
MBK 250 260	250
MBK 270 280	270
PBK
PBK 010-610	010
PBK 11	11
PBK 12	12
PBK 13	13
PBK 14	14
PBK 15	15
PBK 16	16
PBK 17	17
PBK 19	19
PBK 20	20
PBK 24	24
PBK 26	26
PBK 29	29
PBK 30	30
PBK 32	32
PBK 109	109
PBK 110-613	110
PBK 111	111
PBK 112	112
PBK 113	113
PBK 114-809	114
PBK 115	115
PBK 116	116
PBK 117	117
PBK 118-813	118
PBK 119-814	119
PBK 120	120
PBK 121	121
PBK 122	122
PBK 123	123
PBK 124	124
PBK 125	125
PBK 126	126
PBK 127	127
PBK 128	128
PBK 129	129
PBK 130	130
PBK 131	131
PBK 132	132
PBK 133	133
PBK 134	134
PBK 135	135
PBK 136	136
PBK 137	137
PBK 138	138
PBK 139	139
PBK 140	140
PBK 141	141
PBK 142	142
PBK 143	143
PBK 144	144
PBK 145	145
PBK 146	146
PBK 147	147
PBK 148	148
PBK 149	149
PBK 150	150
PBK 152	152
PBK 153	153
PBK 154	154
PBK 157	157
PBK 210	210
PBK 211	211
PBK 212	212
PBK 213	213
PBK 214	214
PBK 215	215
PBK 216	216
PBK 217	217
PBK 218	218
PBK 219	219
PBK 220	220
PBK 221	221
PBK 222	222
PBK 223-825	223
PBK 224-827	224
PBK 225-829	225
PBK 226-831	226
PBK 227-833	227
PBK 228-835	228
PBK 229-837	229
PBK 230-839	230
PBK 231-841	231
PBK 232-843	232
PBK 233-845	233
PBK 234	234
PBK 235	235
PBK 236	236
PBK 237	237
PBK 238	238
PBK 239	239
PBK 240	240
PBK 241	241
PBK 242	242
PBK 243	243
PBK 244	244
PBK 245	245
PBK 246	246
PBK 247	247
PBK 248	248
PBK 249	249
PBK 250	250
PBK 251	251
PBK 252	252
PBK 253	253
PBK 254	254
PBK 255	255
PBK 257	257
PBK 258	258
PBK 263	263
PBK 266	266
PBK 269	269
PBK 325	325
PBK 326	326
PBK 327	327
PBK 328	328
PBK 329	329
PBK 330	330
PBK 331	331
PBK 332	332
PBK 333	333
PBK 334	334
PBK 335	335
PBK 336	336
PBK 337	337
PBK 338-620	338
PBK 339	339
PBK 340	340
PBK 341	341
PBK 342	342
PBK 343	343
PBK 344	344
PBK 345	345
PBK 346	346
PBK 347	347
PBK 348-623	348
PBK 349	349
PBK 350-860	350
PBK 351-861	351
PBK 353-863	353
PBK 354-864	354
PBK 356-866	356
PBK 357-867	357
PBK 358-868	358
PBK 360-870	360
PBK 362	362
PBK 363	363
PBK 364	364
PBK 365	365
PBK 367	367
PBK 368	368
PBK 370	370
PBK 372	372
PBK 373	373
PBK 425	425
PBK 426	426
PBK 428	428
PBK 429	429
PBK 431	431
PBK 432-433	432
PBK 435	435
PBK 442	442
PBK 443	443
PBK 444	444
PBK 446	446
PBK 447	447
PBK 611	611
PBK 614	614
PBK 616	616
PBK 617	617
PBK 618	618
PBK 619	619
PBK 621	621
PBK 622	622
PBK 628	628
PBK 678	678
PBK 684	684
PBK 812	812
PBK 824	824
PBK 826	826
PBK 828	828
PBK 830	830
PBK 832	832
PBK 834	834
PBK 836	836
PBK 838	838
PBK 840	840
PBK 842	842
PBK 844	844
PBK 846	846
PBK 862	862
PBK 865	865
PBK 872	872
PBK 880	880
PBK 884	884

How to select the size

A back-up ring is matched to the same groove as the O-ring it protects. The split type (BU) fits closed grooves; the solid type (BR) is used where it can be slipped over during assembly.

