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patching holding tank?
My holding tank has a small split 1/2" in the top, it is white plastic
(polyethylene?) 27 gallon seems fairly heavy. What is the best way to repair this? -Allen |
bushman wrote:
My holding tank has a small split 1/2" in the top, it is white plastic (polyethylene?) 27 gallon seems fairly heavy. What is the best way to repair this? It's almost impossible to repair a PE tank, 'cuz nothing bonds permanently to it. The only thing that does work is heat welding, which requires melting both enough new poly and enough of the edges of the crack to allow it all to run together to become a single mass again. That takes a bit skill, to melt just enough of the tank without melting enough of it weaken it. Just melting some P-Tex into the crack won't work...'cuz unless the tank wall is blended with it, the same stress that caused the tank to crack in the first place will cause the P-tex to let go. If was a water tank, I'd say give heat welding a try...or even just drill small holes at each end of the crack to keep it from spreading any further. If it doesn't work, it's just water. But a waste tank...if it were mine, I'd bite the bullet and replace it. -- Peggie ---------- Peggie Hall Specializing in marine sanitation since 1987 Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and Other Sources of Aggravation and Odor" http://www.seaworthy.com/store/custo...0&cat=6&page=1 |
"bushman" wrote in
: My holding tank has a small split 1/2" in the top, it is white plastic (polyethylene?) 27 gallon seems fairly heavy. What is the best way to repair this? -Allen 1) Picture the wife's face when she comes aboard right after 27 gallons of rotting s**t has run out of the damned plastic tank into the bilge. 2) Picture YOU trying to clean the bilge after it splits and getting that awful rotting-crap smell out of the cushions, bedding, towels, clothes, everything! 3) Picture YOU at the marine store buying a replacement with 1 and 2 still in your mind, oblivious to the cost of the new tank. -- Larry This jerk called my cellphone and was nasty. Continental Warranty -- MCG Enterprises -- Mepco- 24955 Pacific Coast HWY Suite C303 Malibu California 90265 888-244-0925 Fax: 310-456-8844 Email: Read about them he http://www.ripoffreport.com/view.asp...3&view=printer |
On Thu, 14 Jul 2005 17:56:47 GMT, "bushman" wrote:
My holding tank has a small split 1/2" in the top, it is white plastic (polyethylene?) 27 gallon seems fairly heavy. What is the best way to repair this? -Allen An experienced repair person can "weld" a polythene stick into a cracked polythene tank to mend it. You (and I) probably can't. Brian Whatcott Altus OK |
On Thu, 14 Jul 2005 17:29:02 -0400, Larry wrote:
.... -- Larry This jerk called my cellphone and was nasty. Co#####al Wa###ty -- M#####rises -- M###- 24### Pacif#####t HWY Suite C### M###u California 90###888-244-0925 This signature makes you seem to come off as a whiny grudge bearer with a chip. Is this impression you wanted to send, Larry? Don't just take my word for it, btw Brian Whatcott Altus, OK |
Brian Whatcott wrote:
An experienced repair person can "weld" a polythene stick into a cracked polythene tank to mend it. True...and if it were a water tank, he'd had no trouble finding someone who knows how...just look in the YP for "plastics mfrs." But in nearly 20 years in the marine potty biz, I have yet to find ANYone willing to work on a used waste tank. -- Peggie ---------- Peggie Hall Specializing in marine sanitation since 1987 Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and Other Sources of Aggravation and Odor" http://www.seaworthy.com/store/custo...0&cat=6&page=1 |
Brian Whatcott wrote in
: Is this impression you wanted to send, Larry? Just ignore it. The purpose is so the spambots can collect it. -- Larry This jerk called my cellphone and was nasty. Continental Warranty -- MCG Enterprises -- Mepco- 24955 Pacific Coast HWY Suite C303 Malibu California 90265 888-244-0925 Fax: 310-456-8844 Email: Read about them he http://www.ripoffreport.com/view.asp...3&view=printer |
I have "welded" many polyethylene parts using a common electric soldering
pencil, anywhere from 25 to 125 Watts, and scrap polyethylene from any source. With a little practice, you could do it yourself. Melt, but do not burn, the plastic. Welding kits are also available from Harbor Freight for $30-$40 with "torch" and rods. Not necessarily saying you should, but if you are looking to have something else done anyway, you might want to try it first. BS "Brian Whatcott" wrote in message ... On Thu, 14 Jul 2005 17:56:47 GMT, "bushman" wrote: My holding tank has a small split 1/2" in the top, it is white plastic (polyethylene?) 27 gallon seems fairly heavy. What is the best way to repair this? -Allen An experienced repair person can "weld" a polythene stick into a cracked polythene tank to mend it. You (and I) probably can't. Brian Whatcott Altus OK |
Robert or Karen Swarts wrote: I have "welded" many polyethylene parts using a common electric soldering pencil, anywhere from 25 to 125 Watts, and scrap polyethylene from any source. With a little practice, you could do it yourself. Welding parts together is one thing...but mending a crack in a tank adds another dimension, because you have the weight of the contents--8.333 lb/gal for water and waste, which would be 227 lbs in a 27 gal tank) pushing against the walls of the tank trying to pull the crack apart again...if the contents are shifting while the boat is underway, they're pushing even harder. Then there's quality of the original tank material itself to consider...why it split in the first place. Even if the weld holds, will the same forces that created the first crack cause a split somewhere else? So, as I said earlier, if it were a water tank he'd have little to lose by trying to mend it. But when it comes to waste tanks, the wisest course is replacement. -- Peggie ---------- Peggie Hall Specializing in marine sanitation since 1987 Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and Other Sources of Aggravation and Odor" http://www.seaworthy.com/store/custo...0&cat=6&page=1 |
