Abstract: For the purpose of detecting the presence of surface flaws in tubular members, the surface to be inspected is first coated with penetrant and any excessive penetrant then removed. A device is then moved along the tubular member until that part of the surface to be inspected is reached, whereafter the device is expanded into abutment with this tubular surface. Penetrant that has entered a surface flaw is transferred to the surface of the device, where it can be made visible and studied, subsequent to having constricted the device and removed it from the tubular member. An instrument is provided which includes the device so as to enable a tubular member to be pre-treated with penetrant and penetrant transferred to the surface of the device.