Infrared Temp Guns can be your friend
I have two infrared temperature readers (point and shoot). In the beginning they were frustrating to use, due to my ignorance. I was unaware of what they require to be accurate. These devices are finicky about the surfaces they read accurately.
1) Shiney, smooth or light colored surfaces are a no-no
There are simple fixes that will result in very close readings. Flat black paint or a strip of black friction tape will do the job. The friction tape is more accurate by a small margin.
Try either on a section of pipe. Take a shot at your new target and then a shot three inches away on bare pipe, you will see the difference. Comparing with other reading devices (strap-on bi-metal and digital thermistors) I am now comfortable with the results of the infrared devices.