Conflat (CF) Gasket

100% reliability — Money back guarantee

  • World’s largest selection – 46 sizes in stock
  • Copper – Nickel – Aluminum – all annealed
  • Precision machined – 100% guaranteed
  • Small quantities or OEM
  • Same day shipping to US or EU
  • All CF gaskets manufactured by Bostec in the USA

Full section cutaway assembly of two CF flanges crushing a CF gasket to completion and demonstrating that the HiRim® raised perimeter sits without interference in the free space of the gland.

Sizing Chart

45 Sizes from 13mm to 463mm / HiRim & Conventional CF Gaskets

North American (inches)
Metric (cm)
Bostec #
Inches
OD
ID
Thickness
Standards
Copper OSF Annealed
Nickel 200/201 Annealed
Aluminum 1050 Annealed
1
CF1.00
0.524
0.335
0.080
ASTM
$28.65
$35.82
$30.45
2
CF1.33
0.838
0.643
0.080
840.8 Pos 1/ASTM
$43.99
$54.99
$46.74
3
CF1.33/P2
0.838
0.640
0.075
P2
$43.99
$54.99
$46.74
4
CF2.125
1.290
1.013
0.080
ASTM
$60.55
$75.69
$64.34
5
CF2.125/P1
1.290
1.01
0.075
P1
$60.55
$75.69
$64.34
6
CF2.125
1.295
1.000
0.080
DESY
$60.55
$75.69
$64.34
7
CF2.750
1.894
1.449
0.080
850.6 Pos 2
$95
$119
$101
8
CF2.750
1.895
1.533
0.080
ASTM
$95
$119
$101
9
CF2.750
1.898
1.535
0.080
DESY
$95
$119
$101
10
CF3.375
2.425
2.015
0.080
ASTM
$136
$169
$144
11
CF4.50
3.248
2.402
0.080
DESY
$195
$243
$207
12
CF4.50
3.244
2.504
0.080
855.1 Pos 3
$195
$243
$207
13
CF4.50
3.244
2.610
0.
856.6 Pos 4
$195
$243
$207
14
CF4.50
3.243
2.813
0.080
ASTM
$195
$243
$207
15
CF4.50 CNG
3.240
2.545
0.088
Corning
$240
$300
$255
16
CF4.625
3.598
3.015
0.080
ASTM
$219
$274
$233
17
CF6.00
4.740
2.508
0.080
857.1 Pos 5
$255
$319
$271
18
CF6.00
4.743
4.009
0.080
860.4 Pos 6/ASTM
$255
$319
$271
19
CF6.00
4.740
3.173
0.080
861.1 Pos 7
$255
$319
$271
20
CF6.00
4.740
2.390
0.080
862.2 Pos 8
$255
$319
$271
21
CF6.00
4.748
4.008
0.080
DESY
$255
$319
$271
22
CF6.75
5.568
5.013
0.080
ASTM
$347
$434
$369
23
CF8.00
6.744
6.000
0.080
865.9 Pos 9
$395
$494
$420
24
CF8.00
6.743
6.010
0.080
ASTM
$395
$494
$420
25
CF8.00
6.744
4.004
0.080
866.6 Pos 10
$395
$494
$420
26
CF8.00
6.744
5.185
0.080
867.7 Pos 11
$395
$494
$420
27
7.083
6.299
0.080
870.2 Pos 12
$486
$607
$516
28
CF10.00
8.744
8.008
0.080
875.7 Pos 13
$572
$715
$607
29
CF10.00
8.743
8.010
0.080
ASTM
$572
$715
$607
30
10.031
9.252
0.080
880.0 Pos 14
$587
$734
$624
31
CF12.00
10.748
9.882
0.080
DESY
$1040
$1,300
$1,105
32
CF12.00
10.749
10.007
0.080
ASTM
$1040
$1,300
$1,105
33
CF12.00
10.748
10.220
0.080
885.5 Pos 15
$1047
$1,309
$1,113
34
CF12.50
11.221
10.500
0.080
ASTM
$1262
$1,578
$1,341
35
CF12.50
11.339
10.709
0.080
890.8 Pos 16
$1262
$1,578
$1,341
36
CF13.25
11.589
10.857
0.080
ASTM
$1262
$1,578
$1,341
37
CF14
12.330
11.813
0.080
ASTM
$1406
$1,758
$1,494
38
CF14.25
12.638
12.016
0.080
ASTM
$1406
$1,758
$1,494
39
CF14.25
12.646
12.008
0.080
895.3 Pos 17
$1406
$1,758
$1,494
40
CF14.5
12.843
12.107
0.080
ASTM
$1406
$1,758
$1,494
41
CF16.5
14.836
14.107
0.080
ASTM
$1613
$2,016
$1,714
42
CF18
16.501
15.807
0.080
ASTM
$1733
$2,166
$1,841
43
CF18
16.528
15.906
0.080
900.3 Pos 18
$1733
$2,166
$1,841
44
CF18.5
16.702
15.970
0.080
ASTM
$1733
$2,166
$1,841
45
CF19
18.240
17.717
0.080
910.1 Pos 19
$2340
$2,925
$2,486

