API RP 2X:2004 pdf download
API RP 2X:2004 pdf download.Recommended Practice for Ultrasonic and Magnetic Examination of Offshore Structural Fabrication and Guidelines for Qualification of Technicians.
5.4 REEXAMINATION
Previously qualified personnel should he reexamined when they have not performed nondestructive examination of tubular member construction for a period not to exceed I year. or when a specific cause to question performance arises, or more frequently as required by the operator.
6 Extent of Nondestructive Examination
6.1 TIME OF EXAMINATION
All NDE should he performed at a suitable interval after welds have been completed and cooled to ambient temperature. The interval can range from immediately upon cooling up to 72 hours depending on the grade of steel. Some high- strength steels (60,000 ksi yield and greater) require a minimum interval of 48 to 72 hours due to the possibility of delayed cracking. The operator should approve the interval for all examinations.
The nature of ofTshore installation usually requires operations to he completed in as timely a manner as possible. This may result in a need to begin the UT of pile splice welds before they have cooled to ambient temperature. Elevated temperatures of materials may change sound beam characteristics and should he explored prior to accepting Agency procedures. The operator should approve such an examination and insure the Agency has a qualified procedure that is applicable to this situation.
6.2 EXAMINATION DURING ONSHORE FABRICATION
Wherever possible, examination, repair, and reexamination should he accomplished in the earliest stage of fabrication and before incorporation into the structure. Examination which can be eftèctively accomplished in the fabrication yard should not he delayed until offshore installation.
6.2.1 Examination of Plate for Structural Members
6.2.1 .1 Lamination and inclusions in plate employed for chord members at tubular joint connections often result in separations within the plate thickness when subjected to the strains of welding. Separations which develop by fracture between adjacent discontinuous inclusions are termed lamellar tearing. Similar problems exist in the fabrication and major inclusions which may add to these difficulties during fabrication.
6.2.1 .2 Plate to he employed as chord members at tubular connections (joint cans at nodes) and for the flanges of critical girders requiring substantial stiffening may he ultrasonically examined at the steel mill, prior to purchase, in accordance with ASTM Specifications A 435 or A 578, Level II. These specifications, which are essentially the same, require that only those plates with major flaws that result in the complete loss of sound energy (in other words, plates with lamination) are rejected. Some indication of the suitability of critical application plate may he determined by implementing ASTM A 578, Level II criteria which require additional reporting of some inclusions less than three inches in length. The A 578, Level I, criteria require the additional reporting of major inclusions; however, this specitication may impose special processing at the steel mill and add to the cost of the plate.
A fabrication yard examination or reexamination of plates subjected to mill ultrasonic examination is desirable to further define quality in the areas of projected intersection. The areas of framing should he examined 100 percent along and on either side of the projected line of intersection. Plates or tuhulars found to contain ultrasonic indications should he relocated in the structure or repositioned in the same location to minimize the concentration of imperfections in the projected weld area. Freedom from all ultrasonic indications in a hand at least six inches wide is desirable, but any imperfection which cannot he eliminated from the weld area should be carefully measured as a basis for re-evaluation after completion of welding. Despite the most stringent ultrasonic examination, these measures will not ensure freedom from microscopic inclusion arrays which can subse
