Metal finishing Q&As since 1989
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317L SS surface finishing and pickle & passivate - best way
Q. I have a 10 inch diameter x 17 foot long shell and tube condenser made of 317 L stainless Steel with 904L Stainless steel bonnets on the ends, and titanium tubes. It is to be used in a desalination plant at a nuclear power plant in Japan.
The client specifies that that the unit be "pickled and passivated". We want to make the outside of the shell look nice, so we are thinking of having it blasted with extra fine
[adv: Black Beauty on
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. I need to know if this is considered as pickling and passivation, if not, what chemicals should be used on the material after the blasting.
- Parsippany, New Jersey
2005
A. Mr. Reynolds,
I agree that media blasting the exterior will give you a uniform, attractive appearance. However, this will probably not meet your customers specifications for pickled and passivated. I would assume the interior surfaces that will contact the process stream are the most important to consider. You should use ASTM A380
as a guide for selecting the proper chemicals, contact times, and temperatures. I would recommend you contact a reputable firm near you that is familiar with this type of work and can handle and dispose of the chemicals properly. This HX sounds pricey and I would hate to see you ruin it by exposing it to the wrong chemical solutions. To answer your question directly regarding which chemicals to use, it will probably be some combination of nitric acid and hydrofluoric acid (nasty stuff !). Hope that helps.
- Indianapolis, Indiana
2005
A. Pickle is one process and passivate is another.
Few job shops will be able to handle either process because of the size (and even less will be able to handle both)
- Navarre, Florida
2005
2005
A. As I am only 5400 miles downwind of Japan, I wish to elaborate upon the preceding response.
Don't add or omit anything from the specifications of the customer, ASME, NRC or the Japanese equivalents of these organizations. As considerable engineering went into this HXer, detailed finishing instructions should be available from the customer's engineers. I cannot issue these instructions, but merely suggest that they may be:
Pickle per ASTM B600 (2002) Standard Guide for Descaling and Cleaning Titanium and Titanium Alloy Surfaces. It is likely that all SS & Ti components had been pre-cleaned* before HXer assembly, so a pickling per Paragraph 4.3.2 at about 120 °F for a time of 1-2 minute should suffice. Observe Note 7, which requires a nitric acid to hydrofluoric acid ratio of (at least) 10:1 to avoid hydrogen embrittlement. Within the range of this spec., a solution of 33.2 % nitric acid and 1.6 % hydrofluoric acid is recommended --
ASM Handbook Vol. 5, Surface Finishing (1994), p. 839.
Wash with clean water, high-pressure spray rinse with clean water at 130 °F, rinse in hot DI water and allow to dry.
*Additional Ti cleaning steps in ASTM B600 may be harmful to SS.
Passivate per ASTM A967 Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts. Rinse in hot DI water and allow to dry.
- Goleta, California
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A. I would only add a few comments to the ones above. Pickling and passivation can be accomplished in one process using virgin solution and careful monitoring of the iron content. And while 17' is pretty long, I would not seriously consider immersing the HX. The media blasting originally proposed should be adequate for the exterior surface. The interior can be cleaned, pickled, and passivated by circulating the proper chemical solutions. This can be a little trickier than it might sound. High flow rates are necessary on the shell side to rinse all traces of acid. With that said....I would agree that your customer should provide a detailed specification or reference to follow.
Joseph Lockrem- Indianapolis, Indiana, USA
2005
A. For big stainless steel tanks, use pickling spray jelly for application over large surface area with the special spray bottle. It will avoid problems with dipping a large tank, excessive fumes, etc. With pickling spray jelly you can have much better control; it will be easy to handle the application process. For removing black scales of welding area you may use pickling jelly and then apply pickling spray jelly over entire tank surface. These are as per ASTM A380 and ASTM A967 standards. But, for nuclear projects SS tanks, HF beyond certain limit is not allowed. So, check that with your customer as well.
Vinay Golwala- Mumbai, India
June 28, 2012
Q. The stainless steel frames surrounding port lights on my ocean going yacht are corroding at corners. They are continuously exposed to salt air even when not being splashed in seawater.
The corners only attract a magnet due to having been welded.
Is there a permanent treatment for this condition?
Ocean Cruiser - Colon, Panama
2007
Dear Paul von Wiese,
Use Pickling Jelly on the weld joints and corners where you face corrosion problems. This is proven to remove and prevent corrosion in Stainless Steel. Infact you should be applying at the fabrication stage itself so that corrosion rusting problems don't arise this fast.
- Mumbai, India
July 3, 2012
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