Quote:
Originally Posted by sammyg2
for natural gas you need to use special yellow gas tape, not the standard white stuff. Not sure why, something to do with code.
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I used to run a plant that manufactured PTFE tape. As part of the process raw teflon powder is mixed with pharma grade liquid paraffin which turns the powder into a pliable clay (now you know why teflon makes a poor engine oil additive). This paraffin is removed at the end of the manufacturing process through forced evaporation at high temperature.
Obviously in the interests of efficiency and productivity only so much of the paraffin can be allowed to evaporate. This residue could create a potentially dangerous situation specifically when the tape used on oxygen lines and cylinders as the residual paraffin can react explosively in the presence of oxygen. I can't imagine that this would be the same for natural gas, but I suspect the code is an extension of that applied to oxygen.
For this reason the yellow (oxygen) grade of tape is generally heated to a slightly higher temperature during the evaporation phase of the production process so as to ensure more complete evaporation. In addition to this it is also sent for batch analysis to certify that it has a paraffin content that does not exceed a specific level. These records have to be kept for audit purposes.
As a matter of interest, the paraffin content is actually so extremely low after the regular evaporation process, that even white grade PTFE tape is safe to use on oxygen equipment - the expense of having it certified is simply not justified.