I wrote the first tank gotcha post back in 2011 when we tried to fill our aluminum propane tanks, only to be told that they needed re-certification as they were over 10 years old. Since at the time I couldn’t find anyone to do the re-certification, we had to buy new tanks.
Imagine my dismay when I found that the replacement tanks we got were already long dated—by 6, 5 and 4 years—meaning we only had 4 years before the oldest “new” tank would need re-certification.
Well, that day arrived this spring and so I once again began looking for a place to get the tanks re-certified. Which wasn’t really all that hard—I just went to a company that specializes in propane services. (Why didn’t I think of that last time?)
Anyway, it turns out that finding a recertification guy (RG) is actually the easy part. The hard part is that getting the bronze valve out of the aluminum tank is, at best, a 50-50 proposition, with stripping the threads, thereby rendering the tank useless, the negative outcome. And replacing the valve is exactly what is required by law, at least in Canada, to get a tank re-certified.
So what happened, you ask? Yup, you got it, the threads stripped and we are now on the hook for a new tank after only 4 years of use from the old “new” one. Which is not even slightly financially or environmentally funny or friendly. We asked RG if he could source it but, sadly, his suppliers don’t carry the type we need (sigh).
Now, interestingly, RG told us that manufacturers actually pre-date stamp the tanks by 6 months to ensure that the tanks aren’t long dated before they reach the buyer. And, if they are long dated, they are usually sold at a discount. Which makes me wonder how we got a tank that was already 6 years old? It also makes me wonder why we were charged full price? Do you think that maybe marine suppliers are getting the tanks at a discount because they are long dated and selling them on to ignorant mariners for the full price?
Whatever the answer to that last question, we have no choice but to source these tanks through a marine supplier; however, this time, older and wiser, we are going to have a chat about date stamps before we order the tanks—and then refuse to accept them if they are long dated.
We suggest you do the same.
There is nothing intrinsically “marine” about an Al propane tank. Your best bet for getting a long life tank is by purchasing outside the high priced and dwindling marine supply channels. The RV supply world can generally do better price wise by 15% less here in the States. The other approach is to call a builder friend and ask them to order the tank OEM, — then really prepared to be shocked about markup.
Trying to get the valve out is 98% a lost cause. When in college, I used to repurpose salvaged tanks into hibachis and small lidded grills to cover my incidental expenses. The threads strip because the Al and bronze cold weld (galling) during the threading process and corrosion seals the deal in just a few months. Thermal cycling the threads is a no-starter as it weakens the Al making the tank uncertifiable.
Good idea, we will try an RV supply place next time.
Last time we were in the last days before heading off on a long and challenging voyage and so just added the tanks to an order for a lot of other stuff from a marine supplier.
The key issue to note though is that we got long dated tanks from two different sources, one in the USA and one in Canada, so this does seem to be a marine industry wide problem, which is why Phyllis wrote the above post: as a warning to other cruisers, many of whom will be in a strange place with no car and on deadline when they find that their tank has expired—such is voyaging.
After years of similar frustrations [mostly with finding what we need when we need it…] we switched to the [latest generation] of composite tanks by Viking. [I don’t know if you can acquire/use them in Canada…]
They weigh less than aluminum, have a 15 year life, and are translucent so you can see the liquid content.
The one gotcha I have yet to experience is they must be ‘visually’ inspected every 5 yrs by a ‘qualified’ source [and no valve replacement required.] Being in the vicinity of an authorized ‘Requalifier’ when the time comes may be an issue in itself…
So far so good, however…
Best wishes finding your ideal solution.
Good idea, we will look at that next time.
Having said that, the thing that worries me is that the staff at propane filling stations are not generally, shall we say, the most well informed people on the planet. This is particularly true in remote places.
I have even had them tell me that aluminium tanks are not safe or legal so I worry about the potential reaction to a see through composite tank.
Also, I suspect in many places (perhaps including Canada) the 15 year no valve replacement specification will not be respected by the filling station.
In the past I have used a method of thread replacement in aluminium called a ‘Helicoil’. The remains of the original thread is drilled out and the hole tapped to take a stainless steel thread insert that replaces the original thread. I have not checked the current availability of Helicoils and I don’t know the size you require but they may be a more economical option than replacing the whole tank. I have used Helicoils for the replacement of stripped threads in aluminium cylinder heads, much higher pressures than propane.
Good idea, I’m sure that would work (As aluminium boat owners, we have been using Helicoils for years.)
But the key issue here is that this is not a DIY solvable issue. At least here in Canada the required valve replacement must, by law, be done by a certified professional gas technician and I don’t think these guys are going to have a lot of interest in fussing around with Helicoils.
