Pyrex Cup Micro-Fracturing Issue

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I picked up an HTP Pyrex gas lens (like shown below) kit a few months back and feel like I have been pretty darned careful to physically protect the cup from banging, hitting, shattering, etc..Attachment 1053591When I went to use it last week, I found that the cup has some sort of micro-fracturing all the way around the the arc side of it, but surprisingly is still whole and works "for now". I don't have pics right now, but can upload some tomorrow morning. I am new to using Pyrex cups and not really sure if this was caused by me (most likely) or some other factor. I am wondering if anybody else has encountered this and what the cause could be?The only thing that I can think of right off hand is that I ran a 1/16" tungsten (2% thoriated) at the upper end of its heat range around 125ish amps and warmed the torch up pretty good on a recent project. After a handful of welds, I considered going to a 3/32 tungsten, but was far enough along that I decided to roll with it. Plus, with a thumb gas valve, there has occasional dry starts here and there, which gets that tungsten lighting up pretty bright..If this is a known user error problem, could any of this have caused the fracturing that I am describing? It definitely looks heat related vs impact related.. but I guess pics would help right?Anyway, if there are no quick and dirtys, I'll get a pic up tomorrow for a look-see.-NicheLast edited by NicheFab; 03-24-2015 at 11:13 PM.
Reply:Eh.. so anyway, here are some pics..Attachment 1054601Attachment 1054611Attachment 1054621Is the nut  behind the torch causing this or something else?-Niche
Reply:Cups are rated for 500*, think you got it that hot?What about putting the hot cup onancold bench? I could see that giving you issues.Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:I always hang my torch over my leg when working with it and over something near by when I am between welds. This is to say that I never lay my torch on my table.I was welding during some 15 degree days though.. garage was a bit warmer, but had the door cracked for fresh air though, so not by much.. I am not 100% sure when it happened, as I switch between stick and TIG fairly regularly. I just noticed it last week though when I went to weld a part up..-NicheLast edited by NicheFab; 03-26-2015 at 12:21 AM.
Reply:NicheFabI may have missed this - is your torch - air or water cooled?Opus
Reply:Opus, it is a 17V air cooled torch.-Niche
Reply:I have the HTP Pyrex kit also, haven't had anything like that happen to mine yet. I also am using a WP20 torch though.2 Hobart MIG welders, 1 on the gas 1 flux coreHTP Invertig 221 DV Eastwood TIG200HTP MIG 2400
Reply:Pyrex should remain in the kitchen or laboratory.  As TIG cups, they seem gimmicky.  Buddy of mine who works offshore recently melted a clear cup while welding 1/4" thick 6061-T6 with a SynchroWave 350 and water-cooled torch.  No thanks.  About the only advantage can see with these devices is their non-marring/scratch nature when 'walking the cup' on SS/other materials.Last edited by ManoKai; 03-26-2015 at 07:43 AM.Reason: spelling"Discovery is to see what everybody else has seen, and to think what nobody else has thought" - Albert Szent-Gyorgyi
Reply:Well, thanks for the replies. I picked up a mixed 10 pack of ceramic cups yesterday while swapping out my gas bottles. I have been been meaning to get a handful of saucepans from Goodwill to practice welding couplers in. Maybe I'll come back to it once I get there..-Niche