Re: [Fwd: [STM] Steam line intermediate anchor]

I fully agree with the last post from jcluf (sorry, I did not get your name). No need to introduce a physical anchor in buried piping and all piping calculation (including bellow sizing) should be based on what is called a virtual anchor(which is sometimes physically outside pipelength, hence the name virtual!!). Refer to any standard text regarding buried piping analysis for details. Providing compensators (axial ones I suppose) is OK from design point of view.

However, in case piping is inside a trench (no soil cover), as a good engineering practice, a physical anchor (6x6 restraint) should be provided at a suitable location and bellows be sized based on this anchor location. Also provide a guide on the first support from the expansion joint to limit squarming.

It's good to be back in this mailing group after a gap of almost a month. Thanks to Paul for bringing me back to this technical forum.

Regards,
Pankaj.

• In PipingDesign@yahoogroups.com, "jcluf" <jcluf@y...> wrote:
  > So as to clarify this layout.... The lines enter and exit manholes
  > where there are slip type EJs located. After leaving the side of
  the
  > manhole the line is immediately buried???? Or is it in a casing pipe
  > ??????
  >
  > If the line is buried it will develop whats called and described by
  > some as a virtual anchor... the ground will develop local
  > plastic deformations but in essence will restrain the pipe.
  >
  > A chase pipe is another matter altogether.
  >
  >
  > --- In PipingDesign@yahoogroups.com, Paul Bowers <pbowers@p...>
  wrote:
  > > Forwarded from the Steam list, maybe someone here has some
  insight:
  > >
  > > -------- Original Message --------
  > > Subject: [STM] Steam line intermediate anchor
  > > Date: Tue, 21 Jun 2005 07:59:17 -0500
  > > From: Gephardt, Tim <gephardtt@m...>
  > > Reply-To: steam-list@l...
  > > To: <steam-list@l...>
  > >
  > > To all,
  > >
  > > We have a 16", 60 psig steam line constructed in 1955, and it
  > was
  > > placed in a chase type system with slip style expansion joints in
  > > concrete manholes to compensate for thermal expansion. According
  > to the
  > > original design documents there were no intermediate anchors
  > installed
  > > on runs of steam piping where expansion joints are on either end
  of
  > the
  > > run. Not having an intermediate anchor would allow the steam
  > piping to
  > > grow in the path of least resistance and if the expansion joint
  > travel
  > > was not oversized enough to compensate for the growth of the
  entire
  > run
  > > of piping, the piping would then bump off of the limit stops
  inside
  > one
  > > expansion joint before the piping grew in the other direction. I
  > may
  > > have this situation as when this line was shut down and I was
  > inspecting
  > > for an expansion joint replacement, I noticed that an expansion
  > joint
  > > had only contracted about a half an inch, where it should have
  > moved at
  > > least a couple of inches. This would indicate either a broken
  > > intermediate anchor or a complete lack thereof, from the initial
  > design.
  > > I was just curious if any one else had encountered this type of
  > design
  > > on older lines? I will be doing an exploratory dig at the mid
  > point of
  > > this line coupled with some abatement to search for a broken
  > anchor, or
  > > if there is not an anchor, establish one after I make sure my
  > piping is
  > > not offset too far one direction or the other.
  > >
  > > Thanks,
  > >
  > > Tim Gephardt
  > > Senior Staff Engineer
  > > University of Missouri - Columbia
  > > Energy Management
  > > 417 South 5th Street
  > > Columbia, MO 65211-2030
  > > Phone: (573) 884-9339
  > > Fax: (573) 882-6793