Polypropylene (PP) is a Polyolefin resin polymerized by using a Ziegler-Natta catalyst process. To produce granulate, PP is compounded after polymerization. During the compounding process, phenolic and phosphatic antioxidants and, mostly also, color pigments are added. For some markets noncolored raw material is offered as well, e.g. as inliner for aluminum-stabilized PP pipe or if processors do color the virgin material themselves.
General characteristics of Polypropylene
Polypropylene for pressure pipes offers the following characteristics:
Leight weight / Good creep rupture properties / Good aging resistance / Excellent chemical resistance / Good stress cracking resistance / Excellent welding properties / Excellent abrasion resistance / Good organoleptic properties / High dimensional stability / Excellent noise insulation properties
Some of the mentioned characteristics, for example creep rupture strength, aging resistance and organoleptic properties are influenced by the type and amount of additives used.
Random Polypropylene (PP-R)
Statistical random PP copolymer (PP-R) contains monomer residues arranged according to a known statistical rule. Further reduced crystallinity provides for significantly higher flexibility and impact strength.
Good creep rupture strength and aging resistance at raised temperatures in conjuction with good impact strength have made PP-R one of the most widely used pipe materials for indoor potable water transport.
PP-R was one of the first plastic materials to replace metal for indoor pipe applications. Developed by Chemische Werke Hüls, now Sabic, PP-R at that time became increasingly popular in Western Europe, particularly in Germany, Austria, Spain and Italy. For example, PP-R was the most widely used plastic pipe material in Italy at the peak of its success.
Even compared to other pipe, for example PE-X pipe or aluminum composite pipe which may have superior properties for certain areas of application, PP-R pipe are still the product of choice for construction planers/architects and processors in many markets.
PP-R pipe systems still have one of the best cost-value ratios of all pipe materials and pipe systems used for hot water installations.
The most important suppliers of PP-R compounds are:
|Sabic – Europe||Vestolen||Germany|
|Borealis||RA 130 E, Beta-PPR||Sweden, Austria|
Fig. 3: Manufacturer of PP-R compounds
Reasons for the PP-R unit growth
- PP-R pipe systems have a good price-performance ratio. Pipes and fittings are made of the same, relatively inexpensive material.
- Large-diameter pipes and large fittings can be manufactured economically which makes PP-R pipes a preferred choice for all kinds of large projects.
- Another success factor is the joining technique. With unbeatable inexpensive fittings and simple tools, homogeneous connections can be made very easily and safe by means of polyfusion welding. Comprehensive fitting product lines, also including fittings with metal inserts for screw connections, facilitate all pipeline configurations including the changeover to metal pipe systems.
- Compared to the more flexible and easily bendable pipe, for example made of PE-X or composite pipes, the higher stiffness of PP-R pipes is a disadvantage yet hasn’t been an obstacle in the new PP-R markets.
Because of the current worldwide financial crisis all existing unit growth estimates are obsolete. First of all, short-term changes have to be evaluated before revised estimates can be made. Nonetheless, general trends can be described for PP-R unit growth. These trends allow predictions for the general market development for the years ahead regardless of the actual numbers.
The following trends for PP-R could be observed over the past years:
- PP-R maintains its market position in the main markets, e.g. CIS and Middle East.
- In Eastern Europe, the amount of PP-R material used drops for the benefit of composite pipes in particular.
- Major demand for PP-R continues to shift to Southeast Asia, India and South America.
- The use of PP-R in Western Europe – Italy or Spain mainly – decreases further.
- The established PP-R pipe manufacturers in Europe are confronted with new, internationally focused competitors, for example from PR China or Turkey.
- To remain competitive, Western European pipe manufacturers set up production plants in the PP-R markets, e.g. in Egypt and in Dubai.
- Growing acceptance and unit growth of PP-R in the newer markets increasingly prompt local manufacturers to act.
- Multinational corporations expand into the PP-R business, for example through the acquisition of established PP-R manufacturers in the Czech Republic, Turkey or Poland.
- German or EU quality products are still in demand in many PP-R markets, ususally even if significantly cheaper local products are available.
More Information on PP-R for Hot and Cold Water Installations
However, during recent years changes have occurred with regard to primary end use markets and regional focus. Were PP-R pipes to a large extent used for panel heating systems in the past, more recently these pipes are preliminarily used for potable water installations as well as heating, compressed air, gas or sprinkler pipe. Pipe grids and capillary tubes for ceiling or panel heating or cooling purposes which are also frequently manufactured of PP-R play a special role. A detailed review of the general changes and developments of the PP-R markets can be found in the KWD Market Report “PP-R Pipes for Hot and Cold Water Installations worldwide 2009” (Author is Achim Seydel)