Yep - has to do with your air. I've built a lot of orfices/burners. Trick is to light it up and move your orface close/further from your pipe burner until you get the blue flame you're looking for. May be that your orfice is too big as well. You can solder it shut and take a small drill bit and drill it back out - lide a 65 or 70 - they are like hair when they get that small, so you can usually drill just by using your fingers.
Those are my ideas... shot us some picts of your set up and maybe others will have better ideas.
SOB - mine are very similiar to this - I would go with this design, if you're starting over. It would allow you to just keep drilling holes for the air intake until you get it where you want it for your altitude.
I am in the process of making a pipe burner as you are doing. I have gotten information from this web site, www.tejassmokers.com There is one other site I will post when I find it again. The Tejas people say the first eight inches of the pipe are used for the throat of the burner,and does not have any holes in it. A 32 inch burner has 22 inches of flame. It is their math I am just the messenger. They also recommend the regulator and orifice to use for a build. The pipe size on Tejas burner is 1-1/4" . I will get back with the other site.......Hutch
Sounds like the air/fuel mix is off.I have a pipe burner in my smoker and i have it adjusted for a blue flame with yellow tip.Do you have an air mix valve on it ?I live in ne pa and am also a smoking butcher.