OK, OK... let's just say that sometimes even I show a casual disregard for the fine print of the code. So, take this post as a confession (good for the soul), and not, heaven forbid, as an encouragement to violate the "Holy Writ" of the NEC.
I took a ammo box, formerly used for 40MM ammo:
I added some charcoal:
I set the pipe and cover like so:
The pipe used is schedule 80, 1" PVC. Before long, it drooped like this:
From this, wearing gloves, I made this nice, unscorched bend:
But, alas, all was not happy. I had some heat damage to the asphalt. While I was able to patch (using roofing cement), I took heed and added a pair of pieces of strut to the bottom, to let some air flow under the box.
Oh, I could have cut the pipe a wee bit closer, etc., etc.,... but this is but one example of several bends I had made.
I have two things against heat blankets: a) They cost much more than ammo boxes; and, b) They require electricity to work...and, ironically enough, I was in the process of bringing power to this outbuilding.
352.24 Bends — How Made. Bends shall be made so that the conduit will not be damaged and the internal diameter of the conduit will not be effectively reduced. Field bends shall be made only with bending equipment identified for the purpose. The radius of the curve to the centerline of such bends shall not be less than shown in Table 344.24, column “Other Bends.”
At least we should be aware of the code before we ignore it.
I admit I have field bent RNC with equipment that was not 'identified for the purpose'.
Bob Badger Construction & Maintenance Electrician Massachusetts
Bob, you are, of course, absolutely right. Code requires the use of listed equipment. Someday I might even see that requirement complied with!
Mike, the coals seem to be pretty self-regulating. An even bed of coals = an even heat...and with the clearance you see, it seems to be 'just the right temp.' Best of all, when doing several bends, it is not necessary to "turn it off" between uses. I think that the hot gasses from the coals help them to heat the pipe more evenly than, say, a radiant heater.
Otherwise, Mike, for some silly reason we seem to have no shortage of empty ammo boxes these days. It seems almost as if the Army is emptying them on purpose....