Plastic Pipes
Property
The two principal types of PVC used in the manufacture of pipe and fittings areType I and Type II (ASTM D 1784).
Type I, also called unplasticized or rigid PVC, contains a minimum processing aids and other additives and has maximum tensile and flwxural strength, modulus elasticity, and chemical resistance.It has lower thermal expansion than Type II.
Type II, which is modified with rubber to render it less rigid and tougher, also strength, modulus elasticity, lower heat stability, and less chemical resistance than type I.
Properties of PVC-U
| Property | Test method/Recommendation | PVC-U |
| Yield Stress (MN m-2) at 23C | BS 2782: 1970; Method 30IG | 55 |
| Tensile Modulus 100s 1% Strain (GN m-2) at 23C | BS 4618 | 2.7 – 3.0 |
| Izod Impact Strength (J m-1)* | BS 2782: 1970; Method 306-A | 110 (unmodified)
540 – 800 (impact modified) |
| Relative Density | – | 1.38 – 1.45 |
| Maximum Continuous Service Temperature (C) from Field Experience | – | 60 |
| Coefficient of Thermal Expansion at 20C (C-1) | BS 4618 | 6 x 10-5 |
| Flammability (oxygen index) (%) | BS 4618, ASTM D2863-77 (Fenimore Martin Test) | 45 |
*J m-1 = 1.873 x 10-2 ft. lb. ft. in-1
Source: Doran, DK, Newnes Construction Material Pocket Book; Gutterworth-Heinemann Ltd, Oxford, 1994. [19]
Ignition properties of PVC
| Property | Test method | PVC-U |
| Flash ignition temperature* (C) | ASTM D1929 | 400 |
| Self-ignition temperature** (C) | – | 450 |
| Oxygen index | ISO 4589 | 50 |
| ISO Radiant Core
Ignition time at 30kWm-2 (s) Ignition time at 30kWm-2 (s) |
ISO 5657
– – |
112 33 |
| Needle flame test | IEC 695-2-2 | Non-ignitable |
*The lowest temperature of air passing around the specimen at which sufficient combustible gas is evolved to be ignited by a small external pilot flame.
**The lowest temperature of air passing around the specimen at which, in the absence of an ignition source, ignition occurs by itself.
Source: Doran, DK, Newnes Construction Material Pocket Book; Gutterworth- Heinemann Ltd, Oxford, 1994. [19]
Chemical resistance of PVC-U to some common chemical products
|
Chemical |
Temperature (C) | |
| 20 | 60 | |
| Alcohol (40% aqueous) | ++ | + |
| Antifreeze | ++ | ++ |
| Dish-washing liquid | ++ | ++ |
| Detergent (diluted) | ++ | ++ |
| Furniture polishes | ++ | ++ |
| Gas oil | ++ | ++ |
| Lanolin | ++ | ++ |
| Linseed Oil | ++ | ++ |
| Mineral Oils | ++ | ++ |
| Moist acidic atmosphere | ++ | + |
| Moist alkaline atmosphere | ++ | + |
| Motor Oils | ++ | ++ |
| Petrol | ++ | ++ |
| Seawater | ++ | ++ |
| Vinegar | ++ | ++ |
| Vegetable Oils | ++ | ++ |
Key: ++, resistant; +, practically resistant
Source: Doran, DK, Newnes Construction Material Pocket Book; Gutterworth-Heinemann Ltd, Oxford, 1994. [19]