Isolating Sleeves & Washers, by GPT

Isolating sleeves fit over standard size flange bolts. Isolating washers fit over isolating sleeves. Also available: one-piece sleeves & washers.

GPT Isolating Sleeves

Isolating sleeves are available in the following materials:

  • Mylar
  • Polyethylene
  • Phenolic
  • Nomex®
  • G-7 Silicon Glass
  • G-10 Epoxy Glass
  • G-11 Epoxy Glass

Designed to easily fit over standard size flange bolts and studs within standard size bolt holes, GPT isolating sleeves have a wall thickness of 1/32" (0.79 mm) and are used with separate isolating and steel washers. They are available for standard American bolt sizes from 1/2" (12.7 mm) to 3-1/2" (88.9 mm) as well as metric bolt sizes from 12 mm and larger.

GPT Isolating Washers

Isolating washers have a standard thickness of 18" and are available in the following materials:

  • High Strength Glass Clad Phenolic
  • G-3 High Temp. Phenolic
  • G-7 Silicon Glass
  • G-10 Epoxy Glass
  • G-11 Epoxy Glass

Designed to provide tough, positive isolation. GPT isolating washers are available for bolt sizes from 1/2" (12.7 mm) through 3-1/2" (88.9 mm) and are made to fit over the isolating sleeves.

GPT One-piece Sleeves & Washers

Molded from acetal resin and available for bolt diameters from 1/2" to 1-1/2" (12.7 to 38.1 mm), one-piece sleeves and washers are structurally tough but limited to applications where the flange temperature does not exceed +180°F (+80°C) and compressive loads do not exceed 18,000 psi. They are generally used as single washer sets because they're molded to specific lengths and, in many instances, are longer than the thickness of a single flange. A washer centering ring positions the steel washer on the unit properly to avoid uneven pressures on the washers. G-10 one-piece sleeve / washer assemblies are available for additional strength and convenience.

PSI Steel Washers

Steel washers are designed to fit over the isolating sleeve or the retainer ring on the one-piece sleeves and washers. The outside diameter is sized to fit within the bolt facing on ANSI standard flanges. They are made of 1/8" (3.2mm) thick plated hot-rolled steel.


Sleeve Material Physical Properties

ASTM
Test

Property

Polye-
thylene
Mylar Nomex Phenolic Silicone
Glass
G-7*
Epoxy
Glass
G-10
Epoxy
Glass
G-11
1-piece
sleeve &
washer
D149 Volts/mil 400 4000 400 400 350 400 400 1,200
D695 Compressive
strength psi
N/A N/A N/A N/A N/A N/A N/A 18,000
D229 % water
absorption
0.01 0.8 N/A 1.6 0.10 0.10 0.10 0.22
Operating
temp ºF
-30 to
+180
-75 to
+300
-65 to
+450
-20 to
+225
Cryogenic
to +450
Cryogenic
to +280
Cryogenic
to +320
-30 to
+180
Operating
temp ºC
-34 to
+82
-59 to
+149
-54 to
+232
-29 to
+107
Cryogenic
to +232
Cryogenic
to +138
Cryogenic
to +160
-34 to
+82
D790 Flexural
strength psi
7,000 13,000 20,000 16,000 20,000 55,000 55,000 1,400
Cut-thru resis-
tance ft-lbs
1,800 3,500 4,000 No test No test 16,000 No test 3,400
* = G-7 material should not be used with hydrocarbons, not even trace amounts.
 
1/8" Washer Material Physical Properties
ASTM
Test
Property Glass clad
phenolic
Hi-temp
Phenolic
G-3
Silicone
Glass
G-7*
Epoxy
Glass
G-10
Epoxy
Glass
G-11
1-piece
sleeve &
washer
D149 Volts/mil 500 550 350-400 550 550 1,200
D695 Compressive
strength psi
33,000 50,000 40,000 50,000 50,000-
80,000
18,000
D229 % water
absorption
1.6 0.7 0.07 0.10 0.10 0.22
Operating
temp ºF
-65 to
+300ºFº
-65 to
+392ºF
Cryogenic
to +450ºF
Cryogenic
to +280ºF
Cryogenic
to +350ºF
-30 to
+180ºF
Operating
temp ºC
-54 to
+149ºC
-54 to
+200ºC
-Cryogenic
to +232ºC
Cryogenic
to +138ºC
Cryogenic
to +177ºC
-34 to
+82ºC
* = G-7 material should not be used with hydrocarbons, not even trace amounts.