Whether you choose to have a surface, sprinkler, or micro-irrigation system in your orchard, farm or garden, an essential part of any system is the pipes and connectors that will supply your irrigation system with water from a variety of water sources.

The most popular pipe types for irrigation systems are galvanised piping (silver in appearance) and PVC/plastic piping (usually blue or black). There is also micro-irrigation piping.

Galvanised pipes are covered with a zinc material to make the pipe more resistant to corrosion. The primary use of galvanised pipes is to supply water to homes and buildings. The zinc coating also prevents the build-up of mineral deposits that can clog the waterline.

Galvanised pipes are popular for numerous reasons:

-Higher bursting pressures than conventional water pipes (25bar)
-Can be used to pipe very hot water and cold water (20-125°C)
-Very rigid and robust. Once the pipe has been installed, it will not dislodge or break easily
-Pet/animal friendly. Dogs love chewing pipes, not a galvanised pipe! In dry rural areas, porcupines are known to chew through plastic pipes to get to the water.
-Long life expectancy

Where galvanised pipes can be used:

-Fire sprinkler systems. The high heat and pressure rating make it ideal for supplying water in “fire emergencies”.
-Above ground piping where direct sunlight will cause plastic pipes to perish
-Pipes that are installed in or below paving/concrete or other areas with heavy foot/vehicular traffic, these pipes will not break as easily as PVC or collapse like polyethene pipes

Overall, galvanised pipes will last for many years, although this is largely dependent on the quality of the water. Water with higher sodium levels, as an example, will corrode the pipe from the inside and could knock off a couple of years. A pipe that is corroded from the inside will develop a thinner wall thickness, therefore more likely to burst with higher pressure or when, in colder areas, water inside the pipe freezes.

A galvanised pipe is most commonly installed above ground due to its robust characteristics. It is only used underground when a stronger pipe is needed, as it can become expensive over long distances.

Agrinet’s exclusive brand, K-Brand, has a series of galvanised pipes and associated fittings which are manufactured to the highest quality standards according to local and international standards. One of the most important features is the layer of galvanising is 55 microns thick, this helps prevent corrosion.

Here are illustrations of how galvanised piping can be used within an irrigation system:

Galvanised pipes also come with threading on both ends to easily connect with the use of a socket. Various pipe diameters are available to suit your irrigation system needs.

Technical features of galvanised pipes:

-Seamless pipe helps ensure the structural integrity of the pipe.
-Thread cut with a CNC so that the thread stays within the BSP parameters.
-Pipes are supplied with a thread protector to ensure the thread does not get damaged during transport.
-The manufacturing process ensures that the inside wall of the pipe is smoother compares to competitors. A smoother pipe on the inside means less friction loss and less place for foreign material to snag onto.

Ideal uses:

-A popular application for this pipe is in boreholes, especially in boreholes with high pressure.
-Any pipeline that has high pressure or in areas where external factors require the use of a strong rigid pipe.
-Gas and oil pipelines
-As trunking for cables that are installed in concrete.

CONNECTORS USED ON GALVANISED PIPE

K-Brand, an Agrinet exclusive brand of galvanised fittings offer a wide range of fittings in all shapes and sizes to ensure that any adaption can be made. Whether you need couplings between pipes, elbows to take a corner, Tee-pieces to add another outlet, reducing bushes or sockets adapt to different sizes, Agrinet offers it all!

Technical quality-check features to look out for in galvanised fittings:

• Rust indicates that the galvanising is not up to standard. Proper galvanising protects from rust if the item shows signs of rust while still on the shelf, it is sub-standard
• Seams indicate a forged fitting. Forged fittings are generally a lot weaker as the seams are possible weak spots prone to bursting
• Pitting. Small pinholes on the surface of the fittings indicate an inferior casting process where air got trapped.
• Burring (small pieces of metal) in the thread of the fitting. This could cause a cross-thread or the fitting not to seal properly.
• Smoothness on the inside shows that the manufacturer took care to produce a fitting that will have low friction losses, this shows a high-quality fitting.

