"New" HMS Prince of Wales sinking analyzes

[lwd]

.... Several USN ships experienced structural failure due to welding problems during WW2

Indeed weren't the Lliberty ships rather noted for welding failures?

[Legend]

Yeah they were... but then again at the rate they were spitting those things out was enough that any production method they used would prove to be fairly unreliable. Though I must admit that the modular construction probably did help in all respects.

But back to the subject. Bismarck was welded. Bismarck proved to be far harder to sink. The North Carolina and the South Dakota classes were made in the thirties... weren't they welded? I realize the point that the British believed that the riveted system was superior... but didn't technological collaboration between them and the US show the advantages of the welding?

[dunmunro]

Yeah they were... but then again at the rate they were spitting those things out was enough that any production method they used would prove to be fairly unreliable. Though I must admit that the modular construction probably did help in all respects.

But back to the subject. Bismarck was welded. Bismarck proved to be far harder to sink. The North Carolina and the South Dakota classes were made in the thirties... weren't they welded? I realize the point that the British believed that the riveted system was superior... but didn't technological collaboration between them and the US show the advantages of the welding?

The RN didn't think that riveting was inherently superior and the KGVs were partial welded, IIRC, just that given 1930s technology welding was problematic. AFAIK, the NCs had riveted holding bulkheads.

[Mostlyharmless]

I know little about welding but my understanding is that the British (and Japanese) used D Steels (DuCol) which were strong but relatively hard to weld successfully. Germany, by contrast, had developed ST52 which was easier to weld and may have been developed to combine strength with ease of welding.

[Dave Saxton]

The weldability of the parent metal is crucial indeed. This was the primary problem with the Liberty Ships. The high tensile steel used was generally of poor quality and relatively brittle. This problem was often compounded by hydrogen embrittlement. High quality welds (that are not significantly less ductile than the parent metal) are made possible with steels designed to be welded and using low hydrogen welding consumables and methods.

The weld itself and heat effected zone will almost always be less ductile than the parent metal. For example, British tests of Ducol:
Elongation of parent metal (D-steel) -17%
Elongation of weld and weld zone-5%!

In the case of high speed shock loading and rapid deformation of the structure, this weld will rupture relatively easy, because it can't deform without tearing very much. No wonder they concluded that they should use mainly riveted construction on the KGV class. Nonetheless, riveted construction has far less strength than welded construction.

The strength of a riveted joint is the shear strength of the rivets. The shear strength will be about 60% of the ultimate tensile strength of the rivet. Thus a riveted joint is relatively weak. With welded construction the strength of the joint is the utlimate tensile strength of the weld.

In German weld tests of ST-52 during 1942, and using a low hydrogen welding electrode known as the E52K, the results were:
Parent Metal UTS-53.3kg/mm2 (~77,000 psi)
Parent Metal YTS -37kg/mm2
Parent metal elongation -32%
Weld metal UTS 52.7 kg/mm2
Weld metal Elongation 27.5%

Thus although the weld itself is less ductile than the parent metal the overall strength of the joint is still far superior to riveted construction. One can easily see why ST-52 became the standard material for welded ship construction post war world wide, even now.

In the case of armour grade materials, stainless steel weld metal was and still often is used. Stainless steel weld metals exclude hydrogen, which solves a major problem ,and it is highly ductile with elongations that can exceed 40%. In the case of welded joints of armour grade materials using SS, the weld is less strong than the parent metal, and so once the load exceeds the UTS of the weld; the weld will fail. This point of failure is still far greater than that of riveted construction in most cases, and the weld can deform adequately without tearing.

[mike1880]

The failure of British yards to adopt welding had nothing to do with technical or quality issues. This gives an indication of the factors that prevailed:

http://books.google.co.uk/books?id=bw46 ... ds&f=false

Mike

[Dave Saxton]

It is known (perhaps not commonly) that the trade unions and the ship building companies' managment both, were dragging their heels. This wasn't just looking out for their jobs although that was certainly a major concern. A major problem with adopting welding was the technical knowlege, particulary of mathematics, required not only of the engineers but also of the skilled laborers on site. Time proven traditions of apprenticeship and learning ones trade on the job from elders were no longer sufficient.

However, concerning the KGV class in particular they did consider welding early on and choose riveting instead for the TDS, based on emprical testing.

[dunmunro]

The failure of British yards to adopt welding had nothing to do with technical or quality issues. This gives an indication of the factors that prevailed:

http://books.google.co.uk/books?id=bw46 ... ds&f=false

Mike

The article above, in fact, discusses the Admiralty's use of welding in the early 1930s and goes on to state that Ark Royal, for example, was 75% welded. I disagree that technical and quality issues were not a factor, as they clearly were a cause for concern by the RN, and as Dave has pointed out the development of specialized steels for welding warships was an on-going and rapidly developing area in the 1930s.

