Butt welded or Socket welded

[StoneCold]

Greetings all
I have kind of a delema that I am wondering what other users do.
I am installing a solvent transfer line in a chemical plant. The line is small, 1" sch 40 A106 pipe. Welding is GTAW. I originally spec'd the line out as butt welded. I did not want any solvent hold up in the cracks in case the plant ended up switching the line to another solvent down the road. Cross contamination can be a big quality issue. However I am wondering if I should have just specified socket welded and if they want to change solvents later then we can worry about flushing the line, later. I think the socket welded piping would have saved me about 25% on the job. I have several more of these coming up. What would you reccomend? We are industrial chemicals, not pharma or CGMP.

Regards
Stonecold

 

[racookpe1978]

Talk to your boss: Give him the cost difference, ask permission to either make up a test "flush line" so you can tell what needs to be done for the next line, or develop the plant's spec's for that application to avoid future "lessons learned" costs.

That way, you get credit for (1) asking and (2) trying to improve the next line.

 

[europipe]

Stone, is that saving because You used sw valves?
I know some sites that don´t want that because of expensive interchanging of defect valves.
Greetings

 

[moltenmetal]

Since cross-contamination is a problem for your process, and butt-welding doesn't ELIMINATE crevices and incompletely-drained pockets and other dead zones (i.e. the cavities of ball valves etc.), you will still very likely need to do the flushing.

So the question is: will reducing the amount of flushing solvent or the duration of the flush or the number of times the line is flushed, be worth this 25% extra cost? Doubt it, but that depends on a lot of stuff I don't know, like the expected service life, cost of solvent and recycling/disposal etc.

How about this: if it's just solvent, rather than solvent with product in it, and the solvent is volatile, why not pull a vacuum on the line and evaporate the solvent out of all those nooks and crannies instead? Works just as well with SW as with BW, but might take longer.