Ice Pigging™ Can Clean Cast Iron Pipes…Under the Right Conditions

cast iron pipes

Ice Pigging™ Can Clean Cast Iron Pipes…Under the Right Conditions

Aug 2022

To clean or not to clean…unlined cast iron pipes, that is. A risk assessment on cleaning unlined cast iron pipes using Ice Pigging™, a highly effective and efficient cleaning technique that has been around for decades, is always a must as per Ice Pigging™ protocols, which is always an ethically sound and professional approach.

Cleaning cast iron mains has always been a challenge among industry-level cleaners in that one has to do some form of balancing act on the best approach to take. Traditionally coated internally with coal tar or bitumen (with cement or epoxy linings taking over since the 1970s), which all help reduce pipe corrosions, these pipe linings nonetheless can deteriorate over time. This can lead to the leaching of harmful substances, such as Polycyclic aromatic hydrocarbons (PAHs) including fluoranthene and benzo(a)pyrene, and others that potentially pose health risks for humans.

With the popularity of Ice Pigging™, one would think that it has become the answer to all problems related to cleaning industry-grade pipes. After all, Ice Pigging™ has proven itself to be one of the best all-around pipe cleaning techniques in the industry. It can even be applied to unlined cast iron pipes, which cannot be said for more intrusive methods such as foam pigs and jetting.

Discovered a little over two decades ago, Ice Pigging™ has many advantages. Apart from using less than 50% of water (due to its unique ice slurry composition) compared to a typical swabbing operation, Ice Pigging™ also reduces the process to only a few hours, but with a clean-up quality that is around 1,000 times cleaner than the more traditional ones. Useful in larger pipe diameters and at greater lengths, Ice Pigging™ is synonymous with efficiency and improved overall operational effectiveness. Plus, it is less abrasive or less aggressive, which means it normally preserves the integrity of pipes and its linings. It does not add unnecessary stresses to the pipe network, thereby decreasing leakages and other disruptions. Unlike traditional methods, Ice Pigging™ will not get stuck inside the pipes and, in the rare cases it does, it would simply be left to melt and be flushed out.

Nevertheless, water companies need to carefully consider the options before carrying out any cleaning project, and especially with cast iron pipes, it is important to know that they are in a suitable condition for cleaning. There are, at least, two things to consider.

One is if the pipe has no lining, and especially if active corrosion of pipe walls is present, the so-called ‘red water’ in the supply chain is indicative of high iron levels. As ideal as Ice Pigging™ can be, it is not without its limitations. It is important to clarify that Ice Pigging™ is a pipeline ‘cleaning’ method, not a corrosion control mitigation process. While it is very effective in removing debris and other particulates, it is not an answer to corrosion. If the cast iron pipes have deteriorated and corroded, no amount of cleaning would improve it. The only answer is to replace said pipes.

On the other hand, where there are lining present, Ice Pigging™ could remove biofilm, which is a breeding ground of potentially harmful and infectious viruses and bacteria. Studies have shown that coal tar coatings present in water pipes support the growth of microbiological colonies more than uncoated ones. These linings apparently are a form of ‘nutrient source’ for such microorganisms. These ‘problematic’ outcomes could mean more repairs, maintenance, and treatments for companies.

In any case, Ice Pigging™ operations for cast iron pipes may yield varying outcomes based on different factors. Thus, the need for a thorough risk assessment evaluation using a scoring mechanism in the table shown below. A score of 1 for any of the items means there is a high risk of negative outcome post cleaning. The same goes for a total score below 6 points. This means the companies requesting the cleaning will have to do more investigations of the existing cast iron pipes with a goal to increasing their overall scores.

ElementGuidelinesScore
Historic Water Quality1 – 3
(1: no info or poor results – 3: no historic failures for PAH / Iron)
Pipe Cut Outs1 – 3
(1: no cut out or bitumen lining present – 3: cut out available and the pipe walls looks in reasonable condition)
Ability of Post Cleaning Flushing and Management of Customers1 – 3
(1: no ability to flush post cleaning – 3: ability to flush continually until water quality returns to normal and manage customers with alternative drinking water supplies, if necessary)
Total Score

It is important to note that while Ice Pigging™ has so much to offer, this technology can only do so much. Partner companies also need to do their part in ensuring that they set the proper environment to get the most out of Ice Pigging™ operations, and one that would be cost effective and long-lasting. It takes two to tango, as the saying goes, and this holds true in the Ice Pigging™ pipeline (pun intended).



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