Photo Gallery C5:  Favorable Pipe Conditions

Fortunately, not all ultrasonic investigation produce the type of results indicated by our Photo Galleries.  In fact, many of our UT reports are excellent, and help to assure the building owner of long and reliable pipe service.  All pipe is expected to show some impact due to the unstoppable forces of corrosion.  These may be countered by the natural corrosion resistance of the pipe, such as brass or TP, through the addition of a protective finish such as galvanizing, and / or through the addition of corrosion control chemicals.  When accessible to internal inspection, the absence of internal rust or other deposits, surface pitting, and the observation of a relatively smooth internal pipe wall is an always welcomed finding.

For most investigations, results range somewhat midpoint.  In many examples, a thread leak prompting an investigation will expose the fact that threaded schedule 40 pipe only provides a finite number of years of service and has reached retirement, yet all larger welded pipe still offering another 50 years of reliability.  External corrosion due to lack maintenance at the cooling tower pipe does not necessarily define the need for an entirely new piping system.

For one investigation where the remaining condition of the original 18 in. condenser water pipe from 1941 was questioned during a chiller expansion, ultrasonic investigation revealed the original installation of extra heavy ASTM A72 wrought iron pipe, and a consistent wall thickness approaching 0.475 in.  Such results were certainly a shock to project managers having also learned that their new 18 in. pipe fitting up to the 1941 pipe was undersized at 0.350 in., or about 0.125 in. thinner.  For another, where an HVAC contractor determined a 57 year old condenser water system on the verge of failure by tapping on it with his college ring, UT testing identified the surprising installation of extra heavy Bethlehem steel pipe having another 75+ years of service available.

In fact, we have found many examples of old pipe showing little to no internal corrosion after as much as 80 years of service.  Of course, pipe corrosion is very much dependent upon the service provided in combination with the quality of the material installed and other factors.  Yet even for steam and domestic water systems installed over 100 years ago, we have observed open pipe sections showing little to no wear.  Our findings of very favorable results are declining, however, as older buildings age and newer properties begin experiencing the combined impact of higher corrosion activity acting against lower quality and thinner piping products.