Dimensions per ASTM E2734/E2734M - 10; Licensed to Thomas Kristy, ANSI Order X_354097

Bostec #
DN Sizes (metric)
OD
ID
Thickness
Standards
Copper OSF Annealed
Nickel 200/201 Annealed
Aluminum 1050 Annealed
1
DN10
13.31
8.50
2.00
ASTM
$28.65
$35.82
$30.45
2
DN16
21.29
16.30
2.00
Pos 1/ASTM
$43.99
$54.99
$46.74
3
DN16
21.30
16.20
2.00
$43.99
$54.99
$46.74
4
DN25
32.77
25.70
2.00
ASTM
$60.55
$75.69
$64.34
5
DN25
32.77
25.654
2.00
$60.55
$75.69
$64.34
6
DN25
32.90
25.40
2.00
$60.55
$75.69
$64.34
7
DN35
48.10
36.80
2.00
Pos 2
$95
$119
$101
8
DN40
48.13
38.90
2.00
ASTM
$95
$119
$101
9
DN40
48.20
39.00
2.00
$95
$119
$101
10
DN50
61.60
51.20
2.00
ASTM
$136
$169
$144
11
DN63
82.50
61.00
2.00
$195
$243
$207
12
DN63
82.40
63.60
2.00
Pos 3
$195
$243
$207
13
DN63
82.40
66.30
2.00
Pos 4
$195
$243
$207
14
DN63
82.37
71.50
2.00
ASTM
$195
$243
$207
15
DN63
82.30
64.63
2.240
$240
$300
$255
16
DN75
91.39
76.58
2.00
ASTM
$219
$274
$233
17
DN100
120.40
63.70
2.00
Pos 5
$255
$319
$271
18
DN100
120.47
101.80
2.00
Pos 6/ASTM
$255
$319
$271
19
DN100
120.40
80.60
2.00
Pos 7
$255
$319
$271
20
DN100
120.40
60.70
2.00
Pos 8
$255
$319
$271
21
DN100
120.60
101.80
2.00
$255
$319
$271
22
DN125
141.43
127.30
2.00
ASTM
$347
$434
$369
23
DN150
171.30
152.40
2.00
Pos 9
$395
$494
$420
24
DN150
171.27
152.70
2.00
ASTM
$395
$494
$420
25
DN150
171.30
101.70
2.00
Pos 10
$395
$494
$420
26
DN150
171.30
131.70
2.00
Pos 11
$395
$494
$420
27
DN160
179.90
160.00
2.00
Pos 12
$486
$607
$516
28
DN200
222.10
203.40
2.00
Pos 13
$572
$715
$607
29
DN200
222.07
203.50
2.00
ASTM
$572
$715
$607
30
DN235
254.80
235.00
2.00
Pos 14
$587
$735
$624
31
DN250
273.00
251.00
2.00
$1040
$1,300
$1,105
32
DN250
273.02
254.20
2.00
ASTM
$1040
$1,300
$1,105
33
DN250
273.00
259.60
2.00
Pos 15
$1047
$1,309
$1,113
34
285.01
266.70
2.00
ASTM
$1262
$1,578
$1,341
35
DN273
288.00
272.00
2.00
Pos 16
$1262
$1,578
$1,341
36
294.36
275.80
2.00
ASTM
$1262
$1,578
$1,341
37
313.18
300.10
2.00
ASTM
$1406
$1,758
$1,494
38
321.01
305.20
2.00
Pos 17/ASTM
$1406
$1,758
$1,494
39
DN300
321.20
305.00
2.00
$1406
$1,758
$1,494
40
326.21
307.50
2.00
ASTM
$1406
$1,758
$1,494
41
376.83
358.30
2.00
ASTM
$1613
$2,016
$1,714
42
419.13
401.50
2.00
ASTM
$1733
$2,166
$1,841
43
DN400
419.80
404.00
2.00
Pos 18
$1733
$2,166
$1,841
44
424.23
405.60
2.00
ASTM
$1733
$2,166
$1,841
45
DN450
463.30
450.00
2.00
Pos 19/ASTM
$2340
$2,925
$2,486

