Steve
for Clarification
"Flanges on the autoclave are Ti spiral wound"... i presume means gaskets
are spiral wound
Ti jacket.
Gylon as I recall is s gortex/nylon brand name gasket option. I presume an
apps engineer
selected it. Ferralium is a good choice, it will always be around because
the HF acid plants have to have it, and there are still a gizzillion of them
does your client know that a company (right here in ft sask) developed a
product that separates the gold, attaches to it and it floats to the top.
Gets rid of nasty nasties like your horrible cynaide and leaching, and all
the costly problems such as you describe that go with them. they just use
regular cs piping.
NEarly every gold producer has now switched to it, except the 3rd world
where apparently environment matters less (there a couple of trolls in
there).Wave of the future man.!
Spiral wound may be easier to source but wont be as good. As you say wont seat so well. not easy to get a gasket seating solution for all scenarios with just the spiral wound jacketed format. stick with what works unless it becomes unprocurable. anyway there are other options in soft seat gasketing.
Altecheng@shaw.ca
001(780)465-9762
Fax/Msg(780)465-9762
-----Original Message-----
From: Steve McKenzie [mailto:mechproj@xtra.co.nz]
Sent: Thursday, September 09, 2004 2:36 AM
To: PipingDesign@yahoogroups.com
Subject: [PipingDesign] Spiral Wound Gaskets - Acidic Oxygen Service
Gents+1
an autoclave that I have "inherited" has oxygen injection lines which
oxidise sulphide ore slurry; releasing heat and forming acid. The
object is to shatter quartz encapsulation of gold particles in the
slurry by thermal shock and chemical attack thereby improving
downstream cyanide leach recovery ($$$). It works. Temperatures are
around 250C and pressures around 31 bar.
I think the internal (hot)oxy injection lines are Ferallium (havent
had time to find out) and (cold) external lines are stainless;
probably 316.But much of the wet area pipework is titanium, for
corrosion resistance. Titanium + oxygen is normally a no-no as Ti can
burn in oxygen. Ferallium doesnt burn but is becoming difficult to
source.
Flanges on the autoclave are Ti spiral wound. This is OK because the
oxy concentrations are fairly low and can be adjusted by partial
pressure regulation.
The external 36 bar(cold)oxy lines are flanged (typically 50NB) with
fawn (I think) Gylon gaskets which appear to have held up well (4
years).
However it has been suggested replacing with spiral wound gaskets and
I cant see the point. Presumably the flange faces would need to be
ground, and I expect a spiral wound gasket would not be as forgiving
as Gylon when it comes to alignment and torquing.
The question is: what advantage would there be in changing from Gylon to spiral wound, given successful operating experience with the former?
Personally I can only see disadvantages, but feel I may be missing something.
Your conjecture/experience would be appreciated.
Cheers
Steve
Yahoo! Groups Links Received on Thu Sep 09 13:41:00 2004
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