Results 1 to 14 of 14
  1. #1
    metalmagpie is offline Hot Rolled
    Join Date
    May 2006
    Location
    Seattle
    Posts
    956

    Default caps for acetylene cylinders with coarse threads?

    I have an acetylene cylinder, about 150 cf, that came to me with no cap. I figured oh well, I can pick one up somewhere. But it seems this cylinder has oddball threads: 3.5-8, not the usual 3.5-11 threads. I found caps for sale at MSC, but now I'm curious. Anyone know any history about the threads used on cylinders where the cylinder caps thread on?

    metalmagpie

  2. #2
    Join Date
    Jan 2005
    Location
    Salem, Ohio
    Posts
    4,084

    Cool

    I don't know the history but i have both caps in my collection...Bob
    Look here>>> http://www.rmiorder.com/index.php/br.../cylinder-caps
    Bob Wright Metal Master Fab
    Salem, Ohio Birthplace of the Silver and Deming Drill, all others are copies.

  3. #3
    JoeE. is offline Stainless
    Join Date
    Aug 2006
    Location
    Kansas
    Posts
    1,818

    Default

    Contact the welding supply guy and see if he can get you a cap.

  4. #4
    metalmagpie is offline Hot Rolled
    Join Date
    May 2006
    Location
    Seattle
    Posts
    956

    Default

    Quote Originally Posted by aametalmaster View Post
    I don't know the history but i have both caps in my collection...Bob
    Look here>>> Cylinder Caps - Ratermann Manufacturing, Inc.
    I saw that site when I was googling for caps. No pricing.

  5. #5
    Jim Caudill is offline Stainless
    Join Date
    Nov 2002
    Location
    Dayton, Oh
    Posts
    1,434

    Default

    Around here, I would just wait until I exchange the tank. They will charge you something like $15 for not having the cap on the "turn-in". The one you take home will have a cap on it.

  6. #6
    mobile_bob is offline Stainless
    Join Date
    Oct 2005
    Location
    tacoma washington
    Posts
    1,338

    Default

    i turned in a set of oxy/acet cylinders a couple months back sans caps, they got me for
    5 bucks each to replace the caps.

    not a bad price for having something that takes care of the issue, the replacement cylinder comes with a cap so any oddball thread is their problem.

    apparently it really isn't a problem for them as they seem to have caps to fit everything that needs one.

    bob g

  7. #7
    adama is online now Diamond
    Join Date
    Dec 2004
    Location
    uk
    Posts
    6,793

    Default

    Are caps a leagle requirment over there? There not here, only toxic - special gasses ever have them here.

  8. #8
    metlmunchr is offline Diamond
    Join Date
    Jul 2004
    Location
    Asheville NC USA
    Posts
    8,284

    Default

    Caps are required to legally transport any high pressure cylinder or any flammable gas cylinder above a certain capacity.

    Small acetylene cylinders, like an MC or B size, don't have cap provisions. Nor do cylinders like carbon dioxide and other similar liquefied gases at relatively low pressure.

  9. #9
    Warren's Avatar
    Warren is offline Aluminum
    Join Date
    Nov 2005
    Location
    Sutton NH USA
    Posts
    120

    Default

    The cap thread is usually specified by the original owner of the tank. For example. The local Airgas store where I used to buy gas had bought up several local small suppliers. Thus the tanks were integrated into the system. One of the old suppliers oxy tanks had course threads & the rest did not. So I had to buy & carry one each of the yellow safety caps for my service truck. That was the reason they gave me, there seems to be no standard.

  10. #10
    Join Date
    Jan 2005
    Location
    Salem, Ohio
    Posts
    4,084

    Cool

    Quote Originally Posted by metalmagpie View Post
    I saw that site when I was googling for caps. No pricing.
    Just shoot em an email...Bob
    Bob Wright Metal Master Fab
    Salem, Ohio Birthplace of the Silver and Deming Drill, all others are copies.

  11. #11
    metalmagpie is offline Hot Rolled
    Join Date
    May 2006
    Location
    Seattle
    Posts
    956

    Default

    I found what I was looking for - a source. There is a local business that does most of the hydrotesting for the local business community. They of course see tanks that fail, so the guys who make bells buy scrap tanks there. They have lots of old caps. As it happens I have a WWII-era 100-lb propane cylinder which is heavily made and galvanized so it has no rust. Plus it has threads for a cap - its previous owner thought it was a huge acetylene cylinder. I use cylinders like that for the propane burners in meat smokers, so I decided I'm going to go get it hydrotested. They'll just throw in the cap.

    I know I could just swap it without a cap. Around here we have 3 main welding supply stores: Airgas, Praxair and Central Welding. The one with the cheapest price on acetylene (Praxair) also is the one who charges the most for missing caps. Sigh.

    Some of the people posting on this thread seem to be under the impression that there are many random threads for cylinder caps. Not true. High pressure cylinders use 3-1/8" caps, and they come in 3.5-7 or 3-11 threads. Fuel gas cylinders use 3-1/2" caps, and they come in 3.5-8 or 3.5-11 threads. So for each size there are two threads. Not many, not random, just coarse or fine.

    metalmagpie

  12. #12
    Join Date
    Jan 2005
    Location
    Salem, Ohio
    Posts
    4,084

    Cool

    Cool thanks for the update...Bob
    Bob Wright Metal Master Fab
    Salem, Ohio Birthplace of the Silver and Deming Drill, all others are copies.

  13. #13
    Newman109 is online now Titanium
    Join Date
    Sep 2006
    Location
    Sacramento County, California
    Posts
    2,092

    Default

    Quote Originally Posted by adama View Post
    Are caps a leagle requirment over there? There not here, only toxic - special gasses ever have them here.

    Yes, I believe that they are. I've not seen a tank without the cap except when in use. Years ago I saw a large GN2 (nitrogen) cylinder fall over when I was working in aerospace. The brass neck broke and the tank went about 50 feet and buried itself in a hill side nearby. It was exciting. LOL.

    I have spare cylinders and I store them chained up with their caps on.

  14. #14
    Avanti is offline Cast Iron
    Join Date
    Nov 2003
    Location
    Wauna, WA
    Posts
    398

    Default

    I have been told by 2 different gas suppliers that the course thread bottles are all AIRCO bottles all of which are rental bottles. So you probably will not be able to get that oddball refilled.

    Unless they were lying to me which is at least as likely as not.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •