So I just drilled a 7/8" hole in my kettle. I'm trying to find what's needed to attach a 1/2" NPT thermometer from spike brewing. It would be a locknut and o-rings plus washer, correct? I was hoping I could get them at home depot or something. Do the o-rings need to be food grade? I was also looking on amazon, not seeing much for what I'm searching for. Thanks for any help.