ivisonm
Well-Known Member
Has anyone got experience or information about making GRP fuel tanks?
GRP fuel tanks
- Thread starter ivisonm
- Start date
macd
Well-Known Member
Calder has some info on GRP tanks (which he reckons the best material after ABS plastic). I've made my own (and a holding tank). Both are substantially polyester with an epoxy inner lay-up, and "resin-rich" as Calder likes to call it. The diesel tank's now six years old and has never shown the slightest problem.
Although it's perhaps the least expensive means of making a custom tank, especially for the comptent DIY-er, the materials are by no means cheap...say, in very rough figures, £150 per typical tank. Mine uses a Tek-Tank inspection cover for hose take-offs and returns, plus a (top-exit) tank drain (which in my view every tank should have but most don't).
Please feel free to PM with any specific questions.
Although it's perhaps the least expensive means of making a custom tank, especially for the comptent DIY-er, the materials are by no means cheap...say, in very rough figures, £150 per typical tank. Mine uses a Tek-Tank inspection cover for hose take-offs and returns, plus a (top-exit) tank drain (which in my view every tank should have but most don't).
Please feel free to PM with any specific questions.
SimonJ
Well-Known Member
GRP fuel tanks have been excellent - until now! Easy to make to shape.
However, Ethanol even in very small quantities added to diesel fuel as it has to be for road use has a devastating effect on GRP fuel tanks. It effectively dissolves the resin which turns into a thick jelly which very quickly blocks fuel filters. UK marine fuel, may if you are lucky, be straightforward diesel and not give this problem. In the future it seems that whatever good intentions are expressed now ethanol will end up in marine diesel - and how will you know anyway.
12 months ago I was in a yacht which had to mostly motor from Majorca to Gib then the Canaries. The tanks had just been cleaned and were immaculate. Lovely clean fuel was put in the GRP tanks. The filters quickly blocked and were repeatedly changed - the only explanation (subsequently obtained from experts) was that the Spanish were ahead of the game in complying with EU regs to do so and the fuel supplied (even though for marine use)had added an bio derived ethanol component.
The Americans discovered the same problem with petrol in GRP tanks a year or two ago. It is now known to be a diesel issue too.
I would hope to be contradicted by fuel experts which I am clearly not. I think GRP is the wrong material!
Bobobolinsky
Well-Known Member
Not to confuse the issue, but if biodiesel is produced properly, there should be no ethanol or methanol remaining, any excess, should have been washed away.
We made tanks, by shaping polystyrene blocks, epoxy coat it and finish with GRP, when cured, a little petrol on the polystyrene and left overnight, will hollow out the tank.
We made tanks, by shaping polystyrene blocks, epoxy coat it and finish with GRP, when cured, a little petrol on the polystyrene and left overnight, will hollow out the tank.
shaxi
N/A
seems a bit complicated ,i have never do this job , but i 'd like to learn more knowledge ! thanks for all of your post !
macd
Well-Known Member
SimonJ: I daresay you don't know the answer to this but I'm presuming the "GRP" tanks to which you refer were laid up with vinylester or polyester resins.
For comprehensive info on the problem you describe: http://www.boatus.com/seaworthy/fueltest.asp
This forum also has useful info: http://continuouswave.com/ubb/Forum1/HTML/012667.html
Note that both links primarily concern themselves with petrol/gasoline containing ethanol, rather than diesel fuel.
Although epoxy is regarded as being highly resistant to ethanol, there have been issues with epoxy/GRP light aircraft tanks in the US using 'autogas' (as opposed to avgas): http://www.egyptian.net/~raymacke/Cbnskif17.htm
For a generalised table of epoxy's resistance to various chemicals, see: http://www.engineeringtoolbox.com/chemical-resistance-epoxy-d_786.html
For comprehensive info on the problem you describe: http://www.boatus.com/seaworthy/fueltest.asp
This forum also has useful info: http://continuouswave.com/ubb/Forum1/HTML/012667.html
Note that both links primarily concern themselves with petrol/gasoline containing ethanol, rather than diesel fuel.
