Hello Stressers!!

What can be considered a logical discontinuity in the statement below?

"Field sketches shall be drawn of as-built systems from new connection points, both upstream and downstream of the connection, to the nearest anchor point or logical discontinuity when anchors are not available."

Thanks & Warm Regards,

We are all in the same page in this case. I think it's hard to determine a logical discontinuity mathematically speaking without an anchor in the system, a boundary condition is required to solve the displacement domain, else the system is floating and might cause rigid body motion.

Anyway, just correct if I made misleading statement.

One example is a system that may not have many anchors. This may require you to use assume something else is approximately an anchor, such as a wall penetration, or significantly larger header for a branch connection (including in estimate for header displacement).

Sometimes its just not realistic to model an entire system to capture an elusive anchor

With respect to boundary conditions, your task is to either:
A) Simulate accurately the loads and reactions of the boundary condition,
or
B) Conservatively simulate said loads and reactions,

and

A) Ensure "your" scope doesn't excessively impact "their" scope,
and
B) Ensure "their" scope doesn't excessively impact "your" scope.

This is difficult to capture in a concise manner to direct information collection.

With that said, I've come up with instructions for my opinion for adequate boundary conditions:

1) Hard anchor points, such as piping anchors, ground penetrations, and equipment,
2) Midpoints of extremely long runs of rack piping,
3) First limit that's axial to the tie point,
4) First piping guide after a 90 degree turn beyond the tie point,
5) Midpoint of "expansion loop" resembling piping configurations.

Exceptions for 3) and 4) is that if the piping configuration is imbalanced - i.e. if beyond the limit or guide is another perpendicular straight run of pipe that is much, much longer than that which is represented between the tie point and the guide or limit, then we must pursue the next hard or soft anchor point.

Existing springs that are potentially impacted and requiring modification (or other in-line equipment or attachments similarly at risk to fail) by the addition of "your" piping are considered "in scope" and you must take your boundary conditions further as though the existing piping between "your" pipe and "their" spring is treated as "your" piping for purposes of modeling scope.

Thanks all for that bountiful information. I have been in site survey to check anchor location but found nothing on a very long existing line in a piperack. Anyway the line is not hot, so I would put a virtual anchor in the middle of the line.

Warm Regards,