ALFA Engineering s.r.l. -GASKETS

For over 10 years Alfa Engineering s.r.l. has been a technology leader in the field of high quality sealing and isolating products used to guarantee the safe flow of fluids passing through pipeline transmission, distribution and process piping systems.
An installed base of thousands upon thousands of gaskets and flange isolation kits, effectively sealing
and maintaining the integrity of corrosion mitigation programs everywhere, confirms the effectiveness and reliability of the Alfa system. In fact ,Alfa flange isolation products are relied upon for applications subject to the most severe conditions (both internal and environmental), for specialized or exotic fluids or for applications subject to extreme temperature and pressure fluctuations.
Flange isolation products include a wide selection of isolating/sealing gaskets along with a variety of sleeves and washers. For maximum flexibility, components may be ordered separately or as part of complete flange isolation kits.

All Alfa facilities are ISO 9001 certified with extensive quality control procedures to insure total compliance with productperformance and reliability standards.
Additions to the Alfa line of flange isolation products are the LineBacker ZeroTM sealing gasket, LineBacker 250TM sealing gasket and LineBacker 251TM sealing gasket, all designed to address problems associated with asbestos substitutes and fugitive emissions. This site includes suggested flange isolation material compatibility charts as well as technical specifications and an ordering/work sheet.

Type “E” Gaskets extend to the outside diameter of the flange.
They feature precision located bolt holes, to automatically center the gasket,and offer maximum protection against foreign material “shorting-out” the flange.
Type “E” gaskets may be ordered in any one of the following configurations:
• LineBacker® Sealing Gaskets
• GasketSeal® Sealing Gaskets
• Neoprene Faced Phenolic Gaskets
• Plain Phenolic Gaskets
• Red Devil Gaskets
• Yellow Jacket Gaskets
• Garlock Gaskets
• Teflon® Gaskets

When configured as a LineBacker® Sealing Gasket, the sealing element may be positioned anywhere between the I.D. of the gasket and I.D. of the bolt circle.

Type “F” Gaskets are made to fit within the bolt hole circle of the flange. The O.D. of the gasket extends out to the I.D. of the bolt hole circle for good protection against foreign material “shorting-out” the flange. When configured as a LineBacker® Sealing Gasket, the sealing element may be positioned anythere between the I.D. and O.D. of the gasket.
Type “F” gaskets may be ordered in any one of the following configurations:
• LineBacker® Sealing Gaskets
• GasketSeal® Sealing Gaskets
• Neoprene Faced Phenolic Gaskets
• Plain Phenolic Gaskets
• Red Devil Gaskets
• Yellow Jacket Gaskets
• Garlock Gaskets
• Teflon® Gaskets

When configured as a LineBacker® Sealing Gasket , the sealing element may be positioned anywhere between the I.D. of the gasket and I.D. of the bolt circle.

GasketSeal® Sealing Gaskets

GasketSeal® sealing gaskets are considered one of the most effective methods for sealing and isolating flanges of all types. The gasket consists of two molded semi “O” rings (with precise crown to void ratio) mounted in grooves on opposite sides of an isolating retainer. While maintaining all the advantages of a full “O” ring seal, the semi “O” ring seal eliminates the need for a sealing groove in the flange face to reduce problems associated with alignment. GasketSeal® sealing gaskets incorporate near zero “m” and “y” factors that make it possible to effect a positive seal without tremendous bolt loads required with flat gaskets. GasketSeal® sealing gaskets are available in a wide variety of retainer and sealing element combinations for matching gaskets to service and environmental conditions. Refer to the chart for the GasketSeal® sealing gasket temperature ranges and material compatibilities.

LineBacker® Sealing Gaskets

LineBacker® sealing gaskets utilize a patented rectangular sealing element, referred to as a “quad” ring, in combination with a unique groove design to effectively seal and isolate flanges of all types.
With the unique “quad” ring design, elastic memory is provided for elastomers not normally associated with this characteristic. Materials such as polyimide, TFE (Teflon) and vinyl may therefore be used as sealing elements which dramatically increases the options available for matching gasket materials to service and environmental conditions.This greater variety of materials also provides excellent termperature and chemical range compatability. LineBacker® sealing gaskets incorporate near zero “m” and “y” factors that make it possible to effect a positive seal without tremendous bolt loads that are required with flat gaskets. Refer to chart for LineBacker® sealing gasket temperature range and material compatibilities.

Neoprene Faced Phenolic Gaskets

Neoprene Faced Phenolic gaskets have been used as standard “flat” isolating gaskets in the oil and gas industries for many years. Soft neoprene rubber sheets are factory applied to both sides of a laminated phenolic retainer providing an effective sealing surface. The temperature limit of these gaskets is approximately +175º F. (80º C.).

