Parker O-ring Division The High Performance Leader

The Chemistry of Elastomers Material Technology The Chemistry of Elastomers

Rubber Technology “Rubber” compounds are resilient (elastic) materials made from one or more cross-linked base polymers, reinforcing agents, processing aids, and performance-enhancing additives. Compounds are tweaked for performance variations by adding other ingredients to the base polymer.

Polymers – Basic Information Base polymer determines chemical resistance, rough temperature limits, and rebound resilience. Also provides “baseline” for abrasion resistance, compression set resistance, permeability. Polymer chains must be “glued” together (cross-linked) to achieve resilience and elasticity. Typical curing systems are Sulfur, Organic Peroxides, and Bisphenol.

Compounding - Fillers Fillers are reinforcing agents that add mechanical strength and resistance to abrasion, permeation, and compression set Carbon black: standard for black compounds Silica: standard for non-black compounds Pasticizers are oils and/or polymers used to lower the low temp limit of Nitrile and make the material flow better

O-ring materials used at Kimray Nitrile (NBR) Buna Hydrogenated Nitrile (HNBR) HSN Ethylene-Propylene (EPR, EP, EPDM) Polyurethane (AU, EU) Fluorocarbon (FKM) Viton® Tetrafluoroethylene-Propylene (TFE/P) Aflas® Perfluoroelastomer (FFKM) Kalrez®, Chemraz®, Parofluor®

Standard Materials

Fluorocarbon (FKM) VITON® -15° F to + 400° F V1164-75 Recommended For Petroleum oils Silicone fluids Acids (Black ONLY) Aromatic solvents Halogenated hydrocarbons Air Not Recommended For Ketones Steam and hot water Amines Low temperature Automotive brake fluid Aircraft brake fluid

Nitrile (NBR) Buna -40° F to 250° F N0674-70 Recommended for: Aliphatic hydrocarbons (propane, butane, petroleum oil, mineral oil and grease, diesel fuel, fuel oils) vegetable and mineral oils and greases. Dilute acids, alkali and salt solutions at low temperatures. Water (special compounds up to 100°C) (212°F). Not recommended for: Fuels of high aromatic content (for flex fuels a special compound must be used). Aromatic hydrocarbons (benzene). Chlorinated hydrocarbons (trichlorethylene). Polar solvents (ketone, acetone, acetic acid, ethyleneester). Strong acids. Brake fluid with glycol base. Ozone, weather and atmospheric aging.

Hydrogenated Nitriles (HSN, HNBR) -25° F to 300/325° F Recommended for: Well service Improved methanol and sour gas resistance over nitrile High temperature resistance relative to Nitrile Petroleum oils Water/Steam Dilute acids and bases Aliphatic hydrocarbons Ozone Not recommended for: Polar solvents (methanol and ketones) Strong acids Fuels Chlorinated hydrocarbons Acetone Aldehydes N4007-95, KB163-90, N1231-80, N1173-70

Special Materials

Ethylene Propylene (EPDM, EP, EPR)

Ethylene –Propylene (EPDM, EPR) -60° F to + 250° E0962-90 Recommended for Geothermal Steam service (500°F) Explosive decompression Steam/oil mixtures of less than 10% petroleum fluid Not Recommended for Mineral oil products E0962-90 is unique in that is can withstand continous steam applications at 500°F

Highly Saturated Nitrile (HSN, HNBR)

Low Temperature HNBR -58° F to + 300° F KA183-85 Wide temperature range: Excellent abrasion resistance Excellent wear resistance Good extrusion resistance Extensive testing profile for EOG-specific requirements which include testing in: Methanol Oil Marston Bentley’s oceanic fluids Kerosene Baroid’s Petrofree drilling fluid

Fluorocarbon (FKM)

Low Temp Fluorocarbon(FKM) -55° F to + 400° F V1289-75 V1289-75 has significant advantages compared with other elastomeric seal materials: Compared to GLT FKM: Better low temperature rating than GLT FKM Lower volume swell than than GLT FKM Compared to GFLT FKM: Better low temperature rating than GFLT FKM Better compression set than GFLT FKM Compared to standard FKM Better low temperature rating than standard FKM Lower volume swell than standard FKM Compared to low temperature Nitrile Better compression set than Nitrile Lower swell than Nitrile No dry-out shrinkage Better high temperature rating than Nitrile

