Steel tubing or pipes have the following important advantages over pipes of other materials offered for similar duties.

Greater combined strength and elasticity, giving:

• High resistance to internal and external pressure.
  
  The high tensile strength of steel combined with its elasticity, ductility and freedom from brittleness enable steel pipes to be used with confidence for the highest pressures and under the most onerous conditions.
  
  Steel pipes are particularly able to accommodate handling stresses, stresses arising from abnormal cover, uneven bedding, misalignment or changes of temperature.
  
  In subsidence conditions where severe bending and longitudinal stresses are imposed, steel pipes with their inherent reserves of strength are able to withstand these stresses where pipes of rigid materials, even with flexible joints, would often fail.

• High resistance to shock or vibration.
  
  Stresses much greater than those due to static head can be induced in water by fluctuating pressures, or by shock pressures such as those arising from water hammer. Wherever such conditions exist, or may arise, the high strength and absence of brittleness in steel pipes offer distinct advantages.
  
  Modern traffic conditions impose ever-increasing stresses on roadway foundations. For this reason, it is desirable to avoid laying water mains under roadways. There can be no assurance, however, that future developments will not result in the construction of roadways over mains not designed for such conditions. In these circumstances, steel mains have pronounced advantages over those made of more brittle materials. Steel pipes are practically unbreakable in transport and in service.

Steel pipes are generally made from material having yield stresses and tensile strengths within the following ranges:

Effective protection against corrosion

Steel tube offers a readily galvanised substrate for cost effective corrosion protection. Galvanised offers good abrasion resistance during handling and the nature of the coating allows for corrosion protection even when the coating layer is compromised down to the steel substrate.

Steel tubes lend themselves to the easy application of a variety of paints and coatings for the most arduous of conditions. This unique ability makes steel tube the material of choice where composite conveyance systems are required with high strength, low mass and good corrosion resistance.

Together, the above properties result in thinner pipes and therefore:

• Less mass.
• Less labour in laying.
• Greater capacity for the same outside diameter.
• Greater pressure rating for a given wall thickness.

In addition steel pipes offer:

Greater choice of joints.

A wide variety of joints are available for steel pipes ranging from those with considerable flexibility to others with complete rigidity, namely:

•     Welded joints
•     Klambon joints
•     Flange joints
•     Threaded and coupled

not to mention many other jointing systems. Steel tubes with Klambon couplings, or screwed and socketed to SABS 62, are commonly used in service reticulation systems.

The wide range of available joints gives every variation that may be required in practice, from complete rigidity to angular and longitudinal flexibility, to meet the special purposes and conditions that are involved in conveying water.

Greater carrying capacity

For a given pressure, steel pipes can be made much thinner than pipes of other materials. Consequently they have a greater carrying capacity than pipes of other materials with the same outside diameter.

No breakages

Considerable indirect savings can result from using steel pipes, because they are not subject to the breakages in transit and attendant replacement delays that occur when pipes manufactured from other materials are used resulting in fewer delays in installation.