The metric system is not truely metric in most of the world.
Heat Exchanger tubing and pipe sizes are actually the old English sizes established long long ago.
I laugh every time I look at a European Tubing manufacture catalog and see 12.70mm, 15.88mm, 19.05mm, 25.4mm tubing.
I don't see 10, 15, 20, 25, etc. mm tubing.
Pipe is the same worldwide as far as I can tell.
A couple years ago I did an engineering consulting job for a Chinese Power Plant. All the piping was listed in metric equivalents of standard English pipe sizes and thicknesses.
1) Where you have very dirty water or heavy fouling on one side (which you design to go through the tubes). It's a lot easier to clean the tubes than disassemble and clean the plates.
2) When dealing with hazardous or radioactive substances on one side. You can clean the tube side without having to deal with the hazardous or radioactive materials.
3) When dealing with condensation (Condensers, FW Heaters, Distillers, etc.)
Also:
A) It's easier to find and plug a leaking tube than find a leaking plate; and titanium does develop leaks.
B) Tubes can easily be NDE inspected for degradation via eddy current/remote field/UT, while plates cannot be and require the entire HX to be dissembled to eyeball (which will often miss things NDE inspection would find).
C) Titanium is often galvanically incompatible with system piping and components; and other alloys are in fact a better choice (galvanic corrosion issues with heat exchangers are something I'm an expert at).
I've retrofitted many plate HXs into older power plants, and yet specified 4 times the value of replacement tubed heat exchanges than I've specified plate HX's (Note I had the Title of Heat Exchanger Engineer in a nuclear power plant with a $million+ inspection and testing budget for 14 years, and have specified at least $50 Million in replacement heat exchangers in a variety of fossil and nuclear power plants, and a few industrial plants).
Tubed heat exchanges have an important roll, and always will.
a pre-strainer / filter and or backflush arrangement clears 90% of cloggin issues
closed loop chemical cleanin clears the other 10%
and proper water treatment eliminates most bio fouling issues in closed loop systems anyway
its still easier to pull a [properly assembled & compressed] plate exchanger apart than unroll tubes but why unroll em when you can plug em
but i dont get in depth enough to ndt good workin heat exchangers cause why do it outside critical industries like nuke plants
and of course nobody has plate type condensers
i still got some fluroscein dye at home awaitin the proper st pats day pool party
ive tried to git plates welded for pinholes and nobodyd touch em so yeah i get that its very reactive to oxygen when hot
not only that but first time i walked into the scrapyard with titanium i thought i was carryin gold plated platinum & was shocked by how little its worth
far as galvanic corrosion who dont have a pipe bondin program or sacrificial anodes or cathotic protection?
and ive never dealt with radioactivity thank fuck
the chinese workin with it sounds like a disaster waitin to happen hopefully the management takes safety culture seriously there
To clarify: Plate HX's have a place. So to do Tubed HX' (and spiral tubes, etc., and even direct injection where you mix the fluids).
When building a new plant where you can specify adequate pre-filters plate HX's win out more often than tubed HX's except for condensation service and certain hazardous chemical environments. These modern plants almost always have closed cooling water systems where only 1 set of HX's are exposed to the base cooling water for the plant.
However, when dealing with an existing plant that was built with tubed heat exchangers it is often more economical to replace a HX with a tubed HX in a number of applications than change to a plate HX. Especially if they have raw surface water cooling piped all over the plant.
Tubed heat exchanger materials have evolved to where retubing or bundle replacement was a fairly routine activity (every 5-15 years) to now a rare activity (every 30 years too life of the plant: Admiralty Brass and plain copper has rarely had long life).
Designing HX's that do not have noticeable galvanic corrosion issues within themselves or on the adjacent piping for 40+ years is not simple: The old classic tube/tubesheet/baffle/shell alloys that worked for 100 years and did not cause galvanic corrosion to the adjacent piping are now rarely used. SS, the superferritic SS's, Titanium can cause the adjacent piping to have galvanic corrosion if not done right (especially if connected to carbon steel piping).
All HX materials are subject to other degradation factors other than chemical attack and may need NDE inspections for critical or hazardous applications to minimize to the lowest number possibility of leaks. In those cases tubed HX's often win out over plate HXs.
Galvanic corrsion is not just a problem with titanium. Even high alloy SS used to retube HX's with muntz tubesheets develop galvanic corrosion of the tubesheets after 20 years that threaten the life of the HX (and its the tubesheets that go bad).
Same with SS tube retubes of brass or CuNi tubed condensers with steel tube-sheets.
Getting the right metals to prevent galvanic or using other methods to control it is a huge deal for long life HXs. Titanium is far worse than other alloys - and you really have to be careful (AL6XN, SeaCure, and other super ferritics are also an issue - and I have a lot of experience using them -and desiging appropriate tubesheet, baffle, and shell materials to set down things in small enough increments to not have galvanic corrosion issues within the HX and in the attached piping system.
You cannot install sacrificial anodes on a tube-sheet to protect it or the tubes. There have been attempts to use impressed current - and if that is set wrong it destroys the tubes or the tube-sheet (as many plants can attest)
Plate HX's are fine on closed loop cooling systems. But raw water cooled heat exchangers often cannot be adequately filtered at a reasonable cost. It's quite common to have duplicate HXs and just clean the HX as the most cost effective way (you open them up and run brushes, scrapers, or hydrolance down the tubes).
We did retrofit large self cleaning rotary baskets on one set of raw water HXs for the bulk fouling that occasionally occured; and then found that at least once a year that even those plugged up and the bypass opened during major fouling events; and we had to clean the HXs anyway. When we replaced the HX's we removed those strainers as they were not helping much (and the new HX was designed to handle a lot of fouling).
Even a lot of normal industrial and power plants NDE heat exchangers to locate degraded tubes and shells. Its a lot cheaper to preventively plug and repair shells than wait for the failure.
Where there are hazardous chemicals or safety critical applications... more NDE is done, and done more often. Leaks can be very costly.
Do you prefer the metric system or the imperial system?
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The metric system is not truely metric in most of the world.
Heat Exchanger tubing and pipe sizes are actually the old English sizes established long long ago.
I laugh every time I look at a European Tubing manufacture catalog and see 12.70mm, 15.88mm, 19.05mm, 25.4mm tubing.
I don't see 10, 15, 20, 25, etc. mm tubing.
Pipe is the same worldwide as far as I can tell.
A couple years ago I did an engineering consulting job for a Chinese Power Plant. All the piping was listed in metric equivalents of standard English pipe sizes and thicknesses.
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donteatstuffoffthesidewalk
2 years ago
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pipe sizes are standardized
25mm is roundly one inch pipe but the pipe size has fuckall to do with one inch or 25mm
and the threads are all npt standards no matter where you go
if youre figurin water volumes & weights metric is way easier
1000 liters = 1 cube = 1 ton metric = easy peasy
but any measure i can blast back & forth in my head with no issues
and titanium plate heat exchangers are bulletproof why would anyone use tubes anymore?
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olderdude-xx
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Tubed heat exchanges work best:
1) Where you have very dirty water or heavy fouling on one side (which you design to go through the tubes). It's a lot easier to clean the tubes than disassemble and clean the plates.
2) When dealing with hazardous or radioactive substances on one side. You can clean the tube side without having to deal with the hazardous or radioactive materials.
3) When dealing with condensation (Condensers, FW Heaters, Distillers, etc.)
Also:
A) It's easier to find and plug a leaking tube than find a leaking plate; and titanium does develop leaks.
B) Tubes can easily be NDE inspected for degradation via eddy current/remote field/UT, while plates cannot be and require the entire HX to be dissembled to eyeball (which will often miss things NDE inspection would find).
C) Titanium is often galvanically incompatible with system piping and components; and other alloys are in fact a better choice (galvanic corrosion issues with heat exchangers are something I'm an expert at).
I've retrofitted many plate HXs into older power plants, and yet specified 4 times the value of replacement tubed heat exchanges than I've specified plate HX's (Note I had the Title of Heat Exchanger Engineer in a nuclear power plant with a $million+ inspection and testing budget for 14 years, and have specified at least $50 Million in replacement heat exchangers in a variety of fossil and nuclear power plants, and a few industrial plants).
Tubed heat exchanges have an important roll, and always will.
