Patent ID: 7628532

Claim:
A method of detecting flaws in a weld connecting a wellhead to a casing, the method comprising the steps of: (a) providing a source of pressurized gas; (b) providing an indicator chamber having a housing having upstream and downstream ends and means housed within said chamber housing between said housing ends for receipt of an indicator composition including a marker component impregnated onto a surface within said chamber; (c) securing a first conduit between said source of pressurized gas and the upstream end of said housing; (d) securing a second conduit between the downstream end of the chamber housing and an injection port in said wellhead; (e) injecting the pressurized gas from the source into said first conduit and across the means for receipt of an indicator composition within the chamber housing to form a pressurized gas indicator composition, said pressurized gas indicator composition comprising a mixture of gas from said source and at least a marking amount of the marker component; (f) transmitting said pressurized gas composition out of said chamber housing and into said second conduit; (g) injecting said pressurized gas composition into said injection port between an inner and outer weld of a terminal flange welded to a tubular pipe section or casing, while the weld is at an elevated temperature; (h) monitoring the source of pressurized gas composition for detecting losses in pressure; and (i) passing a marker gas detector probe over the weld for detecting marker component leaking through the weld.