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  • AGRU Technical 08.12 PDF Published September 9, 2013

    55 Guardsman Road Thornhill, Ontario Canada, L3T 6L2

    t. 905.889.7890 f. 905.889.8553 request@chemline.com www.chemline.com

    Page

    Polypropylene 2-8

    PVDF 9-13

    ECTFE (Halar) 14-17

    Behaviour under Abrasive Chemicals 18-19

    Transport & Handling 19

    Sizing of Pipe Diameters 20-22

    Calculating System Pressure Drop 23-30

    Support Distances 31-33

    Thermal Expansion & Flexibility Analysis 34-35

    Welding Methods & Detachable Joints 36-45

    System Testing & Repair 46-47

    Leak Detection for Dual Containment Piping 48-51

    Thermoplastic Piping Systems

    ISO 9001:2008 Certified

    09/13 ©Chemline Plastics Limited 2012 Chemline is a registered trademark of Chemline Plastics Limited

  • Polypropylene Piping Systems

    General Properties of Polypropylene

    Polypropylene is a fairly ductile material at ambient temperature and demonstrates good impact strength. It also has good thermal stability up to 100°C (short-term up to 120°C) especially in comparison to other thermoplastics such as HDPE and PVC. Polypropylene is available in two grades: ● Homopolymer (PPH) made from Type 1 resin according to

    ASTM D 4101, produced from 100% propylene monomer. ● Copolymer (PPR) made from Type II resin produced from 94%

    propylene with 6% ethylene. Copolymer resins generally exhibit better impact strength.

    Physiological non-toxicity Polypropylene (PPR and PPH) comply with the relevant food regulations (according OENORM B 5014 Part 1, FDA, BGA, KTW guidelines). Pipe can be made out of either PPH or PPR material.

    General Properties of Polypropylene (Standard types)

    Behaviour on Radiation Strain PP is generally not very resistant against high energy radiation. On short term exposure to high energy rays, polypropylene may have temporary resistance due to cross linking of the molecular structure. But as time goes on the radiation begins to rupture the molecular chains and thereby damages the material. This behaviour has to be taken into account and a reduction factor has to be used (which has to be determined experimentally). For an absorbed dose of

  • Polypropylene Piping Systems

    General Properties of Modified Polypropylene

    Due to specific requirements in the construction of piping systems, flame retardant and electro-conductive PP has been developed.

    For example, electro-static charges can be generated by the flow of fluids or dust in thermoplastic piping systems so an electro-conductible polypropylene has been developed to enable a connection to ground.

    These modified properties are achieved by the addition of additives, however these result in changes to the mechanical, thermal and chemical properties in comparison to the standard type of PP. The differences can be seen in the table General Properties of PP on page 4.

    Physiological Properties Modified PP types (flame-retardant or electro-conductible PP) have special properties due to the addition of additives. These do not conform to the relevant food regulations and therefore should not be used for potable water or for contact with food.

    Differences to Standard Types of PP PP-R, Black: (Polypropylene-random-copolymer, black coloured) The advantage of this black coloured material is much higher UV resistance than the standard grey PP, with no significant decrease on the impact strength.

    PP-R, Natural: (Polypropylene-random-copolymer, natural) As PP-R natural contains no colour additives, it is used mainly for high purity water piping systems. However this material is not UV resistant.

    PP-H-s: (Polypropylene-homopolymer, flame-retardant) Due to the higher stiffness of PP-H-s, it is well suited for ventilation and degassing pipes as well as for flue lining systems. It may not be used for outdoor applications because it has no UV stabilization.

    PP-R-el: (Polypropylene-random-copolymer, electro-conductible) This material is used if the piping system requires a connection to ground. Due to the high carbon black content, PP-R-el is UV resistant, but shows a reduced impact strength and creep strength.

    PP-R-s-el: (Polypropylene-random-copolymer, flame retardant, electro- conductive) This material has both the properties of the flame retardant and electro-conductible PP. It is used mostly for the transport of easily ignitable media (due to safety concerns) and can replace expensive stainless steel ducting. PP-R-s-el has reduced impact strength compared to normal PP-R and is slightly less chemically resistant.

    General Chemical Properties of Polypropylene

    In comparison to metals where chemical attack leads to an irreversible chemical change of the material, plastics are mostly affected by physical processes. Such physical changes are e.g. swelling and solution processes that will affect the mechanical properties.

