Carbon steel pipework has a number of benefits over its traditional mild steel counterpart, not least in terms of its eco-credentials. Simon Spridgeon looks at the advantages to be gained from choosing this material when specifying pipework
Carbon steel is a versatile metal that can be used on applications as wide ranging and diverse as closed circuit heating and chilled water, wet sprinkler systems, solar heating and compressed air. Whilst, traditionally, mild steel screwed pipework has been used, press fit carbon steel is now widely used and is corrosion resistant in closed heating and chilled water systems so long as the correct procedures are followed. With eco issues being an important consideration on domestic and commercial situations alike, it is well worth taking the time to realise the benefits of opting for carbon steel, particularly over traditional mild steel, in order to fulfil increasingly stringent ecological requirements.

Lightweight carbon steel is up to 50 per cent lighter than traditional steel pipe. This means that not only is installation easier, but as carbon steel uses fewer materials it produces less CO2 during manufacturer. Furthermore, there is less environmental impact in terms of transportation of carbon steel pipework too.

The really good news here is that carbon steel pipe work can be used for a range of applications that may have traditionally relied on copper piping, making it simple for installers to make the switch to a greener way of working.

Carbon steel is suitable for use on closed circuit heating and chilled water applications, wet sprinkler systems, solar heating, plus certain industrial and technical gases and compressed air.

Even better, doing choosing carbon steel is not only a greener option, but could also turn out to be a cost effective option too. Expense is reduced by choosing press fit systems, which cut down on installation times whilst never compromising on safety. Geberit Mapress, available as a carbon steel option, has been proved to reduce costs in excess of 35 per cent according to a BSRIA report, when compared to traditional welded pipe. Such a figure, combined with the eco benefits, means that more and more and installers are sitting up and taking stock of carbon steel piping.

Yet another key benefit of carbon steel is its anti-corrosive nature in closed-circuit systems, however there are a couple of issues that installers should be aware of before going down the eco-friendly path of carbon steel, as problems can occur with carbon steel if it is not installed and commissioned correctly.

The first thing to bear in mind when opting for carbon steel is that prior to fitting the piping must be protected from dirt and damage and, ideally, transported in its original packaging. Pipes should also be protected against moisture and the influence of weather, with the temperature not dropping below the dew point.

Carbon steel products should not be stored alongside stainless steel items to avoid contact corrosion.

For chilled water applications, a vapour barrier must always be maintained in areas where condensation is likely to occur, but if the carbon steel pipe is coated in plastic, extra protection is not required (although the fittings and pipe ends still require protection).

Often, when working on large projects, installers commission and test sections of pipework at a time and then drain them down in between. However, this is really not a good plan with carbon steel as oxygen and water in the pipework that will be residual can begin the corrosion process and once it is started it is almost impossible to stop.

Crucially, the probability of corrosion is increased if oxygen is present in the circuit - concentrations in excess of 0.1g/cu m indicate a greater probability of corrosion. This could occur through compression glands, screw connections or automatic air vent valves if there is negative pressure in the heating system. However, there is no risk of corrosive damage from oxygen that enters when filling and supplementing with water since the amount of oxygen is very low.

Further measures to delay corrosion in carbon steel pipework include adding an oxygen binding substance to the circulating water, setting the pH vale at 8.5 - 9.5 and only using water additives tested and approved by the manufacturer.

Any potential pitfalls of installing carbon steel are simple to avoid and it is well worth the small amount of extra effort required when you consider the long-term gain of a more ecologically sound construction.

A recent re-visit to Mater Hospital in Ireland, where Geberit Mapress carbon steel pipework had been installed some 12 years ago, revealed corrosion free pipework, as effective as the day it was commissioned, proves that with just a few simple precautions this metal could well spell a whole new way of thinking for installers looking for a greener, more cost effective alternative to steel and copper pipework. In fact, Geberit Mapress carbon steel has a service life in excess of 25 years.

Overall, for an eco-friendly, long lasting alternative to traditional mild steel, carbon steel is a more than suitable option and by adhering to a few simple procedural issues we can all look forward to a brighter future.

// The author is product and technical manager for Geberit //