Try the following link:
I, also, switched from Al to a composite tank. The first one, naturally, was from the manufacturer that ended up losing its ICC certification and, as a result, I could not get it refilled. I then bought another 20# capacity tank on the Internet for under $90. It was then only a small battle to convince the propane outlet that this was not the brand that had been recalled, in order to get it filled.
Reading this post, and the comments, makes me wonder why so few cruisers use kerosene/paraffin for cooking and heating. I have a 70L kerosene tank that lasts about 2 years. Of course there are downsides, but I have seen, and experienced so many problems with l.p.g. tanks, and installations, not to mention the high cost, and safety issues.
However, this is a bit like religion, or anchors, it is hard to change minds once made up!
Why, you ask? When we returned from cruising the first time my wife stepped onto the dock, and the first thing she said was “If you ever plan to eat on this boat again you’ll get me a propane stove.”
More complicated to light, blackens pots and the ceiling. I didn’t mind, but I did want to eat again.
My wife and I, witnessed the result of. l.p.g. explosion on a boat, early in the seventies, when we started our cruising career. The result, besides the totally wrecked boat, was 2 people dead, and another 2 very seriously injured and burnt. I do not know if they survived. There were, and have been, no more complaints about the problems of kerosene. Black pots and ceilings, are mainly the result of not preheating properly and clean easily.
I guess I’m with you on that one, see this post.
Having said that, as Bill says I’m pretty sure propane is more dangerous than kero. Having just done a full 5 year service on our system, I have a post brewing on ameliorating the risk from propane.
Why bother with aluminum in the first place? Steel tanks are a fraction of the cost. They can easily be maintained with a little paint now and then to keep them protected and when they do reach end of life you aren’t looking at $300 replacement per tank. It’s more like $40. You could afford to replace them every two years and still be ahead of the aluminum. As for the composites, they are VERY large and don’t fit into many standard propane lockers.
Blair, I agree about the steel tanks. I repaint them, pad attachment points with old inner tube rubber and spray the working bits with Boeshield (wax based anti corrosion spray) and easily get 5 years. Easy.
Why not powder coat the exterior of steel tanks? Cheap, and it should at least double the life expectancy.
We’ve been places where they wouldn’t let aluminum tanks in the yard where propane was sold. Not sure about laws, but the local place had their own rules.
Steel lets you know you have a problem developing with rust stains. Aluminum can get a small pit that goes through the tank with little sign of it. I suspect they had problems in the past, maybe discovering not so visible pits in tanks brought in. I never asked why, we always used steel so weren’t that worried about it.
That’s interesting, but I think rare. I have been using and filling aluminium propane tanks for some 35 years without a problem of that sort.
That’s certainly a good option although probably not one I would choose. Thinking about it did inspire me to write a post though, thank you. Look for it in a week or so.
Other than weight, is there any reason not to use steel?
Composite tanks are great for the reasons mentioned above but if you are cruising the world beware a lot of countries do not allow them to be filled. New Zealand for one the last time we sailed there. But a lot of third world countries one travels to you don’t have to worry as the tanks are usually filled by some local guy who has a small business on the side and who fills them at home.
I can’t speak for any country but the US, but here, modifying a propane tank in any way other than marking it with owner information renders it illegal to refill. Painting and coating steel tanks can hide nascent corrosion.
The kind of proper physical and chemical surface prep required to reduce the risk to that >i>inherent in the tank design itself would cost far more than several replacement tanks.
If you use a steel tank, remove any paper wrapper and adhesive that may have come on the tank, these soak up moisture and salt, and are a primary source of hidden pitting.
When it comes to tank failures, in situ ruptures are rare. usually a rupture occurs on refill, and even those are extremely rare and shrapnel-free* (unlike a SCUBA tank). The main failure mode is insidious and involves leakage of propane via pinhole leaks — which are much smaller than pin-holes or you would hear them. Many of the propane tank leak-fed explosions have occurred on boats with no leak detectors or unattended boats where a leak detector alarm was unheard or ignored and finally silent after the batteries filed.
*If a propane tank is engulfed in fire, all bets are off. They will go through what is called a BLEVE (Boiling Liquid Expanding Vapor Explosion). Tank material will make a difference here, but you don’t want to be close enough to measure the difference.
