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Ted Mooney, P.E. RET
Pine Beach, NJ

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Passivating SS

Hi, I have a customer who has (10) 8" butt welded pipes that need to be passivated. These are located in a waste treatment facility--- Austin, Texas. We are a welding and fabrication co and wee asked to give a bid to do the job. I have never preformed this process. Can you please explain the process and equipment involved? As well as an estimated time to do one of these 8" pipes.

Thanks,

Too few details. What SS? Inside & out? Are the pipes loose or already welded? Just the welds or entire assembly? Have the welds been ground smooth, and was an inert gas purged through the inside during welding? Can plastic sheeting be placed beneath piping to avoid acid etching of any concrete present?

ASTM A380 -06, "Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems," gives some guidance on cleaning welds and passivating piping systems.

Stellar Solutions [a finishing.com supporting advertiser] has a brushable gel (CitriSurfÐ 2210) for passivating welds and difficult-to-immerse assemblies.

Ron,

I'm not sure if you mean 8" long pipes or 8" diameter pipes that are 21' long. Obviously, the logistics will be different for each situation. I would recommend you contact a vendor in your area that is capable of performing this type of work. There can be significant problems down the road if the material is not properly passivated. If you want a description of the passivation process you should purchase ASTM A967 and/or ASTM A380 . You can ask your passivation vendor to provide validation testing (expect to pay something for it) and a full and detailed passivation log sheet/report. This way your have covered yourself should corrosion develop in the future.

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