Sour Gas Service FKM +10° F to + 400° F VP104-85 VP104-85 has significant advantages for the Energy, Oil and Gas industry compared with other elastomeric seal materials Compared to standard A-type FKM Better explosive decompression resistance in sour gas Better amine resistance Better base resistance Better methanol resistance Better steam / hot water resistance Compared to FFKM Lower cost Compared to HNBR Better ED resistance Better steam/hot water resistance Better acid/base resistance Better high temperature performance Compared to high-temperature HNBR Better explosive decompression resistance in sour gas

ETP Fluorocarbon (FKM) -15° F to + 400° F V1260-75 Increased Chemical Compatibility Practically everything Polar and Aromatic solvents Not Recommended For Refrigerant gases Low cost applications Low temperatures Polymer trade name is Viton® Extreme – similar performance to Hifluor®, but usually a lot less expensive.

Explossive Decompression Resistant 15°F to +400°FFKM V1238-95 95 Shore A Durometer Fluorocarbon. Developed for maximum extrusion resistance, good compression set resistance. ED Resistant Applications: High temperature, high-pressure H2S.

FFKM HIFLUOR ® TFE/P Specialty Compounds

Parofluor ULTRA(FFKM) +5° F to + 600° F Recommended For Down hole (sour gas) Drilling mud Amine-based fluids Steam and other aggressive fluids High temperature applications Not Recommended For Refrigerant gases Low cost applications Low temperatures Competes directly with Kalrez ® and Chemraz. ® The best of the best. FF200-75 FF500-75 FF202-90

FFKM Chemical Resistance Properties

Hifluor ® (FKM) -15° F to + 400° F Recommended For Down hole (sour gas) Drilling mud Amine-based fluids Steam and other aggressive fluids Not Recommended For Refrigerant gases Low cost applications Low temperatures Similar chemical properties as Parofluor but about 20% less expensive. V3819-75 V8534-90

Aflas® (TFE/P) +15° F to + 450° F Recommended For Petroleum oils Alcohols Silicone fluids Sour gas Amines Air Steam / hot water Not Recommended For Low temperature Gasoline Poor compression set – primarily used in chemical plants. V1041-80 VP101-80 VP103-90

Explosive Decompression Materials

Explosive Decompression Resistant Compounds N1231-80 (HNBR) E0962-90 (EPDM)- VP103-90 (Aflas®)- V1238-95 (FKM, Viton®)- V8534-90 (HiFluor®)- V8588-90 (Parofluor®, FFKM, Kalrez®)- FF202-90 (Parofluor Ultra®, FFKM, Kalrez®)-

Maximizing life through failure diagnosis Failure Modes Maximizing life through failure diagnosis

Common reasons for O-Ring failure (Often an O-Ring fails from a combination of problems) Abrasion Chemical attack Compression set Cracks in Nitrile rubber Exceeding material temperature limits Explosive Decompression Extrusion and/or nibbling Installation Damage Overfill Spiral failure

Abrasion Looks like the seal is sanded off or flattened on one side of the o-ring. Causes: Poor surface finish O-Ring passes over ports Use of non abrasion resistant material Excessive swell and softening No lubrication

Abrasion Solutions: Check finish and smooth if necessary Use a lubricant or internally lubricated material Use a material that resists wear Use a lower swell material

Chemical Attack The seal swells a lot, shrinks, loses physical properties. Excessive swell, brittleness, and dramatic loss in physical properties. Find a compatible base polymer. Shrinkage: the fluid is probably extracting something from the rubber.

Chemical Attack

Chemical Attack Solutions: Use material compatible with all fluids. Determine percentage of all fluids in the stream. Find a compatible base polymer. Determine compound by chemical analysis and reviewing MSDS. Change compounds (changing the base polymer isn’t always required.)

