"Jim Wilkins" writes:

"Richard Smith" wrote in message ...

Pressure gauge which is removable - connect in line, only when needed

...

although higher than half scale is preferable.

Yesterday

* rebuilt hydraulic cylinder with new seal and it's good

That's the one which started leaking back in mid November
http://www.weldsmith.co.uk/tech/stru...lyse_test.html
when doing this (test of RHS test-weldment)

So now I'm fully rehabilited as "persona grata" amongst my workmates.

Little hint I'd offer - the seal seals so well, do drip some hydraulic
oil on top of it before screwing together the cylinder, so it slides
easily (?!?)


* fillet weld tensile breaking force test rig worked

Pic. of
http://www.weldsmith.co.uk/tech/stru...fwtest_rig.jpg

Time to get a pressure-gauge - to get F=P*A estimate of force.

That said - with Co.'s pump and cyl. (the one I put the new seal in) -
I put the cylinder in the shop press, which has a force-applied gauge
- so when you pump up the pump-and-cylinder, the press's gauge tells
you how much force the cyl. is applying :-)
So I know the pump's relief valve does operate at 700Bar, giving
10Tonnes force on that cyl. And you get in your mind a rough
"calibration curve" of pump handle force to force applied by the
cylinder :-)

Anyway, estimated 8 Tonnes when sample broke.
Did maths just now - cyl. force to force across weld - using
F_r_t=-F_p*L_m-a/2h
(or, if F_w signified "force across the weld",
F_w=-F_p*L_m-a/2h)
of
http://www.weldsmith.co.uk/tech/stru...4_fwbeamt.html
and as
spacing central plate to "hoop"=340mm (set using tape)
L_m-a - say it is 350mm ("hoop" "beds" and can rotate a bit)
and RHS is 100mm "tall"
L_m-a/2h = 1.75
# (/ 350e0 (* 2 100))
# 8*1.75
- and get 14Tonnes
Another estimate of 560MPa for the "G3Si1" ("ER70s-6") weld metal
break strength :-)

This has been consuming my mind for weeks.
Quite something that the hydraulics and the test fell into place on
the same day yesterday! :-)

Best wishes,