24" steam line stress analysis 3

[SIAUPA]

I modelled a 24" steam line that is connected at one end to an existing pipe line coming from plant equipment and at the opposite end to an existing pipe line going into a steam header.
For a complete analysis I include at each end a section of the existing line. This existing line section is from my tie-in point going up to the first left and right anchor.
Is this correct?
Also just because I am connecting to a line, my guess is that the loading on the equipment nozzles where my existing lines are connected is not part of my concern.
Is this true?

 

[richay]

As long as you coded left and right to a real anchor, then "yes" you are correct.

Because forces & moments are not transferred across an anchor, your new line will not put any additional loads on the equipment nozzles (assuming they are on the opposite sides of the anchors on the exiting lines).

Richard Ay
COADE, Inc.

 

[DSB123]

richay,
Not strictly correct. Although the equipment loads will not be affected the anchor loads could well be. As such the revised loadings onto the anchor points on the existing lines need to be reviewed/assessed for acceptance.

 

[shalom69]

I feel that you need to go upto the nearest anchor on the connected lines and not just model a part of teh existing lines.You may need to check the existing supports for teh additional loading,if any, as well.

 

[JohnBreen]

An anchor is six degrees of fixity. I wonder what an anchor for an NPS 24 pipe would look like. Like a huge cube of reinforced concrete?

 

[NozzleTwister]

Right on John!

Most places that I've worked in the last 25 years what's been called an ANCHOR has really been just a Support, Line Stop and a Guide (usually with gaps).

Even if the pipe anchors were comepletely fixed to the structure, the majority of the rotations would pass right through the anchor, the structures are too flexible when compared the the stiffness of 24" pipe.

NozzleTwister
Houston, Texas

 

[DSB123]

NozzleTwister,
Concur with you. I've got the same problem with a boiler supplier who told me that the pipe was "anchored" at a specific point 8 months ago but when the detail came in the point is a combination of a support/linestop and guide so the rotations are not constrained. Also the "anchor" is made up of bolt-on pipe shoes. Who's he trying to kid?