Metal Testing/Failure Analysis, Welding Tests, Certification & Evaluation
Grass Valley, California, USA
(Between Sacramento, California and Reno, Nevada)
Serving California, Nevada and Worldwide by Arrangement
Robert C. Helminiak
Principal Technician and Lab Manager
|Stagnant water in 300 Series stainless steel pipe can result in microbiological corrosion pits. Because microorganisms are present in virtually all aqueous systems, they have the potential to influence corrosion pockets.|
|Shown above is the result of this type of corrosion on 304 stainless schedule 10 pipe which was located in a new sewage treatment plant which experienced many leaks in a very short period of time. The photo above on the left shows numerous small pits round and elongated on the inside of 304 stainless steel pipe. The photo on the right is a photomicrograph showing a cross-section of a pinhole opening on surface of the pipe. Note the large cavern below the surface.
Over the years, we have evaluated corrosion conditions in copper water pipes, galvanized water pipes, stainless steel piping systems, steel boiler tubes, aluminum car radiators, steel fuel tanks, stainless steel in marine atmosphere, and bronze water valves.
|Stress corrosion cracking on off-road vehicle coil suspension spring. Photo 1 and 2 show the result of corrosion under stress. A corrosion pit started on the spring's surface creating a stress riser at the pit. The crack progressed causing the separation shown in Photo 2.|