"do's and don'ts" for connecting pipe fittings on process piping 1

[Mous1747]

Are there any code requirements or rule of thumbs on what i can and cant do when connecting pipe fittings back to back ?
for example is it acceptable to connect a socket-weld flange directly to an elbow ? or connecting a weld neck flange directly to a reducer ?

 

[Jay_]

I don’t think there is any code requirement regarding your question.
However, for fabrication purposes especially for welding, i do not advise to weld directly any type of flange directly to a reducer.
And if the elbow is of a small size, you can’t really weld the flange from the elbow side.
Having a straight pipe before any fitting is always beneficial in case where supports are needed.
Plus in the real world application, you must accommodate your dimensions tolerance with a straight pipe.
So it really depends on your service, application and the method of fabrication.

Detailing is a hobby,

 

[mk3223]

The joint type of the pipe connecting to a fitting should be complied with one of the typical joint as specific in the Code.

IMO, "No" for a SW flange to a SW albow. and "Yes" for a WN flange to the BW fitting.

 

My rule of thumb is that the final assembly should not look like an art installation.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[LittleInch]

Butt weld fitting to fitting is allowed.

SW on the other hand requires a piece of pipe and an external weld so you can't go fitting to fitting. You need at least 1D to get those welds in.

You always need some green length for site fix in x,y abd Z unless the end point isn't a fixed point.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[r6155]

See ASME B31.1 Table D-1 Flexibility and Stress Intensification Factors (Cont’d)
Note (12) For welds to socket welded fittings, the stress intensification factor is based on the assumption that the pipe and fitting are matched in accordance with ASME B16.11 and a full weld is made between the pipe and fitting as shown in Figure 127.4.4-3. For welds to socket welding flanges, the stress intensification factor is based on the weld geometry shown in Figure 127.4.4-2 and has been shown to envelop the results of the pipe to socket welded fitting tests. Blending the toe of the fillet weld, with no undercut, smoothly into the pipe wall, as shown in the concave fillet welds in Figure 127.4.4-1, illustrations (b) and (d), has been shown to improve the fatigue performance of the weld.

Regards