One ring goes on the low-pressure side. With alternating pressure, fit two — one on each side.

Materials

The material is chosen by medium and temperature, not by price:

NBR — the standard for mineral oil, −30…+100 °C. Most common and least expensive.
FKM (Viton) — up to +200 °C, aggressive media, brake fluid. Three to five times the price of NBR.
PU (polyurethane) — high pressure and abrasion, but not above +80 °C.
PTFE — chemicals, very low friction, but poor under compression without support.
EPDM — water, steam, glycol-based brake fluid. Not compatible with oil.

Common fitting mistakes

Three mistakes that make a new seal leak within a day:

Damaged lip during fitting. The seal is pushed over threads or splines without a sleeve — the lip is cut and you cannot see it.
Measuring a worn part. The old ring has lost its shape, so the new size does not seat in the groove.
No back-up ring. Above 160 bar the seal extrudes into the gap.

Frequently asked questions

Is a back-up ring mandatory?
Below 160 bar, usually not. Above that — yes, especially if the extrusion gap exceeds 0.2 mm. At 300 bar the assembly will not survive without one.

What are back-up rings made of?
PTFE with a filler (bronze, graphite, glass fibre) is the standard. For very high pressures POM or fabric composites are used.

Split or solid?
The split type is easier to fit and needs no disassembly. The solid type is more reliable under pressure spikes but requires free access.

Back-up rings sit next to an O-ring or seal and stop it being extruded into the gap under high pressure. Without them the seal fails quickly at pressures above roughly 100-150 bar. We supply PTFE, bronze-filled PTFE, POM and NBR back-up rings in spiral and solid form, as genuine parts with the original dimensions. Selection depends on the groove width, the pressure and whether the ring must be split for installation (spiral). Send the part number or the groove dimensions and we confirm the right ring and material within 24 hours.

Showing 81–96 of 857 results

Frequently Asked Questions

Do you supply genuine parts or Chinese equivalents?

Genuine parts are our main business. If you need a lower-cost option, we can also look for a Chinese-made equivalent with the same mounting dimensions and ratings.

What is the lead time?

It depends on the supplier. If the factory has stock or produces in China, we ship quickly. A factory order that must be manufactured or shipped from abroad takes longer. We confirm the exact date in your quote.

How do I place an order?

Send the part number, a photo of the nameplate, or the machine model. We confirm availability and price within 24 hours.

What are the payment and shipping terms?

EXW by default. 20-50% prepayment, balance before shipment. We can work with your freight forwarder.

What is a back-up ring for?

It supports the O-ring or seal and prevents extrusion in the gap at high pressure.

Which materials do you supply?

PTFE, POM, bronze-filled PTFE and NBR back-up rings, in spiral or solid form.

Are back-up rings genuine?

Yes, genuine parts, following the original manufacturer dimensions.

Back-up rings

Complete size range — 857

How to select the size

Materials

Common fitting mistakes

Frequently asked questions

Back-up rings Hansa Flex BR 24

Back-up rings Hansa Flex BR 240

Back-up rings Hansa Flex BR 241

Back-up rings Hansa Flex BR 242

Back-up rings Hansa Flex BR 243

Back-up rings Hansa Flex BR 244

Back-up rings Hansa Flex BR 245

Back-up rings Hansa Flex BR 246

Back-up rings Hansa Flex BR 247

Back-up rings Hansa Flex BR 248

Back-up rings Hansa Flex BR 249

Back-up rings Hansa Flex BR 25

Back-up rings Hansa Flex BR 250

Back-up rings Hansa Flex BR 252

Back-up rings Hansa Flex BR 254

Back-up rings Hansa Flex BR 255