What are the characteristics of fluid transport lines in an industrial production

An industrial production normally needs to be supported by a series of fluids, such as the water, compressed air or steam.

In order to be able to transport the different fluids necessary for the operation of production plants, it is necessary to be able to count on pipes designed according to the fluid they will have to contain, the distance of the transport, their diameter and the working pressure.

In this article we address the elements that make up an industrial fluid distribution network and what we must take into account to choose the best materials fit for purpose.

A network of pipes for the transport of industrial fluids can fall under the heading of production service networks and, for this reason, their installation and maintenance must be considered in the costs of the systems and in those of maintenance.

Therefore, it is important to design, build and install the best possible pipe network, in in order to minimize general costs and increase their duration over time.

In fact, it is always useful to plan an oversizing, but carefully, of the line and the elements that support it, as it may be necessary, in the future, an increase in the need for fluids required by a possible increase in production volumes, without having to redo the conveyor lines.

The elements that make up a fluid transport line are made up of the following products:

• Pipes

• Connection elements

• Accessories

First of all we can say that the production service lines should be visible and easy to access, so as to be able to carry out the any repairs or inspections, quickly and easily, without compromising production times.

Furthermore, each line must be easily recognizable based on the flow that flows in it, in fact, the data indicating the nature of the fluid can be written on the tubes, in various forms, such as the full name, the abbreviation or the chemical formula.

For pipes carrying dangerous fluids, in addition to the basic colour, the danger symbol and the name or formula of the fluid must be present.

Finally, bear in mind that the piping and all components must be installed in such a way as to:

• do not hinder transit

• do not occupy workspaces

• not be damaged by means of transport

• not constitute a barrier to the diffusion of natural light

Choice of pipes to install

The most common materials that make up the pipes, used in the fluid transport lines in production, are plastic, copper, steel, cast iron and, to a lesser extent, concrete.

For the choice of one typology rather than another, the type of fluid to be transported, the pressure inside the pipe, the temperature of operation, the aggressiveness of the fluid on the line and some environmental considerations of the plant, such as humidity, heat and the aggressiveness of external components.

Furthermore, it affects the choice of pipe, regarding the fluid to be transported, the threading or welding of the joints between the pipes themselves, which will have to take into account the general characteristics of the fluid.

Once the most suitable material and type of joint have been chosen, the diameter and thickness of the pipe are determined. The diameter is determined on the basis of the flow rate of the fluid to be conveyed, taking into account the economic balance of the installation costs, which increase as the diameter of the pipes increases.

Steel pipes

Steel pipes are, by far, the most used type in production lines and are classified according to their use:

• Threadable tubes

• Commercial tubes

• Pipes for mechanical applications

• Pipes for pipelines

• Special tubes

• Galvanized pipes

Steel pipes are used for the transport of liquids, even in the presence of high temperatures, gases, non-alterable substances and pressure.

Cast iron pipes

The nodular cast iron pipes are obtained by centrifugation and are normally equipped with a socket joint with an elastomer gasket, or for particular applications, they are available in flanged version.

They are normally used in the transport of black water or gas, through special coating layers based on the type of fluid to contain.

Copper pipes

Copper pipes are characterized by very high electrical and thermal conductivity, surpassed only by those of silver, furthermore copper is very resistant to corrosion and is not magnetic.

They are used to transport drinking water, combustible gas, medical gases, water for heating and fluids for conditioning and refrigeration. In fact, copper is impermeable to gases, easily bent, resists corrosion and does not age when exposed to solar radiation.

Plastic pipes

Plastic pipes have had a rapid diffusion in recent decades, using them for the transport of liquids and gases, as they possess good resistance to corrosion by chemical agents, they are light. flexible and have excellent dielectric properties.

Thanks to these characteristics, plastic pipes have also found application for the conveyance (under pressure and by gravity) of polluted waste water. On the other hand, those in PVC, for example, are not suitable for operating pressures higher than 16 bar and for temperatures higher than 60°C or for frequent temperature variations.

Finally, they undergo significant aging (which makes them fragile) if they are subjected to prolonged exposure to light and frequent temperature changes.

The main materials of which the pipes of polymeric material are made are:

• Polypropylene (PP)

• Polyethylene (PE)

• Polyvinyl chloride (PVC)

• Glass fiber reinforced plastics (GRP)

Another very important advantage of pipes made with plastic polymers is their remarkable durability, especially those produced in PVC, which can even reach 50 years of operation if stored and protected in a suitable way.

Thermal expansion

The presence of heat in the line must make us reflect, not only on the type of raw material to be used for the pipes, but also on the behaviors that these raw materials may have during the temperature changes depending on the length of the line itself.

Not only must the operating and peak temperatures be kept in mind, but also the thermal shocks that can occur between parts of colder systems and others hotter.

Furthermore, in a straight pipe with a small diameter, the stretching can lead to a bending (buckling) capable of stressing the flanges connecting the pipes to the equipment dangerously.

Automatic translation. We apologize for any inaccuracies. Original article in Italian.