TRACERCO Diagnostics™ - Scan
A major refiner requested Tracerco to perform a TRACERCO Diagnostics™ Scan on a 30” isolation valve to identify the location of a suspected spindle breakage. The work included determining the gate position by use of gamma-ray transmission.
Gamma-ray transmission is an effective and proven technique for locating the position of valve gates. By using this technique over many years, Tracerco personnel have investigated a variety of process problems in a wide range of pipe sizes.
Tracerco was requested to perform a TRACERCO Diagnostics™ Scan of a 30” gate valve to determine the position of a breakage of the valve actuator stem at BP Dalmeny.
The valve spindle was scanned along its length at locations. A reference count was taken through the spindle casing at a position where the scan line was not intersecting the spindle. The initial scan showed a uniform density profile reading along the spindle length, which did not highlight the point of breakage. The spindle was then raised by approximately 200mm and the scan was repeated. This second scan indicated a void at positions 2 and 3 and a reading corresponding to approximately 25mm of steel at position 1 suggesting that the spindle had pulled out of the collar leaving the collar still attached to the valve spade.
The scan showed that the spindle had broken at the position of the spindle collar leaving the collar connected to the valve spade.