Note: Due to improved sealing characteristics and retainer/seal element options, LineBacker or GasketSeal sealing gaskets should be considered in lieu of neoprene faced phenolic gaskets whenever possible.

Flat Gaskets

Flat gaskets are used in special applications such as elevated temperatures that often require materials such as Red Devil or Yellow Jacket. Please contact a ALFA representative for additional information on available options.

Medium

Retainer

Seal

Sleeve

Washer

Temp. Range °F

Temp. Range °C

Acetone

Phenolic

EPDM

Mylar

Phenolic

+32 to +80

0 to +27

Air

G-10

Nitrile

Mylar

Phenolic

-65 to +225

-54 to +107

Ammonia Dry

G-10

Teflon

Mylar

G-10

-65 to +220

-54 to +104

Ammonia (Wet)***

G-10

Teflon

Mylar

G-10

+32 to +100

0 to +38

Bleach

G-10

Teflon

Mylar

G-10

+32 to +80

0 to +27

Butylene (Butidiene)

G-10

Teflon

G-10

+32 to +100

0 to +38

Carbon Dioxide

G-10

Nitrile

Mylar

G-10

+32 to +150

0 to +66

Caustic Soda (NaOH)

G-10

Teflon

Mylar

G-10

-65 to +225

-54 to +107

Cryogenic

G-10

Teflon

G-10

-300 to +280

-184 to +138

Ethanol

G-10

Nitrile

Mylar

G-10

+32 to +100

0 to +38

Ethylene (Ethene)

G-10

Teflon

G-10

+32 to +80

0 to +27

Fuel Oil

G-10

Viton

Mylar

G-10

-20 to +280

-29 to +138

Gas, Natural

Phenolic

Nitrile

Mylar

Phenolic

-65 to +220

-54 to +104

Gas, Sour

Phenolic

Viton

Mylar

Phenolic

-20 to +220

-29 to +104

Gasoline

G-10

Teflon

Mylar

G-10

-65 to +225

-54 to +107

Hydrogen

G-10

Nitrile

Mylar

G-10

-65 to +250

-54 to +121

Jet Fuel

G-10

Viton

Mylar

G-10

-20 to +225

-29 to +107

LNG

G-11

Teflon

G-10

-300 to +100

-184 to +38

Mercaptan

G-10

Teflon

G-10

-20 to +80

-29 to +27

Methanol

G-10

Teflon

Mylar

G-10

+32 to +100

0 to +38

MTBE

G-10

Special Nitrile

G-10

+32 to +80

0 to +27

Nitrogen

Phenolic

Nitrile

Mylar

Phenolic

-65 to +220

-54 to +104

Oil, Crude

G-10

Viton

Mylar

G-10

-20 to +280

-29 to +138

Oxygen**

G-10

Teflon

G-10

-65 to +250

-54 to +121

Pentane

G-10

Teflon

G-10

+32 to +80

0 to +27

Propane

G-10

Nitrileor Teflon

G-10

+32 to +80

0 to +27

Propylene

G-10

Viton

G-10

+32 to +80

0 to +27

Sewage

G-10

Viton

Mylar

G-10

-20 to +280

-29 to +138

Spent Liquor

G-10

Teflon

G-10

+32 to +100

0 to +38

Steam*

G-7*

Teflon

Nomex

G-7*

To +450

To +232

Steam

G-3

Teflon

Nomex

G-3

To +392

To +200

Steam*

Yellow Jacket

No Seal

Nomex

G-7*or (G-3)

to +450*or (+392)

to +268* or (+200)

Styrene

G-10

Teflon

G-10

+32 to +80

0 to +27

Sulphur (Molten)

G-10

Teflon

G-10

+32 to +280

0 to +138

Tolulene

G-10

Viton or Teflon

G-10

+32 to +150

0 to +66

Water (hot)

G-10

Nitrile

Mylar

G-10

+175 to +250

+79 to +121

Water (Potable)

G-10

Nitrile

Mylar

G-10 or Phenolic

+32 to +250

0 to +121

Water (Sea)

G-10

Nitrile

Mylar

G-10 or Phenolic

+32 to +250

0 to +121

White Liquor

G-10

Teflon

G-10

+80 to +280

+27 to +138

* = G-7 material should not be used with hydrocarbons, not even trace amounts.

** = These are organic materials that will feed a fire if a leak occurs and an ignition source exists.

*** = Ammonia (wet) - Data to +100°F (+38°C) only (same materials as dry).

Isolating Sleeves

Isolating Washers - Standard 1/8” Thick

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

Isolating washers 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. ALFA isolating washers are available for bolt sizes from 1/2” (12.7mm) through 3-1/2” (88.9mm) and are made to fit over the isolating sleeves.

One-piece Sleeves and Washers

Steel Washers

Molded from acetal resin and available for bolt diameters from 1/2” to 1-1/2” (12.7 to 38.1mm), one-piece sleeves and washers are structurally tough but limited to applications where the flange temperature does not exceed +180ºF (+80°C) and compressive loads do not exceed 18,000 ALFA.
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.

