Doc. 53 Hygienic Engng. Of Bulk Pack-Off Systems In Process Lines For Dry Particulate Material

Summary

This guideline provides information on what a hygienic weld is and explains the technical requirements for achieving on-axis hygienic (sanitary) welding between tube segments, or between a tube and a control component (e.g. valve, flow meter, instrument tee, etc.).

Orbital TIG welding is the best technique for consistently achieving hygienic welds. The factors that affect the TIG welding process for achieving a hygienic weld are described. Orbital welding and/or mechanised welding is preferred to manual welding due to the resulting superior quality of the welds, greater repeatability and welding traceability. In tube systems, internal post-weld finishing is generally not practical, so the system design should therefore allow and facilitate orbital and mechanised welding wherever possible, to achieve the highest quality welds. This guideline not only provides information on how to achieve hygienic welds and gives a basic understanding of important operating procedures, it also provides information on how to test and verify the systems. Moreover, it provides a section on troubleshooting and describes different defects and how they can be overcome. For more information on weld joint testing, EHEDG recommends consulting Doc. 54 Testing of Hygienic Weld Joints.