Leaking Threads on 4″ nipples

[steve betteridge]

Background: I am project engineer on a job to replace chilled water lines in an industrial building. We have many 10 dia mains with many 4 dia branches to equip. The 4 dia branches consist of thread o let welded to 10 header, 4 nipple, then 4 threaded flange with a 4 butterfly fastened to flange. We are currently in process of pressure testing system.Problem. Most of the 4 nipples leak between nipple and thread o let. The nipples are tight. The 10 spool pieces had set outside for some time before installed and the threads on the thread o lets did have time to rust. The pipe fitters believe they could make the leaks stop if they had some type of pipe dope better than what they have now. The pipe dope they are currently using is LA-CO, Slic-Tite, paste with teflon, heavy duty thread sealing compound. Lable says it is certified to ANSI std. 61.Question: Is there a type of dope that may have better sealing qualities than the one listed above that might do a better job considering the thread o lets had mildly rusted threads. And, are there any other ideas that might help solve this problem.Thanks in advance for any replys.Best Regards Marc

[Marc Q. OwenParticipant]

There are several premium compounds, usually specified for gas systems, that work better. A blue one called Gas-Tite, (if I remember correctly). Rectorseal is also excellent for the job. In your case, it may be that the threadolets distorted from the welding.: Background: I am project engineer on a job to replace : chilled water lines in an industrial building. We have : many 10 dia mains with many 4 dia branches to equip. : The 4 dia branches consist of thread o let welded to : 10 header, 4 nipple, then 4 threaded flange with : a 4 butterfly fastened to flange. We are currently : in process of pressure testing system.: Problem. Most of the 4 nipples leak between nipple : and thread o let. The nipples are tight. The 10 spool : pieces had set outside for some time before installed : and the threads on the thread o lets did have time to : rust. The pipe fitters believe they could make the : leaks stop if they had some type of pipe dope better : than what they have now. The pipe dope they are : currently using is LA-CO, Slic-Tite, paste with teflon, : heavy duty thread sealing compound. Lable says it : is certified to ANSI std. 61.: Question: Is there a type of dope that may have better : sealing qualities than the one listed above that might : do a better job considering the thread o lets had : mildly rusted threads. And, are there any other ideas : that might help solve this problem.: Thanks in advance for any replys.: Best Regards : Marc

[Marc Q. OwenParticipant]

Marc:—Try to locate a supplier that has Blue Megaloc…(Megalock). Not sure of the spelling, but it is the best that I have used in 50 years of plumbing.. I dont have the spec. data. but Im sure that the supplier can help with that. Lots of luck…Bud

[Marc Q. OwenParticipant]

I got your information and am taking it to our purchasing guy. Thanks again for taking the time.Best Regards Marc

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