(C) Specimens are to be weighed to an accuracy of ±1 mg.

(D) Corrosion loss of conventional steel ( ) and corrosion resistant steel (CL21, CL49, CL77 and CL98), calculated by the following formulae:

× × ×

×

× ×

Guidance for Approval of Manufacturing Process and Type Approval, Etc. 2015 215

whereby:

WC : weight loss of conventional steel (g) (average of five test pieces)

W21 : weight loss of corrosion resistant steel after 21 days (g) (average of five test pieces) W49 : weight loss of corrosion resistant steel after 49 days (g) (average of five test pieces)

W77 : weight loss of corrosion resistant steel after 77 days (g) (average of five test pieces)

W98 : weight loss of corrosion resistant steel after 98 days (g) (average of five test pieces)

S : surface area (cm2)

D : density (g/cm3).

(E) The

test is considered to be carried

out appropriately if is between and 0.11

(corrosion rate is between 0.2 and 0.4mm/year).

(F) Where the calculated corrosion loss of conventional steel is less than 0.05 mm/year, the

concentration of H2S may be increased in the simulated cargo oil tank gas. All tests will be carried out at this increased level.

(G) At least 3 values of individual weight loss of conventional steel should be in the range of maximum X and minimum Y measured in grams.

X= (0.11 x S x D)/10 Y= (0.05 x S x D)/10

whereby:

S = Surface area (cm2) D = Density (g/cm3)

(H) Coefficients A and B of corrosion resistant steel, calculated from the test results for 21, 49,

77 and 98 days by least square method. Corrosion loss of corrosion resistant steel is de- scribed as follows:

×

A(mm) and B : coefficient t : test period(days)

(I) Estimated corrosion loss after 25 years (ECL) calculated by the following formula: ECL(mm) = A X (25 X 365)B

(3) Test results of welded joint