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  • Into a mine first time and welding question

    From Richard Smith@21:1/5 to All on Fri Nov 10 08:38:45 2023
    Hello all

    An event for me - first time into a mine:

    http://weldsmith.co.uk/temp/mine/231109_condurrow.html


    The compressed air pipe - not that thick wall - about the same as a
    scaffold tube...
    That could be "got" in one pass with a cellulosic stick ("6010" SMAW) ?

    I am used to rebuilding the railings around storage and construction
    barges when they are wiped off in collisions.
    I'd usually start at the bottom and come up to the top welding "in
    one". No prep. - about 2mm gap - so can "blow a keyhole" and bring
    the keyhole around and up to the top. That is much better than a
    6013/"rutile" "butt-fillet" (a surface bead with neglible
    penetration).
    [In the UK most have never heard of 6010's, or if they have they are
    "aren't they some sort of special pipe-welding rod?" (sic.) - all
    common welds are made with 6013/rutile - high-spec welds with 7018's]
    But is that spec. good enough for a compressed air pipe at 6Bar?

    To weld a compressed air pipe up against the rock - can you cut it
    square to the half-way point, then have a "triangular-ish" cut-out to
    the front, with a fitting insert?
    So you can either weld around the back outside if you could get the
    rod in, watching the root penetration from the front? Or more likely
    given right up against the rock - weld from the inside / bore around
    the rear half, so the penetration bead is on the outside and the rough
    surface is on the inside. Then do two full-penetration welds to
    weld-in the "triangular-ish" insert on the front half of the pipe -
    welding from the outside?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jim Wilkins@21:1/5 to Richard Smith on Fri Nov 10 08:20:58 2023
    "Richard Smith" wrote in message news:[email protected]...

    all
    common welds are made with 6013/rutile - high-spec welds with 7018's]
    But is that spec. good enough for a compressed air pipe at 6Bar?

    ----------------------

    I've seen yield as low as 25KSI given for water pipe made from unknown
    scrap.

    Common US water pipe is rated for 300 PSI.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Richard Smith@21:1/5 to Jim Wilkins on Fri Nov 10 19:02:43 2023
    "Jim Wilkins" <[email protected]> writes:

    "Richard Smith" wrote in message news:[email protected]...

    all
    common welds are made with 6013/rutile - high-spec welds with 7018's]
    But is that spec. good enough for a compressed air pipe at 6Bar?

    ----------------------

    I've seen yield as low as 25KSI given for water pipe made from unknown
    scrap.

    Common US water pipe is rated for 300 PSI.

    I'm thinking of the girth welds. That said - pressure not more than
    100psi - and girth welds are at exactly half the stress of
    longitudinal seams (geometric effect).

    I once went to try to radiograph some 5mm (3/16th-inch) plate seam
    welded in one pass with cellulosics

    (* (/ 25.4 32) 6) ;; 4.762499999999999
    (* (/ 25.4 16) 3) ;; 4.762499999999999

    But when at the Co. with the radiography bunker, none of their welding machines, all inverters, would run a 6010, even "open-arc".

    With very little "subject contrast" by having that uniform 5mm
    thickness including barely different across the weld, and then only
    that 5mm thickness, I was going to be able to use some very contrasty fine-grained photographic paper. Hopefully fantastic sharpness to
    "run the question to ground". But was not to be. So never got to see
    how sound are those one-pass welds in much greater thickness than is
    met in Welding Procedure Specifications for eg. pipe welding.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jim Wilkins@21:1/5 to All on Fri Nov 10 14:58:34 2023
    "Richard Smith" wrote in message news:[email protected]...

    I'm thinking of the girth welds. That said - pressure not more than
    100psi - and girth welds are at exactly half the stress of
    longitudinal seams (geometric effect).

    --------------------------------

    I remember that tank stress problem from college, but not how to calculate
    it.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Richard Smith@21:1/5 to Jim Wilkins on Sat Nov 11 07:09:58 2023
    "Jim Wilkins" <[email protected]> writes:

    "Richard Smith" wrote in message news:[email protected]...