    PP is resistant against diluted solutions of salts, acids and alkalis if these are not strong oxidizing agents. It also has good resistance against many solvents, such as alcohols, esters and ketones. It shows swelling when in contact with solvents such as aliphatic and aromatic compounds, chlorinated hydroxycarbon especially at higher temperatures, but failure is very rare.

    PP resistance can be greatly reduced by stress cracking corrosion due to ampholytics (chromic acid, concentrated sulphuric acid).

    Lyes Alkalis: Diluted alkali solutions (e.g. caustic lye), even at higher temperature and higher concentrations do not react with PP and can therefore be used without problems, unlike PVDF or other fluoroplastics.

    Bleaching Lye: As these lyes contain active chlorine, only a partial resistance is given at room temperature. At higher temperatures and concentrations of the active chlorine, PP is suitable only for pressureless piping systems and tanks.

    Hydrocarbons: PP is only partially resistant against hydrocarbons (benzene as well as other fuels). At ambient temperature, swelling is over 3%.

    Acids Sulphuric Acid: Concentrations up to approximately 70% change the properties of PP only slightly. Concentrations higher than 80% cause oxidation at room temperature. At higher temperatures, this oxidation can even go to a carbonization of the surface of PP semi-finished products.

    Hydrochloric Acid, Hydrofluoric Acid: PP is chemically resistant against concentrated hydrochloric acid and hydrofluoric acid. However, there is a permeation of HCl (concentrations >20%) or of HF (concentrations >40%) through PP, which does not damage the PP material, but can cause secondary damage to surrounding steel construction. Double containment piping systems have proven effective for such applications.

    Nitric Acid: Higher concentrated nitric acid has an oxidizing effect on the PP material. The mechanical strength properties are reduced at higher concentrations.

    Phosphoric Acid: PP is resistant even at higher concentrations and higher temperatures.

    Agru.Technical 08.12 3

    Material Properties

  • General Properties of Polypropylene

    Physical Property

    M ec

    ha ni

    ca l P

    ro p

    er ti

    es Th

    er m

    al P

    ro p

    er ti

    es E

    le ct

    ri ca

    l Pr

    op er

    ti es

    Polypropylene Piping Systems

    † Fire classification B1 only valid for wall thickness of 2 to10mm.

    Specific Density at 23oC

    Melt Flow Index

    MFR 190/5

    MFR 190/2.16

    MFR 230/5

    MFI Range

    Tensile Stress at Yield

    Elongation at Yield

    Elongation at Break

    Impact Strength unnotched at 23oC

    Impact Strength unnotched at –30oC

    Impact Strength notched at 23oC

    Impact Strength notched at 0oC

    Impact Strength notched at –30oC

    Ball indentation hardness acc. Rockwell

    Flexural strength (3.5% flexural stress)

    Modulus of elasticity

    Vicat-Softening point VST/B/50

    Heat deflection temperature HDT/B

    Linear coefficient of thermal expansion

    Thermal conductivity at 20°C

    Flammability

    Specific volume resistance

    Specific surface resistance

    Relative dielectric constant at 1 MHz

    Dielectric strength

    Physiologically non-toxic

    FDA

    UV stabilized

    Colour

    PP-s-el

    1.13

    0.6

    30

    43

    9.5

    2.3

    133

    47

    V-0

    ≤108 ≤106

    no

    no

    yes

    black

    PP-s

    0.93

    0.8

    2.0

    30

    10

    >50

    no break

    28

    9

    2.8

    2.2

    72

    10,400

    37

    5,366

    1,300

    188,600

    85

    85

    1.6

    0.2

    V-2

    E(d2)

    B1†

    >1015

    >1015

    30 bis 45

    yes

    no

    no

    Ral 7037

    dark grey

    PP-B

    0.93

    0.5

    1.3

    26

    10

    >50

    no break

    80

    40

    8

    3.2

    50

    7,250

    20

    2,900

    1,100

    159,500

    68

    75

    1.6

    0.2

    94-HB

    B2

    >1015

    >1015

    30 bis 40

    yes

    no

    no

    Ral 7032

    grey

    PP-R

    0.91

    0.5

    1.25

    25

    12

    >300

    no break

    22

    4

    2.5

    45

    6,520

    20

    2,900

    900

    130,500

    65

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