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donteatstuffoffthesidewalk
2 years ago
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well shit youre right
but
a pre-strainer / filter and or backflush arrangement clears 90% of cloggin issues
closed loop chemical cleanin clears the other 10%
and proper water treatment eliminates most bio fouling issues in closed loop systems anyway
its still easier to pull a [properly assembled & compressed] plate exchanger apart than unroll tubes but why unroll em when you can plug em
but i dont get in depth enough to ndt good workin heat exchangers cause why do it outside critical industries like nuke plants
and of course nobody has plate type condensers
i still got some fluroscein dye at home awaitin the proper st pats day pool party
ive tried to git plates welded for pinholes and nobodyd touch em so yeah i get that its very reactive to oxygen when hot
not only that but first time i walked into the scrapyard with titanium i thought i was carryin gold plated platinum & was shocked by how little its worth
far as galvanic corrosion who dont have a pipe bondin program or sacrificial anodes or cathotic protection?
and ive never dealt with radioactivity thank fuck
the chinese workin with it sounds like a disaster waitin to happen hopefully the management takes safety culture seriously there
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olderdude-xx
2 years ago
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olderdude-xx
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To clarify: Plate HX's have a place. So to do Tubed HX' (and spiral tubes, etc., and even direct injection where you mix the fluids).
When building a new plant where you can specify adequate pre-filters plate HX's win out more often than tubed HX's except for condensation service and certain hazardous chemical environments. These modern plants almost always have closed cooling water systems where only 1 set of HX's are exposed to the base cooling water for the plant.
However, when dealing with an existing plant that was built with tubed heat exchangers it is often more economical to replace a HX with a tubed HX in a number of applications than change to a plate HX. Especially if they have raw surface water cooling piped all over the plant.
Tubed heat exchanger materials have evolved to where retubing or bundle replacement was a fairly routine activity (every 5-15 years) to now a rare activity (every 30 years too life of the plant: Admiralty Brass and plain copper has rarely had long life).
Designing HX's that do not have noticeable galvanic corrosion issues within themselves or on the adjacent piping for 40+ years is not simple: The old classic tube/tubesheet/baffle/shell alloys that worked for 100 years and did not cause galvanic corrosion to the adjacent piping are now rarely used. SS, the superferritic SS's, Titanium can cause the adjacent piping to have galvanic corrosion if not done right (especially if connected to carbon steel piping).
All HX materials are subject to other degradation factors other than chemical attack and may need NDE inspections for critical or hazardous applications to minimize to the lowest number possibility of leaks. In those cases tubed HX's often win out over plate HXs.
I wish you the best...
Galvanic corrsion is not just a problem with titanium. Even high alloy SS used to retube HX's with muntz tubesheets develop galvanic corrosion of the tubesheets after 20 years that threaten the life of the HX (and its the tubesheets that go bad).
Same with SS tube retubes of brass or CuNi tubed condensers with steel tube-sheets.
Getting the right metals to prevent galvanic or using other methods to control it is a huge deal for long life HXs. Titanium is far worse than other alloys - and you really have to be careful (AL6XN, SeaCure, and other super ferritics are also an issue - and I have a lot of experience using them -and desiging appropriate tubesheet, baffle, and shell materials to set down things in small enough increments to not have galvanic corrosion issues within the HX and in the attached piping system.
You cannot install sacrificial anodes on a tube-sheet to protect it or the tubes. There have been attempts to use impressed current - and if that is set wrong it destroys the tubes or the tube-sheet (as many plants can attest)
Plate HX's are fine on closed loop cooling systems. But raw water cooled heat exchangers often cannot be adequately filtered at a reasonable cost. It's quite common to have duplicate HXs and just clean the HX as the most cost effective way (you open them up and run brushes, scrapers, or hydrolance down the tubes).
We did retrofit large self cleaning rotary baskets on one set of raw water HXs for the bulk fouling that occasionally occured; and then found that at least once a year that even those plugged up and the bypass opened during major fouling events; and we had to clean the HXs anyway. When we replaced the HX's we removed those strainers as they were not helping much (and the new HX was designed to handle a lot of fouling).
Even a lot of normal industrial and power plants NDE heat exchangers to locate degraded tubes and shells. Its a lot cheaper to preventively plug and repair shells than wait for the failure.
Where there are hazardous chemicals or safety critical applications... more NDE is done, and done more often. Leaks can be very costly.