이규확
2004-05-17 22:45:16
5
659
안녕하십니까? 간만(?)에 현장에 문제가 생겨서 이렇게 문의를 합니다.
위에 언급한 제목과 같은 건을 ASME B31.3, ASME Section VIII(8) 등을 찾아 보았는데 찾을 수가 없더군요. (혹시 위에 언급한 내용중에 있는지도 모름. Code 가 조금 서툴러서)
참고로 저의 현장의 공사용 舊 Spec 을 유첨하였습니다. (그냥 참고만 하시와요)
통상 두께의 3배 혹은 5배 정도 인 것은 알고 있는데, 정확한 근거가 있는지요.
많은 고수님들의 답변을 기다리겠습니다.
태국 라용에서
이규확 2004-05-17 일 오후 8:43분
SES-ES-96-51PipingWorkr1.pdf
위에 언급한 제목과 같은 건을 ASME B31.3, ASME Section VIII(8) 등을 찾아 보았는데 찾을 수가 없더군요. (혹시 위에 언급한 내용중에 있는지도 모름. Code 가 조금 서툴러서)
참고로 저의 현장의 공사용 舊 Spec 을 유첨하였습니다. (그냥 참고만 하시와요)
통상 두께의 3배 혹은 5배 정도 인 것은 알고 있는데, 정확한 근거가 있는지요.
많은 고수님들의 답변을 기다리겠습니다.
태국 라용에서
이규확 2004-05-17 일 오후 8:43분
SES-ES-96-51PipingWorkr1.pdf
In addition to above answer, here is a summary of ASME Section VIII, Div.1, 2006.
- ASME Section VIII, Div.1, UW-9(d) : minimum distance the centers of long seams ; 5 times the thickness of thicker plate.
- ASME Section VIII, Div.1, Fig. UW-13.1 (b) : minimum distance between the ends of girth seams ; 4 times the thickness of thin plate.
- ASME Section VIII, Div.1, UW-14(d) : minimum distance between the ends of girth/long seams (Category A,B , or C joint with 1 1/2" thick or less) and the edge of opening ; at least 1/2"
Hope this helps,
- ASME Section VIII, Div.1, UW-9(d) : minimum distance the centers of long seams ; 5 times the thickness of thicker plate.
- ASME Section VIII, Div.1, Fig. UW-13.1 (b) : minimum distance between the ends of girth seams ; 4 times the thickness of thin plate.
- ASME Section VIII, Div.1, UW-14(d) : minimum distance between the ends of girth/long seams (Category A,B , or C joint with 1 1/2" thick or less) and the edge of opening ; at least 1/2"
Hope this helps,
It depends on the client`s specification (e.g., Distance > 3t or > 5t or min. 2") because most of the industry codes do not have the limitation. However I can remember JIS B8270 had some limitation about the distance between weld seams as a recommendation practice 10 years ago (?).
Please be aware that client`s specifications normally recognize the requirement as "should", not "shall".
Good luck,
Thomas J.C. Eun
Please be aware that client`s specifications normally recognize the requirement as "should", not "shall".
Good luck,
Thomas J.C. Eun
Mr. Thomas Eun
I would like to express my thankful mind to you in your reply.
By the way I received a lecture from you about November 1999 at the Academy of Construction Technique, Kang-Nam, Seoul, Korea.
As I mentioned my question, I could not find the requirements or criteria. But on my position, I have to show the value to client.
Thank you once again.
from Lee, Gyu-Hwag
I would like to express my thankful mind to you in your reply.
By the way I received a lecture from you about November 1999 at the Academy of Construction Technique, Kang-Nam, Seoul, Korea.
As I mentioned my question, I could not find the requirements or criteria. But on my position, I have to show the value to client.
Thank you once again.
from Lee, Gyu-Hwag
Happy to meet you again.
Please reference WRC 453 (summary below) and API 650-2003 (para 3.1.5.2.b).
