API RP 2X:2004(2015) pdf download

API RP 2X:2004(2015) pdf download.Recommended Practice for Ultrasonic and Magnetic Examination of Offshore Structural Fabrication and Guidelines for Qualification of Technicians.
Note: These blocks do not produce exact equivalents between the SI and customary systems and dlbe ctm,idcr-j,on to this Iict should he goen r. critical eainination.
7.6 PREPARATION FOR EXAMINATiON
Prior to ItteJI1ptIr1g cvaluation of a weld in the structure. UT personnel should become thoroughly familiar with the design by reference to the specifications and construction drawings. The nominal thickness of specific connections should be noted and compared to values obtained by incasurement during the weld examination.
The resuks of the visual inspection during the fit-up should be reviewed to ascertain areas likely to result in poor weld quality or areas where the root location has been modified.
A final visual inspection of the weld should be performed for detection of undercut, incomplete fill or excess roughness which would interfere with a meaningflul ultrasonic examination.
7.6.1 Index of Weld Root
Subsequent to the weld bevel preparation. including any field trimming during fit-up. and prior to welding of the root pass. the member from which scanning is to be performed should be scribed or punch-marked at a specific surface distance from the root face to ensure an exact in&x of the root face location after completion of welding. See Figure 12. This marking is particularly important for T. K, and Y connections where measurement from other index points becomes difficult or impossible after completion of welding. The distance of the scribe line or line of punch marks from the root face is optional, hut care should be exercised to displace the marks a sufficient distance from the bevel edge to assure retention after welding. These marks provide an exact location of the root face during the ultrasonic examination and aid in differentiation of root defects from acceptable root protrusions.
Pile splice bevel preparation should be index marked on the stabbing guide side of the preparation at the yard before load-out. The opposite side root preparation can be marked after pile cutoff and beveling at the installation site. Four marks around the circumference yield adequate marking if a banding strap is employed as a transducer alignment guide during scanning of the root area (see Figure 13).
7.6.2 Surface Preparation
The surface fftnn which scanning is to be achieved should be cleaned to remove all scale or coating (for example by grit-blasting or power brushing) to assure continuous coupling during the examination, particularly if flaw sizing is based on amplitude technique. Uniform thin him coatings ,uust be accommodated by use of transfer corrections. Where local conditions of roughness or weld-splatter exist. it is recommended that the local areas be smoothed by methods other than grinding (a sander on a soft pad is one acceptable method).
Regardless of the quality of the surface finish. it is recommended that transfer corrections he utili,ed in all cases.
7.6.3 Thickness Measurement
The thickness of each member from which scanning is to he achieved should he determined and recorded for use in the flaw location determinations. Thickness should he ascertained at four points around the circumference on tubular members and every six feet along welds in flat plate connections to assure detection of allowable variations.
The value of thickness obtained should be compared to the construction drawing requirements and any discrepancies ouiside of specified tolerances reported to the inspector.
7.6.4 Base Metal Examination
The enfire area from which scanning is to be achieved should be examined by the longitudinal wave technique to assure freedom from lamination or other laminar-type Ilaws which could inLcrlrc with sound wave propagation.
If defects or considerable variation in aucnuation arc found, it is important that their influence on the weld cxamination be taken into account and the scanning technique adjusted to ensure complete examInation of the weld.
77 SCANNING TECHNIQUES
Probe manipulations employed to detect discontinuilies in the weld area are termed scanning and the success of the entire examination depends on the selected probe. instrument sensitivity, and transducer mosements employed during this phase of the examination.