I use simple steel LNG tanks from Camping Gaz the only issue is keeping them rust free which is relatively easy.. I simply stripped off all the factory paint and painted them with an epoxy primer… “International Interprotect”.. (5 coats) and then a couple of coats of polyurethane 2 pack paint. Some rubber pads prevent the tank from moving and getting scratched. I know it is a sledgehammer to crack a nut type approach but 5 yrs later the tanks are still pristine.
In so far as safety… The usual gas detectors for leaks and carbon monoxide as well as replacing the flexible hoses regularly and a little bit of discipline where I shut of the gas supply at the tank when the stove is not in use. A bit of a pain true, but the peace of mind is more than worth it plus it also means that I visually “see” the tank frequently so anything amiss is hopefully spotted early.
Nice article, much to think about when buying tanks.
When it comes to risk of tank explosion (BLEVE), propane tanks has a safety valve that works well when the tank is stored upright. This will release the pressure in case the bottle is exposed to high temperature. If there is a fire, the flames ignite the gas and therefore it is no big problem with explosion.
My experience is that woven composite cylinders have a construction that makes them safer in a fire. The binding polymer will burn when it gets hot enough, but the composite fibers will keep its shape and releasing the gas (as a safety valve). This applies to whole woven bottles, and not the composite bottles that was molded in two parts, and there has been a recall on these.
It is easy to see if the bottle is full woven or molded together in the middle.
Regarding the installation of a gas detector sniffer, do not fix it with silicone and do not clean equipment with solvent based or hydrocarbon as these can contaminates the instrument sensors and cause spurious readings.
The safety valves do seem to work on tanks that are in good condition, but the boat would still likely be a total loss, see below.
Of the five BLEVE explosions I know of, two involved steel tanks with pitted metal (in both cases near the foot welds) that let go before the relief valves popped. The other three involved fires so intense the pressure rise in the tank exceeded the relief valves’ ability to depressurize the cylinder. At the one I was present for (a fire department demo), the jetted gas flames from the relief valve created a blow torch which melted aluminum in its path.
As always, thanks for shining the light of your engineering training and experience on the issue in this comment and your last.
You could be a real lifesaver with these comments.
For example, our propane locker is above our engine room, so based, on your comments, I will be adding jettisoning our propane tanks to our procedures in case of engine room fire.
Pleased to be of service. Another observation.
Our boat fire in 1996 was precipitated by a broken bendix gear retention spring which allowed the starter motor to drift into engagement with the engine flywheel with the engine running about 2500 rom, turning the starter motor into a generator pumping hundreds of amps upstream into the heavy harness and batteries.
The heat from this melted and vaporized the insulation material on the wiring and the paint on the starter motor. The battery switches looked like something Dali would have painted.
The smoke was extremely dense and was kept from flashing to flame by the engine compartment’s restriction of oxygen to the fuel (the vaporized insulation in this case). The problem began to resolve itself when the main battery cable melted in two. This cut the heat from the wires, but caused a sharp temperature rise in the starter motor which melted and seized, killing the engine (which could not be stopped until this happened).
The vaporized insulation was extremely toxic. EXTREMELY TOXIC. I kept it out of my lungs by breathing (sorta) through a wet tea towel tied around my face that I planned to wrap around the engine air intake to starve it to stop. The fuel shut off was in a seat locker with open access to the engine compartment.
This entire mini disaster lasted about 7 minutes. And there were other complications — open railroad bridge waiting for us, heavy current, no docks but “no open flame” fueling docks, transmission could not be disengaged with engine refusing to shut down.
Lessons Learned. I added toxic filter masks to our firefighting kit. I added goggles. I moved the fuel cut off valve out of the space that was open to the engine compartment to a space two bulkheads away. We added a 135 amp isolation switch between the starter motor and the batteries so that if this happened again, damage would be limited to the starter motor alone. Turning it to “ON” was not part of the starting drill. We switched it to “OFF” once the engine was running.
As we were being towed to the yard, checked the Surrette batteries. They were at 120 deg F, and electrolyte had sprayed all over the tops. The digital regulator was a paperweight. All told, that $17 spring cost us about $5K. Had the smoke in the engine compartment flashed to flame, it might have cost us the boat and our lives.
The yard told us this bendix failure mode was not rare and they often retrofitted isolation switches.
It is certain, propane is not to be trifled with. We should really use Metate in boats, this gas is lighter than air.
It’s good this theme is illustrated, many are not thinking so much that there is a reason for the strict rules for the replacement of bottles and safety valves.
