EXCLUSIVE Was THIS the fatal flaw that doomed Titan? How 'peanut butter' glue used to join 22ft sub together was never certified to work in deep seawater

Daily Mail​

4 days ago

Glue used to hold the doomed Titan submersible together was never certified to work in deep seawater, it can be revealed today.
Henkel, the German adhesive giant which manufactured the resin in question, said it was only ever marketed for the aerospace sector.
Although it admits the glue can safely be used 'in other applications', Henkel 'does not certify its products for various uses'. A spokesperson said: 'It is the end user's responsibility to test their design to ensure proper performance.'
Sources from inside Henkel had no idea their glue was even used on Titan until MailOnline told them, and confirmed it was 'not specified for usage under water'.
Questions are now being asked as to whether the choice of glue was partly to blame for the 22ft sub's catastrophic implosion on June 18, 2023.
All five passengers onboard were killed near instantaneously when the vessel caved in on itself.
Cruising 12,500ft beneath the Atlantic Ocean, they were just minutes away from getting a glimpse of the Titanic's wreck.
One world leading expert said he would never have advised OceanGate, the firm which operated Titan, used the Loctite EA 9394 Aero resin to bond the carbon fibre hull and titanium sections of the submersible together.
Loughborough University's Dr Christian Stone, who specialises in corrosion, said it effectively turned the sub into a giant battery.
The paste, listed online as possessing 'excellent strength' and having 'improved wet properties', contains between 30 and 40 per cent powdered aluminium.
By using the metallic-based glue, OceanGate's CEO Stockton Rush, who died in the implosion, may have introduced a fatal flaw into his 'experimental' submersible.
Titan's maintenance log noted on June 17 a problem with 'unsightly' sealant joining the titanium to the carbon fibre. The crew 'ground off bumps' to make a 'smooth surface'.
Dr Stone, whose expertise is in galvanic corrosion – an electrochemical process where one metal will, when placed in certain environments such as seawater, sacrifice itself on behalf of another, said this should have been seen as a major red flag.
He told MailOnline: 'If you put two metals together and they're connected electrically to a media which conducts electricity like seawater you make a battery.
'One side of that battery will corrode and give up ions. The other side will actually be protected.
'At the corroding side, we call this the anode and that makes acid. The other side is the cathode in which case in our case that will be carbon fibre or titanium and that will make alkaline.
'How quickly that anode side, the corroding side, corrodes depends in part on how conductive the environment is.'
The wreckage of Titan showed that much of the five-inch thick carbon fibre hull delaminated and pulled apart into different layers as well as losing its bonding to the crucial titanium ceal
Dr Stone said the 'unsightly' area on the joint could have been evidence of aluminium oxide – the result of the corrosion.
Without testing, he cautioned it is difficult to determine how big an effect this would have had on the Titan's structure.
Dr Stone warned that 'in the most extreme circumstances', this might have potentially triggered a 'very small amount of honeycombing'. Any gaps would have weakened the hull's structure and left it vulnerable to the extraordinary force exerted by the ocean.
He said this reaction would begin once Titan was exposed to any salty air but would 'accelerate once they are within the water'.
Dr Stone added: 'This will be especially potent when they are going in and out of the water many times because then it will also get exposed to oxygen as well as water, which is good for corrosion.'
Dealing with the unsightly sealant by grinding it off was also unwise.
He said: 'If they were repeatedly cleaning that kind of sealant, they may have actually done more damage cleaning it than would have occurred due to the corrosion.
'The use of vibrating tools on brittle materials such as epoxy (resin) can have a damaging effect on the stress cycle of these things. It all depends on what the engineering margins are in these extreme environments.'
Lower safety margins would result in a greater danger of failure.
Ultimately, Dr Stone told MailOnline that the product they used was designed for high altitudes and not the deep sea.
He said: 'I would have advised them to use a filler material that was inert and does not conduct electricity.'
Dr Stone said OceanGate should have spent more time testing, including the use of accelerated corrosion and stress testing.
He added: 'I would also recommend preventive measures such as anodizing the titanium, coating the carbon fibre, and coating the sealant as well just to remove any chance of any of them interacting to make a cell and a battery.'
When building his submersible, Rush appeared in a promotional video showing his team applying the glue to craft using large plastic spatulas.
He said the product was 'like peanut butter' and thicker than Elmer's glue.
Showing absolute confidence in his problem-solving skills and ability to think independently, Rush told the camera that attaching carbon fibre to titanium 'is pretty simple, but if we mess it up, there's not a lot of room for recovery'.
A US Coast Guard investigation into the June 2023 tragedy is expected to publish a report into the disaster before the end of the year.
As part of the investigation, experts at the National Transportation Safety Board examined the wreckage which was recovered from the scene.
Examining the crucial joint, the NTSB found: 'Most of the adhesive originally used to bond the hull to the titanium segment had disbonded from the machined end of the hull piece, but there was an approximately 3.5-inch-long patch where some adhesive bits were still attached.'
The glue had failed to hold the sub together, although it is not thought to be the underlying factor behind the implosion.
Donald Kramer, senior materials engineer of the NTSB, wrote: 'The aft dome, aft segment, aft portions of the hull, and rails were located together in a comingled mass. The forward dome was located by itself.'
The sub had failed at the front, investigators believe.
Much of the imploding sub behind the very front was sent hurtling towards the rear dome, hitting it with such force it twisted the titanium ring which was glued to the hull, and ripped out several of the heavy duty bolts screwing the two parts together.
OceanGate has suspended all exploration and commercial operations following the disaster.