# Copper vs. Diesel



## pdqaltair (Nov 14, 2008)

What am I missing? This seems rather obvious.

We know that copper and zinc are very bad for fuel stability (gasoline and diesel). Every engine manufacturer and fuel manufacture says so. And yet West Marine keeps selling brass fuel valves and fittings, and we keep buying them. I learned a long time ago in the oil business that his was just not done.

_______________

ASTM D975 (this is the basis diesel standard) Appendix X2.7.2: Fuel Storage Conditions:

Copper and copper-containing alloys should be avoided. Copper can promote fuel degradation and may produce mercaptide gels. Zinc coatings can react with water or organic acids to form gels which rapidly clog filters.

Cat installation guidance.

http://pdf.cat.com/cda/files/3375312/7/Diesel+Fuel+Diesel+Fuel+Systems+LEBW4976-04.pdf

Material. Black iron pipe is best suited for diesel fuel lines. Steel or cast iron valves and fittings are preferred.

CAUTION: Copper and zinc, either in the form of plating or as a major alloying component, should not be used with diesel fuels. Zinc is unstable in the presence of sulfur, particularly if moisture is present in the fuel. The sludge formed by chemical action is extremely harmful to the engine's internal components.

Cummins installation guidance. https://www.cumminspower.com/www/literature/applicationmanuals/t-030_p115-132.pdf

Diesel Fuel Piping. Diesel fuel lines should be constructed from blackiron pipe. Cast iron and aluminum pipe and fittings must not be used because they are porous and can leak fuel. Galvanized fuel lines, fittings, and tanks must not be used because the galvanized coating is attacked by the sulfuric acid that forms when the sulfur in the fuel combines with tank condensate, resulting in debris that can clog fuel pumps and filters. Copper lines should not be used because fuel polymerizes (thickens) in copper tubing during long periods of disuse and can clog fuel injectors. Also, copper lines are less rugged than black iron, and thus more susceptible to damage.

Note: Never use galvanized or copper fuel lines, fittings or fuel tanks. Condensation in the tank and lines combines with the sulfur in the diesel fuel to produce sulfuric acid. The molecular structure of the copper or galvanized lines or tanks reacts with the acid and contaminates the fuel.

Yanmar manual http://www.mackboring.com/DAN/files/application1010201130329PM63nj.pdf piping is specified as rubber or steel (page 9).

----

Yes, I know the CG allows copper tubing. They also allow non-tinned wire, so it is clear they are focused on safety minimums, not best practices.


----------



## Don L (Aug 8, 2008)

Not WM's fault for selling something that is made for use in the fuel systems. But I think the issue is the ever constant choices between being and doing "best" verse just doing "good".


----------



## Minnewaska (Feb 21, 2010)

This is good info I never knew. I swear, I replaced or repaired quite a few copper fuel lines in my earliest cars, as a kid. Perhaps the issue is how long the fuel remains in contact. In a car, burning a tank or two per week, is it less of an issue? In a powerboat, it may be similar, if the boat is used often (most don't seem to be). Much longer sit time in a sailboat, for sure.

I will have to take a look at mine. The tank is either SS or aluminum. Most of the visible fuel line is hose, but I'm not sure about the fittings at the tank.

Interesting stuff. I don't know why you call out WM, I dare say every chandlery in the nation carries the same stuff.


----------



## capta (Jun 27, 2011)

All I can say is that my copper fuel lines and brass valves are 34 years old and seem to be doing just fine????? My Racor fuel filters are made from cast aluminum???


----------



## pdqaltair (Nov 14, 2008)

Minnewaska said:


> This is good info I never knew. I swear, I replaced or repaired quite a few copper fuel lines in my earliest cars, as a kid. Perhaps the issue is how long the fuel remains in contact. In a car, burning a tank or two per week, is it less of an issue? In a powerboat, it may be similar, if the boat is used often (most don't seem to be). Much longer sit time in a sailboat, for sure.
> 
> I will have to take a look at mine. The tank is either SS or aluminum. Most of the visible fuel line is hose, but I'm not sure about the fittings at the tank.
> 
> Interesting stuff. I don't know why you call out WM, I dare say every chandlery in the nation carries the same stuff.


Exactly. A few weeks in a car don't matter. A line that goes one-way from a #2 tank to a home furnace does not matter.

No, I have no special criticism of WM. That was unfair. I actually like West Marine. But I do think this is something they could communicate, as they do many things.


----------



## aloof (Dec 21, 2014)

capta said:


> All I can say is that my copper fuel lines and brass valves are 34 years old and seem to be doing just fine????? My Racor fuel filters are made from cast aluminum???


