Guyz, I am using ordinary sticks to measure preheat temperature and looking for a better option. Can you give any advice for a more advanced method? A gauge, a kind of thermometer etc.
Thank you.
Barbaros,
The temp stix are quite reliable, and some times, low tech IS the way to go. The infrared guns can be unreliable due to surface color and texture. I prefer to have both on hand. Using the gun first and the temp stix for accurate verification. Quality control of the chemistry is pretty reliable (I'd say infallible) and the stix will let you know exactly where you are out of bounds.
Tempil sticks have been around a long time, and there is a good reason for it...they are simple to use, don't require an expensive annual calibration and best of all, they work.
The guys are right. If you get into guns you have emissivity issues to worry about as superflux indicated.
Nothing wrong with guns. They can work quite well. But they have complications. I prefer sticks.
I concur with all the previous posters.
When it comes to unquestioned reliability the temp stix are the way to go. I prefer to see them in use when I go into a shop as a TPI. BUT, I then usually carry a gun in my pocket at all times. It allows me to do a quick check to make sure they are maintaining the heat and not going over the max if working to WPS's or Seismic codes that state a max temp. If at all concerned I ask for them to re-check their temp with the stix.
As a side note, the probes are probably more reliable than the guns on most surfaces. But for documentation you still have calibration issues to deal with.
Have a Great Day, Brent
I agree with the other posters - temp sticks are simple and reliable and cheap (relatively). I have never had anyone argue with the use of a temp stick, nor ask to have it calibrated. And the batteries never need replacing.
Regarding the temp sticks, I like the Markal brand better than Tempil simply because the Tempil case is so weak. I used to wipe out Tempils all the time by putting them in my pants pocket and then squating, kneeling, sitting or whatever. The case would bend, breaking the crayon into pieces. I think the Markal case is an improvement in this regard, although it would be an improvement if it were made more durable too.
http://www.markal.com/prod/132/thermomelt-temperature-stiks.aspx
By scrappywelds 
Date 07-17-2011 03:02
Edited 07-17-2011 03:05
Some of the new Tempil sticks have a hard square plastic or polymer case with a thumb wheel to move the stick in and out. Pretty nice built in pocket clip too. Tempil sticks are almost idiot proof they are the way to go but the guns are good for at a distance checks.
I also agree with the answers that have been posted above; but if you insist in using a method other than sticks, you can use a portable thermocouple. It consists in a probe that contains one of the thermocouple ends and a small box that contains the other end, together with an instrument (actually a milliamp meter graduated in degrees F or C) that will read the temperature. The interconnecting wires, compensated of course, complete the set.
You touch the hot surface with the probe tip and read the temperature on the instrument.
Now, take into account that preheat temperature is not as critical as soaking temperature, for example, so sticks perform all right. Two or three degrees above or below the desired one won't make any harm. As we say in Brazil, you want to buy a Mercedes when all you need is a Volkswagen Beetle.
Giovanni S. Crisi
Sao Paulo - Brazil
we used calibrated pyrometers to confirm post weld heat treatment and interpass temperatures. They work well and are accurate. Usually overkill for most welding applications, but still more robust than the temp stix because they give a reading
