SIP (Sterilize or Steam In Place) is a timed sterilization of the upstream and downstream biopharmaceutical production train with clean steam. It is part of the 5 step sanitization routine that occurs after every production batch, and follows the final rinse after CIP. Every square cm of all process piping and vessels that come in direct or indirect contact with process inputs, process and process outputs is “sterilized” to insure that there is no microbiological activity in the system.

Clean Steam (made from USP Purified water)is circulated through all of the process tubing during this stage and enters large vessels through spray balls (engineered nozzles) imbedded in the vessel ceiling.

SIP is a temperature validated process, meaning that the sterilization even must be proven, by measuring the temperature of the event and recording the data. The minimum sterilization regimen requires the injection of clean steam into all piping and vessels for a minimum of 12 hour after the vessels reach a minimum temperature of 250°F (121°C). See Figure below.

Picture of temperature/time chart

Validation temperature sensors (RTD’s, Thermocouple’s or Thermister’s) are placed at the condensate outlets of process equipment to make sure that the sterilization temperature meets the specific regimen designed for the process system. The sensing elements are usually designed with integral sheathes and Tri-Clamp connections, and are clamped to tubing tee’s; or the element is inserted into a Tri-Clamp Thermowell connected to a mating tee. The sensors are normally located 12 to 18 inches (300 – 450mm) upstream of the clean steam trap where the condensate exits the piping or vessel. See Figure below.

Mark 94 illustration

Recorded time/temperature (like top graphic) is stored in a PLC, Distributed Control System, or standalone database for later use by the company quality folks and auditors.

It is important to understand the information above before we discuss how thermostatic steam trap operation can affect the occurrence of temporary validation faults.

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