PVC : the long term building material Joël Fumire Research & Technology SBU Vinyls São Paulo, 2005
PVC in building • PVC is one of the most used plastics in building Why ?
PVC in building Building means … • … Strength , see the rigidity modulus ! • … weather resistance in all climates • … well adapted to specific use (e.g. pipes) • … Durability from 30 to > 100 years • … competitive cost ! • … recyclable
Rigidity in Sewage Key property : annular stiffness. Directly related to the E-modulus of the material : Stiffness : SN = K. E. I / D3
Good Weathering resistance UV-resistance : PVC can be formulated easily to be used on a long term basis in very sunny climates
PVC adapted for use : drinking water pipes Key properties : • Pressure resistance • No modification of the water quality • Long term durability
PVC adapted for drinking water pipes Key property : long term pressure resistance PVC-U PE100 50 y.
PVC adapted for drinking water pipes No modification of water quality : • No significant leaching of substances to the water • No taste or smell transferred to water • PVC pipes comply with the requests of drinking water contact in the most severe regulations (CEE, NSF, BGVV, etc…) • Excellent resistance to bacteria growth • PVC is approved for drinking water transportation in the majority of countries
Other key properties for PVC pipes • Chemical inertia towards many chemicals : • Cleaning liquids, acids, • No sensitivity towards oxidising substances • Good Fire resistance • Among plastics, PVC is one of the most difficult to ignite. • It is self-extinguishing
Durability • PVC pressure pipes are in use since more than 60 years • PVC pressure pipes are designed theoretically for 50 years but can last more than 100 years • PVC Window profiles are used since more than 40 years and are still performing well
Pressure pipes 60 years old – Dr Nowack study • Study realised in Germany : published in KRV (1995) by Dr. Nowack • PVC pipes were produced and installed in Bitterfeld in 1935-1940 with the technology available at that moment (physical, chemical) Pipes from 1938 extracted from Bitterfeld
Pressure pipes 60 years old – Dr Nowack study • Tests on these pipes show that : • Burst-pressure curve is still linear with no "knee" • Burst-pressure at 60°C is found still > 5 N/mm² after 600 h • Some of the pipes are still operating today at 20°C under 5.0 bar with satisfactory performance
TNO study on residual lifetime of PVC pipes • Are 50 years old pipes to be replaced ? • Study was realised between 2002 and 2005 by the Dutch institute TNO Science and Industry(A. Boersma & J. Breen) • Water pipes from the 1950's until today were excavated and extensively tested :
TNO study on residual lifetime of PVC pipes • Physico-chemical analysis : • The K values were close to 66 (1 exception at 72) • The level of gelation was between 38% and 80% (the pipes from the 1970's showed the lowest gelation) • Analysis of the transformation of the stabiliser system indicates negligible consumption (at room temperature)
Mechanical testing : Craze initiation is affected by the physical ageing and by fatigue phenomenon Burst pressures are still at a good level (and still compliant to ISO standard) TNO study on residual lifetime of PVC pipes
TNO study on residual lifetime of PVC pipes • Main conclusions of this study are : • No chemical degradation appears • Gelation : seems to be correlated with craze initiation • Fatigue could lead to an increased mechanical ageing • Production and laying conditions induce additional stresses in the material • The lifetime can be expected to be 100 years or more for high quality produced and installed pipes.
Window frames since the 1970's • Window frames are installed since the 1960's • This window was installed in Germany in1972 • and is still in operation after more than 30 years of good operation! • Usually PVC frames are not replaced because of damage
Competitive price : costs of piping systems (installation and assembling) Steel Cast Iron Cast Iron PE Steel Cast Iron PVC-U Steel PE PVC-U PE PVC-U Source : DVGW 1998 DN 100 DN 200 DN 150
Recycling • Today in Europe > 7 000 t/y of PVC is recycled in pipes • For homogeneous rigid PVC, recycling is mainly a collecting process • For composite material (or heavily contaminated PVC) a special separation process has been developped :
Recycling • PVC material can be extruded several times • The problem is the availability of recycled material since the articles installed in the 1970's are not available for recycling !