Weld Neck vs Slip-on Flange Application
Weld Neck vs Slip-on Flange Application
(OP)
What is the reasoning behind using 150# and 300# weld necks vs. slip-ons for welded piping systems? My feelings have been that weld necks are the better choice for fittings which allows bolting clearances; and slip-ons for straight run pipe. Is there a common practice which states that or a code reference?





RE: Weld Neck vs Slip-on Flange Application
I guess our reasoning is more on the reliability of a weld neck vs a slip-on than anything else. It also helps that weld necks are done in a shop and slip ons in the field, there is a cost factor difference there as well.
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RE: Weld Neck vs Slip-on Flange Application
The Weld-neck flange is attached to pipe or fittings with a Butt-weld. The Butt-weld can be X-rayed to insure the weld quality.
The slip-on flange is attached to pipe or fittings with two fillet welds (one on the out side and one on the inside). These welds do not allow for proper X-ray weld quality verification.
RE: Weld Neck vs Slip-on Flange Application
RE: Weld Neck vs Slip-on Flange Application
Back in the "old days" when pipers would exchange "borrowed" design details on paper I remember seeing one that depicted welding slip-ons to buttweld elbows.
Like attaching coconuts to swallows, it MIGHT work, but it's just plain wrong.
RE: Weld Neck vs Slip-on Flange Application