1. Parker O-ring Division
The High Performance Leader

2. The Chemistry of Elastomers
Material Technology
The Chemistry of Elastomers

3. 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.

4. 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.

5. 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

6. 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®

7. Standard Materials

8. 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

9. 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.

10. 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
N , KB163-90, N , N

11. Special Materials

12. Ethylene Propylene (EPDM, EP, EPR)

13. 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
E is unique in that is can withstand continous steam applications at 500°F

14. Highly Saturated Nitrile (HSN, HNBR)

15. 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

16. Fluorocarbon (FKM)

17. Low Temp Fluorocarbon(FKM) -55° F to + 400° F V1289-75
V 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

18. Sour Gas Service FKM +10° F to + 400° F VP104-85
VP 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

19. 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.

20. 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.

21. FFKM HIFLUOR ® TFE/P
Specialty Compounds

22. 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.
FF FF FF202-90

23. FFKM Chemical Resistance Properties

24. 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.
V V

25. 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.
V VP VP103-90

26. Explosive Decompression Materials

27. Explosive Decompression Resistant Compounds
N (HNBR)
E (EPDM)-
VP (Aflas®)-
V (FKM, Viton®)-
V (HiFluor®)-
V (Parofluor®, FFKM, Kalrez®)-
FF (Parofluor Ultra®, FFKM, Kalrez®)-

28. Maximizing life through failure diagnosis
Failure Modes
Maximizing life through failure diagnosis

29. 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

30. 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

31. 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

32. 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.

33. Chemical Attack

34. 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.)

35. 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.

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

37. Compression Set

38. 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

39. 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.

40. Cracks in Nitrile Rubber

41. Cracks in Nitrile Rubber

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

43. 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.

44. 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.

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

46. Explosive Decompression

47. 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 V

48. 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

49. Extrusion and Nibbling

50. Extrusion and Nibbling

51. Extrusion and Nibbling

52. Extrusion and Nibbling

53. 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

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

55. Installation Damage

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

57. 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

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

59. 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

60. Spiral Failure

61. 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

62. Questions