Eccentric Reducers!

Hi Guys

I am not a piping designer but a Pipefitter. I have a couple of questions which I am sure are pretty elementary to the guys on this forum.

Firstly, I would like to know Is it possible or practical to use eccentric reducers with the flat side on top? If so, in what type of application would this be practical?

and secondly I would like to know, what the difference is between a normal butt weld reducer (eccentric or concentric) and a swage reducer of the same diameters?

thanks in advance

Regards

Hi pipeman1984,
Yes, it is common practice to orient eccentric reducers both flat side up and flat side down. A common example of using an eccentric reducer in a flat side up arrangement is in pump suction piping immediately before the pump nozzle in order to avoid creating a vapor trap in the line.

The difference between swages and reducers is that swages have a straight portion on the ends (male ends) for insertion into the female end connection of a socket-weld or threaded fitting. This straight portion is a plain end when inserted into a socket-weld fittting and threaded when inserted (known as thread engagement) into a threaded fitting. The choice of reducer or swage is dependent on the end connections of the fittings as called out in the piping classes. Butt-weld to butt-weld would be a reducer, but when any combination of socket-weld and/or threaded is involved then a swage is required for the insertion capability. For instance, if your piping class calls for all fittings NPS 2 and above to be butt-welded, then you'd be using a 3 x 2 reducer beveled both ends (BBE) to reduce pipe sizes. If on the other hand the piping class calls for NPS 3 and above fittings to be butt-welded and NPS 2 and below fittings to be socket-welded, then you'd be using a 3 x 2 swage beveled large end (BLE) by plain small end (PSE). And, for this same piping class, if you needed to reduce from NPS 2 to NPS 1 then you'd use a 2 x 1 swage plain both ends (PBE).

Regards,
Flowr8

Welcome to the forum Mr. pipeman1984! …It's always good to hear from other tradesmen (especially construction) that deal with piping so everybody gets to "see" other issues and questions that pop up (kind of a cause and effect type of thing). I'd like to add $0.02 more cents to the good info my colleagues have passed on to you. You’ve noticed swages are longer, one reason as stated by Mr. Flowr8, however there is another reason. When changing sizes in small bore piping (2" & below) making a abrupt change, as with reducers or other type fittings (red. bushing i.e.), can cause a disruption in the flow so you don't get the “laminar flow” the process people like to see. With the transition stretched out the chance of flow disruption is less of an issue and there is a better chance of maintaining the good flow characteristic.
On the question of eccentric reducer positioning, I have used them with the flat on the side! This was on a project where we retro fitting new to existing piping systems, and I was trying to avoid new construction. SO there use and position is only limited by the need. …Good Luck!

Thank you all very much for the replies. Very Useful.

Also thank you jop for the link.

I talked with my foreman the other day at work regarding this question and his reply was "you know, I am not really too sure". Another response when talking to a lot of the more experienced Pipefitters regarding the orientation of fittings and system components is "because the drawing says so".

I feel that it is it better to understand why you are doing something instead of just doing it because the drawing says so.

I do have one more question. Last week I was installing some 1" socket weld piping and the drawing called for the gate valves to have a 3mm hole (thats 1/8" to the guys in the states) bored through the gate. What is the reasoning for this.

Thanks in advance.