Dimensions per ASTM E2734/E2734M - 10; Licensed to Thomas Kristy, ANSI Order X_354097

Full section cutaway assembly of two CF flanges crushing a CF gasket to completion and demonstrating that the HiRim® raised perimeter sits without interference in the free space of the gland.

Most Sizes in Stock for Same-Day Shipment

HiRim® CF Gaskets: A Radically Better CF Gasket, Designed for Super-UHV

Bostec Conflat (CF) gaskets are precision machined so they fit properly and are 100% reliable. They won’t contaminate your processes with unwanted burrs, abrasive contaminants or manufacturing debris. ID edge transitions are smooth to minimize entrapped particles and the flat (mating) surfaces are machined with a precise circular ring pattern, (flat to 6Ra,) which helps the knife edge seat into the gasket for a perfect seal.

Tolerances are held to tenths and all surfaces are “as-machined”—not polished or otherwise modified post-machining. Abrasives are not used. Our inspection process ensures no radial scratches are visible at 10X magnification and the gaskets are free from inclusions and other blemishes. In short, these are the finest CF gaskets manufactured anywhere!

Full section cutaway assembly of two CF flanges crushing a CF gasket to completion and demonstrating that the HiRim® raised perimeter sits without interference in the free space of the gland.

HiRim CF Gaskets Outperform Conventional CF Gaskets

Full section cutaway assembly of a two CF flanges crushing a CF gasket to completion and demonstrating that the HiRim raised perimeter sits without interference in the free space of the gland..
  • Self-protecting—won’t scratch
  • Easy to handle in production environments
  • Self-centering
  • Easy to install and remove
  • Directly interchangeable—fits all CF flanges
  • Guaranteed 1 x 10-11 leak rate
  • 100% reliable—100% yield, guaranteed!

The highest quality CF gaskets manufactured anywhere, bar none!

 

HiRim® CF Gasket Advantages

Interchangeable with Conventional CF and DN Gaskets

HiRim gaskets are self-protecting, easy to install and remove, self-centering and dimensionally identical to conventional CF gaskets. Drop them directly into your existing flanges—no alterations necessary!

HiRim gaskets are precision machined so they fit properly and are 100% reliable. They won’t contaminate your processes with unwanted burrs, abrasive contaminents or manufacturing debris. ID edge transitions are smooth to minimize entrapped particles and the flat (mating) surfaces are machined with a precise circular ring pattern, (flat to 6Ra,) which helps the knife edge seat into the gasket for a perfect seal. Tolerances are held to tenths and all surfaces are “as-machined”—not polished or otherwise modified post-machining. Abrasives are not used. Our inspection process ensures no radial scratches are visible at 10X magnification and the gaskets are free from inclusions and other blemishes. In short, these are the finest gaskets manufactured anywhere!

