we would like to inspect our cooling water under ground piping after ten years operation of the plant.Is there any suitable NDT procedure for doing this title?We have not any catodic protection system due to the original design of the plant.The pipes are carbon steel and protected only by external wrapping. best regards masoud

MASOUD Mr M.J Cronin had given the guideline for this. Adding further to Mr M.J.Cronin's suggestion to have pipe crawler inspection, the limitation in using crawler may be due to block valves or globe valves in the system. Quick shutting ball valves if installed in the system may be one severe limitaion for pipe crawler use. Also if any orifice plates have been installed this will be also a severe limitation. You may have to remove these for free travel of pipe crawler assemblies with heads suiting to the geometry of the pipe to be inspected. For smaller dia pipes, say 4" or 6" NB, if miter bends had been used during original fabircation of under ground pipeline, there will be a limitation to use pipe crawler assembiles. Normally the bends shuold be 5 Dia (i.e., five times the diameter of the pipe being survey at the bends) the size of the line for crawler assembly to go through easily. For larger dia pipeline there should be no problem for crawler inspection even with miter bends of 3 dia or 2 dia. If the installed length of the pipeline is less than 500 metres then Inspection cost of bringing US crawlier pipe inspection company for this will become cost prohibitive. If it is cross country pipeline of 200-300 km then economics will be good to engage pipe crawlier inspection services. I think in Middle East there will be some pipe crawler inspection companies like Vetco Inspection Services / Tuboscope etc who should be able to support you well at short notice and with all accessories and tools for inspection using small pipe crawler head and also for large diameter pipelines. Trust this is of help to you C.V.Srinivasan Nishi Engineers Pvt Ltd Chennai India Sept 28 E-mail:nishi@vsnl.com/nishi@hathway.com >masoud, > >I suggest that you consider a robotic video survey of the >this system to pinpoint areas of gross corrosion and >degradation. Pipe inspecting robots have been in use for at >least twenty years...... > >Several USA companies offer a video evaluation by "pipe >crawler" and have had much experience with cooling water >systems. A permanent video record is made of the internal >condition. > >As I recall, some machines can offer a "spot " ultrasonic >test of the pipe wall thickness and can sample/extract >corrosion coupons for later evaluation. > >Minimum pipe size is 4 inches NPS and the cable tether can >go to aprox 700 ft or longer. The pipe crawlers can go >around some (larger diameter) bends and can move vertically >up pipe risers. > >My opinion recollections only..... > >MJC