smooth sphere vs unsmooth sphere

From:  Greg Leyh [SMTP:lod-at-pacbell-dot-net]
Sent:  Saturday, April 04, 1998 4:35 AM
To:  Tesla List
Subject:  Re: smooth sphere vs unsmooth sphere

> Note that for the same Emax, the surface charge density in the sphere is:
> qmax/area = qmax/(4*pi*r^2) = e0*Emax =8.85e-12*3e6=26.6 uC/m^2.
> If you use 25 uC/m^2 instead, Emax=25e-6/8.85e-12=2.82e6,
> and the rule for Vmax become Vmax=2.82 MV*r.
> Antonio Carlos M. de Queiroz
> http://www.coe.ufrj.br/~acmq

I was wondering if the charge density limit can be used
for de-rating a sphere with a broken surface, such as the
ones I am using, made out of concentric rings. 
The 7ft sphere is made up of 1.5" dia pipe, spaced on 3.5"
centers, and appears to breakout around 1.5MV. 
A smooth 7ft sphere would breakout at 1.06m x 3MV/m = 3.2MV.