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General Plumbing and Gasfitting Talk => Plumbing => Ask Plumbers (Trade) => Topic started by: bowtieboy on October 17, 2012, 08:36:48 PM

Title: gate valve postion
Post by: bowtieboy on October 17, 2012, 08:36:48 PM: hi all, have a job coming up where i have to replace some 50 and 65 mm flanged gate valves on a commercial installation hot water flow and return circut, that's around 40 years old, these valves have failed to shut off and i am wondering if is because they had debri in the bottoms of the gates,i wont know till i pull them all out, but thats my guess, and if its the case, what do you think about mounting the new valves wheel down.....the pipe work is all horizontal. any one got a thought on this? ::)
regards
Title: Re: gate valve postion
Post by: robbo on October 17, 2012, 09:17:57 PM: hi guys/bowtieboy, what about using `Ballvalves`or installing some sort of filter before the valve. there should not be much debris or corrosion in heating pipes as the water is heated it loses it`s corrosive ability it normally produces a sludge type material, good luck, cheers
Title: Re: gate valve postion
Post by: bowtieboy on October 17, 2012, 09:30:24 PM: hi Robbo, these are domestic hot water flow and return lines,and i would be concerned that using ball valves will cause issues if they are operated fast,possibly causing water hammer (this is a system that involves around 500 meters of pipe work) 50 mm and 65mm.
that's why i have opted to fit gate valves again,there is nothing new in this system with but welded copper pipe work too! ::)
Title: Re: gate valve postion
Post by: integrated on October 17, 2012, 09:49:30 PM: Hey bowtie - I had some not so long ago in a rest home flow/ret - mine didnt shut off at all not even partially due to erosion - similar age

gate valve should be ok to go back in - make sure DZR

i think it will be something similar - IF however it is just crap under gate then i dont see why you could not try as you suggest as a quick/cheap fix

however if debri is getting to the flow/ret hot water supply where is it coming from? where else is it getting to and what other damage is it doing to other valving/tapware/pumping etc?

maybe prudent to install strainer to water supply somewhere accessible on water main into property?

butt welded copper is awesome - fusion or soldered?
Title: Re: gate valve postion
Post by: o2b007 on October 18, 2012, 12:42:21 PM: I would use stainless steel 50mm ball valves and butterfly valves for the 65mm you will always have issues with gatevalves on a hot water system as the constant heat seems to weaken the brass over time have replaced so many gate valves on commercial systems because of the spindle breaking or pitting in the brass
Title: Re: gate valve postion
Post by: 07442 on October 18, 2012, 07:53:00 PM: Whatever goes back in, it wont last as long as the first valves installed there. Flanged ballvalves or butterfly valves is what I would put back in, but with advise for the owners to use (or exercise) the valves every 3 or 6 months - as we all know, they will last longer in that situation if used regularly.
Just my $2.00 + $50.00 consultancy fee + gst. (got huge licensing fees coming up)
Title: Re: gate valve postion
Post by: bowtieboy on October 18, 2012, 08:32:51 PM: haha, thanks guys, box of beer on the way, ;).