Are these parts ok to use in mash tun set up

I went to lowes today to get parts to hook up to my ball vavle that I bought from my lhbs. I want to pick up a reducer to put a tube on so after looking at about 100 parts that wouldn't fit I found a nylon hose barb that was perffict fit. It's lead free. Is this ok to use as a one time only part. I have parts coming to me but I was hoping they'd be in by now. Also bought danco o-rings #15. Are they safe to use? The kettle ball vavle i bought didn't have one for the inside and I understand why but I am putting this into my 5 gallon igloo cooler.

The nylon will be fine, MLT temps are relatively low. I finally ordered a number of high temp o-rings in various sizes so I have them on-hand now (http://www.brewershardware.com/O-Rings/). Many brewing websites have them in the typical sizes we use.

I had placed an order and didn't get an o-ring. Not sure if these are high temp o-rings. Will just buy the right ones to make sure.

Thanks for the tips.