Good afternoon,
Thks for your reply.
ASTM has indeed adopted this standard. Attached is a copy of one of its pages for your reference and on which my query is based.
The design code is 31.1 .It is for a power plant .
Now, my query as before is;-
The client has prepared the PMS . My company has not for the project. In the subject PMS which is for water system (pressure 5 kg/cm2 50 degree temp), the client has stated that for pipes upto DN50, all weld joints are to be socket welded. However in the branch table, the client is considering a butt welded tee for a run pipe of DN80, or DN 100 and a branch pipe of DN40, DN50. For the same branch diameters, but the run pipes above DN 150 and so on, the client is considering sockolet which is right.
On questioning the client about the contradiction between the branch table and the statement of socket welded joints, it indicated that it was a matter of cost. (This I consider doubtful as for other run pipes, anyway he is considering sockolets. ).Assuming still, that indeed it was a cost issue, the client should have added a footnote accordingly ion the PMS. He has not done it and does not intend to.
The second part of the query is as below;-
When I referred the above mentioned ASTM std, I found out that ASTM was recommending socket welded or threaded fittings for run and pipes upto DN50. However here, it was also recommending butt welded tee or lateral for run pipes of 2 ½", 3" 4" and branch of DN 2" OR 1 1/2''.
Considering that this would create a confusion, I contacted ASTM committee. Unfortunately, apart from saying that butt welded joints are also suitable(certainly in their own right)if they comply with the code requirements, they could not throw light as to why in such a manner it has been included without offering proper explanation. If one has to accept their logic, then even for branch pipes of 1"also, and runs of 2 ½" or 3", they could have included a butt welded tee but they have not done.
Hence your opinion is required about the correctness of my client's actions.
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Raghuram Bathula
Sent: 03 July 2018 11:13
To: Materials-Welding
Subject: [MW:28026] ASTM F681 - Standard Practice for Use of Branch Connections
What is your construction code and application?, i don't think ASME adopted this standard.
If PMS is developed and approved for the project you should stick to it, unless you have valid reasons need to document and get it approved.
On Tue, 3 Jul 2018 at 09:16, Hemant W Joshi <hwjoshi@tce.co.in> wrote:
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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