HiRim CF gaskets are a proprietary development of Bostec Engineering, first released in 2016 conforming to SEMI F19 and ASTM B46.1.

Full section cutaway assembly of a two CF flanges and conventional CF gaskets compared to HiRim CF gaskets showing their interchangeability.

Self-protecting – won’t scratch.

Slide them across a table or drop them on the floor; the raised edge keeps the gasket surface safe from scratches or damage.

Easier to install and remove.

Qualification testing of Bostec HiRim CF gaskets at CERN showing HiRims are easier to remove than standard CF gaskets.

Easy placement in vertical assemblies.

Exploded view of Bostec HiRim CF gaskets showing that the raised perimeter does not obstruct flange closure and that they are easier to install in vertical assemblies.
Full cross section showing assembly progression of HiRim CF gaskets.

Bostec CF Gaskets are Precision Machined – Not Stamped

Most components in any modern UHV process are precision machined to tight tolerances with highly polished surface finishes. Your gaskets should be no different! Precision gaskets fit properly, are 100% reliable and do not contaminate with unwanted burrs, abrasive contaminants or manufacturing debris.

Bostec H-Seals are machined on all surfaces and are completely free of burrs. Gasket faces have precise machining grooves in an annular ring pattern to ensure the knife edge seats into the gasket.

Surfaces are less than Ra 0.6 (circular) and delivered “as-machined”—not polished or otherwise modified post- machining. No abrasives are used.

Our inpection process ensures no radial scratches are visible at 10X magnification, and the gaskets are free from surface inclusions and other blemishes.

In the world of super-UHV, the cost of a single failed gasket is 1000X the cost of the gasket itself. It makes no sense to use inferior gaskets and risk failure.

Detailed cut away of HiRim CF gasket assembly showing the gasket in mid-air where knife edge indentation is fully visible.

Common Problems with Stamped CF Gaskets

Conflat flanges and gaskets were developed in the early 1960’s before the rigors of ultra-pure and super-UHV were commonplace. The original design was a simple flat gasket punched from sheets of copper, keeping costs low. However, stamping is a crude process, leaving burrs, shear-tear and rolled-over edges on the gaskets. These defects violate ultra-pure standards specifying smooth surfaces and fully swept flow paths to minimize entrapped particles.

To remove jagged edges and burrs, stamped gaskets are typically tumbled in an abrasive medium and the medium itself becomes an embedded contaminant in the gasket surface. Tumbling simply rolls burrs over, as opposed to removing them. This traps even more contaminants to polute processes.

Stamped gaskets are produced from rolled sheet material that is, by nature, uneven and micro-pitted from the rollers. Thus, the finished gasket has a contaminated, micro-pitted surface that can itself trap particles.

Stamping is an imprecise process. CF design clearances are tight—only 0.0035″/0.09 side to side. Shear tear and edge rollover make for sloppy tolerances so CF gaskets don’t always fit properly.

In contrast, Bostec gaskets are precision machined to high tolerances with perfect surface finishes in order to be 100% reliable.

Bostec CF Gaskets Magnified

20X DN63 Copper
30X DN63 Ni 200/201
*20 & 30X magnification of Bostec CF gaskets

Qualifying Bostec CF and HiRim Gaskets at CERN

Qualification testing of Bostec HiRim CF gaskets, testing in vacuum assemblies reduced to 2.5 x 10 -10 torr, note vacuum leak detector readings.

Easy to Order by Intuitive Part Names

Bostec’s extensive offering in vacuum gaskets features an intuitive part numbering format, allowing the customer to identify the product by the characters contained within the part number.