Description
Lamons sleeve and washer sets, when combined with our sealing/isolation gaskets, complete a Flange Isolation Kit. For a successful flange isolation kit, it is critical to use the appropriate material for your application. Compressive strength, flexural strength and cut- through resistance are key material physical properties that should not be overlooked.
Washer Design Specifications:
Available for bolt sizes = 0.50" (12.70mm) to 2.75" (69.85mm)
Steel back-up washers need to be supplied with the same O.D. and I.D. as the isolation washer. This graphic illustrates a steel back-up washer and phenolic isolation washer with different O.D. and I.D. sizing.
The compressive load from the steel back-up washer is not equally distributed over the phenolic washer, causing the phenolic washer to crack. If this occurs, the gasket may not receive proper load and electrical isolation will most likely be lost.
![]() |
Single Washer Set (per bolt/stud)
|
||
|
![]() |
Double Washer Set (per bolt/stud)
|
||
|
Specifications
ASTM |
Test Method |
Mylar |
G10 |
Nomex |
D149 |
Dielectric Strength, Volts/Mil. Short Time |
4,000 |
750-800 |
600 |
D570 |
Water Absorption (%) |
0.80 |
0.50 |
7.00 |
D790 |
Flexural Strength (psi) |
13,000 |
65,000 |
18,000 |
|
Cut Through Resistance |
Low |
High |
Low |
|
Temperature - Operating |
-75°F (-59³C) to +302°F (+150°C) |
Cryogenic to +302°F (+150°C) |
+65°F (-54°C) to +450°F (+232°C) |
ASTM |
Test Method |
G10 |
G11 |
Phenolic |
Steel (HC) |
G3 |
D695 |
Compressive Strength (psi) |
65,000 |
63,000 |
25,000 |
65,000 |
55,000 |
D149 |
Dielectric Strength, Volts/Mil. Short Time |
750-800 |
550 |
500 |
800 |
500 |
D570 |
Water Absorption (%) |
0.05 |
0.10 |
1.60 |
0.30 |
1.00 |
|
Temperature - Operating |
Cryogenic to +302°F (+150°C) |
-100°F (+73°C) to +392°F (+200°C) |
+65°F (-54°C) to +220°F (+104°C) |
Cryogenic to +302°F (+150°C) |
-100°F (-73°C) to +392°F (+200°C) |
Lamons isolating sleeves are designed/manufactured to fit over standard size flange fasteners (bolts/studs) with standard size bolt holes.
SLEEVE DESIGN SPECIFICATIONS:
ISOLATING WASHERS (G10, G11, PHENOLIC, G3, STEEL HC)Lamons isolating washers are designed/manufactured to have positive isolation characteristics and provide excellent compressive strength.
STEEL WASHERS/HC WASHERSHC - Hardened 1050 steel with proprietary isolation coating has excellent dielectric properties and withstands UV. It is also abrasion resistant and will not break under compressive loads. They combine the technical features of steel into an isolating washer.
STEEL BACK-UP WASHERS/ZP WASHERSZP - Zinc Plated 1050 carbon steel washers are used as our standard steel back-up washer when packaged in kits with retainer washers and isolating sleeve material. |
|
Lamons Standard Packaged Sleeve/Washer Sets. These sets have been selected from specification data as determined by industry usage over the years for flange isolation and cathodic protection. Single/Double choice is indicated after Packaged Set choice: S = Single, D = Double
![]() |
E = Economy |
|
![]() |
S = Standard |
|
![]() |
T = High Temperature |
|
![]() |
V = Value |
|
![]() |
Model T11 |
|
![]() |
Model V11 |
|
![]() |
Model M |
|
![]() |
XX = Customer Specified |
Lamons will provide washers in bulk quantities of 100. Sleeve material may also be purchased in bulk and is shipped and supplied in the lengths shown in the chart.
NOTE: It is suggested that bulk sleeve material be cut in a controlled environment. If cutting in the field, installers should be well versed in determining appropriate sleeve length and have experience with cutting.
|
![]() |
![]() |
![]() |
![]() |
Cut Through Resistance and Flexural Strength are critical in selecting sleeve material for your flange isolation kit application. As nominal pipe size increases, as well as ANSI or API class, the fasteners (bolts/studs) increase in size and torque is generally higher. Larger and heavier stud bolts with higher torque loads can more easily cut through material during installation. This is more likely to occur if flanges and bolt holes are not in perfect alignment.
Use or specify G10 sleeve material as a standard for all applications. Or consider G10 sleeves for applications of Nominal Pipe Size 12-inch and larger and ANSI pressure class 600# and higher.
The above graphic shows an example of a Mylar Sleeve being shredded; the bolt threads are cutting through the sleeve while misalignment is cracking the sleeve. Electrical isolation can be lost if your sleeve material does not have excellent cut through resistance. Isolation tests will fail and installation costs will increase significantly.
A full length sleeve passes entirely through both flanges, both isolation washers, and half way through the steel back-up washers on each side.
Note: When using mis-matched flanges or flanges with different widths take precise measurements and account for the additional length needed to pass through washer set configuration. If you are unsure of proper length please consult the factory engineering support.
Bolts/Studs with smooth shank portions should not have a diameter greater than the maximum diameter of the threads. If this is the case, the sleeve may not fit over the shank portion. The adjacent graphic shows shank/threads sized differently, which will cause problems during field installation.