Water-based fire system piping must be periodically examined internally in order to comply with NFPA 25, Inspection, Testing and Maintenance of Water-Based Fire Protection Systems. The standard way to achieve compliance with the code is to drain the system, open it up and look inside. This is time consuming and potentially disruptive, among other issues the industry has with the requirement.
But this is not the only method available to comply with NFPA 25. Ultrasound or ultrasonic technology is available as an alternative and less-disruptive testing protocol, according to an article in NFPA Journal. The sprinkler industry has used two forms of this technology for years with good results, the article says.
One option is pulse echo ultrasonic technology. This measures remaining wall thickness by bouncing a straight beam signal through the pipe, which bounces back off the back wall. The accuracy of this measurement is down to the thousandth of an inch, says the article.
The other ultrasonic option is guided wrap wave, which sends a wave around the circumference of the pipe, creating a signature. This is then compared against the signature of a pipe in perfect condition. Discrepancies between the two measurements can indicate a number of issues, such as corrosion, ice plugs and other changes.
The article states there is controversy in the industry on the necessity and appropriate frequency of internal fire system pipe testing. While that debate continues, this is at least an additional method to comply with the code in the meantime.
Read the article.