焊接轮廓用于疲劳改善Word格式.docx

1、Methods of Fatigue Behavior Improvement by Weld profiling and NDE used for CNOOC Panyu 4-2/5-1 JacketsBy Charlie Chin Chan ChongASQC Certified Quality Engineer, ASNT NDT Level III JM1715,MICorr, SenAWeldI, European Welding InspectorNACE Senior Corrosion Technologist.A Discussion on the Methods of Fa

2、tigue Behavior Improvement by weld profiling for Panyu 4-2/5-1 JacketsSynopsis:This paper presents a discussion on various methods which Contractor may use to perform the weld profiling activities on Designer designated fatigue sensitive joints.Even in the absence of Designer designation, the Weldin

3、g Inspector should ensure the weld profiles comply with the AWS D1.1 Table 2.7 requirements Level II as a minimum, applies to pre-qualified TKY joints for intermediate and heavy sections where the code requires different level weld profiling.1. Introduction:For fatigue behavior improvement by weld p

4、rofiling, it is important that the activities are carried out by the fabricator in correct manners. Following is a write-up summary of API 2A WSD and AWS D1.1 requirements and proposals that may assist the fabricator in achieving this objective.2. Discussion. 2.1 The Codes.Acceptable offshore practi

5、ces usually call for either AWS D1.1 or API 2A WSD requirements on weld profiling. The Designer should specify the applicable code. API 2A WSD Section 11.1.3d was the applicable section called by Designer.2.1.1 API 2A WSD Section 11.1.3dThe section stated that where controlled weld profiling has bee

6、n considered the weld surface should merges smoothly with the adjoining base metal and approximates the concave profile shown in Figure 11.1.3 either as weld or with profile grinding. The required profile check is by a profile disk with diameter equal or greater than the brace thickness and the notc

7、hes relative to the desired weld profile are considered unacceptable if there is a 0.04in. （1 mm） gap between the disk of the specified radius and the weld, either at the toe of the weld or between passes.The weld toes should also be MPI tested to check for surface and near surface defect.2.1.2 AWS

8、D1.1 2.36.6.6The applicable Projects welding code is AWS D1.1. For T-, Y-, and K-connections, two levels of fatigue performance are provided for in Table 2.7. Level I and Level II. Depending on the limiting branch member thickness, four types of weld profile requirements are specified, namely1. Stan

9、dard flat weld profile in conformance with Figure 3.82. Profile with toe fillet in conformance with Figure 3.93. Concave profile, as welded, conformance with Figure 3.10 with disk test per 2.36.6.6（1）4. Concave smooth profile conformance with Figure 3.10 fully ground per 2.36.6.6（2）The designer shal

10、l designate when Level I is to apply; in the absence of such designation, and for applications where fatigue is not a consideration, Level II shall be the minimum acceptable standard. AWS D1.1 Section 2.36.6.7 It is therefore important to note that even in the absence of Designer designation, the We

11、lding Inspector should ensure the weld profiles comply with the Table 2.7 requirements Level II as a minimum. The required Concave smooth profiles as shown in Figure 3.10 areOne should note the following clauseIt is important to note that the weld profiles for 2.36.6.6（2） shall be smooth and fully g

12、round.Following is the AWS D1.1 section C2 Non Mandatory Commentary on Fatigue Behavior Improvement by weld profiling. （C2.36.6.6 Figure C2.20） The figure gives describe 2 types of weld profile grinding requirements namely;1. Concave profile, as welded, conformance with Figure 3.10 with disk test pe

13、r 2.36.6.6 （1）2. Concave smooth profile conformance with Figure 3.10 fully ground per 2.36.6.6 （2）The AWS D1.1 section C2.36.6.6, Non Mandatory Commentary on Fatigue Behavior Improvement by weld profiling was proposed to ensure more effective in maintaining Class X1 fatigue performance over a wide r

14、ange of thicknesses. However the commentary also recognizes it shortfall, saying that even by grinding with the permissible notch depth further reduced to 0.01 in. （0.25 mm）; if it merely flattening the tops of the individual weld passes, while leaving sharp canyons in between, does little to improv

15、e the fatigue performance, even though it would meet the letter of the disk test. A tighter requirement was suggested. It was suggested by the C2.36.6.6 commentary that it may be more effective to grind the entire weld profile smooth for both fatigue category I and II. （Whole of the relevant section

16、 of commentary was attached for further reading Appendix II）.2.2 NDEFor conformance with the codes requirements, the codes call for the detection of surface breaking and near surface breaking significant discontinuities. AWS and API codes both call for MPI detection of surface discontinuities. As the grinding direction