The copper acts as a catalyst, they say. So it is not consumed or harmed in the reaction that damages the fuel.

In Diesel engines the fuel is recirculated thru the copper fittings every few hours. So catalyzed fuel is returned to the tank to cause problems later rather that being burned as in a typical gasoline engine. As said above.

Are the Racor filters made of aluminum or zinc pot metal? Plus, many aluminum alloys contain copper...

Are not most tanks on fuel trucks made of aluminum?


----------



## pdqaltair (Nov 14, 2008)

aloof said:


> The copper acts as a catalyst, they say. So it is not consumed or harmed in the reaction that damages the fuel.
> 
> In Diesel engines the fuel is recirculated thru the copper fittings every few hours. So catalyzed fuel is returned to the tank to cause problems later rather that being burned as in a typical gasoline engine. As said above.
> 
> ...


Copper. Yes, it is a catalyst and is not consumed. Only a few 5-20 ppm are required for serious trouble.

Nope, we can't get away from 100% of the copper because of engine fittings. But that is very limited and an additive with an effective metal deactivator is very effective. For most of us, this sort of "patch" is the key to fuel storage stability.

I would lay long odds that the Racor alloy does not contain copper or zinc. Parker filtration has been in this business since the beginning of trucks, does OEM supply to the folks that ban copper (many trucks come through with Raycor equipment, and they make the on-engine filters too), and you won't see brass in the catalog. Not even a brass barb.

Yes, Aluminum is the most common metal in tankers and bulk loading equipment. No copper, galvanized, or "pot metal" in this equipment.

You will occasionally see bronze; although it does contain copper, there is no zinc and the corrosion rates are very low. But most fuel vendors only accept steel, aluminum, and SS.


----------



## MedSailor (Mar 30, 2008)

Almost all my fuel lines are copper....

While I'm listening and learning I'm not yet worried enough to replace them sll.

Which additive stabilizes this problem?

Sent from my SAMSUNG-SGH-I537 using Tapatalk


----------



## JimsCAL (May 23, 2007)

pdqaltair said:


> You will occasionally see bronze; although it does contain copper, there is no zinc and the corrosion rates are very low.


Not true. There are many types of bronze and many contain some zinc. Typically about 10 percent or so, but sometimes as much as 30 to 40 percent.


----------



## sulli (Mar 9, 2013)

I have a Monel tank 1/4 in Monel I plan for fuel lines will this be problem with Diesel fuel


----------



## pdqaltair (Nov 14, 2008)

JimsCAL said:


> Not true. There are many types of bronze and many contain some zinc. Typically about 10 percent or so, but sometimes as much as 30 to 40 percent.


Correct. I was thinking of phosphor bronze.

Just avoid copper all together.


----------



## MedSailor (Mar 30, 2008)

pdqaltair said:


> Correct. I was thinking of phosphor bronze.
> 
> Just avoid copper all together.


What about those of us with copper in the system. Any advice besides replacement (many boat bucks)?

MedSailor


----------



## Markwesti (Jan 1, 2013)

Only problem with black iron tanks ( I know you are talking fittings ) is they don't last that long compared to Alum. tanks . My dad had a Grand Banks 36 with black iron fuel tanks , it was about 20 yrs. old when he sold the boat , it passed survey . We saw the new owner about 3 mos. later , the tank leaked and needed replace . In order to get to the tank it was necessary to dismantle a large part of the boat , cost was over 30K . My dad was shocked and offered to pay , but the owner refused .


----------



## RichH (Jul 10, 2000)

Here's a recent tech paper on the degradation effect on (bio)diesel vs. the various metals in the OP discussion. Although this paper's focus is for bio-diesel, the degradation is the essentially same with petro-diesel although at an exponentially lower reaction rate, even with the absence of the very aggressive organic acids sometimes found in 'bio-diesel'.

Although copper, etc. has been the 'usual' in recreational boating since Methuselah, the small rates of corrosion are usually 'insignificant' .... if you understand that all fuels have a limited 'shelf life' after exposure to air/oxygen and water uptake.... and are infected with biologicals.

Further and from a practical standpoint, be VERY aware - _especially, during those financial/market periods when common diesel is 'super-costly'_- that unscrupulous fuel dealers have been known to 'dilute' petro-diesel with reclaimed (and sometimes un-reclaimed) used cooking oils ... and which will exceed by MUCH MORE than the 5% standard limit for blending 'reclaimed' cooking oils into petro-diesel which are sometimes 'marketed' as bio-diesel 'blends'. These 'reclaimed' oils contain very aggressive 'organic acids' (Oleic Acid, etc.) and which besides affecting the catalysis/degradation of the fuel also are an incompatible HELL on the common polymers (hoses/gaskets/O-rings) used in diesel fuel systems. Hint: use your nose at the end of the fill nozzle before filling.

