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Custom Radial Seal Rings



Radial seal ring assemblies are used to seal the clearance between a rotating or reciprocating shaft and the stationary housing on many types of machines.

Carbon-graphite radial seal assemblies were developed to help solve serious leakage problems that occur when materials such as leather, plastic, composite or elastomeric materials are utilized in the stuffing box seals installed on industrial blowers, pumps and other turbo machinery. These problems occur because of wear, thermal degradation, chemical attack and dimensional stability problems with elastic seal ring materials.

To accommodate some anticipated movement in a reciprocating or rotating shaft such as thermal expansion or run out, carbon-graphite radial seal rings are normally designed to float with OD clearance within a chamber in the stuffing box. This allows a close clearance seal to be maintained between the OD of the shaft and the ID of the carbon-graphite seal ring. Leakage around the OD of the carbon-graphite seal ring is minimized by using a close clearance between the width of the carbon-graphite seal ring and the width of the metallic seal housing cavity.

There are two types of carbon-graphite radial seal rings. “Close clearance” carbon-graphite seal rings are one piece, solid rings that are made to fit with close clearance on the OD of the rotating or reciprocating shaft. If the shaft is expected to expand because of thermal expansion, the carbon-graphite ring should be shrink-fitted into a metal retaining ring. This affords the carbon graphite/metal assembly the same thermal expansion rate as the shaft. The metal retaining ring shrink fitted around the carbon graphite clearance seal should be of the same metal as the shaft. This allows the close clearance between the shaft OD and carbon-graphite seal ring to be maintained even at high temperatures.

Contacting carbon-graphite seal rings are made from at least three segments and are tensioned onto the shaft with a “garder spring” around the OD of the segments. Usually a set of two rings with mutually off-set joints are placed in each cavity of a stationary, metallic holder. The garder spring holds the segments against the shaft OD with a pressure of about two psi. Multiple sets of segmented carbon-graphite ring can be used to seal gas pressures up to 800 psi.

Sometimes referred to as packing rings, Carbon-graphite radial seals are used to seal both liquid and gases.

The carbon-graphite radial seal rings are manufactured by Metcar and can meet the most stringent customer specifications. Metallized Carbon Corporation’s technical department is available to provide information regarding optimum carbon-graphite materials for specific applications.






Specifications

Material

Over 150 grades of our proprietary carbon/graphite METCAR material are available. Our engineers will select the optimum grade based on application, environment, shaft/housing materials, RPM, etc.

Temperature Rating

-400 to 1000 ºF

Pressure Rating

Up to 800 psi

Size Limit

Up to 60" OD

Applications

Adjustable burners
Aircraft turbine engines

Blenders

Furnace exhaust blowers

Industrial blowers

Mixers

Oil free piston compressors

Screw type compressors

Ship propeller shafts

Steam turbines

Water Pumps

Water turbines

Liquids Handled

Acids
Alkalies

Anhydrous ammonia

Beverages

Bleaches

Boiler feed water

Diesel Fuel

Dry Cleaning Fluids

Dyes

Freon

Fuel oil

Gasoline

Heat transfer oils

Hydraulic oil

Hydrocarbons

Jet Fuel

Kerosene

Lacquers

Liquid air, carbon dioxide, argon and ethane

Liquid chlorine

Liquid oxygen, nitrogen and hydrogen

LPG

Molten Metals

Molten sulfur

Oil mist

Plating Solutions

Potable water

Propane

Sea water

Solvents

Tanning Liquors

Xylene

Gasses Sealed

Air
Ammonia (Dry)

Argon

Carbon Dioxide

Chlorine (Dry)

Ethane

Ether

Ethylene

Freon

Hydrogen

Hydrogen Chloride (Dry)

Hydrogen Flouride (Dry)

Hydrogen Sulfide

Iodine

Natural Gas

Nitric Oxide

Nitrogen

Nitrous Oxide

Oxygen

Phosgene

Propane

Propylene

Steam

Sulfur Dioxide (Dry)

Vacuum

QA/QC Practices

All raw material physically tested prior to machining
DCC/CMM dimensional measurement/verification

Optical measurements

Compliances

All gaging and measurement equipment is calibrated and fully traceable to NIST Standards
ISO9001-2008


 MORE IMAGES 

·  Metal Encased Radial Seal Ring


 DOWNLOADS 

Metcar Physical Properties
(PDF, 447KB)


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