LNG 저장탱크 구조물의 종합적 상태평가기준 개발

A Development of Representative Condition Evaluation Standard for LNG Storage Tank Structures

Abstract

LNG저장탱크가 노후화 됨에 따라 외벽 콘크리트에 균열, 철근부식 등 결함이 발생할 경우, 손상 종류 및 정도에 따라 구조물의 붕괴 등 대형사고 발생 위험이 존재하게 된다. LNG저장탱크는 2014년부터 정밀안전진단이 시작 되어 안전점검이 수행되고 있으며, 부재별 상태평가기준은 2016년 1월에 개정되어 적용하고 있다. 상태평가는 액화천연가스 저장탱크에 대한 외관 조사 및 재료시험 결과를 바탕으로 저장탱크에 대한 상태를 평가하는 것을 말하는 것으로 유지관리에 있어서 중요하다. 또한 각각의 LNG 저장탱크 대표상태를 나타내는 종합적 상태평가기준이 유지관리 시 중요하지만, LNG저장탱크 외조 콘크리트에 대한 관련 기준이 국내 외에 부재하여 상태평가 기준 개발 필요하다. 이 논문에서는 LNG 저장탱크 구조적 특성 검토, 부재별 상태평가 기준현황 분석, 부재별 가중치 부여를 통한 종합적 상태등급 산정 방안을 수립하였다. 부재별 가중치 산출은 AHP(Analytic Hierarchy process)기법을 이용하고 전문기관의 설문조사 등을 통해 종합적 상태평가 기준을 개발하였다.

As the LNG storage tank is aged, if there is a crack in the outer wall concrete or corrosion of the reinforcing steel, there is a risk of a major accident such as collapse of the structure depending on the type and degree of damage. Since 2014, LNG storage tanks have undergone precise safety diagnosis and safety inspection has been carried out. The condition evaluation criteria for each component have been revised and applied in January 2016. The condition evaluation standard is to evaluate the status of storage tanks based on the appearance survey and material test results of LNG storage tanks and it is important for maintenance. In addition, the representative condition evaluation standard that shows the comprehensive state of each LNG storage tank is important in maintenance, but the related standard for LNG storage tank outer concrete is not available in Korea and abroad, and development of the condition evaluation standard is necessary. In this paper, we examined the structural characteristics of LNG storage tanks, analyzed the status of the condition evaluation criteria for each member, and developed a comprehensive status rating system by weighting the members. We used the AHP(Analytic Hierarchy Process) technique and developed a representative conditon evaluation criteria through surveys of professional organizations.

Fig. 1. Classification according to tank positions

Fig. 2. Above-ground of LNG storage tank(Elevated concrete base)

Fig. 3. Above-ground of LNG storage tank(Base heating)

Fig. 4. In-ground of LNG storage tank

Fig. 5. Procedure of AHP analysis

Fig. 6. Hierarchy construction for Above-ground of LNG storage tank(Elevated concrete base)

Fig. 7. Hierarchy construction for Above-ground of LNG storage tank(Base heating)

Fig. 8. Hierarchy construction for In-ground of LNG storage tank

Fig. 9. Hierarchy construction for durability of LNG storage tank

Fig. 10. Analysis results of above-ground(Elevated concrete base) according to specialized organization.

Fig. 11. Integrated weight results of above-ground (Elevated concrete base).

Fig. 12. Analysis results of above-ground(Base heating) according to specialized organization.

Fig. 13. Integrated weight results of above-ground (Base heating)

Fig. 14. Analysis results of In-ground according to specialized organization

Fig. 15. Integrated weight results of In-ground

Fig. 16. Analysis results of durability according to specialized organization

Fig. 17. Integrated weight results of durability

Table 6. Weights of each member according to LNG storage tank types

Table 1. Application range of condition rating for members of LNG storage tank

Table 2. Weight ranking results of above-ground (Elevated concrete base) according to specialized organization

Table 3. Weight ranking results of above-ground (Base heating) according to specialized organization

Table 4. Weight ranking results of In-ground according to specialized organization

Table 5. Weight ranking results of durability according to specialized organization

Table 7. Criteria according to defectability range