For years pipework contractors have installed compressed air systems in either black iron or galvanised steel pipe. Familiarity has been a major factor along with the fact that material costs are low compared with other piping systems. However the cost of materials must be weighed against many factors and these days old habits are giving way to modern pipework systems.
A major influence is the question of time on site. A pipework system will need screwing together and although fittings are easy to come by specialist threading equipment will be needed to complete the task. To obtain a decent thread some form of lubricant or pipe cutting fluid must be used after which cleaning of each joint will be necessary. To make the joint air tight a sealing compound will also be needed. Time consuming and laborious work particularly if there are many pipe joints and fittings to be installed.
Another issue is weight. This type of pipework is heavy and therefore will need extra labour and people on site to handle it properly. Most compressed air pipework systems are installed overhead making the work doubly difficult. More so when a factory is in full production below, this happens all the time with retrofit systems compared with installing in a new construction.
So what are the alternatives. While stainless steel pipework is and obvious choice pipework contractors are increasingly using aluminium for airlines as they carry with them many advantages. Sure the cost is higher per metre than steel pipework but the advantages are many.
First of all aluminium does not corrode and scale. Many airlines carry some moisture even after drying and eventually this causes scaling inside the pipework. The damage caused by scale fouling delicate compressed air tools and equipment cannot be under estimated. In extreme cases, loose scale can completely clog a line or damage equipment connected to a line. Also corrosion and loose scale affects air quality and makes it unsuitable for applications that require clean air.
Then there is the little matter of weight. Aluminium pipework is lighter than steel and therefore more easy to install (read less labour needed). Aluminium pipe systems are much easier to install and to modify than steel or copper pipe. Labour savings of 50% can be achieved, since aluminium pipe is supplied ready for use. No particular preparations beyond cutting, deburring, and chamfering are required, nor are special tools needed. Using a quick connect click together system each joint is leak free and will remain so. Its estimated that at least 10% of threaded joints will leak at some time in their lives driving up costs as compressors have to work harder to maintain pressure.
The only drawback is one of initial cost, pipework installation engineers will have to shell out more initially but the labour savings in installation or modification in later years pays dividends over an over.