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By Pratap Gidvani
Managing Director
Rolastar Private Limited, Mumbai
Pratap Gidvani is a B. Tech. (Hons) from IIT Bombay with an MBA from the University of Pittsburgh, USA. His company.s only activity is ductwork fabrication. He can be contacted at ho@rolastar.com and the company's website www.rolastar.com furnishes useful info on ductwork.
In India, ducting clearly features high on any list of project headaches. Yet, for all the effort the end-result in most cases satisfies no one – the quality of ducting continues to be poor, project completion times unduly long and most contractors claim to lose money on this activity.
From the owner/end-user's perspective, the economic penalties are even more acute. Ducting typically represents less than 1% of the overall building costs but is almost always on the project's critical path. As such, the potential savings for the end-user on interest charges alone – from faster completion of the work – are generally more than the entire cost of installed ducting. Further, excessive air leakages from poorly constructed ductwork result in energy losses that verge on being shameful.
The irony is that it is easily possible to obtain good ductwork in India even today. One has merely to look at a site-fabricated duct installation (Photo 1 - indeed one of the better examples) and compare this with a typical modern factory-fabricated ductwork erected under a professional approach to site management (Photo 2).
So why does the industry permit the situation to continue?
The consultants fault the contractors for not doing "a good job"; the latter point to their dependence on unreliable tinkers and margins squeezed so tight that they cannot "afford" to do it any better. Unfortunately, this reflects an industry more distracted by apportioning blame rather than seeking workable solutions.
And the solution is quite straightforward. To raise the level of ducting in India, the industry must bring about a change concurrently at three basic levels, viz: how ductwork should be fabricated, how assembled and erected and the standards under which the ducting system is to perform. We examine each of these below.
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In my considered opinion, the most important factor inhibiting change from taking place fast enough is a lack of a robust, industry-wide standard covering ductwork.
A frequent argument against change is that the newer ducting solutions are said to be more expensive than the conventional practice of site fabrication. This is indeed perverse. It would be perfectly reasonable if such a practice gave the desired end-result but when it clearly doesn't, the appropriate reference point must be a re-defined standard of performance acceptable to the industry and not existing practice.
Consider the evidence. The only "domestic" standard covering ducting (IS 655-19631) available today is unfortunately silent on virtually every important fundamental performance criteria related to ducting. These include air leakage, noise, vibration and structural rigidity to name a few. It is therefore not uncommon to read tender specifications that include statements such as “leakage should be as low as possible”. This is obviously meaningless as an engineering specification and serves only to perpetuate an industry grossly under-performing its potential.
Fortunately, there is a clear recognition by the industry for the need to radically revamp the BIS standards on ducting. Some progress has also been made on this with a few leading consultants having prepared drafts of revised specifications.
The change required, however, is formidable and the process of change also needs to be accelerated substantially. Indeed, a good case can be made for the industry adopting a well-tested, comprehensive international standard such as SMACNA2.
Either way, it is time for a body such as ISHRAE to put its engineering, organizational and financial muscle behind the effort in a concerted manner.
Ultimately, of course, the quality of the project specifications and how well it is enforced that will shape the quality of the installed ductwork. Till such a time as an acceptable industry-wide standard is available for ducting, our recommendation is for the industry to base its tender specifications on SMACNA duly modified for the specific project environment. Reference may also be made to the model ductwork specifications for tender documents from the website: www.rolastar.com
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Sheet metal fabrication today draws on a wide array of specialty machines such as coil-handlers, folders, notchers, shears, presses, profile cutters, edge-formers, lockformers, flangers and punches amongst others. Further, many of these are CNC controlled (see Photo 3). To not use such equipment and technology would be to miss out on the full extent of the benefits available for quality and speed.
At the same time, it is necessary they be operated in a controlled environment of a factory rather than be carted from site to site. As such, the days of moving some basic finishing machines such as lockformers to site are clearly dated. In addition, there are several other benefits from carrying out the fabrication away from the job site, such as lower scrap and wastage, cleaner job sites (Photo 4) which permits greater efficiency in work, lower noise and less pilferage.
A few years ago it became fashionable to specify "factory-made" ducting. Of course this resulted in some operators demanding qualification on the basis of merely having a garage-type workshop with very basic equipment. In today's context, it is therefore necessary to clearly define the fabrication technology acceptable.
Typically, today's state-of-art technology will involve:
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The traditional approach essentially involves the HVAC contractor dumping raw material at site and the ducting sub-contractor essentially taking it from there. The assembly and erection of factoryfabricated ducting, however, imposes a much greater requirement for the contractor's direct involvement in two important areas.
First, in the planning, co-ordination, and control of the job with some of the key activities:
Second, to raise the productivity of the work at site: productivity gains at site translate to both speed of job completion and cost savings. The potential for dramatically improving this with pre-fabricated profiles is so vast that one just cannot afford to miss on it. We have seen several instances of jobs that would take some weeks, being completed in as many days and by a fraction of the number of people involved.
To achieve this, however, will require both proper tools and tackles appropriate for the work at hand and training in their use. This includes small tools (both electrically operated and manual ones (Photo 7) as well as some larger material handling equipment and rigs such as hoists (Photo 8) and scaffolding. A few of the more progressive contractors already maintain such equipment.
Change, as we all know, is never easy. But is it achievable? In this case, most certainly yes – and the opportunities are just amazing. Believe me, I've seen it.
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