Yes, slip on flanges should be wholly welded on both sides, with no weep holes. The weld should be complete, no stitch.
Now, this apply to pressure vessels and piping. If there's another application that allows slip on flanges to be stitch welded and contain weep holes, I frankly don't know.
Giovanni S. Crisi
Sao Paulo - Brazil
Hello Giovanni, I had been told at one time that the weep holes were tattletales(a way to indicate leaks as they develop). Is this completely off base, or is this just something that someone has come up with on their own and outside of what code would indicate? Would appreciate your input. Best regards, Allan
ASME B31.3 2004 Appendix F - Precautionary Considerations
F308 FLANGES AND GASKETS
F308.2 Specific Flanges
Slip-On Flanges. The need for venting the space
between the welds in double-welded slip-on flanges
should be considered for fluid services (including vacuum)
that require leak testing of the inner fillet weld,
or when fluid handled can diffuse into the enclosed
space, resulting in possible failure.
This is not a code requirement however and I dont recall having seen this in the field.
All of the slip-on flanges I have seen/welded/dealt with have been double welded. The precautionary statement mentioned earlier is of some value. I would also direct you to B31.3, Section 308.2.1:
(a) A slip-on flange shall be double-welded as shown
in Fig. 328.5.2B when the service is
(1) subject to severe erosion, crevice corrosion, or
cyclic loading
(2) flammable, toxic, or damaging to human tissue
(3) under severe cyclic conditions
(4) at temperatures below −101°C (−150°F)
(b) The use of slip-on flanges should be avoided
where many large temperature cycles are expected, particularly
if the flanges are not insulated.
Hope this helps.
Thanks guys!!! That was exactly what I was looking for.
Thanks again!
Kix