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PIPE TO FLANGE ALIGNMENT ON FABRICATION

PIPE TO FLANGE ALIGNMENT ON FABRICATION

PIPE TO FLANGE ALIGNMENT ON FABRICATION

(OP)
Whilst we all appreciate that a flange should normally be welded at right angle to the pipe as it is designed to do, does anyone have any absolute maximum limits for angular angular misalignment. A limiting factor will of course be the pipe outside dimater/flange internal diameter clearance to physically allow such alignment.
Thanks

RE: PIPE TO FLANGE ALIGNMENT ON FABRICATION

The fabrication tolerances that are outlined in the Piping Fabrication Institute's, PFI Standand ES-3, Figure 1 is what I always see as the acceptance standard.

NozzleTwister
Houston, Texas

RE: PIPE TO FLANGE ALIGNMENT ON FABRICATION

NORSOK L-004 might be an easier document to get hold of (free download)

Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/

RE: PIPE TO FLANGE ALIGNMENT ON FABRICATION

WillShi, If you are working on an oil or gas transmission line, the regulations regarding “miter joints” will likely apply to alignment of welded flanges. See below.


CFR 49, PART 192 § 192.233   Miter joints.
 (a) A miter joint on steel pipe to be operated at a pressure that produces a hoop stress of 30 percent or more of SMYS may not deflect the pipe more than 3°.

(b) A miter joint on steel pipe to be operated at a pressure that produces a hoop stress of less than 30 percent, but more than 10 percent, of SMYS may not deflect the pipe more than 12 1/2° and must be a distance equal to one pipe diameter or more away from any other miter joint, as measured from the crotch of each joint.

(c) A miter joint on steel pipe to be operated at a pressure that produces a hoop stress of 10 percent or less of SMYS may not deflect the pipe more than 90°.


http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=3547893655ccdc055a348d49d0007f25&rgn=div5&view=text&node=49:3.1.1.1.3&idno=49#49:3.1.1.1.3.5.9.6

RE: PIPE TO FLANGE ALIGNMENT ON FABRICATION

ASME B31.3 and PCC-1 list fabrication tolerances

RE: PIPE TO FLANGE ALIGNMENT ON FABRICATION

vzeos

Some clients have specs that forbid "miter joints", we usually get around it by using this code reference and calling them "crooked cuts".

Greg Lamberson
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com

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