Threadolet branches

Hey Allen,
Here's a good question. Is this actually a piping branch or is there a threaded piece of something going into the threadolet? Maybe a corrosion coupon or a pig zig or another maybe a transmitter or something else that requires the treaded connection. That's the only reason I can see you requiring a threadolet that you would need to backwelded. Otherwise if its an actual piping branch, then I visualize you requiring a valve as well. If thats the case then I would be questioning the P&ID itself and following your project branch tables as god. Maybe process is showing the piping as threaded and you and/or they were just assuming it includes a TOL. My belief is that its actually a SOL-nipple PBE-SWxNPT valve-then threaded piping to wherever. Is that possible?

i have just checked our branch table for oil pipeline designs and the thredolet sizes you have quoted agree with what we would use on a standard oil pipeline job.
the 'olet is a good fitting to use for these minor size take off points on relatively large header pipe sizes. they are designed to compensate for the loss of area due to the hole being cut into the header pipe to create the branching outlet. due to their rugged design and shape no further reinforcement is req'd and they are in-expensive, easy to install and easily procured (3000lb or 6000lb). with a stub-in connection on an oil line we would need to get the stress engineer to check crotch stresses based on design conditions (may need re-pad). with the olet no further calcs are req'd regards the fitting...just a pipe stress check for the overall piping arrangement.
the thredolet (NPT) gives you a female thred you can screw directly into. some clients require that we also seal weld around nipple to thredolet...not such a great idea as you can crack the weld due to thermal expansion of the nipple during welding. for sockolets it is therefore important to leave an insertion gap of 1/8" to allow the nipple/pipe to thermally expand during welding. we would then nominate 100% of these type of branches be "gap shot" on an oil pipeline i.e. X-ray to make sure gap exists.