Hello everybody ,
first does anybody know in which code am i going to find the tolerances about piping allignmen. Does the pipe has any tolerance about its allignment (vertical & horizondal) or i am oblided to follow my isometric. e.g if my vertical axis of pipe if 1 degree off i am oblige to cut my joints and fix it?
Pipes have an "out of roundness" tolerance of 1% of the nominal diameter.
A 24 inches pipe (610 millimeters), for example, will have an out of roundness tolerance of 6,1 millimeters, roughly 1/4 of an inch.
When you face one pipe end with the other one, the tolerances will show up and very seldom the two pipes will be aligned. You'll have to use strongbacks and wedges to align the ends before trying to weld them.
Giovanni S. Crisi
Sao Paulo - Brazil
Sorry Bud, but that's too broad of a question.
The applicable code is the one that is specified in the contract for the paticular job you're working on.
Whether or not you have to make repairs is dependant on the code you're working to and any Customer's and/or Employer's specs that have been added on.
Tim
that's my problem my friend. Nowhere is mentioned this. The contract does not make it clear.
The most logical is to be mentioned somewhere in asme but i can not find it...
Thks anyway
By 46.00 
Date 03-10-2013 17:21
Edited 03-10-2013 17:23
I think you are meaning something different to the replies you are receiving. As a rule, look at your issued drawings, they should have a detail referencing some standard for tolerance etc. This is what you are looking for.
You will not find °% out of square tolerance in ASME IX or B31.3 etc.
By 803056 
Date 03-10-2013 17:01
Edited 03-10-2013 17:48
Hello John;
We may have a communication problem with your question.
I see one of the responses relates to the roundness of the pipe. That may not be the information you are seeking.
Are you interested in finding out the permitted vertical and horizontal alignment along the axial centerline of two lengths of pipe? In other words, is your concern that the centerline of the pipe is not aligned so the edges of the butt joint are not in the same plane?
I checked a few ASME piping codes and I have paraphrased what they have to say on the subject of alignment and misalignment:
I checked two ASME piping codes, B31.9 Building Services and B31.8 Gas Transmission Lines, for the alignment requirements. The only requirement was that the welds joining the ends of the pipe must be tapered to accommodate the misalignment.
ASME B31.1 for Power Piping is more definitive on the subject. Chapter V, paragraph 127.3 Preparation for Welding, A.4(c) alignment states; the internal misalignment of the ends to be joined shall not exceed 1/16 inch unless the piping design specification states a different allowable misalignment.
ASME B31.3 for Process Piping for Normal Fluid Service, Chapter V, paragraph 328.4.3 Alignment (a) Circumferential Welds (1) states the tolerance must be per the contractor's WPS and the engineering design. (2) If the external surfaces of the components are not aligned, the weld shall be tapered between them.
My recommendation would be to request a copy of the contractor's welding documentation, i.e., their WPS and QC manual, to see how they intend to address the situation. If misalignment is not addressed, direct your concerns to the owner.
Best regards - Al
