FFG 7类咨询号06-95上部结构焊接ref / a / ltr / navsea /-// ref / b / doc / navsea /-// narr / ref a is ffg7 aer n0。13-94，用于上层建筑关键焊缝检验的被动对抗(pcms)材料和防滑清除，1994年12月19日第335 /9940号。参考b是navsea DRWG 150-5604994 rev e, 146k船的质量保证要求。/ / POC / P。J. regis / lcdr /-/ loc: Arlington va / tel: DSN 332-1304 x113 / tel: (703) 602-1304 x113 // rmks /1。本课程提供关于ffg7上层建筑关键区域焊接修复的指导。2.背景a.从历史上看，ffg7级舰船的上部结构经历了广泛的开裂。裂纹的原因已经确定是高设计应力和低质量焊接的结合。在一些情况下，裂缝已经蔓延到02层的露天甲板。 THE MOST PREVALENT CRACKING OCCURS AT FRAME 200.5 ON THE 02 LEVEL. B. SHIPALT FFG 7-86K WAS FIRST INTRODUCED TO ALLEVIATE CRACKING PROBLEMS. THIS SHIPALT WAS NOT COMPLETELY SUCCESSFUL, THEREFORE, SHIPALT FFG 7-146K WAS DEVELOPED AND IMPLEMENTED. SHIPALT 146K INCORPORATES MORE STRINGENT QUALITY ASSURANCE MEASURES AND WELDING PROCEDURES. C. DUE TO CONCERN THAT THE HIGH STRESSES AND POOR QUALITY WELDING MAY PRODUCE CRACKING AT OTHER AREAS OF THE FFG 7 CLASS SUPERSTRUCTURE, POST SHIPALT 146K INSTALLATION SHIP CHECKS HAVE BEEN UNDERTAKEN BY NSWCCD-SSES AND LBNSY TO MONITOR THE EFFECTIVENESS OF THE ALTERATION. TO ASSIST NSWCCD-SSES AND LBNSY AND ALLOW FOR SHIPS FORCE INSPECTION OF CRITICAL WELD AREAS, REF A WAS DEVELOPED. THIS AER CALLS FOR THE PERMANENT REMOVAL OF PCMS AND NON-SKID FROM CRITICAL WELD AREAS IDENTIFIED DURING POST SHIPALT 146K INSTALLATION SHIP CHECKS. REMOVAL OF THE SPECIFIED PCMS MATERIAL WILL NOT ADVERSELY AFFECT THE PERFORMANCE OF THE REMAINDER OF THE COATING. D. GOOD WELD QUALITY IS MANDATORY IN THE PRESENCE OF THE HIGH DESIGN STRESS AREAS SUCH AS FOUND ON THE FFG 7 02 LEVEL. ACHIEVING GOOD QUALITY WHEN WELDING ALUMINUM REQUIRES METICULOUS ADHERENCE TO CLEANLINESS AND PROCEDURES. POOR ALUMINUM WELDING WILL CRACK. 3. ACTION. A. ALL FFG 7 CLASS SUPERSTRUCTURE WELD REPAIR WORK SHALL CONFORM TO REF B OR NSWCCD-SSES EQUIVALENT QUALITY ASSURANCE PROVISIONS. B. TACK WELDING ON CRITICAL WELD AREAS OF THE SUPERSTRUCTURE AND CORRESPONDING INTERIOR OVERHEADS AND BULKHEADS IS PROHIBITED. SUPERSTRUCTURE CRITICAL WELD AREAS ARE DEFINED AS ANY STRUCTURAL WELD BETWEEN FRAMES 180 AND 230. C. NSWCCD-SSES (CODE 6233) SHALL BE CONTACTED PRIOR TO ANY WELDING WITHIN 24 INCHES OF ANY CRITICAL WELD AREA TRANSVERSE BUTT WELD. D. SHIPS FORCE SHALL REPORT TO ORIG AND NSWCCD-SSES THE FOLLOWING ITEMS IF FOUND IN THE SUPERSTRUCTURE CRITICAL WELD AREA DURING NORMAL ROUTINE INSPECTION: (1) ANY CRACK IN AN EXISTING TRANSVERSE BUTT WELD. (2) ANY DECK CRACK OVER A LONGITUDINAL STIFFENER. (3) ALL PREVIOUSLY REPAIRED CRACKS. (4) ANY CRACK OVER 6 INCHES IN LENGTH. (5) ANY CRACK WITHIN 24 INCHES OF A TRANSVERSE BUTT WELD. E. SHIPS FORCE SHALL ACCOMPLISH REF A AT THE EARLIEST WINDOW OF OPPORTUNITY. 4. FOR COMNAVSURFLANT/COMNAVSURFPAC - RECOMMEND: A. TASKING FFG 7 CLASS SHIPS TO ADHERE TO PARA 3 ACTIONS. B. TASKING IMA ACTIVITIES TO ADHERE TO PARA 3 ACTIONS. 5. FOR LBNSY (CODE 250.1) - ENSURE ALL SHIP ALTERATIONS UNDER DEVELOPMENT, WHICH REQUIRE SUPERSTRUCTURE WELDING, CONFORM TO REF B OR EQUIVALENT WELDING QUALITY ASSURANCE PROVISIONS. 6. FOR SUPSHIPS - ENSURE REF B IS ADHERED TO PRIOR TO AND DURING INSTALLATION OF SHIPALT FFG 7-146K. 7. THIS CLASS ADVISORY HAS NO IMPACT ON EOSS, PMS, OR CMP. IT WILL BE CANCELLED AT THE DISCRETION OF THE ORIG AND CNSL/CNSP. 8. NAVSEA POC IS JOHN STONE, PMS335TH, DSN 332-1304 X115 OR COMM (703) 602-1304 X115. NAVSEA WELDING POC IS JOHN DORN, SEA 03M2, DSN 332-0206 OR COMM (703) 602-0206. NSWCCD-SSES STRUCTURES POC IS MARTIN COHEN, CODE 625, DSN 443-7651 OR COMM (215) 897-7651.// BT
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