Re: TRANSITION PIECE

if the cause of deterioration is erosion, wont a thicker elbow get eroded later and then you end with the same problem - a leaking piping system. you'll end doing a reactive maintenance over and over again in addition to messing up the production schedule. There is also the issue of safety here.

perhaps there are some better alternative that is economical and effective other than using a thkcer fitting.

• In PipingDesign@yahoogroups.com, "M. Engineer" <kahabib@...> wrote:
  >
  > Dear colleagues
  >
  > I don't see a reason to put a transition piece to weld
  > 4 inch sch. 40 pipe with 4 inch sch. 80 elbow for
  > example. In many refinery applications we install some
  > time thicker elbows than the matching pipe to resist
  > thinning due to erosion in elbows specially at
  > distillation column overhead lines. I just would like
  > to add that in case the welding ends of pipe or
  > fitting exceeds the wall thickness of the matching
  > pipe resulting in an unequal external and/or internal
  > diameters, it is better that the welded joint design
  > to comply with Fig. 434.8.6(a)-(2) of ASME B31.4.
  >
  > Khalid Mahmoud
  > Jeddah Refinery
  >
  > --- Richard Beale <r_beale@...> wrote:
  >
  > > Hi Eric,
  > > A transition piece is a piece of pipe of heavier
  > > wall thickness that has
  > > been taperbored down to a lesser wall thickness.
  > > These are used in
  > > butt-weld piping. For example, let's say that we
  > > have to connect NPS 4
  > > sch 80 BW and NPS 4 sch 40 BW fittings or pipe. A
  > > piece of NPS 4 sch 80
  > > is cut and taperbored at one end to sch 40. These
  > > are usually
  > > pre-fabricated items and are often assigned a
  > > specialty item number.
  > > They show up in not-to-common circumstances. What's
  > > yours? I don't
  > > believe there is a standard for the length. You need
  > > to accomodate the
  > > taperboring and beveling at both ends. 300mm is a
  > > pretty common length I
  > > would say. Other members please correct me if I am
  > > wrong about this last
  > > part.
  > >
  > > Richard B
  > >
  > >
  > > -----Original Message-----
  > > From: PipingDesign@yahoogroups.com
  > > [mailto:PipingDesign@yahoogroups.com]
  > > On Behalf Of Eric Wan
  > > Sent: January 3, 2008 2:58 PM
  > > To: PipingDesign@yahoogroups.com
  > > Subject: [PipingDesign] TRANSITION PIECE
  > >
  > >
  > >
  > > DEAR everybody,
  > >
  > > What is transition piece and any code and
  > > dimensioning can be found?
  > >
  > > Thanks
  > >
  > > Eric
  > >
  > >
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