Basic Materials used for Piping
There are numerous basic materials used for piping, though regularly used materials are listed below with their grades and service applications. Here we are listing some of the basic materials, broadly used in piping industries.
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Carbon Steel (CS)
General: Using within min. – 29°C to max. 425°C
The Carbon Equivalent (CE) for carbon steel intended for welding shall not exceed 0.43% base on the long formula: CE=C + Mn / 6 +( Cr + Mo + V ) / 5 + ( Cu + Ni ) / 15
Applications:
Service – Noncorrosive piping system (fresh water, plant air, nitrogen, fuel gas, etc.)
Pipes -ASTM A106 Gr.B, API 5L Gr.B
Fittings -ASTM A234 Gr.WPB
Forgings – ASTM A105
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Low Temp Carbon Steel (LTCS)
General: Using if the minimum service temperature is below – 29°C
Applications:
Service – Low temperature non-corrosive piping system (flare system)
Pipes -ASTM A333 Gr.6
Fittings – ASTM A420 Gr.WPL6
Forgings – ASTM A350 Gr.LF2
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Austenitic Stainless Steel (SS)
General: The use of austenitic stainless steel in offshore is limited to a maximum service temperature of 60 °C
Using when the corrosion rate is too high to use carbon steel (typical more than 3mm or 6mm max. corrosion allowance for the design life)
Any hydrostatic testing of austenitic stainless steel shall be conducted with water containing less than 2 mg/kg chlorides, and any open ends sealed after drying to ensure no moisture ingress.
Applications:
Service – Fuel gas, chemical injection, instrument air, wet hydrocarbon (corrosive).
Pipes – ASTM A312 Gr.TP304/304L, ASTM A312 Gr.TP316/316L
Fittings – ASTM 403 Gr.WP304/304L, ASTM 403Gr.WP316/316L
Forgings – ASTM A182 Gr.F304/304L, ASTM A 182 Gr.F316/316L
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Duplex Stainless Steel (DSS)
General: Using when the design condition is exceed the limit do SS316.
Any hydrostatic testing of austenitic stainless steel shall be conducted with water containing less than 2 mg/kg chlorides, and any open ends sealed after drying to ensure no moisture ingress.
Applications:
Service
Pipes – ASTM A790 UNS S31803
Fittings – ASTM A815 UNS S31803
Forgings – ASTM A182 Gr.F51
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Alloy Steel (AS)
Elevated Temperature Services
General: CrMo heat resistant steel contain 0.5~9% Cr and 0.5~1.0% Mo. Carbon content max 0.20%
Supplied in normalized and tempered, quenched and tempered or annealed condition.
These Alloy Steels are used up to max temperature about 650 °C.
Applications:
Pipes – ASTM A 335 Gr.P11, A335 Gr.P22
Fittings – ASTM A234 Gr.WP11, A234 Gr.WP22
Forgings – ASTM A182 Gr.F11, A182 Gr.F22
Low Temperature Services
General: Application with temperature from 0 °C to –195°C, Nickel steels is typically used
Applications:
Pipes – ASTM A 333 Gr.3
Fittings – ASTM A420 Gr.WPL3
Forgings – ASTM A350 Gr.LF3
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Non Ferrous Alloy
Nickel Alloys
Including Inconel and incoloy.
Commonly used because of the high ppm.
Monel
Monel is a nickel-copper alloy, 10%~90% commonly used
Service: sea water
Copper-Nickel
Cu-Ni90/10, Cu-Ni70/30
Services: sea water piping system
Titanium(Non Alloyed Grade)
Good corrosion resistance, especially chlorite induced pitting and stress-corrosion cracking
Good resistance to oxidizing media, e.g. nitric acid
Titanium (Alloyed Grade)
Resistance to reducing media superior to non-alloyed titanium
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Thermoplastic
Plasticised Polyvinyl chloride->PVC
Un plasticised PVC->UPVC
Polyethylene->PE
Polyamide->PA
Polypropylene->PP
Polyphenylenesulpone> PPS
Cross linked Polyethylene> PEX
Polyketone> PK
Polyetheretherketone> PEEK
Fluoropolymers
PolyTetra Fluoro Ethyleme>PTFE
Polychloro trifluoro ethylen>PCTFE
Perfluoralkoxy>PFE
Fluorinated ethylene propylene>FEP
Poly vinylidene fluoride>PVDF
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Non-Metallic
Glass fibre Rainforced Plastic>GRP
Glass fibre Rainforced Epoxy>GRE
Glass fibre Rainforced Vinylester>GRV
Using
No use in hydrocarbon and methanol system
Max internal design temperature 20 bargs
Design temperature range for -40°C up to 95°C for epoxy and up to 80 °C for vinylester
Commonly used for the sea water system in offshore
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Elastomeric
Natural Rubber>NR
Styrene Butadiene Rubber>SBR
Neoprene Rubber>CR
Butyl Rubber>IIR
Chloro sulphonated polyethylene>CSM
Nitrile Butadiene Rubber>NBR, HNBR
Ethylene Propylene Rubber>EPDM
Fluoro elastomers>FKM
Perfluoro Polymer>FFKM
Fluor Silicone Rubbers>VMQ, PMQ, FMQ
Polyurethane Rubbers>AU,EU