It surprises me that some countries do not fill composite bottles. It must be from former construction flaws. Composite cylinders have surprised me positively on fire. In one case we had a warehouse with very many composite bottles on fire. We cooled down the bottles and the surrounding areas, but none of the bottles exploded. I do not think the outcome would be as lucky with metal bottles. One danger you point out when the safety valve burning flame hit the neighboring bottle. About falling bottles or stored wrong so the safety valve is in the liquid phase, we get trouble. The valves are designed to relieve pressure in the gas phase.
One should think carefully to extinguish a gas fire if the bottle has a leakage and it is not only the safety valve that relieves the pressure. Gas will leak and later have a great chance to be ignited by hot objects. When cooling the bottles where the safety valve releases gas , the valve closes at around 70 ° C.
Fire in boats can be fatal, especially smoke from PVC cables and other plastic products. Engine compartment soundproofing is an issue we do not often think about. We think it is good enough as long as it is approved, but it is not so.
There is a big difference between the approved products, the requirements are too low.
A fire in the engine compartment will develop rapidly. Here a good foaming material will be crucial for the fire development. I think that the CE and ISO standard here in Europe is more for the benefits of the boat builders than for their customers.
Hi Odd Arne,
Great information, thank you. Being the lightning fast brain I am, I just realized that you must be a professional firefighter!
10 points, John 🙂
My background complicates the choice of a boat, I look and ask about things others have never asked for. I am certainly a boatyards nightmare! But I’ve seen so many fires and accidents that could have been avoided with a little more knowledge and imagination. So now our fate is in the hands of Boreal, after a long search of the best compromise on a vessel.
I get a little reassured of the articles I read here, so thank you for an informative website.
We were delighted when composite bottles entered the civil market. They had been used for rocket and satellite fuel tanks from many years prior. However the rocket world (mine) has a history of 100 percent inspection and one time use. This did not capture a statistical base of performance data relative to the civil market. This meant considerable expense faced both producers and regulators as these tanks migrated from the space world to modern aircraft to civil use. Those countries and companies which could afford it, paid the tab. However many governments are not willing to import or are slow to import standards without them going through the (also expensive) ISO process.
We were delighted with out composite tanks on our current boat until the company was driven out of business and the ICC certification was cancelled for our mandrel-wound 10# tanks. Whether this action was justified or not, we’ll never know. In the meantime, we are back to using aluminum which we replace every four years whether they appear to need it or not.
Four years? Could you expand on your reasons.
Our SCUBA tanks require recert every five years. While the pressures are lower with propane tanks, the construction is also less robust and their operating environment is more hostile. I hose the SCUBA gear with freshwater each use. Not so the propane tank. It sits in a locker that breathes humid air in and out in temps approaching 35 deg C. I can feel salt rime on the tanks when wide AM-PM temp swings lead to condensation overnight.
So we said five years for our propane tanks to bring them in line with our SCUBA, and then we subtracted one for the construction and environment issues. Since even at four years valve removal (if you can find a shop to do it) is iffy because of cold welding in the threads, we decided buying a new tank was preferable to the hassle of recert (and loss of $ on a fail). Yes it’s a bit more expensive, but it minimizes a maximum regret.
We have had horizontal tanks for years.
Recert is a hassle, but OK in the US since they do not change valves.
One recert guy said that the only tanks that fail are those which are visibly very beaten up and/or grossly corroded
We will probably replace with the fibreglass ones at some time, but have not yet found a horizontal one.
Our locker is very convenient, but will not take a decent sized vertical one.
Getting any tank refilled in some countries, like the UK, is impossible, so we just buy a local tank and decant by inverting the donor and heating it gently with a hot air gun, or sunshine if available.
Concerning the ability of starter motors and related equipment to cause a fire, as mentioned by ChrisW, we have a 300 amp circuit breaker in the starter circuit which would prevent such an incident. All the cables have an ampacity well above 300. Last time I looked at ABYC standards, they were quite tolerant of not having a breaker or fuse in such lines.
Some additional information. Our battery bank selector switches were rated for 525 amps intermittent and 350 continuous. They were 10 sec crank rated at 1000amps. The cables were 4/0 AWG.
The switches melted to dripping plastic in seven minutes.
In doing the math after the fact, the yard electrician and I figured the starter motor was sending roughly 600-650 amps peak upstream.
I am currently refurbishing my 40′ boat and therefore appreciating all comments on propane or other cooking fuels. Before reading this, I was considering to install a 220 V oven and cooking surface as there is a pre-installed 4 KW gen on board. However, I will still keep propane for fueling the outside BBQ: therefore no LPG leaks to the bilge. Please comments!