Although epoxy is regarded as being highly resistant to ethanol, there have been issues with epoxy/GRP light aircraft tanks in the US using 'autogas' (as opposed to avgas): http://www.egyptian.net/~raymacke/Cbnskif17.htm
For a generalised table of epoxy's resistance to various chemicals, see: http://www.engineeringtoolbox.com/chemical-resistance-epoxy-d_786.html
Last edited:
basil421
Well-Known Member
Many years ago I was involved in the manufactuer (in-situ) GRP tanks for deisel power boats. We chose a bis-phenol polyester resin (can't remember the number now but it was made by a well known resin manufaturer in Wellingborough). These tanks performed well.
I can say it all comes down to the correct choice of resin and ensuring the final internal surface is completely cured. The surface cure of polyester resins are naturally inhibited by atmospheric oxygen. This uncured layer eventually "dries" by the evaporation of styrene monomer but could be redisolved by solvents in the fuel which could gum up the works. As long as air is excluded from the final surface before it gels (say by the use if a plastic sheet) the tank will be fine.
Post curing the tank with steam would also be recommended.
If more information is required I suggest you contact the resin manufacturers.
I can PM a link to the resin manufacturers data sheet if you let me know.
I can say it all comes down to the correct choice of resin and ensuring the final internal surface is completely cured. The surface cure of polyester resins are naturally inhibited by atmospheric oxygen. This uncured layer eventually "dries" by the evaporation of styrene monomer but could be redisolved by solvents in the fuel which could gum up the works. As long as air is excluded from the final surface before it gels (say by the use if a plastic sheet) the tank will be fine.
Post curing the tank with steam would also be recommended.
If more information is required I suggest you contact the resin manufacturers.
I can PM a link to the resin manufacturers data sheet if you let me know.
BACUS
Well-Known Member
grp fuel tanks
have you checked what your boat insurers require .
do they have to be ce marked
regards
Bacus
have you checked what your boat insurers require .
do they have to be ce marked
regards
Bacus
ivisonm
Well-Known Member
Lots of good info!
I was going to get plastic ones made, but GRP ones could be moulded into the hull and more of the internal space.
If there is a possibility of the resin not being cured in part on the inside surface, could a different coating be applied to the inside for chemical resistance to ethanol?
I was going to get plastic ones made, but GRP ones could be moulded into the hull and more of the internal space.
If there is a possibility of the resin not being cured in part on the inside surface, could a different coating be applied to the inside for chemical resistance to ethanol?
Cookee
Well-Known Member
Scott Bader and all others always aim for the very conservative attitude - the critical thing is the ethanol / methanol content and what it does to GRP tanks. Does anyone know of a material that will stand up to it?
Cookee
Well-Known Member
Looking around on other threads I found this company: http://www.bridgeportchemical.com/index.htm I'm going to get in touch and see if their products will help.
basil421
Well-Known Member
Looking at the Scott Bader data sheet it looks like Crystic 199 (which is not a Bisphenol but rather an Isophthalic resin) will resist the following.
100% Methanol at temperatures up to 35ºC,
95% Ethanol up to 30ºC,
100% Deisel up to 45ºC and
100% Petrol up to 40ºC.
As the bottom of an in-situ tank is going to be in contact - through the hull - with sea water the contents are unlikely ever to get above 30ºC I should think this would be the one to go for.
The chemical resistance assumes that the glass reinforcement will be completely wetted out without voids and the laminate should be made with a generous resin glass ratio. Post curing using steam if possible or even just hot air for six hours should be carried out.
For belt and braces "insurance" you can always give the inside a coat of epoxy after completion
If in doubt you could try giving the technical chaps at Scott Bader a call. It's many, many years since I have been in contact with them but I always found them to be extremely helpful.
100% Methanol at temperatures up to 35ºC,
95% Ethanol up to 30ºC,
100% Deisel up to 45ºC and
100% Petrol up to 40ºC.
As the bottom of an in-situ tank is going to be in contact - through the hull - with sea water the contents are unlikely ever to get above 30ºC I should think this would be the one to go for.
The chemical resistance assumes that the glass reinforcement will be completely wetted out without voids and the laminate should be made with a generous resin glass ratio. Post curing using steam if possible or even just hot air for six hours should be carried out.
For belt and braces "insurance" you can always give the inside a coat of epoxy after completion
If in doubt you could try giving the technical chaps at Scott Bader a call. It's many, many years since I have been in contact with them but I always found them to be extremely helpful.
ivisonm
Well-Known Member
Will give them a ring after Christmas is over... Too cold for using resin anyway..
