[MW:28023] ASTM std

Can anybody provide their views on the following :-

 

I have a piping related query  as indicated below and would be grateful if you can provide your views.

 

It may be known that ASTM F 681 is a std related to branch connections for Carbon steel and other piping .

 

Now, generally socket welded joints are widely recommended and used  for non-hazardous services , utility services for pipe sizes upto DN 50 or 2 inches . Accordingly the std recommends pipe fittings suitable for it such as welded outlet (socket or threaded)  as is shown in the attachment .

 

Butt welded fittings also are suitable for such sizes in their own right.

 

Now the query is , in case you are already indicating in the Piping Material Specification of say for water service (design temp 50 degrees , pressure 5 kg/cm2)that for sizes upto DN50, all joints should be socket, how much correct would it be , if you include a butt welded tee as a branch fitting of size say a DN80 (2.5 inches) run size X DN 40 (1.5 inches ) branch size in your branch table or for that matter a butt welded tee for DN 80 X DN 25 . ? My client has prepared such a table and he is not providing any technical answer. At least if some body wants to use the butt weld for any reason, the PMS needs to mention it.

 

Ideally one should go in a for a sockolet or a half coupling .

 

Cost of o-lets such as sockolets should not be an issue to determine the selection of butt welded tee, when as it is you are including them in your branch table for higher run sizes.

 

The ASTM people could not provide a definite answer to my query except that both butt and socket are acceptable.

 

I feel the ASTM should add a note that both types cannot be considered acceptable if the Piping Specification specifies one type only.

 

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