How many years does a scuba tank last? Making sure your equipment is in working order is every certified diver’s responsibility. The cylinder holds your air, so it is natural to want to verify its integrity.
Read more about what else divers do for their own safety.
Let’s have a look at how divers do this. We will also learn the possible lifespans of scuba cylinders.
How Many Years Does a Scuba Tank Last?
I have witnessed aluminum tanks that have successfully passed hydrostatic tests 3-4 times. This means the tank is 10 to 15 years old. The manufacturer conducts the initial hydrostatic test. Subsequently, tanks need to pass these tests every 5 years. Certain parts of the world require more frequent hydrostatic testing.
In the US, the DOT (Department of Transportation) controls scuba cylinders.
While wrong, many dive shops agree that a properly cared for aluminum tank has a service life of about 20 years.
In reality, aluminum tanks by engineering can withstand the stress of 100000 refills or 10000 hydrostatic tests. In effect, this means the tank will last an enormously long time.
More practically, however, it really depends on the care and handling of cylinders. Near the ocean, the saltwater has the ability to accelerate corrosion. Large pressure and temperature changes can affect a tank’s lifespan. All this can reduce the tank’s lifespan.
Aluminum vs Steel
Aluminum tanks are more common in tropical waters where most recreational diving happens.
A modern and properly cared for steel tank lasts up to 50 years.
Considering the number above that sounds like less time. Steel tanks require more maintenance and are more susceptible to corrosive damage.
So, how do you make sure your tanks are safe? Always check your visual inspection and hydrostatic test dates fall within your dive date according to regional requirements.
The Visual Inspection
Every scuba diving tank requires a visual inspection annually. Trained technicians inspect the tank both inside and outside. They look for obvious dents in the material, very small cracks in the material, as well as corrosion. They also inspect the valve and use a snake camera featuring different imaging modes to clearly see the inside of the cylinder.
The Hydrostatic Test
Hydrostatic tests require specialized equipment. This test is to ensure the integrity of the material.
Can this tank still withstand the pressure of refills?
In order to ensure this, technicians fill the tank to about 5/3 of its maximum capacity with water. Effectively overpressurizing the tank. During this time, the tank resides inside an armored tank filled with water to ensure the technicians’ safety.
Steel or aluminum at this extreme pressure will flex. The technician measures the amount of flex using the displacement of water around the tank. If successful, the tank resumes its original shape. If the metal is too fatigued and rips the cylinder fails its hydrostatic test.
Tanks that pass their test receive a stamp on the outside directly into the material. That way it is clearly visible to divers planning on using it.
Condemned tanks often serve as furniture and other creative fixtures in dive destinations.
Don’t Blow It
So when considering how many years does a scuba tank last, always remember to check your visual and hydrostatic test dates before accepting a tank for a dive. This is your responsibility as a certified diver. If you are considering purchasing a tank, always ensure that this tank has a good and documented history of visual inspections and hydrostatic tests. If I were to consider buying my own, I would pay a professional to take a look at the tank, basically doing an inspection right there and then.