Hello all

I have recently been asked to update a standard drawing design which includes a 1" nozzle projecting from a larger diameter elbow. But the problem in terms of structural strength, welding practicality etc is whether to make it a 'set on' or 'set in' nozzle. Has anybody else out there looked into the pros and cons of each possibility? Any advice, links, references etc would be really appreciated.

Cheers.

Check Out Our Whitepaper Library. Click Here.prex (Structural) 15 Sep 03

10:22

If inside of wall is accessible a set in nozzle is highly preferred, as a full penetration of good quality is easier to obtain. Also, if a full penetration is not a must, the set in nozzle may be welded with two fillet welds.However, when vessel wall thickness becomes large (over 3/4"?) and is much larger than that of the nozzle, a sit on nozzle may become more practicable. Weld thickness becomes smaller and this occasionally may allow to avoid a PWHT.

prex

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donf (Chemical) 15 Sep 03 13:37

ASME B31.3 Figure 328.5.4D shows both - either method is acceptable (be sure to verify if add'l reinforcing is required.)

My preference is the "set on" (a.k.a. saddle on) method - because it's self-supporting during fit-up. You don't have to worry about the nozzle or branch dropping through the hole before the welder gets a tack in place.

Also, the "o-let" family of branch connection fittings are intended to be "set on" the pipe.

Regards,