Document gaJepn17MwV60B36g6oLvo4Lq

To: Distribution Interoffice Communication From: Date: Subject: R. C. Tebo - Houston, Tx. April 15, 1988 ADDENDUM TO THE RVCM STUDY It has come to my attention that some people may have misinter preted some of the points brought up in the RVCM Study (RVCM Study, November 23, 1987). I have attached a brief summary which should help clarify the issues which were in question. Please attach this addendum to the front of your copy of the RVCM Study. I hope that this document will answer all questions you may have. Richard C. Tebo Process Engineer /mb Attachment Distribution: Houston: JHM / EJM / LZK / RDM / TWH / WLWc / RRS Aberdeen: VEM / PJK / DWH Ponca City: LGH / RBQ / SEM / CJM / JLI File: A-120.1 009/PED39 CCR 000005317 RVCM Study Addendum INTRODUCTION The purpose of this document is to help clarify some potential mis interpretations about the RVCM Study (November 23, 1987). Please attach this document to the front of your copy of the RVCM Study. The questions raised from the RVCM Study were classified into the following 4 groups: 1. Clarification of Terms 2. Plant Policies/Procedures 3. Potential Projects 4. New Technology 3265 These group questions are further described below. CLARIFICATION OF TERMS To eliminate confusion, some ambiguous terms and phrases will be further clarified. There were a few questions about what is meant when a process is statistically "not in control". The term "in control" is a statistics term of art referring to the relationship of process data to standard statistical deviations from an expected process norm. The terms "in control" or "not in control", when used as a statistics term of art are not synonymous with the ordinary common usage of such terms. There is some question also with the statement that some of the RVCM data was 'excessively high'. In this case, excessively high data points referred to RVCM data points which exceeded 10 ppm. Of all the in plant railcar data analyzed, only 3% of the data fell into the category of being over 10 ppm. PLANT POLICIES/PROCEDURES RVCM railcar sampling is done on "in plant resin". By no means are these levels found in resin which is shipped to customers. Vista currently has a plant policy which says that no resin will be shipped out of the plant at levels higher than 10 ppm. The resin found to be above 10 ppm is either aerated further to remove more RVCM or is used internally in Aberdeen and processed such that when it leaves the plant it is well below 10 ppm. With regard to small blend tank aeration air problems, the original report did not intend to imply that plant personnel did not take action when aeration problems occurred. The RVCM report intended to suggest that we try to minimize the lag time between when aeration problems start and when operators learn about them. 009/PED39 OCR 000005318 POTENTIAL PROJECTS The list of potential projects in the RVCM Study was not a recommenda tion that these projects be implemented, but rather was a list of all the possible projects thought of. Some of the projects, such as increasing air capacity with another compressor when needed, are already being done. Some of the projects mentioned in the study would have a very small impact on RVCM. Heating the silo aeration air, for example, might be able to reduce RVCM by ten percent relative for old technology 5265 resin. With new technology, RVCM levels are lower and little or no benefit is expected. Some of the other projects are not recommended because there is no data to show that they would have an effect on the RVCM of the new tech nology resin. Since one of the RVCM Study*s conclusions was that we should try to minimize times when aeration air was low, the study recommended some type of alarm system be implemented to alert operators of aeration problems. This could be done by a local alarm system or by administrative controls, and either way would be effective. The RVCM Study did recommend that PED look into the aeration air sparger pluggage in the small blend tanks. PED is looking into other types of sparger designs which would minimize pluggage of the spargers due to power failures and calcium deposits. By monitoring air flows with local instrumentation, operators will be able to predict when a sparger needs to be cleaned before the sparger completely plugs, avoiding times when there is little or no blend tank aeration. NEW TECHNOLOGY As the RVCM Study was being issued, the plant switched to new tech nology to make the 5265 resin. The effect of the switch on RVCM is great; RVCM in 5265 has been shown to have decreased by up to a factor of 8. Table I shows the magnitude of this change. Since the magnitude and variability of the RVCM is now at very low levels, none of the potential projects listed in the study is expected to have a noticeable effect on RVCM. 009/PED39 CC R 000005 31 9 Table I 3265 SWITCH TO NEW TECHNOLOGY EFFECT ON RVCM Season Winter Spring/Autumn Old Technology RVCM 2200 ppb 600 ppb New Technology RVCM 260 ppb 150 ppb RVCM levels will continue to be monitored and charted to determine if the switch to new technology allows the system to come under statis tical control. 009/PED39 cca 000005320