Single flange face alignment tolerances 3

see ASME PCC-1, 2013 version

As far as I'm aware no ASME standard addresses the nozzle angular orientation tolerance identified in your sketch.

For vessels it's common to specify that nozzle tolerances must comply with PIP standard VEFV1102 or JIP33 standard IOGP S-619. For heat exchangers nozzle tolerances must comply with TEMA standards.


-Christine

Thank you for the direction.

See ASME B31.3
335 ASSEMBLY AND ERECTION
335.1 Alignment

(c) Flanged Joints. Unless otherwise specified in the
engineering design, flanged joints shall be aligned as
described in (1) or (2), and (3).
(1) Before bolting, mating gasket contact surfaces
shall be aligned to each other within 1 mm in 200 mm
(1/16 in./ft), measured across any diameter.
(2) The flanged joint shall be capable of being bolted
suchthatthe gasket contact surfacesbearuniformly onthe
gasket.
(3) Flange bolt holes shall be alignedwithin 3 mm (
1/8in.) maximum offset.

Regards

Christine has it right. The CoC (Code of Construction) has no such requirements as related to the attachment. PIP and JIP have some guidance, but theyre not a code requirement. As such, ASME doesnt spell it out that specifically.

Huub
- You never get what you expect, you only get what you inspect.

The sketch is a piping, so ASME B31.3 is the code.

Regards

The sketch shows a clear indication of the tolerance, it is mandatory and no Code applies.

Regards.

My involvement with this subject is agitators, and in my experience the nozzles are only as aligned as you require them to be. If they need to have a particular alignment (such as an agitator mounted on the top nozzle that needs to be concentric/square the bottom nozzle that holds the agitator foot bearing), you need to declare it and confirm it.

I don't think vessel manufacturers are trying to be sloppy, but welding together pipe and flanges is not highly precise work. With vessels being sourced all around the world for the most competitive prices, it doesn't seem to be getting better on average.

Hello,

in the field of piping, EN 13480 has normative dimensional tolerance requirements for a case similar to your illustration.

Please check chapter 5.6 Tolerances and ANNEX (Normative) B Dimensional tolerances for fabricated spools of EN 13480-4 Metallic industrial piping –
Part 4: Fabrication and installation.

In Chapter 5.6 there is a reference to EN ISO 13920 and other requirements.
AnneX B fig. B.1 - Dimensional details of spools presents some aspects from your facebook illustration.

best regards,

Cyril

If you have a flange nozzle connecting to something local like an instrument that does not have a second pipe connection, the only critical dimensions are the ones in the flange standard (or something else), and those relating to the function of the instrument.
If you have a flange that connects to pipe that runs some distance, or connects to other vessels, correct fitup may require making a final weld after bolting up the flange on a hard spacer the same thickness as your compressed gasket. If you replace the vessel, do not expect the flange faces to fit your pipe without some adjustments.

However if I ordered the spool to the OP drawing, just like r6155 indicates, The drawing states the tolerance on the flange is mandatory. I would expect the fabricator to meet the requirement, unless we withdraw the requirement in writing.

Hi FacEngrPE
The nozzle flange is manufactured, inspected, and hydrostatically tested with full equipment in the shop, so repairing the misalignment with the piping is not possible as you propose.

Regards