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.

ASTM

Test Method

Polyethylene

Mylar

Nomex

Phenolic

Silicone Glass G-7*

Epoxy Glass G -10

Epoxy Glass G-11

One-piece Sleeve & Washer

D149

Dielectric Strength
Volts/Mil (Short Time)

400

4000

400

350

400

1,200

D695

Compressive Strength psi

N/A

18,000

D229

Water Absorption
%

0.01

0.8

N/A

1.6

0.10

0.22

Operating Temp.
°F

-30 to +180

-75 to +300

-65 to +450

-20 to +225

Cryogenic to +450

Cryogenic to +280

Cryogenic to +320

-30 to +180

°C

-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

1,400

Cut Through Resistance
ft-lbs.

1,800

3,500

4,000

No Test

16,000

No Test

3,400

* = G-7 material should not be used with hydrocarbons, not even trace amounts.

ASTM

Test Method

Glass Clad Phenolic

Hi-Temp Phenolic

Silicone Glass G-7*

Epoxy Glass G -10

Epoxy Glass G-11

One-piece Sleeve & Washer

D149

Dielectric Strength
Volts/Mil (Short Time)

500

550

350-400

550

1,200

D695

Compressive Strength psi

33,000

50,000

40,000

50,000

50 - 80,000

18,000

D229

Water Absorption
%

1.6

0.7

0.07

0.10

0.22

Operating Temp.
°F

65 to +300

-65 to +392

Cryogenic to +450

Cryogenic to +280

Cryogenic to +350

-30 to +180

°C

-54 to +149

-54 to +200

Cryogenic to +232

Cryogenic to+138

Cryogenic to +177

-34 to +82

* = G-7 material should not be used with hydrocarbons, not even trace amounts.

Flange Isolation Kits

Flange isolation kits are available for all flange sizes,types, pressure ratings and materials. Each kit isindividually and securely packed in a reinforcedcorrugated 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

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 Method

Plain Phenolic

Neo-Faced Phenolic

G-3 Hi-Temp Phenolic

G-7* Silicone / Glass

G-10 Epoxy/ Glass

G-11 Epoxy/
Glass

D149

Dielectric Strength
Volts/Mil (Short Time)

500

550

350-400

550

D695

Compressive Strength
(psi)

25,000

50,000

40,000

50,000

50,000+

D229

Water Absorbtion
(%)

1.6

0.7

0.07

0.10

D257

Insulation Resistance
Meg Ohms

40,000

46,000

2,500

200,000

D790

Flexural Strength
psi

22,500

60,000

27,000

60,000

75,000+

D785

Hardness
Rockwell “M”

115

105

115

D256

IZOD Impact Strength
Ft-Lbs/Inch

1.2

12.0

8.0

14.0

12.0

D638

Tensile Strength
psi

20,000

42,000

25,000

45,000

43,000

D732

Shear Strength
psi

10,000

18,000

20,000

22,000

Temperature Range
Degrees F

-65 to +220

-65 to +175

-65 to +392

Cryogenic to +450

Cryogenic to +280

Cryogenic to +349

Temperature Range
Degrees C

-54 to +104

-54 to +79

-54 to +200

Cryogenic to +232

Cryogenic to +138

Cryogenic to +176

* = G-7 Material should not be used with hydrocarbons, not even trace amounts.

Nitrile

Viton

Teflon

Neoprene

EPDM

Degrees Farenheit

-65 to +250

-20 to +350

Cryogenic to +450

-40 to +175

-65 to +300

Degrees Celsius

-54 to +121

-29 to +177

Cryogenic to +232

-40 to +79

-54 to +149

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

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 rotected 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.

General/Economical

Flange Isolation Kit Specification

Materials for flange isolation kits on pipes containing water, aqueous fluids or natural gas (up to 221ºF, 105ºC) 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.

Top of the Line

Flange Isolation Kit Specification

Materials for flange isolation kits on pipes containing natural gas, oil and aqueous fluids (up to 280ºF, 138ºC) 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 quadring seal shall be pressure energized. The G-10 retainer shall have a 550 volts/mil dielectric strength and a minimum 50,000 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 G-10 sleeve (extending half way into both steel washers) for each flange bolt. The G-10 shall be a1/32 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.

Warranty

All products are warranted against failure caused by manufacturing defects for a period of one year. Any product found to be so defective and returned within one year from date of shipment will be replaced without charge.
The above warranty is made in lieu of, and we disclaim, any and all other warranties, expressed or implied, including the warranties of merchantability and fitness for a particular purpose, and buyer agrees to accept the products without any such warranties.
We hereby disclaim any obligation or liability for consequential damages, labor costs or any other claims or liabilities of any kind whatsoever.