Seal testing is performed in the operation and performance qualification steps of validation. For PQ, ISO 11607 Part 2 says that three consecutive successful production runs are typically evaluated at the established sealing parameters. Manufacturers determine the frequency of subsequent in-process seal testing based on risk assessment considerations.
“One of the biggest problems we see is that companies are not testing enough,” says Charlie Webb, certified packaging professional, Van der Stahl Scientific Inc. (Wrightwood, CA).
“As a result, they are receiving FDA 483 warning letters and, in the worst case, incurring product recalls, for seals produced outside specification,” Webb says,
Van der Stahl's MS 451 PV heater sealer with integrated peel strength and seal integrity test devices promotes a "forced compliance" approach to in-process seal testing.
“The validation process is front-loaded,” he adds. “Most people can create a cogent validation, even with modest equipment. [But] production creeps away from the spirit of validation, as manufacturing is left to production and maintenance staff.”
Van der Stahl’s MS 451 PV heat sealer integrates a peel-strength tester and the company’s VIU seal integrity inspection device. The on-board units support ATSM F 88 and ASTM F 1886 seal testing. Webb says the machine supports a “forced compliance” model that systemizes and automates compliance.
Companies can discover sealing failures at the point of packaging, in the interim between quarterly or annual peel studies.
“Testing cycles tend to be calamity-based, after failures occur,” Webb says. “Companies need to discover if there is a problem before they ship 100 cases to hospitals worldwide. The MS 451 PV prompts additional testing, performed in a mechanized and standardized fashion.”
The operator is prompted to perform the peel test at pre-set intervals. The system records testing events, pass or fail status, peel strength values, and time and date. If the seal fails to meet the seal strength specification, the machine locks up until a supervisor enters a four-digit code and investigates the problem.
Seal integrity testing is reported as pass or fail with the VIU visual testing aid. Offered also as a freestanding unit, VIU features a low-angled light wash over the seal area, with 3X magnification. Van der Stahl provides a laminated reference card for helping operators exploring the possible causes of seal topography anomalies.
Companies can avoid the high costs of managing failures, with testing that is easily performed during production, Webb says.
“Many of our customers are doing hundreds of seals per day on machines with four to five times that capacity. If you are pulling one out of 100, that’s a statistically high sample population. Other customers are producing less than 25 pouches per day, and performing 100% inspection.”