<html><head></head><body><div style="color:#000; background-color:#fff; font-family:verdana, helvetica, sans-serif;font-size:13px"><div id="yui_3_16_0_ym19_1_1503064189869_8047"><span id="yui_3_16_0_ym19_1_1503064189869_8156">Jon, </span></div><div id="yui_3_16_0_ym19_1_1503064189869_8047"><span><br></span></div><div id="yui_3_16_0_ym19_1_1503064189869_8047"><span id="yui_3_16_0_ym19_1_1503064189869_8169">Crack propagation might be a problem with a threaded hole in a pressure hull but I think you could use a tapered insert with no problem as long as the insert were strong enough to compensate for the hole. Poly-carbonate inserts have been approved as a repair plug for acrylic hulls and it is basically the same idea.</span></div><div id="yui_3_16_0_ym19_1_1503064189869_8047"><span><br></span></div><div id="yui_3_16_0_ym19_1_1503064189869_8047"><span>Greg</span></div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1503064189869_8170"><br><br></div><div class="yahoo_quoted" id="yui_3_16_0_ym19_1_1503064189869_8283" style="display: block;"> <div style="font-family: verdana, helvetica, sans-serif; font-size: 13px;" id="yui_3_16_0_ym19_1_1503064189869_8282"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_ym19_1_1503064189869_8281"> <div dir="ltr" id="yui_3_16_0_ym19_1_1503064189869_8280"> <font size="2" face="Arial"> <hr size="1"> <b><span style="font-weight:bold;">From:</span></b> Jon Wallace via Personal_Submersibles <personal_submersibles@psubs.org><br> <b><span style="font-weight: bold;">To:</span></b> Personal Submersibles General Discussion <personal_submersibles@psubs.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Friday, August 18, 2017 9:51 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> [PSUBS-MAILIST] Tap instead of weld<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_ym19_1_1503064189869_8285"><br><div dir="ltr" id="yui_3_16_0_ym19_1_1503064189869_8284"><br></div><div dir="ltr">On a thicker hull, installing a small penetrator (1/4 male NPT), is <br></div><div dir="ltr">there any structural reason why one could not just drill a tap such a <br></div><div dir="ltr">fitting instead of welding it?<br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1503064189869_8286"><br></div><div dir="ltr"><br></div><div dir="ltr">Jon<br></div><div dir="ltr"><br></div><div dir="ltr">_______________________________________________<br></div><div dir="ltr" id="yui_3_16_0_ym19_1_1503064189869_8287">Personal_Submersibles mailing list<br></div><div dir="ltr"><a ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br></div><div dir="ltr"><a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br></div><br><br></div> </div> </div> </div></div></body></html>