1. Materials Selection – Non Metals
PTRT 1309
Corrosion Basics
Chapter 5 – NACE Book
Materials Selection – Non Metals
Prepared by Dr. Capone

2. Non metallic Materials
Generally refers to plastic or fiber-reinforced plastics (FRP)
Also refers to
Wood
Concrete
Cement
Mortar
Cement asbestos
tile

3. Wood Excellent corrosion resistance (fasteners)
Not generally used today
Expensive to construct, install and maintain
Coated steel tanks now generally superior economically

4. Cement and Concrete Reinforced offshore structures
Foundations for equipment
Linings for tank bottoms, internal pipe coatings, secondary containment basins
Generally resistant to corrosion except for reinforcing materials
Alkaline cement forms passive layer on reinforcing materials which if damaged can cause corrosion to occur
Generally caused by chlorides or oxygen
Corrosion of rebar generally leads to cracking and/or spalling of the concrete

5. Minimizing Corrosion in Concrete
Least permeable composition of concrete
Low in contaminants
Several inches between outside and rebar
Fusion bonded epoxy (FBE) Coatings (powder coating)
Alkalization and/or realkalization
Cathodic protection
Surface coatings (stop penetration of environment into concrete)

8. Rebar in gelatin with chloride
Rebar in gelatin with chloride and nitrite.

9. Cement-Asbestos Used until the early 1970’s
Homogeneous mixture of Portland Cement, Asbestos fibers and Silica
No longer allowed due to serious health risks
Caution must be taken when exposed to this material on older sites (licensed abatement company required)

10. Transite pipe (cement-asbestos)

11. Plastic (Polymeric) Materials
Most widely used non-metallic materials in the oil field
Most under-used corrosion control option
Mostly due to misapplication of the products as a direct replacement for steel
Various properties must be factored into decision to use plastics
Thermal expansion (high)
Long-term creep
Temperature limitations
Chemical resistance
Exposure to UV

12. Plastic (Polymeric) Materials
Using modern design information plastics are quite acceptable for a variety of oilfield applications
Downhole tubing
Flowlines
Facility piping
Tanks
Internal components for water handling vessels
Many plastics available with different physical, chemical and mechanical properties

13. Plastic (Polymeric) Materials
Plastic = nonmetallic compound usually synthesized from organic compounds through polymerization (linking of complex molecules)
Generally fall into two broad categories
Thermoplastic materials
Can be melted or reformed with little or no change to their properties
Lower temperature limits yield less severe service environments
Styrene, PVC, polyethylene, etc
Thermosetting materials
These plastics are “cross-linked” and do NOT melt
Higher temperature limits
Epoxy, polyester

15. Thermoplastics Common thermoplastics
Polyvinyl chloride (PVC)
Polyethylene (PE)
Low-density PE (LDPE)
High-density PE (HDPE)
Polyproplyene (PP)
Used for low-pressure piping, pipe liners, chemical storage drums
Fabrication is similar for all
Pelletized feed stock is melted
Extruded or injection molded into finish forms
Cooled and thus rehardened

18. Thermosetting Plastics
Usually known as FRP – Fiber Reinforced Plastic
Falls into general class of materials called composites
Fiberglass
Carbon-fiber
Other fibers
Generally resin (epoxy or polyester) in impregnated with fiber mats

19. Also examine figures on page 89 in large textbook

20. Fiber reinforced pipe Generally manufactured by
Filament winding
Centrifugal casting
Glass or ceramic fibers are saturated with resin (epoxy or polyester)
Correct resin selection for specific applications is critical

22. Joining Methods Heat Welding Solvent Welding Threaded connections
Heating element (sometimes IR) used to soften the joints
Compressed and fuse together (upset can occur)
Solvent Welding
Chemical solvent softens the plastic which then fuses (often called gluing)
Threaded connections
Schedule 80 usually specified for threaded joints
Working pressure usually reduced by 50%

23. Application of Non-metallic pipe
Three important factors
Chemical resistance
Mechanical properties
Economics
Usually the primary concern
Most materials discussed in this chapter are resistance to oil field fluids
Some absorption can occur which causes weakening
Service or environmental factors must be considered
See Table 5.2, page 91
Mechanical Properties
Pressure and Temperature Ratings
Surging can be 10x – 15x the average pressure in the line

24. Typical Applications Thermoplastics FRP
Flow lines – between well head, separators, tank battery
Gathering lines – oil, water or low pressure gas
Salt water lines – disposal systems and drains
Liners – for steel pipe in high pressure applications
Fuel lines – for gas engines
FRP
Used for all of the above
Tubing for injection and disposal wells

25. Advantages and Disadvantages
Immune to corrosion by water
Lightweight = lower freight and handling costs
Quickly and easily joined and installed
No external corrosion protection required
Smooth internal surface yields lower friction losses
Disadvantages
Limited working temperature and pressure
Limits are difficult to predict
Careful handling is required
Must be protected from sunlight, freezing, fire
Weeping can occur in low quality FRP
Low resistance to vibration and surging

26. FRP Tanks Most numerous are the small oilfield chemical tanks
Inner layers designed to protect against chemical attack and are typically structural
Outer layers designed to prevent atmospheric absorption and UV degradation
See Table 5.2, page 91
FRP sucker rods – still have metal connections

27. Elastomers Common uses as seals and packing Also used in tank liners
Most common seals are:
Nitrile (Buna-N)
EPDM (ehtylene-propylene-dienemonomer)
Flourocarbon
HSN (Highly Saturated Nitrile)

28. Selection of Seals