API PUBL 932-A:2002 pdf download

API PUBL 932-A:2002 pdf download.A Study of Corrosion in Hydroprocess Reactor Effluent Air Cooler Systems.
The UOP survey also reported on the performance of various alloys for RAC tubes and piping. corrosion of iMher components and in addition discussed air cooler tube fouling. The report concluded with a list of design and operating recomn’iendat ions which support the 1975 NACE study but did not add an’,’ further enlightenment or provide new guidelines for dealing with the problem.
5 1998 API Survey
The present study was initiated in 1997 and consisted of tM() parts:
I. A preliminary survey to obtain a broad overview of the problem within the task group meinhers experience.
2. An interview proccss of selected companies in which details of their corrosion experiences were explored.
5.1 PRELIMINARY SURVEY—BROAD OVERVIEW
A brief questionnaire was sent to all task group members inviting them to provide general information about two units within their company’s operations where the corrosion experience in one unit was significantly different from the other. Any unit that had experienced a catastrophic event such as an explosion or fire was to be included. Where possible the second unit would be one that had a predictable and essentially trouble free corrosion record.
The preliminary questionnaire is shown in Figure 4. The survey was divided into three major categories.
I. LeeI fdisrrrss. This was intended to gjsre a measure of the severity of the corrosion problems experienced for each unit and to identify units with poor experience from those with good experience.
2. &onornic levels. Another measure of the seriousness of the corrosion problem is the frequency with which equipment replacements have to be made or if a large capital investment in alloy replacements is believed to be necessary. This category provided some insight into those aspects.
3. C’orrnsion wnirnl. The level of elIo,t needed to keep corrosion under control is an indication of the seriousness of the problem to the owner. Included in this category were some corrosion coiitrol nleasures and the quality of inspection.
Unftrtunaiely, in attempting to keep the survey brief to elicit maxinnini and timely resnonse. sonic line items contamed more than one subject. This ambiguity has been taken into accoUnt in drawing conclusions from the responses and does not appeas to be a major deterrent to the usefulness of the results.
Table 2 is a complete compilation of the responses received. The categories discussed above are listed at the left side o the table. Each column represents an individual unit identified by a code letter which has been used consistently through the remainder of this report. The type of unit is identified by a code letter as follows:
IICU hydrocracking
HTU hydrotreating—this includes hydrodesulfurization and hydrodenitrification units.
Table 3 summarizes the data from he responses and the Ibllowing conclusions have been drawn,
a. Out of 24 units included in the survey:
• Five units reported fires and explosions.
• Four units reported unscheduled outages.
• Ten units reported experiencing corrosion but manage it by regular replacement of carbon steel or have substituted alloy for carbon steel.
• Five units reported no significant corrosion.
h. A total of 12 units have substituted alloy for carbon steel.
c. Ten units use alloy extensively.
d. Two units report low corrosion rates but have experienced fires. This indicates locali7ed corrosion resulting in a serious leak.
e. Only two units report using inhibition. One of these had an unscheduled outage.
f. Fifteen plants use regular inspection, that is. inspections conducted at planned intervals, usually at unit turnarounds.