Material for cooler

[maintennance]

One of the Client specification says that the lube oil system ( as per API 614 Chapter3) shall be completely in Stainless steel ( cooler shell, tubes , tube sheet, filter housing valves, pipelines etc). The reason for asking SS410 cooler tubes is said that the cooling water have about 350 ppm of chloride . The reason asking stainless steel material complete in the Lube oil side is that to avoid the rust collection in the system.

Thanks to clarify whether Admiralty brass is suitable for 350ppm chloride water? Whether rust collection will be there as envisaged by the client in the lube oil system?

The above lube oil system is going to be used for pump and motor bearing lubrication. My opinion is that , the reservoir and the lube oil pipings alone can be in Stainless steel and rest of them can be in carbon steel .Thanks to evaluate my stand.

 

[ccfowler]

Placing your question in a Materials forum would be a much better way to get a more useful answer. Also, it would be best to describe your system in more detail so others can better understand the specific situation.

In my own experience, I have often found "stainless steel" to be used to fix "problems" as though it were some sort of magical material that can solve any problem. Usually, "stainless steel" used in such a fashion seems to be regarded as being a singular, almost sacred material by people who commonly are unaware of the many grades and their variety of properties. Long ago, I began regarding the discovery of "stainless steel" in a troubled system as a very important warning sign to investigate that system and its problems with very great caution. In most cases (probably at least 4 out of 5), the use of "stainless steel" was a major factor in subsequent problems that were often more serious than the problem that brought on the use of "stainless steel" as the presumed magic solution.

In one particularly spectaularly expensive misapplication of "stainless steel" in a new construction situation, it was ultimately learned that "stainless steel" had been specified initially (with no reference to a particular grade). [In reality, #316 may have been at least a tolerable choice for its particular corrosion resistance capabilities in this application.] Unfortunately, the person specifying the materials for this job discovered, upon reading a suppliers' catalogs, that in fact numerous grades of stainless steels were available. Of the grades that were readily available in sufficient quantites at the time, #416 was chosen on the basis of that being the highest number designation, and on that basis alone, it was simply presumed to be "the best" grade. An almost incredible sequence of events arising from this material selection resulted in greatly excessive initial materials costs compounded by subsequent, needlessly costly construction site difficulties, and needless subsequent corrosion related problems that "stainless steel" was chosen for the purpose of avoiding. (Several people could have enjoyed long, lavish retirements on the money that this one blunder wasted.)

Valuable advice from a professor many years ago: First, design for graceful failure. Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs. Only then can practicality and economics be properly considered.

 

[maintennance]

Thank you ccfowler for your reply. Exactly i am also in line with your opinion. Actually the cooler shell proposed is ss316 and filter housings are ss304.The reason i raised this query in this pump forum is that these lube oil coolers will be used for the rotary equipments and i would like to get the opinion of the users. Whether carbon steel coolers will pick up the rust and circulate in the system?Thanks to clarify.

 

[ccfowler]

Your lube oil should not be circulating chlorides unless the cooler is leaking into the oil, and that would not be a situation where lots of stainless steels would matter much to system survival. Does someone have a great dersire to have lots of shiny stainless steel for appearance purposes? A system that starts out clean and is only filled with lube oil that is kept in good condition will not experience any internal rust problems. External rusting can be controlled with suitable coatings.

You may need to protect your lube system from internal sweating due to excessive cooling and allowing exposure to moist ambient air. If this is a potential problem, then plan to use suitable means to protect your system.

Valuable advice from a professor many years ago: First, design for graceful failure. Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs. Only then can practicality and economics be properly considered.