Compression Set O-Ring Conforms to shape of groove Looks like the seal has been flattened or deformed. Causes: Happens whenever rubber is compressed -- is accelerated by: excessive or insufficient squeeze high temperatures Chemical attack due to incompatible fluids.

Compression Set HI HC HR Compression Set = amount of loss / initial deformation Compression Set = (HI – HR)/ (HI – HC) Compression Set = (.100 - .090) / (.100 - .075) Compression Set = (.010) / (.025 ) = .40 Compression Set = 40% Just an example to show numbers.

Compression Set

Compression Set Solutions: Evaluate gland dimensions Evaluate material check for proper squeeze consider tolerances consider ID stretch and cross section reduction Evaluate material check for compatibility with fluids and temperature use set resistant compound

Cracks in Nitrile Rubber Evenly spaced radial cracking around the circumference of the O-Ring (typically Nitrile) -- especially where it’s stretched. Causes: Ozone, UV light, Fluorescent light, Electric motors. There is ozone in the air around us, and this can be enough to destroy an O-Ring.

Cracks in Nitrile Rubber

Cracks in Nitrile Rubber

Cracks in Nitrile Rubber Solutions: Coat o-rings with a silicone or petroleum lubricant Choose a base polymer that is naturally resistant to ozone

Low Temperature Failure Seal leaks at low temperatures only. As seal materials cool to within 15oF of their minimum operating temperature, they lose resilience. Any movement may allow leakage of low viscosity liquids and gases. Low temperature changes are not permanent and do not damage the seal. Use a seal material with improved low temperature performance.

High Temperature Failure Rubber “melts” or becomes brittle. Every rubber polymer has a temperature above which it begins to break down. Thermal degradation is permanent and irreversible. Use a seal material with improved high temperature performance or cool the seal gland area.

Explosive Decompression Internal or external cracks, ruptures, blisters. Causes Gasses permeate material and when system is rapidly decompressed, gas quickly escapes leaving ruptures

Explosive Decompression

Explosive Decompression Solutions: Slice cross section at blister or rupture and look for internal fissure to verify explosive decompression is cause Determine application pressure and decompression rate Slow decompression rate Use explosive decompression resistant material Use a more explosive decompression resistant material such as V1238-95.

Extrusion and Nibbling Looks like one side of the seal is chewed off. Is caused by high pressure “pushing” the O-Ring into a gap between the metal surfaces. Causes. High pressure Excessive clearance Excessive swelling and softening

Extrusion and Nibbling

Extrusion and Nibbling

Extrusion and Nibbling

Extrusion and Nibbling

Extrusion and Nibbling Solutions Evaluate gland design Use InPHorm or extrusion chart to determine pressure rating If gland can be widened, use backup ring Evaluate material Use higher pressure material Use material compatible with the environment Use extrusion resistant compound if necessary

Installation Damage Sheared, torn, nicked cut appearance Causes: sliding over threads insufficient chamfer improper size no lubrication

Installation Damage

Installation Damage Solutions: cover threads during installation use lubrication chamfer and smooth edges use correct size

Overfill Appears similar to extrusion, but nibbling is on both sides, or O-Ring takes set with visible ridge over groove edge. Causes Insufficient void space in groove Excessive swell in system fluids Improper size O-Ring

Overfill Solutions: Use proper groove width Use lower swell material Use smaller cross section if squeeze is not reduced below recommended minimum

Spiral Failure Looks like a split wrapping around the ring. Causes: Happens when the seal on a piston or rod “grips” instead of slides in one spot (common with long, slow strokes). Can happen on static seals with pressure cycling. ID to CS aspect ratio, reciprocating Installation damage Soft material No lubrication

Spiral Failure

Spiral Failure Solutions: Can be prevented by using a smoother surface, lubricating uniformly, using a stiffer rubber compound, or using an engineered seal. Use proper cross section for inside diameter to provide stability in groove for reciprocating seal Use a lubricant or internally lubricated material evaluate surface finish, chamfer, sharp edges Use different cross section shape to provide stability in groove

Questions