Re: Flanges near creep range

From: <Paul>
Date: Thu Aug 23 2001 - 23:11:00 EDT

Usually the exchangers are aluminum in cold boxes. We used solon washers and a variety of flange insulating kits.

http://www.dracomech.com/miscparts/solon.htm

We also used explosion-fused transition joints to make the material spec change from Al to SS.

For likely maintenance areas, a "cage" is built inside the cold box and filled with mineral wool insulation, with a removeable panel. Not as good as perlite, but the trade-off is needed for accessibility. The entire cold box is dynamically purged with waste N2 from the process with a couple of inches of pressure to avoid moisture infiltration.

I am unaware of any code covering these things, as far as I know it's just specialty industry practice.

Paul

---

Geoff wrote:

> I can recall on an LPG extraction plant that the cold box
employed aluminium
> piping. The bolts were fitted with Belleville (disc) washers to
account for the
> thermal strain between construction temperature and operating
temperature. You
> couldnt get back into the cold box to tighten the bolts as it
was insulated.
> Also if the unit was taken off line the strees in the bolts
would increase
> because of differential rates of thermal expansion between the
aluminium and the
> ss bolts. Is this something covered by the code or just some
ingenious concept
> invented by the specialist engineers used to design the plant?
Received on Thu Aug 23 23:11:00 2001