WELDING CONTAMINATION IN SANITARY WELD FITTINGS

[imagineers]

So I guess my question is, once stainless 304 pipe is welded toghether through butt weld joint or whatever, and food or beverage is passing through the pipe, can the weld cause any kif of food contamination as it the fluid of food passes by it if that makes sense?

 

[EdStainless]

If the food products are acidic then you can get corrosion of the welds.
It really isn't food contamination because you are dissolving a few grams of metal into 10000's of liters of food. It usually works out to ppb levels.
I have seen both foods and beverages attack 304 and 316, even when the tubing and welds were all high quality. Know your products, with a focus on pH, Cl, and temp.

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P.E. Metallurgy, Plymouth Tube

 

[metengr]

There are strict requirements for welding in the food and pharmaceutical industries. The following provide guidance on materials and welding;

3-A Sanitary Standards, Inc. (

http://www.3-a.org),

the National Sanitation Foundation (NSF) (

http://www.nsf.org),

and Underwriters Laboratories (

http://www.ul.org),

 

[EdStainless]

Actually even though the specs listed cover sanitary equipment they are very weak.
Better specs are ASME BPE and EHEDG. The address materials, design, and fabrication.

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P.E. Metallurgy, Plymouth Tube