Reducing Fittings

But even the purchases decsription which go to vendor specify only one schedule. Pipeclass doesn't go to vendor but purchse descriprion goes and it specifies only one schedule. I think let me find out some logical reason from some senior guys and may be if i get convinced i will post it in the forum

Thanks

Ok, let's get a sample Piping Specification for our educational purposes. I did a Google search with key words "Piping Specification" and found this pdf.

www1.superpit.com.au/uploaded/su ... ign_28.pdf

Now, if you open it up, turn to page 4 of 19. Supposed you want to specify a 2" x 3" Ecc. reducer, then you have to tell the vendor that you want 2" x 3" Ecc. reducer, schedule XS x STD. Otherwise how would he know.

If you still need logical reason, then this one may be good for you www.sewerhistory.org/images/mi/m ... _Specs.pdf

Great entertainment.

3" x 2" reducer may be defined as SCH XS only as i dont see any problem for welding of SCh XS 2" end of the reducer with SCH STD pipe. Refer to ASME B16.25 and you can get the answer.

I said i need to talk to some senior guy who has got good experience. Let me find one and i will post the answer.

No need to scratch head and waste time doing NVAs.

Just to put my bit in!
I dont see how you can say the, quote "But even the purchases decsription which go to vendor specify only one schedule."

Even in PDS, a reducer is (generally) selected by using MATCh for the end Schedule/Thickness, this then selects the Schedule of the pipe or Component the Reducer is connected to. The description then picks up the Schedules as the example below:

Pipe Class (PCD) Entry for Pipe
PIPING 1 2 2 301 - S-160
PIPING 1 3 3 301 - S-XS

Pipe Class (PCD) Entry for redu
Reducer
Code NPD A Sch/Thk NPD B Sch/Thk ItemCode
6Q2C28 1 3 3 301 - MATCH 5 2 301 - MATCH 6F240LXC2CC2A

Purchasing Description
6F240LXC2CC2A 'ECC.REDUCER A234-WPB SMLS BE 3"x2" XS x SCH160'

I don't know of any manufacture that makes piping fittings with different schedules. It's more common to have the same schedule through out the fitting. However I have run across situation where we mated up different schedule piping systems, and normally what I've done is call out the heavier wall for the fitting, then specified a "back taper" on the thinner wall connection point. This is where they taper the I.D. of the fitting so it matches the thinner schedule. Trick here is the taper angle has to be 4 to 1 to get proper flow thru the fitting. AND to be honest the times I've done this, the client had the heavier schedule fittings in stock and was just trying to save money by using them. My $0.02 anyway ...Mark

It is normal to quote both schedules when ordering reducing fittings although they are usually only made to the thickest wall.
If you are lucky the supplier will counter bore the thinner wall end before delivery.
Since the description used on the order is usually the same as on the fabrication Isometric, This should prompt the fabricator to do the counter boring if the supplier has not.