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Flange Isolation Kits, by GPT

Available for all flange sizes, types, pressure ratings and materials.
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GPT Flange Isolation Kits

GPT Flange isolation kits are available for all flange sizes, types, pressure ratings and materials. Each kit is individually and securely packed in a reinforced corrugated cardboard box, which is clearly labeled as to its contents for convenience in warehousing and field use. Very large diameter gaskets are packaged separately from the sleeves and washers for convenience in storing and handling.
Each gasket is labeled with:

  • Materials (Retainer Material or Retainer / Seal Element Combination)
  • Pipe Size
  • ANSI Class
  • Date of Manufacture
  • Type Flange (Weld Neck or Slip-on)

Sleeves and washers are enclosed in a strong polyethylene bag to eliminate any possibility of loss. A chart showing the recommended sequence for tightening flange bolts is also included with each kit, as well as with each individual gasket.
Common LineBacker® & GasketSeal® Sealing Gasket Physical Properties
 
ASTM
Test		 Property Plain
Phenolic		 Neo-faced
Phenolic		 Hi-temp
Phenolic
G-3		 Silicone
Glass
G-7*		 Epoxy
Glass
G-10		 Epoxy
Glass
G-11
D149

Dielectric strengths,
Volts/mil

 500 500 550 350-400 550 550
D695

Compressive strength,
psi

 25,000 25,000 50,000 40,000 50,000 50,000+
D229

Water absorption, %

 1.6 1.6 0.7 0.07 0.10 0.10
D257

Insulating Resistance,
Meg Ohms

 40,000 40,000 46,000 2,500 200,000 200,000
D790

Flexural strength, psi

 22,500 22,500 60,000 27,000 60,000 75,000+
D785

Hardness Rockwell "M"

 85 85 115 105 115 115
D256

IZOD Impact,
Strength ft-lbs/inch

 1.2 1.2 12.0 8.0 14.0 12.0
D732

Shear strength, psi

 10,000 10,000 18,000 20,000 22,000 22,000
D229

Operating temp, ºF

 -65 to
+220		 -65 to
+175		 -65 to
+392		 Cryogenic
to +450		 Cryogenic
to +280		 Cryogenic
to +350

Operating temp, ºC

 -54 to
+104		 -54 to
+79		 -54 to
+200		 -Cryogenic
to +232		 Cryogenic
to +138		 Cryogenic
to +177
* = G-7 material should not be used with hydrocarbons, not even trace amounts.

 

Seal Element Temperature Limits
Nitrile Viton Teflon Neoprene EPDM
-65 to +250°F -20 to +350°F Cryogenic to +450°F -40 to +175°F -65 to +300°F
-54 to +121°C -29 to +177°C Cryogenic to +232°C -40 to +79°C -54 to +149°C

Consider both retainer and seal element temperature limits together
for GasketSeal® and LineBacker® Sealing Gaskets.

 

Flange Isolation Washer Sets
    
Single Washer Set

Single washer set flange isolation kits include the following items for each bolt:

  • One - 1/8" thick steel washer
  • One - Isolating washer
  • One - Isolating sleeve

Application Considerations:
In buried applications, single washer configurations may be used to allow the Cathodic Protection (CP) current to reach the nuts and bolts. If desired, nuts on the opposite side of the cathodically protected flange may be included as part of the CP system.
Double Washer Set

Double washer set flange isolation kits include the following components for each bolt:

  • Two - 1/8" thick steel washers
  • Two - Isolating washers
  • One - Full length isolating sleeve

Application Considerations:
Double washer configurations may be used for added protection against the possibility of "shorting out" the nuts and bolts. In addition, double washer sets electrically isolate the nuts and bolts from both flanges.
One-Piece Sleeve and Washer Sets

One-piece sleeve and washer set flange isolation kits include the following items for each bolt:

  • Two - 1/8" thick steel washers
  • One - One-piece Isolating sleeve

Application Considerations:
Easier to install, one-piece sleeves also allow the inspector a visual indication of sleeve usage. Due to the relatively low compressive strength of this material, its use is not recommended for high pressure or large diameter flanges that require high torque loads.

 

Typical Specifications

General / Economical

Flange Isolation Kit Specification
Materials for flange isolation kits on pipes containing water, aqueous fluids or natural gas (up to 220°F, 104°C) shall consist of the following components:

Isolating and Sealing Gasket
One full-faced isolating and sealing gasket, LineBacker Sealing Gasket - Type "E", 1/8" thick, phenolic retainer containing a precision tapered groove to accommodate the controlled compression of a nitrile quad-ring sealing element. Sealing element placement shall accommodate either flat, raised or RTJ face flanges. The quad-ring seal shall be pressure energized. The phenolic retainer shall have a 500 volts/mil dielectric strength and a minimum 25,000 psi compressive strength. The full faced flange isolating gasket shall be 1/8" less in I.D. than the I.D. of the flange in which it is installed.

Full Length Bolt Isolating Sleeves
One full length Mylar sleeve (extending half way into both steel washers) for each flange bolt. The Mylar shall be a 1/32 inch thick tube with a 4000 volts/mil dielectric strength and water absorption of 0.8% or less.

Washers
Two, 1/8 inch thick, glass clad phenolic isolating washers for each bolt. Their compressive strength shall be 33,000 psi, dielectric strength 500 volts/mil and water absorption 1.6% or less.
Two, 1/8 inch thick steel washers for each bolt. The I.D. of all washers shall fit over the isolating sleeve and the steel and isolating washers shall have the same I.D. and O.D.

Quality
Flange isolating kits shall be manufactured at a facility that has a registered ISO 9001:2000 Quality Management System. Submittals shall include copy of valid registration.

Top of the Line

Flange Isolation Kit Specification
Materials for flange isolation kits on pipes containing natural gas, oil and aqueous fluids (up to 280°F, 138°C) shall consist of the following components:

Isolating and Sealing Gasket
One full faced isolating and sealing gasket, LineBacker Sealing Gasket - Type "E", 1/8" thick, G-10 retainer containing a precision tapered groove to accommodate the controlled compression of a Teflon (or Viton) quad-ring sealing element. Sealing element placement shall accommodate either flat, raised face or RTJ flanges. The quad-ring seal shall be pressure energized. The G-10 retainer shall have a 550 volts/mil dielectric strength and a mini-mum 50,000 psi compressive strength. The full faced flange isolating gasket shall be 1/8" less in 1.D. than the I.D. of the flange in which it is installed.

Full Length Bolt Isolating Sleeves
One full length G-10 sleeve (extending halfway into both steel washers) for each flange bolt. The G-10 shall be a 1/32 inch thick tube with a 400 volts/mil dielectric strength and water absorption of 0.10% or less.

Washers
Two, 1/8 inch thick, G-10 isolating washers for each bolt. Their compressive strength shall be 50,000 psi, dielectric strength 550 volts/mil and water absorption 0.10% or less. Two, 1/8 inch thick zinc plated, hot rolled steel washers for each bolt. The I.D. of all washers shall fit over the isolating sleeve and both the steel and isolating washers shall have a same I.D. and O.D.

Quality
Flange isolating kits shall be manufactured at a facility that has a registered ISO ISO 9001:2000 Quality Management System. Submittals shall include copy of valid registration.