Heathus OMD, Manual

Page: 53 / 60

53
VII. Centering of Leakage Detection
Whenever combustible vapors are detected in the soil or
substructure atmospheres, additional tests will be con-
ducted to determine the extent of the spread of the gas.
The pattern of spread, as well as the relative volume of
gas throughout the spread, will be observed to establish
the logical source of the leakage indication.
VIII. Classification of Indicated Leakage Areas
Each location where combustible vapors are detected and
centered will be evaluated and classified, in the opinion
of the consultant, as a 1(C), 2(B), or 3(A) leak location.
(Leak grades based on A.S.M.E. standards.)
1.
Grade 1(C) - A leak that represents an existing or
probable hazard to persons or property, and requires
immediate repair or continuous action until the con-
ditions are no longer hazardous.
2. Grade 2(B) - A leak that is recognized as being non-
hazardous at the time of detection but requires sched-
uled repair based on probable future hazard. Sched-
ule for repair after Grade 2 locations are completed.
3. Grade 3(A) - A leak that is non-hazardous at the time
of detection and can be reasonably expected to re-
main non-hazardous.
The purpose of classification is to arrange the locations
in order of priority to assist the operator in scheduling,
pinpointing and repair.
THE CLASSIFICATION IS A JUDGEMENT BY THE
CONSULTANT BASED ON THE INFORMATION
AVAILABLE TO HIM. It in no way indicates the condi-
tion of the pipe or the size of the leak in the pipe or the
amount of gas leaking on concealed piping.
S
URVEY