    I'm thinking of the girth welds. That said - pressure not more than
    100psi - and girth welds are at exactly half the stress of
    longitudinal seams (geometric effect).

    --------------------------------

    I remember that tank stress problem from college, but not how to
    calculate it.

    "Hoop stress" is the circumferential stress
    The longitudinal stress is is related to the "pi.r^2" area
    Seeing diagrams is best.
    If I wrote the equations here it would not "bring it ot life"
    Having "got it", you can forget the formulae but do the diagrams and
    re-derive the equations.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jim Wilkins@21:1/5 to Jim Wilkins on Sat Nov 11 07:35:14 2023
    "Richard Smith" wrote in message news:[email protected]...

    "Jim Wilkins" <[email protected]> writes:

    "Richard Smith" wrote in message news:[email protected]...

    I'm thinking of the girth welds. That said - pressure not more than
    100psi - and girth welds are at exactly half the stress of
    longitudinal seams (geometric effect).

    --------------------------------

    I remember that tank stress problem from college, but not how to
    calculate it.

    "Hoop stress" is the circumferential stress
    The longitudinal stress is is related to the "pi.r^2" area
    Seeing diagrams is best.
    If I wrote the equations here it would not "bring it ot life"
    Having "got it", you can forget the formulae but do the diagrams and
    re-derive the equations.

    --------------------------------

    The valuable simplification I learned from it was that the sum of forces on
    the end supports of a curved surface ("reaction"), such as an arch, can be treated as though it was a straight beam, instead of having to integrate one component of the force resolution across the curve.

    https://toolbox.igus.com/motion-plastics-blog/how-to-calculate-surface-pressure-for-plain-bearings
    "..the simple calculation that uses the bearing length and diameter is ultimately the more practical and precise one."

    When I designed the hydraulic bucket loader for my tractor I used brass
    water pipe for the pivot pin bearings because the calculated maximum
    pressure was excessive for sintered Oilite. When I took it apart after
    several years of clearing snow and hitting rocks etc under it one pin was slightly bent from an accident but the bushing to pin clearance had barely changed.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From David Billington@21:1/5 to Richard Smith on Sat Nov 11 22:42:35 2023
    On 10/11/2023 19:02, Richard Smith wrote:
    "Jim Wilkins" <[email protected]> writes:

    "Richard Smith" wrote in message news:[email protected]...

    all
    common welds are made with 6013/rutile - high-spec welds with 7018's]
    But is that spec. good enough for a compressed air pipe at 6Bar?
    ----------------------

    I've seen yield as low as 25KSI given for water pipe made from unknown
    scrap.

    Common US water pipe is rated for 300 PSI.
    I'm thinking of the girth welds. That said - pressure not more than
    100psi - and girth welds are at exactly half the stress of
    longitudinal seams (geometric effect).

    I once went to try to radiograph some 5mm (3/16th-inch) plate seam
    welded in one pass with cellulosics

    (* (/ 25.4 32) 6) ;; 4.762499999999999
    (* (/ 25.4 16) 3) ;; 4.762499999999999

    But when at the Co. with the radiography bunker, none of their welding machines, all inverters, would run a 6010, even "open-arc".

    With very little "subject contrast" by having that uniform 5mm
    thickness including barely different across the weld, and then only
    that 5mm thickness, I was going to be able to use some very contrasty fine-grained photographic paper. Hopefully fantastic sharpness to
    "run the question to ground". But was not to be. So never got to see
    how sound are those one-pass welds in much greater thickness than is
    met in Welding Procedure Specifications for eg. pipe welding.

    Richard,

    I had a look to find out what the problem might be running 6010 on
    inverters and came across this thread https://forum.weldingtipsandtricks.com/viewtopic.php?t=16665 , it
    suggests adding an old transformer welder in the circuit to add
    inductance to get it to run 6010. I expect my old MaxArc rectifier might
    do the same as it's just a full wave rectifier in a box with a large
    inductor for smoothing.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)