SpaceX traces Starship test-stand explosion to failure of pressurized nitrogen tank

[Admin]

The giant explosion that destroyed a SpaceX Starship vehicle on the test stand this week was likely caused by the failure of a pressurized nitrogen tank, the company said.

SpaceX traces Starship test-stand explosion to failure of pressurized nitrogen tank : Read more

 

[Unclear Engineer]

I read elsewhere that the postulated explosion of the tank would have had to occur at a lower pressure than its "proof" pressure, which I assume it had already be subjected to in a "proof test". So, how is that possible? It is wrapped with fibers coated with binder (epoxy?) for its strength, so is this some sort of cycle (pressure of temperature) caused fatigue of the composite structure?

 

[contrarian]

One has to also wonder why the leak of a non-flammable gas would cause an explosion.

But, I am reading that this pressurized nitrogen source is used (in part) for maintaining pressure in the fuel tanks to prevent methane from boiling off. Perhaps this is the cause of the explosion - leaking nitrogen allowed some methane to boil off, priming the upper stage for detonation.

 

[Unclear Engineer]

The nitrogen did not just "leak", it caused the vessel containing it to explode with force. Watching the video, that seemed to then cause the upper, then lower propellant tanks to explode, and then the tanks on the ground to the left of the Ship in the picture. Not clear if it was shock wave or fragments damaging the other tanks.

(It would have been helpful if the subject article for this thread had included the video showing the sequence of explosions.)

 

[contrarian]

The nitrogen did not just "leak", it caused the vessel containing it to explode with force.

I am not reading this anywhere. The article of this thread says:

"Initial analysis indicates the potential failure of a pressurized tank known as a COPV, or composite overwrapped pressure vessel, containing gaseous nitrogen in Starship's nosecone area, but the full data review is ongoing,"

A failure can be anything from a leak to a full explosion. If the COPV did indeed explode, that would be a major screw-up somewhere.

 

[Unclear Engineer]

"SpaceX Starship upper stage explodes during countdown to engine test firing
"Updated on: June 19, 2025 / 5:58 PM EDT / CBS News

"The dramatic explosion of a SpaceX Starship upper stage rocket during a test at the company's Starbase facility on the Texas Gulf coast late Wednesday may have been triggered by the rupture of a high-pressure nitrogen tank, SpaceX founder Elon Musk said Thursday."

Note the word "rupture". I don't know where you get the idea it was just a "leak".

 

[contrarian]

I stand by my statements. A rupture is not explicitly an explosion. It can simply be a fracture that would result in a leak of N2 gas or liquid, which could then cause damage elsewhere.

Googles AI also refers to a rupture of this N2 tank:

"The rupture of the COPV likely caused damage to surrounding structures and potentially ruptured fuel transfer tubes, leading to a leak of liquid methane and liquid oxygen. "

There are too many references to this AI quote to chase down where this came from, but it seems possible that a leak from a ruptured N2 tank caused additional damage, which ultimately led to the explosion.

As the quote says, a "rupture......likely caused damage". I don't think they would use the term "likely caused damage" if the COPV violently exploded. If that happened, it would cause damage elsewhere. And since N2 gas would not result in a fiery explosion in any event, damage elsewhere seems the only explanation for this dramatic disassembly.

Apparently we need to wait for more analysis by SpaceX engineers.

 

[Unclear Engineer]

One has to also wonder why the leak of a non-flammable gas would cause an explosion.

You said it yourself, so why are you now arguing that it could have been a leak while news sources are calling it a rupture and saying that it likely damaged the other tanks feed lines?

Oh, I get it - you just have to live up to your chosen name here.

 

[contrarian]

You said it yourself, so why are you now arguing that it could have been a leak while news sources are calling it a rupture and saying that it likely damaged the other tanks feed lines?

Oh, I get it - you just have to live up to your chosen name here.

As I said, I stand by my statements. A rupture could most certainly lead to a leak of the vessel, which never exploded. It appears to have ruptured, causing it to leak, resulting in a downstream explosion.

You are assuming that a rupture means an explosion. It does not :

Rupture: A rupture is a physical break or tear in a material or structure. This can happen due to various reasons like excessive pressure, stress, or material fatigue.

It is not an explosion.

 

[Unclear Engineer]

Too silly to continue with.

Will just let investigation catch up with the speculation.

Meanwhile, look at the video and note that the first plume from near the top of the vehicle did not seem to be a fireball.

 

[contrarian]

Will just let investigation catch up with the speculation.

Good idea. As you have noted before, the learning curve is ongoing. Musk says this is a first time failure for this device, but it could ultimately point to some other problem inherent in all the other failures. At least they appear to have solid data to investigate the cause.

 

[Hevach]

One has to also wonder why the leak of a non-flammable gas would cause an explosion.

But, I am reading that this pressurized nitrogen source is used (in part) for maintaining pressure in the fuel tanks to prevent methane from boiling off. Perhaps this is the cause of the explosion - leaking nitrogen allowed some methane to boil off, priming the upper stage for detonation.

Pressure vessels don't just leak. Go to YouTube and search "safety fail gas cylinder" and you'll get a lot of videos of people grabbing heavy gas tanks by the valve and trying to move them. The threads come loose a bit and the valve blows out like a bullet and the tank becomes a missile. It is an incredibly energetic process that will blow holes in concrete floors and steel walls cannot contain.

These COPVs are larger and higher pressure than any of the welding gas or compressed air cylinders you'll see those videos. And like a garage wall can't contain a broken scuba tank a rocket wall can't contain a broken COPV. Except now you're adding incredibly reactive liquid oxygen to the mix. Even if the methane tanks were empty you have the kind of fire that makes first responders retire and write a book.

 

[contrarian]

Pressure vessels don't just leak. Go to YouTube and search "safety fail gas cylinder" and you'll get a lot of videos of people grabbing heavy gas tanks by the valve and trying to move them. The threads come loose a bit and the valve blows out like a bullet and the tank becomes a missile. It is an incredibly energetic process that will blow holes in concrete floors and steel walls cannot contain.

These COPVs are larger and higher pressure than any of the welding gas or compressed air cylinders you'll see those videos. And like a garage wall can't contain a broken scuba tank a rocket wall can't contain a broken COPV. Except now you're adding incredibly reactive liquid oxygen to the mix. Even if the methane tanks were empty you have the kind of fire that makes first responders retire and write a book.

I am very familiar with all of this. A tank turned into a hazardous projectile is still not an explosion. It is more like a rocket - or like you wrote, a missile.

Finally, if the methane tanks were empty, we would not have seen the fiery explosion that occurred, even with a leak of O2. There would not have been such a violent explosion with just a rupture of the N2 vessel.

 

[Hevach]

Yes, you would. The structure of the rocket would not contain the energy of a COPV rupture and it would spill the liquid oxygen. Liquid oxygen is an extremely powerful oxidizer and in the presence of even poor quality fuel requires very little energy to ignite. The heat of metal breaking and the various forms of spark and flash creates by energetic collisions are enough to ignite it.

There have been several incidents of pressure vessel ruptures in rockets and every one ended in a catastrophic explosion.

 

[contrarian]

Liquid oxygen is an extremely powerful oxidizer and in the presence of even poor quality fuel requires very little energy to ignite.

Oxygen, liquid or gas, is not going to burn or explode on its own . It needs something to ignite. And the only thing to cause such a rapid explosion in this case would have to be another gas mixed in with it. And for this system, that could only have been methane.

 

[Unclear Engineer]

https://www.mdpi.com/2075-4701/10/1/128
"Metal combustion is one of the main issues threatening service safety in oxygen-enriched atmospheres, leading to unexpected explosions in rocket engines."

 

[contrarian]

"Metal combustion is one of the main issues threatening service safety in oxygen-enriched atmospheres, leading to unexpected explosions in rocket engines."

And exactly where in the ship do you expect to find so much metal that would cause such an enormous explosion?

I see the paper refers to combustion of steels, nickel alloys, and titanium alloys. Does anyone seriously believe that the ship exploded from a mixture of O2 and some metal?

That would be a very interesting observation to be sure. Please provide references rather than pure speculation for a scenario to define this explosion as something other than LOX and methane.

 

[Unclear Engineer]

The person providing speculation in this thread, and self-contradictory speculation at that, is Contrarian. Why?