How hard would it be to make something like this?

http://www.brownells.com/.aspx/pid=1078/Product/HOT_WATER_CLEANING_TANK_PIPE_BURNER

What are the chances of me blowing myself up while doing so?

I made this one.  It works great.

Although I'm not sure it's what you're going for.

I'm looking for something to heat up tanks for parkerizing.

It's not hard.  I made one years ago to heat up bluing tanks.  The link ragedracer1977 put in his post is a good way to put together the gas injector––my setup is similar.  The tube on my burner is one inch conduit with a cap on one end and the gas injector on the other.  The conduit has 1/16 hole drilled in a line every two inches or so.



For your purposes, you don't need a pressure valve.  go to your local bigbox store and buy a replacement valve/connection for a gas grill.  I simply cut off the connector that goes to the grill, slip the hose over on the gas injector and tighten it with a small hose clamp.



I also welded up a stand out of angle iron that will hold my tank and burner.  The burner is held on the stand by u-bolts.

I built this for a friend.
It's a dual tank rig with pipe burners for his parkerize and degreasing operations.  He had been using an inefficnent burner that only worked for one tank at a time. It was time for an upgrade. Both tanks are 40"x6"x6" with covers, one tank is used for degreasing is made from mild steel and the other is stainless steel for the parkerize solution.

The unit needed to be able to be moved easily for keeping the shop clean and with tank covers, the liquids stay in the tanks when moving the unit by covering the tank when cold with Saran Wrap. One end of the unit has fixed wheels and the other locking swivel castors.

The pipe burning is the key to uniform heat distributed across the tank.   The pipes were 4' 3/4" black pipe with endcaps.  The hole pattern was 7/64" holes 1 inch spacing for 40".  The ends were given some space for clamping the pipe to the framework.  The control end is all brass having a brass 3/8" flare male (propane fitting) to 1/4" male, 1/4" Brass ball valve shutoff a 1/4" to 1/8" reducer (pipe endcap is drilled just large enough to fit the 1/8" end through)and a 1/8" female endcap that I drilled with a #55 hole.  The Drilled Brass cap went on inside the steel pipe cap holding it tight. With Propane, a blue flame is the most efficient, if you have yellow flames you have too much fuel and not enough mixed air.  Some time went into the tuning of the venturi (mixing area where propane comes out and receives air). The venturi endcap needed 6 holes 1/4" drilled to allow for enough air to mix with the propane.  The holes left enough integrity for the mount of gasline and not interfere with either the caps or pipes threads.

Some minor work is needed for mounting the pipes and its ready for paint.  More Pictures to come after just before and after paint.










Here is the last of the rig ready for paint.  We ended up with a different shutoff valve the small red handle was made in Italy.  It functioned just as fine as the yellow handled shutoff.  Both easly allowed the flame to be run as low as 3/8 inch flame up from the pipe.
After a couple of Acetone rub downs the steel will get a few coats of white enamel.  The heat may burn some off but the rest will be well protected.






Here is the gas fittings.  Tighten with a wrench using gas tape on the threads.