Yesterday I ran across a picture in a book of a pipe which had been welded into
a semi-spherical closed end. If you think of the top half of a tennis ball cut
in half with a chop saw, then rotated 90° and again cut in half (so that the top
half of the tennis ball was cut in quarters) and then the quarters were lifted
straight up, if you just looked at that upper profile of the tennis ball and
then if you layed out a proportional pattern on the end of a piece of pipe and
cut away the material in between the "petals", then the tabs could be forged
over into a semispherical shape and welded up to form the shape I saw yesterday.

I thought it looked cool. Naturally, being the curious type, I started thinking
about how to lay it out on a pipe from first principles. Hoo, boy, that one is a
tricky layout problem. Anyone know how to approach it?

GWE

It is a pretty straightforward development. If you can develop pipe
intersections then it is not much different. Start with a side view of the
profile and an end view.
The pieces of orange peel or petals so to speak can be draw in both
views then true distances extracted. You can decide on how many sections
you want cut. Only four sections is crude. Six or even eight on a six inch
pipe looks much better.
If you have say six sections you only need one pattern. Split the
circumference with lines then trace your marks onto the outside of the pipe.
Once you have cut your petals take a rosebut and heat the petals. Don't
rush hammering in the petals. Take it carefully heating at the base of the
petals and bending them with your hammer gently and evenly. Work your way
to the tips and as the sides close they should make contact supporting the
shape.
I was told that such an end will take the hammering effect of the fluid
better than a flat plate closing off the end.
Randy


"Grant Erwin" wrote in message
...
Yesterday I ran across a picture in a book of a pipe which had been welded
into a semi-spherical closed end. If you think of the top half of a tennis
ball cut in half with a chop saw, then rotated 90° and again cut in half
(so that the top half of the tennis ball was cut in quarters) and then the
quarters were lifted straight up, if you just looked at that upper profile
of the tennis ball and then if you layed out a proportional pattern on the
end of a piece of pipe and cut away the material in between the "petals",
then the tabs could be forged over into a semispherical shape and welded
up to form the shape I saw yesterday.

I thought it looked cool. Naturally, being the curious type, I started
thinking about how to lay it out on a pipe from first principles. Hoo,
boy, that one is a tricky layout problem. Anyone know how to approach it?

GWE

Grant Erwin wrote:
Yesterday I ran across a picture in a book of a pipe which had been
welded into a semi-spherical closed end. If you think of the top half of
a tennis ball cut in half with a chop saw, then rotated 90° and again
cut in half (so that the top half of the tennis ball was cut in
quarters) and then the quarters were lifted straight up, if you just
looked at that upper profile of the tennis ball and then if you layed
out a proportional pattern on the end of a piece of pipe and cut away
the material in between the "petals", then the tabs could be forged over
into a semispherical shape and welded up to form the shape I saw yesterday.

I thought it looked cool. Naturally, being the curious type, I started
thinking about how to lay it out on a pipe from first principles. Hoo,
boy, that one is a tricky layout problem. Anyone know how to approach it?

GWE

That's called an orange peel. The layout is described in detail in "The
Pipe Fitter's and Pipe Welder's Handbook" by Thomas A. Frankland, also
called the Frankland book by many pipe fitters. Looks like data is
provided for 4 to 8 "arms" depending on the size of the pipe.

Gary Brady
Austin, TX

Grant Erwin wrote:

Yesterday I ran across a picture in a book of a pipe which had been welded into
a semi-spherical closed end. If you think of the top half of a tennis ball cut
in half with a chop saw, then rotated 90° and again cut in half (so that the top
half of the tennis ball was cut in quarters) and then the quarters were lifted
straight up, if you just looked at that upper profile of the tennis ball and
then if you layed out a proportional pattern on the end of a piece of pipe and
cut away the material in between the "petals", then the tabs could be forged
over into a semispherical shape and welded up to form the shape I saw yesterday.

I thought it looked cool. Naturally, being the curious type, I started thinking
about how to lay it out on a pipe from first principles. Hoo, boy, that one is a
tricky layout problem. Anyone know how to approach it?

GWE

http://www.tpub.com/content/construc.../14251_109.htm