While ago Jody did video about socket weld and talked a little bit of ASME B31. code.
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Well I ran into these welds at my work. Line is high purity line and that's why I'm wondering that are these welds clean enough for system
Funny thing here is that smaller diameter pipes/valves are welded with socket welds, but larger ones with full penetration using butt-welds. So what the heck!!
Is socket welds used on larger sizes at all? If not where goes the limit?
Here couple of photos. Pipe is 42.3x3.25 mm / 1 1/4 inch and what ever that thickness is
Markus,
I'm not sure what the upper limit is but I do have up to 4" ones throughout the plant. We have plenty of SS socket welds in our high pressure ultra high purity Hydrogen lines.
Braehill wrote:Markus,
I'm not sure what the upper limit is but I do have up to 4" ones throughout the plant. We have plenty of SS socket welds in our high pressure ultra high purity Hydrogen lines.
Is it then that in high purity water systems for example full penetration is needed, because the risk of corrossion and not just because the inpurities?
The decision of socket-weld versus full-penetration butt-welds has nothing to do with purity of the product stream. It's an engineering decision between the efficiency of the weld versus the efficiency of the joint. The socket weld is preferred where pressure is more important than flow (note the sharp angles of socket-weld fittings), and the butt-weld is preferred when flow is more imprtant than pressure (note the long sweeps of butt-weld 90's).
The engineers will tell you about Reynolds numbers, which are measures of the efficiency of flow, but the short answer is, "flow" demands long corners, and pressure doesn't care.
In a food grade situation the product stream would be affected by a socket weld fitting. The voids would trap particles that would be impossible to clean out.
Socket welds will all be removed. Reason being the fear of corrosion, as the fluid inside is quite aggressive. Stainless is preferred quite prone to crevice corrosion, so it's good thing to replace socket welds to butt welded ones I think.
I weld stainless, stainless and more stainless...Food Industry, sanitary process piping, vessels, whatever is needed, I like to make stuff.
ASME IX, AWS 17.1, D1.1
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