Date of Defense
Date of Graduation
Chemical and Paper Engineering
Andrew A. Kline, Paper Engineering, Chemical Engineering and Imaging
Peter E. Parker, Paper Engineering, Chemical Engineering and Imaging
Betsy M. Aller, Industrial and Manufacturing Engineering
This report details the upgrade of Pfizer’s Active Pharmaceutical Ingredient-Low Endotoxin Water (API-LEW) distribution system. The current system is suffering from chloride induced stress corrosion which has caused pitting and cracking throughout the exterior portions of the loop. The system will eventually fail catastrophically if an update is not undertaken. Many variables and system constraints are considered to maintain the API-LEW grade water.
The system operates at 65 ○C and maintains turbulence to prevent any microbial growth. The distribution loop spans 8,500 feet of 4 inch diameter stainless steel pipe which is carried on trestles that are exterior to each point of use building. The loop is pressurized by an initial pump in the generation building and re-pressurized approximately half way through its path. The temperature is maintained by a single countercurrent heat exchanger located in the water’s generation building. The flow through the loop is controlled by an automation system. This system controls filling of storage tanks within each point of use building based on current tank levels. Tank filling rates are based on zone filling dictated by the automation set points. Priority filling ranks are based on building API-LEW usage. The current system is oversized due to regulatory changes that were made after the loop was installed resulting in reduced API-LEW demand.
The system was installed with a polyiscocyanurate insulation product that is extraordinarily effective in preventing heat loss throughout the loop. When the loop was initially designed a cost versus risk analysis was performed to determine if preventative measures to avoid corrosion were necessary according to literature available in the late 1990’s. This analysis showed that the loop was outside the corrosion zone, so while a vapor retarder was used inconsistently, a pipe coating was not applied. However, corrosion has occurred, so a proper vapor retarder, improved insulation and a pipe coating must be included in the system upgrade.
Many options will be discussed including removing unnecessary piping and using a smaller diameter in the replacement of the pipeline. Due to large production rates at the site, system shutdowns must be minimized if not avoided completely. The option that the team recommended was to shorten the loop and to use Saran 560 vapor retarder, Thurmalox-70 pipe coating, and TRYMER 2000 XP insulation. In this option the loop was rerouted, which removed 100 feet of extraneous piping, and the pipe diameter was reduced to 3 inches. This option is the most cost effective option for the system upgrade, while minimizing if not eliminating production disruption.
Sherburn, Tiffany M., "Replacement Options For the AP1-LEW System" (2012). Honors Theses. 2238.
Honors Thesis-Open Access