Corrosion Loss of the Shell Plates of the General Cargo Vessels and the Lumber Carriers According to the Age

일반화물선과 원목운반선의 선각외판 부식도의 선령별 변화

Corrosion loss of the shell plates of the steel vessels are measured and analyzed on the thirty cargo vessels and fifteen lumber carriers of which nationality belong to Korea. Thickness of the shell plates were determined at the every observed points set along the fore and aft line and perpendicular to it, by use of the ultrasonic thickness meter. Difference of the thickness between the original and the determined shell plates are given as the corrosion loss at the present age. The results obtained are summarized as follows: 1. On the cargo vessels, (1) The total mean of the corrosion loss is greatest at the light waterline, in every age class of the vessels. (2) The total mean of the corrosion loss on the fore and aft line shows little difference, even though it is slightly greater at the fore part, in every age class of the vessels. (3) Corrosion loss along the perpendicular line grows greater in the order of freeboard, load waterline, upper bilge line and light waterline, within the 16 of the age of the observed vessels. Its order varies to freeboard, upper bilge line, load waterline and light waterline in the age of 35. Corrosion loss at the light waterline and load waterline, in the age of 35, shows 3 times of it at the freeboard, and it at the upper bildge line shows twice of it at the freeboard. The fact significates the corrosion grows rapidly around the waterline. 2. On the lumber carriers, (1) The total mean of the corrosion loss is greatest at the upper bilge line, in the every age class of the vessels. (2) Total mean of the corrosion loss on the fore and aft line shows little difference, even though it is slightly greater at the fore part, in every age class of the vessels. (3) Corrosion loss along the perpendicular line is least at the freeboard and greatest at the upper bilge line, and its value at the upper bilge line shows twice of it at the freeboard. 3. The total mean of the corrosion loss of the lumber carriers shows almost twice of the cargo vessels.

한국국적을 가진 일반화물선 30척과 원목운반선 15척의 외판부식도를 선령별로 조사한 결과는 다음과 같다. 1. 일반화물선 1) 전평균부식도는 어느 선령급에서나 경흘수선부가 가장 크다. 2) 선수미방향의 전평균부식도는 어느 선령급에서나 선수부가 중앙부나 선미부보다 크나, 큰 차이는 없다. 3) 깊이 방향의 부식도는 선령 16년 이하에서 건현부, 만재흘수선부, 하부만곡부, 경흘수선부의 순으로 크다. 또 35년에 있어 부식도는 경흘수선부와 만재흘수선부는 건현중앙부에 약 3배, 상부만곡부는 그것의 약 2배 되어 수선부가 가장 부식이 심함을 나타낸다. 2. 원목운반선 1) 전평균부식도는 어느 선령급에서나 상부만곡부가 가장 크다. 2) 선수미방향의 부식도는 어느 선령급에서나 선수부가 가장 크나, 큰 차이는 없다. 3) 깊이 방향의 부식도는 어느 선령급에서나 건현부가 가장 작고, 상부만곡부가 가장 커서 그 부식도는 건현부의 약 2배가 된다. 3. 일반화물선과 원목운반선. 원목운반선의 부식도의 전평균은 일반화물선의 그것의 약 3배나 된다.