Table Of Contents

Title:

Piping and Valves

Doc. No.

L-001

Annex

C

EDS

NOL1

Project: NORSOK

Company:

Rev.Date:

 20.09.99

Rev:

1

 

O'LET SPECIFICATION

 

  1. The O'let design listed (WOL) may vary from different vendors.
    The design shall be documented to be accepted for use, at least according to ASME B31.3.
    The design shall include stress intensity factors.
    The cover filet weld area, tc, shall not be included in the WOL design calculations.
    The WOL design shall be based on a maximum design pressure derived from the header nominal wall thickness (Th). Note that area replacement according to ASME B31.3, section 304.3.3 may not be feasable for thin walled pipe. Alternative methodes should be considered.
    The WOL shall if possible be standardised on ranges of headers within the following limitations for the Weldolet thickness, i.e. size of main weld "w":
    - Th < 10 mm: w <= 1.5 x Th
    - Th >= 10 mm: w <= 2.0 x Th
    where: w = weld thickness (excluding the Cover Field Weld)
    Th= nominal header wall thickness. The design (including vendors dimensional standards) of the O-lets requires acceptance from Company on this basis.
  2. O'lets with integral flanges (weldoflange, nipoflange) shall:
    - Meet the requirements as outlined in note 4 above.
    - Dimensions of flange shall comply with requirements of ASME B 16.5.
    - The O'let shall be designed so as to provide bolt holes to straddle symmetrically the plane through the centerline of the O'let and the pipe header line when welded to the header

    Nipoflanges shall be designed to provide an overall length from flange facing to the outer wall of the header pipe as follows:
    - Rating CL 150 - CL 1500, DN 15 - DN 50: 150 mm plus root gap.
    - Rating CL 2500, DN 15 - DN 40: 150 mm plus root gap.
    - Rating CL 2500, DN 50: 165 mm plus root gap.