GN 012.28 - Unfused Chaplet and Leak in Carbon Steel Valve

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Category: Use & In-Service Inspection

 

APEK - AICIP
GUIDANCE NOTE

SIGNS OR INDICATIONS IN IN-SERVICE
INSPECTION OF PE

UNFUSED CHAPLET AND LEAK IN CARBON STEEL VALVE

APEK GN 012.28
Case 28

Rev 0
Issued: 02/01/2010

1 Figure

        

2 PE involved

Hydrofluoric acid (HF) piping system. Cast steel stop valve.
P = 1.5MPa; T = 70oC.

3 Sign(s)

Uneven suspicious valve body surface; later leakage and staining.

4  Location of Signs

Side of valve body near bolted damage.

5 When & Where occurred

2000; valve 3 years old; in Australian refinery.

6 Detection & Investigation

VT.

7 Failure mode(s)

(damage mechanisms)

Leakage, corrosion, (low cycle fatigue).

8 Most probable causes

 Initial unfused chaplet almost through full thickness; and
In-service corrosion and low cycle operation.

9 Outcome

 Major hazard as HF is highly toxic; extra cost.

10 Most Possible Prevention

Improved casting manufacture, examination, testing and conformity assessment (inspection).

 RG

 

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Revised 15/04/2014  SA