Pipes and fittings installation: temperature and related problems

During pipes and fittings installation it is important to consider the connection between temperature variations and the problems that may arise from them. The extreme climatic conditions influence both the laying process and the lifespan of the products but also their proper performance, thus causing problems for the entire system. In aqueducts and public networks, managing authorities choose materials based on different criteria ranging from ease of installation to corrosion resistance, also taking into consideration the cost-effectiveness and the life of the products.

Therefore, which are therefore the most common pipes and fittings used on site and which are the most commercialized ones that can guarantee the right balance?

Most common pipes and fittings on aqueducts

Starting from the principles that lead administrations and managing authorities, let’s see together which solutions are currently available on the market:

1. Cast iron and steel pipes: Widely used in the past, cast iron pipes have shown certain problems related to mechanical and traction strength over time. Gradually, this material has been replaced by spheroidal cast iron, which is, among other things also fragile and subject to corrosion. Compared to the previous ones, steel pipes represent a lighter and more convenient solution. However, the limits of steel lie in its sensitivity to electrolytic and galvanic currents, as well as in its poor corrosion resistance with aggressive water
   

   1. Concrete pipes.

2. Concrete pipes: concrete is a material that generally can be brittle and weak in traction, therefore, the pipes are reinforced by iron armour and covered with bituminous fiberglass sealant. They certainly have good corrosion resistance and a long durability. Moreover, the high laying costs, primarily due to weight, as well as the brittleness and incomplete waterproofing, have led to this technology being overtaken by plastic pipes.
   

   2. Cast iron pipes.

3. Pipes in plastic materials, the most common ones: Thanks to low costs, lightness and longer pipe length as well as a much easier transport and installation, plastic pipes are currently the most widely used ones. One of the most important advantages is related to the chemical resistance of the material; plastic material is indeed the most suitable to handle temperature variations and potential installation problems of pipes and fittings
   

   3. PE pipes for water network.

Plastic materials characteristics and temperature resistance

As we already saw, plastics guarantee an optimal solution for water systems. But how do they behave when the temperature changes? PE pipes, therefore HDPE (high density) or LDPE (low density) are unbreakable, non-toxic, flexible and insulating and can be used safely at temperatures ranging between – 20°C and + 60°C. The PE pipes, will change in the presence of ice and then return to their original shape without creating critical pipeline damages. Despite their high resistance, extreme climatic conditions are not to be underestimated since they have influence on the physical status of the water that flows inside the pipes and those could slow down and influence the laying operations.

Temperature variations and installation problems for pipes and fittings

Pipe laying and embedding

The very cold-weather, as well as the extremely hot one, influences the installation of the piping system. The pipes, to counteract the frost and the consequent interruption of the water flow, require to be buried. The width of the excavation should be at least 20 cm around the diameter of the pipe and at least 1m above the pipe.

If this is not possible, it is necessary to protect the pipe with means of concrete or different casing. Obviously, the excavation procedures, besides being a cost themselves, are made even more complex and expensive by extreme climatic conditions.

Installation of joints and fittings

Another critical aspect is the junction of the pipes through the application of custom fittings.

With regards to the joints, the problem that may arise could be related both to a correct installation and to a correct laying, for which time may expand with a consequent increase of costs. Which are the available solutions on market?

1. Fittings with butt fusion welding and electrofusion joints: here we should consider that this type of fittings require a welding process that could be compromised by extremely high or extremely low temperatures, since it has to be carried out between -5°C and +40°C. Furthermore, you have to consider the difficulty in reaching certain areas due to the snow in winter or extremely high temperature during the summer, especially considering the necessity to bring all the required equipment, such as welding machines.
2. Compression fittings and push-fit fittings: this type of fittings can speed up the laying process. Generally speaking, it is necessary to consider how the installation should anyhow consider all the precautions used for pipes and for potential accessories to insert and tighten the fittings.
   

   5. PE pipe installation for a Swedish project, during winter

The installation time of pipes and fittings is here the key factor to consider if you want to keep costs down. Several couplings, moreover, includes a preparatory phase of rounding the pipe of 1 or 2 mm of thickness, to ensure the proper welding between the joint and the outer wall of the pipe. Time is money, especially when the extreme weather can invalidate and slow down the transport and the laying operations.

In conclusion, temperature variations cause an additional slowdown in all on site operations, forcing installers to take expensive precautions in many ways.