WRT the fire from the starter and proposed solutions, there are multiple mechanical failures which could trigger a fire. As the fire is confirmed, my emergency list would be as follows:
1. You must identify the cause promply and react accordingly OR if you cannot accertain the source of the problem, you must shut down engine(s), generator, and cut all electrical power; and
2. Then and only then you use the extinguisher(s).
If you are successful, you have time to investigate on your floating boat; otherwise it will be time to think evacuation as a fibreglass boat will be burning fast. Therefore, the only mandatory additional safety measures to my boat will be alternative ways to shut down my auxiliary and the generator while an extinguisher readily available close by the battery master switches enabling me to access them and turn them off.
As you point out so well, although propane has it’s dangers, other alternatives, such as electricity, are hardly hazard free.
To me I would not even think of being in a situation where I would need to run a generator every time we needed to cook, or even make a cup of tea.
My thinking is that with proper management and installation rigour the risks of propane can be brought to acceptable levels.
More coming in a future post.
Thanks for the update on this. Two years ago, we faced the dilemma of what to do with our 10lb aluminum tanks that were out of date. I read a lot online, including your previous post on the subject, and ended up buying powder coated steel tanks that are 11lbs for about $90 delivered each. If the old tanks passed recertification, the cost to recertify would have been almost identical to buying a new steel tank (half the cost but for only half the time interval). My thought on the steel ones is that we will probably dispose of them instead of recertify them as they will likely be starting to rust at that point. As much as this bothers me, I just couldn’t see any other viable alternative given the cost and time commitment of the alternatives. Hopefully there is a composite tank that fits our lockers 8 years from now when we next face this issue. For the time being, our steel ones are not showing any rust yet.
On a side note, I really wish that designers could go to something more standardized so that we could eliminate the huge selection of tanks. The boats that can take the 20lb tanks common on grills have a real advantage in my opinion.
I appear to have messed up an intended earlier comment, I have been offshore and tried to send it on an unfamiliar system where it got lost, apologies! I repeat my comment below, plus a bit:
Basically, I cannot understand, for the life of me, why experienced and knowledgeable people, those contributing to this extensive subject for instance, insist on using gas (LPG, I am a Brit and we use the word differently) on cruising sailing boats! The problems, inconveniences and risks are repeated many times in the foregoing comments.
Having a horror, if that is not too strong a word, of fire or explosion anywhere, working in the Oil & Gas Business for the past fifty years I can claim some experience, I banished gas (LPG) from my boat about fifteen years ago. I use a diesel cooker, high tech electronic controls, a bit slow to react compared to gas, a bit expensive for the initial purchase but no gas anywhere on my boat and none of the huge problems, space, regulatory and detection equipment associated with using gas! Not completely hazard free but one must make a determined effort to ignite it! Diesel engine, diesel heating, including water heating, and diesel cooking, one tank serves all! The only gas on board is petrol (gasoline) for the dinghy outboard and that worries me, I might save up for a diesel outboard!
I think we might want to cut this comment stream off since we are getting a long way off the topic of what tanks to use and expiry of tanks into general cooking fuel safety issues.
I have a chapter pending on the things we can do to ameliorate propane explosion risk and when I post that, we can continue this discussion.
That way all the great input from everyone will be available in a logical place on an ongoing basis.
Sorry if I wandered too far off topic!
Not at all. My only concern is that you are bringing up a really important topic—relative fuel safety—and I don’t want to see the resulting discussion lost on a relatively obscure post like this one.
The chapter I’m planning will be part of an online book and therefore your thoughts and the discussion that provokes will be available front and centre for years to come.
Having just filled, successfully, two expired AL tanks (8 years expired) I wondered why not just get a couple of steel tanks. With most of the swap tank places all around, rusting should not be an issue? Just find a new one when you bring the old one in. At least in the States. Most gas stations have this service.
I’d like to add my two cents if anybody has read this far onto the comments. I bought a Viking composite tank three years ago and have had nothing but troubles filling it in the states. Especially if I am cruising and don’t have a vehicle in port. Uhaul is now one of the major players in the refill biz and they have a nationwide blanket policy of no composites. Trying to find a hardware store that will refill is about 30 % successfull. I’m not sure what my success would be internationally. I may have to go back to steel to guarantee lpg, or try to refill with a heated up inverted tank, not inspiring. I read this discussion hoping to find an improvement with aluminum but it seems it has is nea-Sayers as well, not to mention filling challenges.
Well that’s disheartening, but thanks for the report that will help others.
I have never had a filling station turn down an in date aluminium tank, so that may be the best bet. See this post for some thoughts on steel: https://www.morganscloud.com/2015/07/19/boat-maintenance-dont-go-broke-saving-money/