vent and drain connections 1

[pipe15]

If I want to use a threaded cap on the outlet of each vent/drain valve pipe nipple then I guess I have to account for the threading allowance. Using 1" pipe, it seems that I will have to use Sch 160 even in low pressure applications in order to meet the required minimum wall considering the thd allowance of 0.07".

Could I consider using a vent/drain valve that is socket welded on the inlet and threaded on the outlet? I would then just use a threaded plug in the outlet and forget about the pipe nipple at the valve outlet. This would simplify my pipe spec and allow me to specify either sch 40 or 80 small bore pipe as long as I do not thread it.

How does this sound?
thanks
Mark

 

[pennpiper]

Your suggested solution is the right thing to do based on the information you have given us. It will also work fine for the drains and for PI connections.

I have seen it done on many projects in various materials.

Go for it!

 

[katmar]

Welding a threaded socket onto the pipe is a far more practical way of doing it. In fact, I cannot ever recall seeing a threaded hole directly into a pipe. But then, I have very seldom needed to use Sch160 pipe.

You do not say what size your drain valve is. The way I read it, the 1" pipe is the one you want to tap into. With pipes this small it would be better to install an equal tee and then weld your threaded socket to the branch of the tee, unless you are using 1/2" drain valves.

Harvey

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[pennpiper]

Katmar,
I will try to be diplomatic with this. Your answer indicates to me that you do not have the training, experience or the basic knowledge of piping. I suggest that you find someone who does know piping and have them explain the details involved with the original question.

 

[katmar]

PenPiper, I am sure you are right. The problem seemed so crazy to me, that it is most likely that I did not understand the question. In future I will stick to the hydraulics questions and leave the mechanical questions for you mechanical boffins. I presume it is the cap that pipe15 wanted to thread and not the actual pipe? It's not the first time I've got the bull by the udders. Thanks for the correction.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[pipe15]

I think I will restate my issue. For all sizes of process pipe, the large bore pipe is butt welded, and most of the small bore pipe is socket welded. all process pipes will need vents and drains. These will all be 1" in size. I will come off of the process pipe with either a sol or nipolet/pipe/valve arrangement. out of the valve could be another pipe nipple (socket welded at the valve and threaded at the other end), followed by a threaded cap. however, even if the design conditions of the process pipe only warrants the 1" pipe to be sch 40 or 80, it has to be sch 160 in order to account for the threading allowance (0.07" in this case). this requires me to specify both sizes in the pipe spec, with notes for applicability as to where to use the optional wall thickness. on the other hand, if I get the valve with a socket on the inlet and a FNPT on the outlet I could use a threaded plug and eliminate the threaded pipe nipple/cap issue altogether.
so, is this option viable? What kind of premium do I pay for a given valve with these different end preps over one that has a socket on both ends?
Of course, all this is based on the assumption that the outlet of a single valve arrangement for a vent or drain must meet the design conditions of the process pipe when calculating the required minimum thickness. I do not imagine that this pipe is 'exempt' from the code requirements.

thanks to all
mark

 

[katmar]

Mark, your revised problem statement is so clear that even a chemical engineer could understand it! I see now why my previous response caused PP to get his knickers in a knot and I will leave it to him to give you the right advice. My apologies for muddying the waters.

Harvey

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[STYMIEDPIPER]

YOU ARE CORRECT REGARDING CODE TO THE FIRST VALVE. DEPENDING ON YOUR DESIGN CONDITIONS AND THE PROCESS MEDIUM THRU THE PIPE (ie BOILER WATER , HIGH PRESSURE STEAM, ETC) YOU MAY BE REQUIRED TO USE WOL AND WELDED END VALVE.

IF NOT, I HAVE USED THE SW x THR'D END VALVES WITH GREAT SUCCESS

 

[jte]

mark-

I'd say the simple approach for you is to use a 1" SOL with a 1" socket x thread extended body valve with a threaded plug. No pipe nipples to deal with at all.

jt

 

[zuccus]

Pipe15,

You can buy valves that have a sw male connection by a threaded female end as stymiedpipe said. You can put the sw male end directly into your sol. Then install a plug into the female end.

They are often used for pressure instrument connections.
I will warn you now though that they are not cheap.

One thing that I have seen done in the past but be warned your specification may not allow this (this was in low pressure water service). You can only do this with 3-pieve valves. Buy half the valves you need sw x sw, and buy half the valves you need threaded x threaded.

Since you are supposed to take the valve apart when making the sw connection inorder to not ruin the valve, you can now combine the two and get a much cheaper sw x threaded valve. Not sure if this is kosher or not, but like I said I saw it done.

Zuccus