The threads on the K-Brand galvanised products have been cut with a CNC machine to ensure accuracy, that combined with the cleaning of all excess burring, ensures a tight fit, but to make the connection watertight here are three methods used to prevent / repair leaks in galvanised pipe:

PVC pipes are typically used underground where they are protected from external factors due to the brittle nature of the pipe material. These pipes are most commonly used with “aggressive” water as they are more resistant to corrosion and is a more budget-friendly option, compared to galvanized or copper pipes. PVC pipes are mostly used for large irrigation systems, due to that fact that they are available in larger diameters, therefore able to transfer more water than most other types of pipes. However, plastic pipes do have a shorter life span as it can deteriorate with environmental factors.

SABS pipe can last up to 20-30 years underground. Proper installation is important:

• The pipe must be 1m underground.
• A layer of fine sand, at least 100mm thick must be poured below (bedding) and over (blanketing) the pipe to prevent sharp stones from puncturing the wall of the pipe

Above ground but indoors, the life expectancy will be similar to that of underground installation. Above ground exposed to the elements, climate plays a major role, so anywhere from 5-15 years. Maybe even less when exposed to all-day direct sunlight, especially if a non-SABS pipe was used.

Although choosing a PVC pipe seems pretty simple, there are a few things to keep in mind:

• Colour. With water pipes, it is preferable to use blue. Beige pipes are seen as sewerage pipes, it’s not recommended to confuse the two. Black PVC pipes can be used for water but are very low pressure (below 1 bar) pipes and are not recommended.
• Seams. Again, seams indicate weakness and that the wrong extrusion process was used.
• The writing on the pipe will indicate pipe size, class, and whether a SABS mark is present or not.
• The class printed on the pipe indicates the maximum working pressure. Class6 = 6bar, class10 = 10bar, etc.
  Pro tip: make sure that the black O-ring rubber is in the pipe when purchasing, they often fall out. 

The most common fittings used are known as “solvent weld” fittings that, with the use of a PVC glue, is applied onto the PVC pipe. When set, the joint/fitting will be able to handle up to 16bar in pressure.

Other fittings, known as “PVC fabricated” are custom made to accommodate different angles, outlets or adaptions.

what to look for when buying these connectors:

-The PVC pipe must fit snugly into the fitting, any play indicates either a sub-standard fitting or pipe.
-Name brands are not just important on clothing, make sure that the fitting comes from a reputed manufacturer or wholesale dealer, like Agrinet.
-Pressure rating indicated on the fitting. No rating likely means it is not able to handle normal pressure, so it will probably burst.
-Colour. Stay away from beige / white fittings that look similar. Grey-black for solvent weld fittings and blue for

LDPE (low-density polyethene) and HDPE (high-density polyethene) are the most common types of piping used in irrigation, whether for your little vegetable patch on the balcony of your apartment or much larger farm irrigation projects. These pipes are black and almost always used underground. LDPE is usually the favourite between the two because the fittings (nylon inserts + clamp or full flow) used on LDPE are cheaper than the fittings (compression fittings) that are used on HDPE. Another reason for the popularity of polyethene pipes is that they are resistant to corrosion and cheaper than other pipes used for irrigation.

Green PVC standpipes available in various lengths and diameters, to suit your exact irrigation needs. Both ends of the pipe have threading to easily use connecters.

Copper pipes are not recommended to be used as water pipes for irrigation purposes as they are more commonly used as water supply to a house or building. Copper pipes are more prone to freezing when temperatures drop and are also more easily crushed. Despite being able to use copper piping for extended periods as it is resistant to corrosion, it has quite a high cost.

Many options are available when it comes to piping for irrigation systems and selecting the ideal pipe for your system will depend on the system’s volume water requirements, size, budget constraints and quality requirements.

For more information on irrigation piping, please contact Agrinet’s technical irrigation team or systems team on enquiries@agrinet.co.za, or call them on 012 657 2222.

To learn more about DIY Garden Irrigation, follow Agrinet on social media and our website to see newly posted blogs in this series first.