Issue link: https://www.e-digitaleditions.com/i/1067339
32 January 2019 Tablets & Capsules Entries should be timely and in chronological order, and the information should be adequate to present a robust audit trail in the event of a deviation or inspection. The log book is the tool for reconstructing the entire bag management cycle and knowing who did what, when, and Photo 2: Repairs such as the patch shown here can make predicting the repaired bag's expected usable life challenging, because a repair to one area of a bag does nothing to prevent failure elsewhere on the bag. Figure 3 Microscopic view of bag thread abrasion a. Image of warp thread without wear b. Image of warp thread showing abrasive wear Flat areas indicating thread wear on inside of bag how, along with any comments on unusual observations or issues that require corrective action. Bag inspection is largely a qualitative process of evaluating the bag's condition and fitness for use. Wear, shrinkage, and other damage is inevitable. Look for pin holes, rips in the fabric, splitting or parting seams, threads unraveling, and abrasion to the fabric surface. Figure 2 shows some common types of bag wear, while Figure 3 shows a microscopic view of bag thread abrasion. Because the degree of damage is somewhat subjective, it's a good idea to have a second technician also examine the bags. The question of whether to repair or replace a worn bag often depends on the preference of the individual site. Sites can create policies to guide technicians when determining acceptable levels of wear or dam- age. Any small defects in the fabric and stitching may propagate and contribute to material loss or even a complete rupture and batch failure. Determining what can and cannot be repaired is largely done by the site technicians and operators that routinely work with the filter bags. Sharing onsite observations with your bag supplier, either in photos or by sending the damaged bag to them to evaluate whether or not repair is appro- priate can help educate your site's technicians, so that they can eventually make repair decisions on the spot. Photo 2 shows a typical patch made to close a tear in a fluid bed dryer bag. Such repairs can make predict- ing the repaired bag's expected usable life challenging. For example, a repair made to patch a hole, stitch a rip in the fabric, or close an open seam will do nothing to prevent failure from an abraded surface or the opening of a loose stitch elsewhere in the bag. For this reason, many companies choose not to repair bags and instead set criteria for how much damage is acceptable before a bag must be removed from service. Companies that do allow bags to be repaired and returned to service will sometimes assign different part numbers to the repaired bags to distinguish them from bags that have never been repaired. This helps with tracking a repaired bag's performance and remaining usable life. T&C Edward S. Novit is business de velopme nt manager at Freund-Vector (319 377 8263, www.freund-vector.com). Many companies choose not to repair bags and instead set criteria for how much damage is acceptable before a bag must be removed from service.