|Name||1/2 in. x 6 in. Cut-Off Riser (10-Pack)||15 in. Irrigation Flags (10-Pack)||3/8 in. Funny Pipe Coupling||1/2 in. M x F Swing-Joint Elbow (10-Pack)|
|Irrigation System Component||Riser||Accessory||Fittings & Connectors||Fittings & Connectors|
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Thanks for your question. I agree with the previous answer that taping the sprinkler riser connection generally isn't needed. In my testing (I have capped a sprinkler head to observe without nozzle spray), these connections may leak a few drops a minute when hand-tightened. As stated in the other answer, this is in the part of the system that is not continuously pressurized (only when a zone is active), and very slight leaking doesn't affect the sprinkler head range or flow rate significantly. And as mentioned, do tape the supply side connections such as on the water supply side of valves, since they are under constant pressure (the risers aren't used in that application - just mentioning as an example).
I believe that these are 1/2 inch "MNPT" threaded: Male - National Pipe Taper (see https://en.wikipedia.org/wiki/National_pipe_thread). This means that the threads are tapered for sealing, often without any thread sealant/tape required. By the time you make a couple turns, the threads are self sealing tightly, and you can't tighten any more. The other model you mention are probably MNPS threaded: Male - National pipe straight, which means you may need sealant/tape to seal the joint. This information should really be included in the item's description to remove any ambiguity.