Serrated Washers

Available in Stainless Steel as standard, these "shake-proof" Serrated Washers fitted internally to the equipment and before a locknut act as an anti-vibration device to prevent the cable gland or other cable entry device and locknut arrangement from inadvertently loosening in service.

Note: Alternative materials are also available. Please refer to Table "E" of the Ordering References page detailed below. e.g. 20SW4 for M20 Stainless Steel Serrated Washer, 050NPTSW4 for 1/2" NPT Stainless Steel Serrated Washer.

Metric Serrated Washers Table

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Metric - Serrated Washers
Ordering Reference
(Plated Steel)
Reference Diameter Minimum Thickness External Diameter
16SW M16 3.7 25.5
20SW M20 3.9 32.5
25SW M25 3.9 40.0
32SW M32 3.9 43.5
40SW M40 3.9 64.5
50SW M50 3.9 80.0
63SW M63 3.9 100.0
75SW M75 3.9 112.0
90SW M90 4.1 135.0
100SW M100 4.1 144.6
150SW M115 4.1 159.0
Dimensions are displayed in millimetres unless otherwise stated


Ordering Reference (Brass) Reference Diameter "A" Minimum Thickness External Diameter "B"
16SW M16 0.144 0.995
20SW M20 0.152 1.268
25SW M25 0.152 1.560
32SW M32 0.152 1.697
40SW M40 0.152 2.516
50SW M50 0.152 3.120
63SW M63 0.152 3.900
75SW M75 0.152 4.368
90SW M90 0.159 5.265
100SW M100 0.159 5.639
115SW M115 0.159 6.201
All dimensions are in inches unless otherwise stated


NPT Serrated Washers Table

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NPT - Serrated Washers
Ordering Reference (Plated Steel) Reference Diameter Minimum Thickness External Diameter
050NPTSW 1/2" NPT 0.152 1.268
075NPTSW 3/4" NPT 0.152 1.560
100NPTSW 1" NPT 0.152 1.697
125NPTSW 1-1/4" NPT 0.152 2.516
150NPTSW 1-1/2" NPT 0.152 3.120
200NPTSW 2" NPT 0.152 3.900
250NPTSW 2-1/2" NPT 0.159 4.368
300NPTSW 3" NPT 0.159 5.265
350NPTSW 3-1/2" NPT 0.159 5.639
400NPTSW 4" NPT 0.159 6.201
Dimensions are displayed in Millimetres unless otherwise stated


Ordering Reference (Brass) Reference Diameter "A" Minimum Thickness External Diameter "B"
050NPTSW 1/2" NPT 0.152 1.268
075NPTSW 3/4" NPT 0.152 1.560
100NPTSW 1" NPT 0.152 1.697
125NPTSW 1-1/4" NPT 0.152 2.516
150NPTSW 1-1/2" NPT 0.152 3.120
200NPTSW 2" NPT 0.152 3.900
250NPTSW 2-1/2" NPT 0.152 4.368
300NPTSW 3" NPT 0.159 5.265
350NPTSW 3-1/2" NPT 0.159 5.639
400NPTSW 4" NPT 0.159 6.201
All dimensions are in inches unless otherwise stated


Additional information

CMP WP SerratedWashers_0310 Issue 1