[RF]

But against a background of worldwide recession in steel manufacture in the early 1930's which would have inhibited development of specialised steels because of the lead costs involved and also the lack of long run economies of scale due to the initially restricted amount of work.
The article is also illuminating in highlighting some of the restrictive trade practices inherent in British shipyards at the time.

[dunmunro]

One of the major conclusions that our Committee of which I am chairman is the failure of riveted joints under contact and explosive loads. Bismarck is an exception, as she was 95% welded construction. That is one of the reaons why she was hard to sink. Mr. Monro is mistaken in his criticism of our conclusion on the significance of the those seven near miss 500 kilogram bombs. If he read the the Bucknill Report as I did and interviewed some of the survivors as I did, it was clear that there was internal flooding going on after this bombs' explosions. In the Battleship book concerning Prince of Wales I had to rely solely on suvivor testimony as there was no photo imagery from the wreck site until Kevin Denlay and Andrew Fock made their visit in 2007 for a complete photo survey of the wreck. This event coupled with research into the behavior of riveted joints clearly indicate that there was rivet failure involved, not only with the bomb attack, but also with the torpedo attacks. Further revision of this paper will occur with analysis of new data that will clearly show why the first torpedo hit was so devastating. That information was not available in 1980 when Volume II of Battleships was published. Mr. Munro also has not answered in criticism of why those folds occurred when the air pocket, if it existed would have been at the bottom of the tank and not at where the air folds occurred because the ship was upside down when it arrived at the seabed. The paper was written with the intent of gathering opposing views and my co-authors and I welcome constructive criticisms.

Bismarck was 95% welded, but a notable exception was her riveted SPS holding bulkhead - the only part of the ship specifically designed to resist pressure waves.

I have reviewed all the data I can find regarding near miss damage to RN ships. I have been unable to find any descriptions of damage to other ships that would provide an analog to the longitudinal indentations and collapse found on PoW along her SPS. Even the near miss on PoW that occurred on Aug 31 1940 does not appear to have caused similar longitudinal indentations and the damage caused by that hit was confined to the outer void compartment directly abreast the near miss as the photo published on page 43 confirms. The RN experienced hundreds of near misses during the war, including many to CVs with a similar SPS design yet I can find no reports of extensive longitudinal collapse of the SPS outer voids resulting from these near misses. I do not have access to the UK Archives to do an extensive search of RN damage reports, so I have had to rely on the limited information here:

http://www.dcfp.navy.mil/mc/museum/War_ ... ritish.pdf

and in general descriptions of wartime damage to specific RN ships published in a variety of other sources.

PoW's hull has 3 dish shaped indentations on it, noted in Death of a Battleship and while the two dish shaped indentations on the port side might have conceivably indicated two simultaneous explosions that combined to create a pressure wave that caused a sudden collapse of the SPS outer void layer, the starboard side has only one dish shaped area and it is highly unlikely that the resulting pressure wave could have caused such extensive deformation. However the existence of such pressure waves seems to fly in the face of physics and simple logic. The pressure from an underwater explosion falls off rapidly with distance, in accord with the inverse square law. Similar near misses, including the Aug 31 1940 explosion that damaged PoW failed to create similar damage despite a dish shaped indentation on the hull from the near miss that appears to be very similar to those found on PoW's wreck. A torpedo hit on Indomitable centred on the hull just under the armour belt, also failed to create a similar longitudinal tear in Indomitable's outer SPS voids:
http://www.godfreydykes.info/INDOM_2.jpg
http://www.godfreydykes.info/DAMAGE%20C ... 0REAL!.htm

On May 1 1942, KGV collided with the destroyer HMS Punjabi cutting the DD in half. The DD's depth charges exploded, causing extensive shock damage to KGV but apparently little damage to KGV's SPS outer voids.

The Hull of PoW, like most ships, must be stoutly constructed along the bilge keels and the turn of the bilge to prevent structural damage when the ship is dry docked. In contrast the SPS under the armour belt is lightly constructed to minimize splinter damage from a torpedo hit. The hull where the SPS outer void meets the armour belt therefore seems to be the most likely area to fail from outside water pressure, especially as this part of the hull is deeper than the bilge keels. The resulting failure allows the incoming water to then compress the air trapped in the area of the bilge keel, to the same pressure as the outside water, preventing further collapse.

