API 650, Roof Nozzle API 650, Roof Nozzle MOHAMMED89 (Mechanical) (OP) 5 Apr 15 10:36 Dear All, What is the minimum & maximum thickness of the roof nozzle neck as per API 650? RE: API 650, Roof Nozzle IFRs (Petroleum) 5 Apr 15 11:23 Per API 650 figure 5.19, roof nozzle necks should be "standard weight line pipe". Follow the specs for the pipe used. Annex F tanks have different requirements, see F.7.2.3. RE: API 650, Roof Nozzle MOHAMMED89 (Mechanical) (OP) 5 Apr 15 12:53 Thank You IFRs, So "...roof nozzle necks should be "standard weight line pipe"." So it is not mandatory its recommendation only. isn't it. So is it possible to use with Schedule 80? RE: API 650, Roof Nozzle IFRs (Petroleum) 5 Apr 15 13:20 My apologies. API 650 does not say "should be", those were my words. API 650 figure 5.19 includes an arrow pointing to the nozzle neck with the works "standard-weight line pipe" on the other end of the arrow. There is no corresponding text in the body of the standard. That said, in my opinion, using thicker pipe would not be a violation of the standard. To quote the Foreward of the standard: "The design rules given in this Standard are minimum requirements. More stringent design rules specified by the Purchaser or furnished by the Manufacturer are acceptable when mutually agreed upon by the Purchaser and the Manufacturer. This Standard is not to be interpreted as approving, recommending, or endorsing any specific design or as limiting the method of design or construction"