Article: Influence of light, temperature and metallic ions on biodiesel degradation and corrosiveness to copper and brass


----------



## pdqaltair (Nov 14, 2008)

Steel vs. aluminum. There is absolutely no reason not to use aluminum for many fittings, with consideration given to galvanic corrosion where relevant. Most filter housings (Raycor) and antisyphon valves are aluminum.

Those that already have copper. One hint would be to subscribe to Practical Sailor. There are several articles over the past few years regarding additives. However, you will find that Star Tron, Stabil D, and Valv Tect will all reduce the problem by an order of magnitude. There are also additives that will make it worse. The NMMA is pushing for standards for additives, because they have found that more than 50% of additives on the market do more harm than good. I agree with that, based on what I have seen.

RichH. I need to study that article. Several quick thoughts:
1. Water and salt are major factors. If the fuel is REALLY dry, copper reaction will be slower, no question. They ran the tests at significant moisture levels, though within biodiesel spec.
2. Actual corrosion is not required, just an active surface.
3. Oxygen. Because of recirculation, if there are any leaks, oxygen saturation may be high. This is another reason why returns must be submerged.
4. Cheap biodiesel. Everything you said. Another problem we see occasionally is cross contamination with ethanol.
5. pH. I've seen a lot of low pH fuel (4-5), probably related to the above. Doesn't help.


----------



## RichH (Jul 10, 2000)

MedSailor said:


> What about those of us with copper in the system. Any advice besides replacement (many boat bucks)?
> 
> MedSailor


Make sure that the filter's water sump, etc. is at the very _lowest_ 'altitude' in the system, so that any _free_ water in the system 'will' gravity drain (from the lift pump and from the tubing from the tank) TO the filter bowl 'sump'. It should all be gradual downslope TO the filter/sump; 'valleys' are water traps. 
Less free water in contact with the oil = less corrosion/less reaction, & less acidic 'activity'.

Other -
Overall, keep the _minimum_ amount of fuel onboard ... only what you need + some reserve for emergencies, etc. 
Dont 'top off the tank' without a good reason - ever!.
Dont buy potentially 'stale' (beyond 45+ day old 'shelf life') fuel (same as previous sentence).
Drain the tanks for long term layup. 
Buy your fuel from a high-turnover (fresh) depot. 
Use a biocide. 
Every decade or so pull out and inspect the existing copper tube for wall thickness, and severe internal wall surface 'roughness', etc. When its convenient or with failing copper tube, change to automotive SS tubing & buy a tubing bender and flaring tool. 
Inspect and CLEAN the tank when needed. 
Replace the deck fill O-rings on a regular basis.
Dont use 'compression fittings', only double flared or ring-seal, etc. connectors.

extra- if your usual fuel source has 'heavy sulfur' content / _LOW_ pH, consider to use additional 'filters' containing 'fullers earth'. 
eg.: http://www.jaxonfiltration.com/Clays-Sorbents-Materials.html ... would be rare for such a need in the US/Canada if your not buying 'bulk' fuel (refinery 'stumps') .... Caribb./ #2 from Venezuela 'heavy' crude is 'different' (sour).

;-)

All simple MAINTENANCE. All 'simple' and cost next to 'nuthin'.


----------



## Minnewaska (Feb 21, 2010)

MedSailor said:


> What about those of us with copper in the system. Any advice besides replacement (many boat bucks)?
> 
> MedSailor


I highly suspect, with your motor-sailor, you're going to turn your fuel over often enough, not to need to worry.

If you do, can you switch to fuel hose? Suspect there is some ABYC input on that.


----------



## pdqaltair (Nov 14, 2008)

SS tubing is NOT USCG approved. It is in the regs.

Copper corrosion is not required, only an active surface, from my understanding and experience. Like Pt in a converter.


----------



## albrazzi (Oct 15, 2014)

MedSailor said:


> Almost all my fuel lines are copper....
> 
> While I'm listening and learning I'm not yet worried enough to replace them sll.
> 
> ...


Interesting discussion but with an aluminum Tank and rubber lines and proper filtration I am free to move on to other maintenance issues with a clear mind. Copper (flared) is fine but old school, I don't know how many people I have talked to with fuel supply or run issues that didn't get fixed until the lines were replaced Its the first thing I do on a new boat. Copper is great even when it turns green but with long term vibration and stress it will fail. Supply lines will shut the motor down return lines will contaminate the bilge.
After 30-35 years everything but the hull needs service of refit.


----------

