Applying nitrogen in a 34,500V transformer

Is it possible to apply nitrogen using the oil sample port? I noticed on the transformers that I serviced had two ports on the outside, one for oil sampling (bottom port) and one for nitrogen (top port). However, when I unscrewed the top port to apply nitrogen there was no adapter or nipple for me to attach too.

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For a transformer of that size there should be a nitrogen fill port, typically right around the air pressure gauge (or on the gauge itself). Sometimes you get small padmount units with no port, these just have a pull pin to equalize pressure.

I didn’t see any other port to insert nitrogen. Is it possible to apply nitrogen through the oil sample port?

Sometimes the nitrogen fill just looks like a small cap on the pressure gauge. I have never filled nitrogen from an oil sample port but in theory it could be done if above the oil level. You would need to come up with a custom fitting for the tubing.