Isolation Plan

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Reference Sections:  AS2885.1 S 4.8.2 Item (viii)

P1 Cl4.8.2 Item (viii) states "shall include automatic leak detection systems", which is a change from previous edition referring to "automatic failure detection". Is this a deliberate change in wording to increase the sensitivity of detection methods or is it just clarifying that any leak is a failure? I see that the note still reads as automatic failure detection system.

(Susan Jaques)

This change was not meant to create any change in requirements. It’s clarifying that in the AS 2885 sense of the defined term “failure (event)”, all failures are not necessarily leaks (and detection systems on liquid pipelines need to detect leaks, not restriction of supply).

This has to do with the term “failure” now being a defined term – actually now it’s ‘failure event’ defined term … though “failure” on its own was a defined term previously.

In our exercise of putting small-caps on all defined terms, a search-and-replace would have come up as small caps here for the use of “failure” – failure was a defined term… in the last round of revisions it was changed to failure event.

But the use of ‘failure” here is not in the context of the defined term Failure Event, which includes both ‘loss of containment’ or ‘restriction or shutdown of supply affecting the community” – which is not what a detection system is meant to detect – a detection system for liquid lines should detect leaks. (screen shot of defined terms from Part 0 below)

This is a case where we might have been over conscious of replacing defined terms where context means another word can be used. And it’s also a case where, in the note, we must have missed the second used of ‘failure’ in the second sentence of the note.


Further Question: Is the intent here to mandate the use of sophisticated proprietary continuous monitoring systems or is the type of automatic system entirely up to the operator with consideration to the controls in place and consequence of the loss of containment event? i.e. an ATMOS or other proprietary system vs a simple flow balance or pressure monitoring.

(Peter Tuft) It’s up to the Licensee to identify a system appropriate for the specifics of the pipeline. Simple flow balance or pressure monitoring would be fine for a short simple system. If the committee had wanted the sophisticated proprietary systems the words would have made that clear.