[WRC Bulletin 453] July 2000 (32pp)
API 653 requires compliance with the API 650 weld spacing requirements, including the spacing between the nozzle reinforcing plate or insert plate attachment welds and the tank bottom. This project includes a review of the present weld spacing requirements in various national and international above ground storage tank and pressure vessel codes and standards, as well as the past experience with lesser weld spacing requirements than those permitted by API 650. This review indicates that that there is satisfactory experience with the 4 inch (100 mm) minimum weld spacing permitted in British Standard 2654 between the toe of the nozzle attachment weld or insert plate weld and the toe of the bottom corner weld. Additional studies are performed as part of this project to provide justification for reducing the weld spacing requirements for storage tanks repaired or altered in accordance with API 653. Stress analysis shows that for all the tanks considered in this report, the shell stresses from liquid pressure at 4 inches above the bottom are generally acceptable and are usually lower than at 10 inches above the bottom. The overlap of welding residual stresses in adjacent welded joints is evaluated. The circumferential tensile residual stresses change into circumferential compressive stresses within about 2 inches from the weld. The radial residual welding stresses generally are lower than the circumferential stresses, but dampen out more gradually. Fracture mechanics calculations evaluate critical flaw sizes. The calculated critical flaw sizes generally are larger at 4 inches than at 10 inches above the tank bottom in the tanks selected for this study due to lower stresses at the 4" location. Fatigue is considered at nozzle attachment welds, assuming a fatigue strength reduction factor of 4 and a shell membrane stress of 17500 psi. This results in about 1,400 allowable fatigue cycles, regardless of closeness of the nozzle reinforcing plate attachment weld to the tank bottom. Based on these studies and the satisfactory past experience with the 4" (100 mm) minimum weld spacing requirement in BS 2654, it is feasible to reduce the present weld spacing requirement in API 653 to no more than 4 inches (100 mm) between the toe of the nozzle reinforcing plate or insert plate attachment weld and the toe of the bottom fillet weld for shell plates not exceeding 1½ inches in thickness and materials not exceeding 50 ksi specified minimum yield strength, providing that limitations and additional requirements are met. The recommendations in this report apply strictly to the 4 inch weld spacing strictly for API Standard 653. This work recommends that the current spacing used in API 650, while conservative, be left unchanged to provide for retrofitting tanks with double bottoms without moving every nozzle and fitting.
Good luck,
Thomas Eun in Canada
teun@suncor.com
Please reference WRC 453 (summary below) and API 650-2003 (para 3.1.5.2.b).
[WRC Bulletin 453] July 2000 (32pp)
API 653 requires compliance with the API 650 weld spacing requirements, including the spacing between the nozzle reinforcing plate or insert plate attachment welds and the tank bottom. This project includes a review of the present weld spacing requirements in various national and international above ground storage tank and pressure vessel codes and standards, as well as the past experience with lesser weld spacing requirements than those permitted by API 650. This review indicates that that there is satisfactory experience with the 4 inch (100 mm) minimum weld spacing permitted in British Standard 2654 between the toe of the nozzle attachment weld or insert plate weld and the toe of the bottom corner weld. Additional studies are performed as part of this project to provide justification for reducing the weld spacing requirements for storage tanks repaired or altered in accordance with API 653. Stress analysis shows that for all the tanks considered in this report, the shell stresses from liquid pressure at 4 inches above the bottom are generally acceptable and are usually lower than at 10 inches above the bottom. The overlap of welding residual stresses in adjacent welded joints is evaluated. The circumferential tensile residual stresses change into circumferential compressive stresses within about 2 inches from the weld. The radial residual welding stresses generally are lower than the circumferential stresses, but dampen out more gradually. Fracture mechanics calculations evaluate critical flaw sizes. The calculated critical flaw sizes generally are larger at 4 inches than at 10 inches above the tank bottom in the tanks selected for this study due to lower stresses at the 4" location. Fatigue is considered at nozzle attachment welds, assuming a fatigue strength reduction factor of 4 and a shell membrane stress of 17500 psi. This results in about 1,400 allowable fatigue cycles, regardless of closeness of the nozzle reinforcing plate attachment weld to the tank bottom. Based on these studies and the satisfactory past experience with the 4" (100 mm) minimum weld spacing requirement in BS 2654, it is feasible to reduce the present weld spacing requirement in API 653 to no more than 4 inches (100 mm) between the toe of the nozzle reinforcing plate or insert plate attachment weld and the toe of the bottom fillet weld for shell plates not exceeding 1½ inches in thickness and materials not exceeding 50 ksi specified minimum yield strength, providing that limitations and additional requirements are met. The recommendations in this report apply strictly to the 4 inch weld spacing strictly for API Standard 653. This work recommends that the current spacing used in API 650, while conservative, be left unchanged to provide for retrofitting tanks with double bottoms without moving every nozzle and fitting.
Good luck,
Thomas Eun in Canada
teun@suncor.com
공지사항
Except when the longitudinal joints are radiographed 4 in. each side of each circumferential welded intersection, vessels made up of two or more courses shall have the centers of the welded longitudinal joints of adjacent courses staggered or separated by a distance of at least five times the thickness of thicker plate.