Near misses occurred frequently to RN ships during WW2. Extensive longitudinal failure of the hull along the SPS outer void spaces appears to be rare enough that it is not mentioned in any source that I have access to.

[alecsandros]

I have re-read the entire topic today.
I think there's one question that needs be answered :
Would PoW have survived without the first torpedo hit? (presuming everything else would go as in the historical mission - 4-5 other torpedo hits + 1 bomb hit)

My impression, formed from reading both the sinking analysis and GD "Allied BBs", is that, with or without the early hit, PoW would have been sunk.
Maybe it would have lasted longer under fire, but the flooding coming from the other torpedo holes was so severe and rapid that I don't think an experienced crew could have saved her.

The TDS simply failed to protect the ship from 330pds warheads, as proved by the damage delivered by the other 4-5 torpedoes and by the near misses. What was initialy created to withstand 1000pds warheads proved drasticaly inept to handle torpedoes half that size.

[RF]

I am inclined to think alecsandros that given thenumber of attacking aircraft that you are probably right.

[dunmunro]

I have re-read the entire topic today.
I think there's one question that needs be answered :
Would PoW have survived without the first torpedo hit? (presuming everything else would go as in the historical mission - 4-5 other torpedo hits + 1 bomb hit)

My impression, formed from reading both the sinking analysis and GD "Allied BBs", is that, with or without the early hit, PoW would have been sunk.
Maybe it would have lasted longer under fire, but the flooding coming from the other torpedo holes was so severe and rapid that I don't think an experienced crew could have saved her.

The TDS simply failed to protect the ship from 330pds warheads, as proved by the damage delivered by the other 4-5 torpedoes and by the near misses. What was initialy created to withstand 1000pds warheads proved drasticaly inept to handle torpedoes half that size.

The info regarding the underwater damage in G&D's Allied BB's should be treated with caution as much of it is based upon outdated info, especially the info on page 241 . PoW's SPS was never defeated.

There were 4 torpedo hits:
1 port side aft with a 330lb warhead, that caused extensive flooding, this hit was aft of the SPS.
3 starboard side, with 450lb warheads, that caused very limited flooding. The only torpedo hit on the SPS was abreast B turret and diver examination shows the SPS holding bulkhead to be intact abreast the area of the hit, despite the SPS void spaces having been counterflooded which reduced the effectiveness of the SPS.

Even with the historical damage, there was some probability of survival if flooding along B prop shaft could have been contained by keeping the shaft shut down. If the historical hit on the port side aft never occurred, then PoW would not have been in any danger of sinking, and would have retained steering and full power and thus the additional 3 hits may not have occurred or if they did, the number of hits would have been greatly reduced.

[alecsandros]

3 starboard side, with 450lb warheads, that caused very limited flooding. The only torpedo hit on the SPS was abreast B turret and diver examination shows the SPS holding bulkhead to be intact abreast the area of the hit, despite the SPS void spaces having been counterflooded which reduced the effectiveness of the SPS.

From the attached paper, this seems very hard to believe. Torpedo hits 1 - 3 from the second attack caused significant damage and lead to the loss of the ship (which could still be saved at that time). At least this is what I understand from "Death of a battleship":

Torpedo hit no 1 (of the second strike)"struck the hull right at the bow, [...] tearing a hole [...] 7 meters in diameter right through the ship. [...]. This caused the imediate flooding of the 2 peak tanks", etc...
Torpedo hit no 2 (of the second strike)caused a "huge plume of oil and water to shoot up alongside turret B, Washrooms on the lower deck and the living spaces on the middle deck were flooded [...]" Etc..
Torpedo hit no 3 (of the second strike)
"Occured abaft Y turret, stoping the turbines in A engine room", etc...

"These 3 torpedo hits were decisive because they negated all damage-control efforts to set a flooding boundary in the stern".

Indeed, the crucial hits (no 1 and 4) were both astern, so off the TDS. Also, torp hit no 2 was well aft of the TDS.
This leaves us with torpedo hit no 3, directly in the TDS. The authors of "Death of a battleship" wrote:

"The TDS performed well, with one exception. Part of the gas jet from the torpedo explosion did vent into the Seamen's Mess Deck over the impact area near Frame 109"[...] "The British system was unable to contain the explosion completely within the system"

[Bgile]

"The TDS performed well, with one exception. Part of the gas jet from the torpedo explosion did vent into the Seamen's Mess Deck over the impact area near Frame 109"[...] "The British system was unable to contain the explosion completely within the system"

dunmunro has previously stated he thinks that was a "feature". It doesn't look like the British felt that way back then.