{"id":47,"date":"2021-12-13T11:27:30","date_gmt":"2021-12-13T16:27:30","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/ductfittings\/?post_type=chapter&p=47"},"modified":"2022-08-15T14:21:54","modified_gmt":"2022-08-15T18:21:54","slug":"seams-sd-and-pittsburgh","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/ductfittings\/chapter\/seams-sd-and-pittsburgh\/","title":{"raw":"Seams- S and D and Pittsburgh","rendered":"Seams- S and D and Pittsburgh"},"content":{"raw":"
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  1. [embed]https:\/\/www.youtube.com\/watch?v=iKUiZefQd_U[\/embed]\r\n\r\nStudy the shop drawing. In this drawing, we have the addition of Pittsburgh seams and an S&D connection to account for\r\n\"\"<\/li>\r\n \t
  2. Using our shop drawing, we start by subtracting a \u00bd\u201d at each end where the air flows through. This is where our arrow comes in handy. Cross out the original dimensions and replace them with new ones, where required.<\/strong> \u00a0This will change different dimensions on different fittings, but if we follow the rule, it will always work. <\/span><\/strong><\/span>Show different fittings, with an arrow, having the \u00bd\u201d removed<\/span><\/li>\r\n<\/ol>\r\n
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    • Next, we want to think where any Pittsburgh seams will go.\u00a0We need to think about how the fitting will be assembled. We have to ask ourselves, where do the seams go? The cheeks will always have a flange and the heel, throat or wrapper will have a pocket.<\/strong> \u00a0The ends, where the air flows through, are the only spots with no seams required, this is where the S&D allowance will go\r\n\"\"<\/strong><\/strong> <\/li>\r\n<\/ul>\r\n
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      1. We can then do our blank size calculations. These are done in the same way, but we NEED <\/strong>to use any shortened dimensions, not the original ones<\/li>\r\n \t
      2. The last step is to add 1\u201d to each end where the air flows through. The blank size is not complete until the 1\u201d has been added\"\"<\/li>\r\n \t
      3. Draw the blanks. With S&D, we will need to draw all of them\r\n\"\"<\/li>\r\n \t
      4. Draw the arrow to indicate airflow<\/li>\r\n \t
      5. Draw a 1\u201d line at each end where the air flows through\r\n\"\"<\/li>\r\n \t
      6. Draw any seam allowances. Flange on the cheeks and a pocket on the heel, throat or wrapper\r\n\"\"<\/strong><\/strong> <\/li>\r\n \t
      7. We can now revert back to the same process as a welded fitting.\u00a0Keep in mind that EVERYTHING must be done within the 1\u201d S&D allowance. Any arcs, lines, transitions or radius points must be drawn inside the 1\u201d<\/strong><\/li>\r\n<\/ol>","rendered":"
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