UG-36 & eccentric reducer requirements

[timsch]

I have a design that must be PED approved which contains a 5x3"NPS eccentric reducer fabricated from wrought Inconel 625 (spec B366). The manufacturers drawing for this reducer, while not fully detailed, has enough detail to indicate that the largest half-apex angle is nominally greater than 30deg. The PED inspector is pushing back on our standard calculations for this component based on this angle being greater than 30deg.

In looking at UG-36 where I see this angle addressed, it looks to pertain to shell components made from plate. Do these requirements apply to fittings made from wrought alloys? If not, what section (if any) would this component fall under?

 

[SnTMan]

timsch, in UG-36 I see no mention of product form, i.e. "plate". Is your reducer made to a recognized standard, such as B16.9? If so, see UG-44.

I have no idea how this all might relate to PED.

Regards,

Mike



The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[timsch]

Thanks for the reply Mike.

No standard for manufacturing was specified when these parts were ordered. The dimensions provided by the manufacturer exactly coincide with those required by B16.9 for length and OD's at each end. However, this part appears to have been wrought to achieve the outer dimensions while the inner dimensions were achieved by machining. I don't know if this machining is allowed in B16.9 or if both OD and ID must be achieved by working rather than machining the material.

It may be a moot point anyway since B16.9 is limited to wrought carbon and alloy steel, whereas this material is Inconel 625

 

[Afox88]

Looking at B16.9-2012 (correct me if this changed in a newer version, if their is one), Section 5 says the following.

"Wrought fittings covered by this standard shall be in accordance with ASTM A234, A403, A420, A815, B361, B363, B366, or the corresponding standard listed in Section II of the ASME Boiler and Pressure Vessel Code."

As fittings that are Inconel 625 are SB-366, they should fall well within the scope of B16.9 and should not be required to meet any specific apex angle.

 

[Afox88]

To your other point, I don't have any justification I can find at this time, but I do not think their is any issue with machining a fitting down to the final size you need. It is simply part of the manufacturing process, as long as the dimensions are correct at the end. I cannot find B16.9 anywhere in B16.9 that agrees or disagrees with my thoughts.

 

[timsch]

A-88, thanks for the additional information. I have an older version of B16.9, and if as you say Section 5 has been expanded since its release, that is very good to know.

I'd agree with you regarding final machining, but when Wrought is used in the name of the spec itself, it does give me pause....