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Just a small technical correction, Peggie. The weight of salt water is, in
fact, 8.33 lb/gal, but that is misleading. The pressure exerted is .444 psi/ft. So if the tank is 2 ft deep, the pressure is only .888 psi, which would also be the pressure on the walls at the bottom of the tank. The total force on the wall if the tank were 1.3 ft wide on a side (for about 27 gal) would by 166 lbs. As long as a true "weld" is achieved equal to or greater than the wall thickness, its integrity will be as great as the wall itself. I have certainly welded the bottoms of polyethylene buckets one foot deep without any problems. I can't speak to the integrity of the tank itself, of course. BS "Peggie Hall" wrote in message .. . Robert or Karen Swarts wrote: I have "welded" many polyethylene parts using a common electric soldering pencil, anywhere from 25 to 125 Watts, and scrap polyethylene from any source. With a little practice, you could do it yourself. Welding parts together is one thing...but mending a crack in a tank adds another dimension, because you have the weight of the contents--8.333 lb/gal for water and waste, which would be 227 lbs in a 27 gal tank) pushing against the walls of the tank trying to pull the crack apart again...if the contents are shifting while the boat is underway, they're pushing even harder. Then there's quality of the original tank material itself to consider...why it split in the first place. Even if the weld holds, will the same forces that created the first crack cause a split somewhere else? So, as I said earlier, if it were a water tank he'd have little to lose by trying to mend it. But when it comes to waste tanks, the wisest course is replacement. -- Peggie ---------- Peggie Hall Specializing in marine sanitation since 1987 Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and Other Sources of Aggravation and Odor" http://www.seaworthy.com/store/custo...0&cat=6&page=1 |
Interesting point that the static pressure due to hydrostatic head only. But Peggie also mentioned a hydrodynamic effect - shifting the fluid around in a seaway - and that force *is* sensitive to the mass of fluid. Brian Whatcott Altus, OK On Fri, 15 Jul 2005 16:07:21 -0700, "Robert or Karen Swarts" wrote: Just a small technical correction, Peggie. The weight of salt water is, in fact, 8.33 lb/gal, but that is misleading. The pressure exerted is .444 psi/ft. So if the tank is 2 ft deep, the pressure is only .888 psi, which would also be the pressure on the walls at the bottom of the tank. The total force on the wall if the tank were 1.3 ft wide on a side (for about 27 gal) would by 166 lbs. As long as a true "weld" is achieved equal to or greater than the wall thickness, its integrity will be as great as the wall itself. I have certainly welded the bottoms of polyethylene buckets one foot deep without any problems. I can't speak to the integrity of the tank itself, of course. BS "Peggie Hall" wrote in message . .. Robert or Karen Swarts wrote: I have "welded" many polyethylene parts using a common electric soldering pencil, anywhere from 25 to 125 Watts, and scrap polyethylene from any source. With a little practice, you could do it yourself. Welding parts together is one thing...but mending a crack in a tank adds another dimension, because you have the weight of the contents--8.333 lb/gal for water and waste, which would be 227 lbs in a 27 gal tank) pushing against the walls of the tank trying to pull the crack apart again...if the contents are shifting while the boat is underway, they're pushing even harder. Then there's quality of the original tank material itself to consider...why it split in the first place. Even if the weld holds, will the same forces that created the first crack cause a split somewhere else? So, as I said earlier, if it were a water tank he'd have little to lose by trying to mend it. But when it comes to waste tanks, the wisest course is replacement. -- Peggie ---------- Peggie Hall Specializing in marine sanitation since 1987 Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and Other Sources of Aggravation and Odor" http://www.seaworthy.com/store/custo...0&cat=6&page=1 |
Peggie Hall wrote:
Then there's quality of the original tank material itself to consider...why it split in the first place. Thank you, someone is thinking realistically. Certainly there are good ways to repair cracked poly, including adding a welded doubler. But polymerized plastics do age with time & whatever their enviromental conditions may be, and begin to lose certain properties. Unless it were a clear case of freeze damage or a known one-incient overpressure burst (both unlikely?), it ought to be replaced & will be much cheaper replaced in the end. If you must make an *interim repair* due it being the middle of an intinerary or pending reciept & R/R of a tank, and *if* you know how to weld poly, you can stitch it together, double it & static hydro it in-place (suggest at least 2x the head of deck pumpout fitting). Accept that you won't be saving any time, work or money in the end, but adding to them. |
"Robert or Karen Swarts" wrote in
: Just a small technical correction, Peggie. The weight of salt water is, in fact, 8.33 lb/gal, but that is misleading. The pressure exerted is .444 psi/ft. So if the tank is 2 ft deep, the pressure is only .888 psi, which would also be the pressure on the walls at the bottom of the tank. The total force on the wall if the tank were 1.3 ft wide on a side (for about 27 gal) would by 166 lbs. What is it when the bow slaps a 15' wave hard? This is the pressure at the marina dock.... -- Larry This jerk called my cellphone and was nasty. Continental Warranty -- MCG Enterprises -- Mepco- 24955 Pacific Coast HWY Suite C303 Malibu California 90265 888-244-0925 Fax: 310-456-8844 Email: Read about them he http://www.ripoffreport.com/view.asp...3&view=printer |
Certainly no guarantee, but Harbor Freight has a plastics welding rig
for about $40. http://www.harborfreight.com/cpi/cta...emnumber=41592 |
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