What is the meaning of L2 = "Length of Effective Thread" for NPT threads, mentioned in standard "ASME B1.20.1 Pipe threads, general purpose"? Note: the standard includes formula L2 = (0.8D+6.8)/n, where D is the outside diameter of the pipe, and n are the threads per inch.
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$\begingroup$ So what is "n"? Would assume effective length is the length of thread providing the seal. $\endgroup$– Solar MikeCommented Aug 28, 2023 at 20:13
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$\begingroup$ Thank you for your input. I specified the definition in the post. The same definitions can be found in the mentioned standard ASME B1.20.1. Please clarify "length of thread providing the seal". You can tighten the thread past the seal condition, so it is not clear what you mean. $\endgroup$– FuzzyCommented Aug 28, 2023 at 20:22
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$\begingroup$ Effective usually designates for some load-bearing purpose (could be sealing or even structural as with a bolt - which I believe was ~3 threads for almost all of max load). If you have more than the effective amount, you gain almost nothing over having only the effective amount. $\endgroup$– AbelCommented Aug 29, 2023 at 1:29
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$\begingroup$ Is this an English problem? ie lack of understanding the words? $\endgroup$– Solar MikeCommented Aug 29, 2023 at 4:36
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A Google search shows:
In $ASME B1.20.1$ standard for general-purpose pipe threads, $L2$ refers to the "Length of Effective Thread."
$L_2 \ $defines the usable length of the threaded portion on a pipe, where engagement with another threaded component (like a fitting or another pipe) takes place. The purpose of specifying the Length of Effective Thread is to ensure proper, leakproof, and secure connections between threaded components while allowing for variations in threading and assembly.
The formula $L2 = (0.8D + 6.8) / n$, is, as you mention, used to calculate the Length of the Effective Thread.
