Pipeline Assemblies

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References:
AS2885.0 Cl 1.5.48 Defined Term
AS2885.1 Section 5.9 Pipeline Assemblies

Pipeline Assembly is a defined term referring to an assembly of pipe and components with simple functionality, such as a scraper or mainline valve; typically (but not always) the piping design is to AS2885 rather than a station piping code.

Is an MLV a “station”? (ref Part 0 diagram)

(Peter Tuft) In common usage the term "MLV" ("mainline valve") can mean three different things, and they are very often conflated:

1. The actual valve (just the valve by itself),

2. The piping assembly that contains the valve,

3. The station that contains the piping assembly plus other infrastructure.

So the answer to the question is that Meaning 1 is not a station, Meaning 2 is not a station, but Meaning 3 is a station. It is good practice to be clear in distinguishing these meanings, particularly to refer to "mainline valve assembly" or "mainline valve station" as appropriate.


Barred tees: What is the reason behind the addition of Clause 5.6.2(e) in AS 2885.2-2016 (Clause 5.6.2(d) in 2020 version), which states that "pig bars shall not be welded directly to the high stress areas around the extrusion neck"?

On any forged fitting it is recommended to only weld at the weld preparation area, as stresses caused by welding can cause cracking at subsurface features such as laminations. This is often not detected using Magnetic Particle Inspection unless it is surface breaking. The passage of the pig could then cause failure of the bars and a stuck pig scenario.

This diagram is a guide (not definitive) showing how the pig bars are welded to the pup piece rather than the extruded neck.