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  1. #1
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    Shell manufacturing video-1939

    I found this very interesting.

    https://youtu.be/BPGqLjnNIJY

  2. The Following 12 Users Say Thank You to Terreplein For This Useful Post:

    AE501 (24th March 2020), aust303 (23rd March 2020), DICKAREN (23rd March 2020), doppz92 (24th March 2020), Lostround (23rd March 2020), M8owner (23rd March 2020), no3nh4 (24th March 2020), ron3350 (23rd March 2020), Slick (23rd March 2020), Snufkin (23rd March 2020), TimG (23rd March 2020), tnor_fr (23rd March 2020)

  3. #2
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    What wonderful machines. Today, the M42 HE 3 inch projectile is very hard to find. I have only found two in the last six years. I checked one of them, and it has the spot welded disk on the bottom. I am amazed that is necessary as a safety precaution to keep hot gases from getting into the explosive. I suppose the forging process would have cracks in the bottom for some percentage.
    Last edited by M8owner; 23rd March 2020 at 03:15 PM.

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    Terreplein (24th March 2020)

  5. #3
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    The concern is that the grain flow of the projectile base is parallel to the chamber pressure acting upon it, thus there is a possibility of 'piping' - the combustion gases at very high temperature and pressure working their way along the grain. The gas check plate/disc has its grain flow perpendicular to that of the projectile base.

    TimG

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    Terreplein (24th March 2020)

  7. #4
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    I have only seen American WWI and WWII projectiles with the disk on the bottom. I have not seen this done on any of the other projectiles in my collection from Russia, German, France, UK. I worked for a bearing company as an engineer for ten years; steel making, metallurgy, fabrication and heat treatment were daily conversations. I do not recall ever hearing the topic of "piping". However, we were never trying to contain hot gas at 20,000 PSI either.

  8. #5
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    I was taught about 'piping' exactly as TimG described it, but after inspecting ammunition for some years, never ever saw a shell fitted with a base plate.
    I was amazed to see a plate fitted to both the 105mm Pack How and 155mm for M109 of US origin.
    I assumed it was to prevent 'piping' although there was no reason given for it in our pamphlets and they are very thin.
    Having researched this further, I find that originally the plates were screwed into a threaded recess in the base to prevent 'piping' into the base of Lyddite filled shell. Apparently, sensitive picrates and gases are produced by the reaction of picric acid and steel and although the interior metal was varnished, this could break down over time.
    The reason we were taught about 'piping' was because there were still Lyddite filled coast defence shell in service at that time.
    All these 7.2", 9.2", 12" shell were stored in one particular UK Ammunition Depot, where they had a lot of overhead rail handling equipment and unless you served there you would never come across such shell.

  9. #6
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    For the US rounds it started around WWI. You very rarely if ever see the base plates on the 3" FG HE, but all of the 75mm HE and up have them. The original base plates on the 75mm were brass and the 155mm used copper. Under the plates were also a lead disk. The plates were set in a milled channel and then "caulked", using lead strips to seal the plate in. They must have figured out that just the steel plate could do the job with less cost and time. I've also seen where the lead disk moves under the plate on 155mm MK I rounds because of centrifugal force and tends to "puddle" to one side, which could possibly affect accuracy. This practice of using base plates has continued with US HE rounds until quite recently. A little bit ago I was shown a new US 155mm HE that didn't have the base plate. And thus a key ID feature for US EOD techs is no longer there.
    I watched this video a couple of days ago. Fascinating.
    Last edited by bacarnal; 24th March 2020 at 11:23 PM.
    ALL ORDNANCE SHOWN BY ME HAS BEEN INERTED AND HAS NO LIVE FILLERS.

  10. #7
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    Quote Originally Posted by M8owner View Post
    I have only seen American WWI and WWII projectiles with the disk on the bottom. I have not seen this done on any of the other projectiles in my collection from Russia, German, France, UK. I worked for a bearing company as an engineer for ten years; steel making, metallurgy, fabrication and heat treatment were daily conversations. I do not recall ever hearing the topic of "piping". However, we were never trying to contain hot gas at 20,000 PSI either.
    Have a look at the french 75 mm HE shells, not sure if these exist without the soldered base plates, have seen most with a base plate. The german picric shells had very thick walled bases and the later thin walled shells were not filled with picric acid. Just some 17 cm Minenwerfer shells made from forged steel too had screwed base plates.

    The german shells were tested during WW1 in exactly the same way as in this video. In 2nd WW many were also tested for Brinell hardness.

 

 

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