ASME B31G:2012 pdf free download

ASME B31G:2012 pdf free download.Manual for Determining the Remaining Strength of Corroded Pipelines.
(h) metal loss in pipe material having ductile fracture initiation chara ertks(see paras, 1.7(e) and (1)1 unless using a L.cvel 3 assessment in accordance with paras. 2.2(b) and 2.4
(i) metal loss in pipe operating at temperatures above ambient within the range of operating temperature recognized by the governing standard, and provided material strength properties at temperature are considered
(j) metal loss in pipe operating at any level of allowable design hoop stress (see paras. 1.4(a) and (b) for additional considerationsi
(k) metal loss in pipe where internal pressure is the primary loading (see para.s. 1.4(c) and (d) for additional considerational
1.3 Exclusions
This document does not apply to the following:
(a) crack-like defects or mechanical surface damage not completely removed to a smooth contour by grinding
(b) metal loss in indentations or buckles resulting in radial distortion of the pipe wall larger than 6% of the pipe outside diameter, unless a l.evel 3 assessment is performed in accordance with para. 2.4
(c) gnawing corrosion, selective corrosion, or preferential corrosion affecting pipe seams or girth welds
(d) metal loss in fittings other than bends or elbows metal loss affecting material having brittle fracture initiation characteristics (see paras. 1.7(e) and (f)( unless a Ivel 3 assessment is performed in accordance with para. 2.4
(f) pipe operating at temperatures outside the range of operating temperature recognized by the governing standard or operating at temperatures in thecruep range
1.4 AdditIonal Considerations
The user is cautioned that additional considerations may apply in certain situations, described below.
(a) Pipe operating at low hoop stress levels due to internal pressure (e.g.. less than 25% of SMYS) may be perforated by corrosion without inducing structural material failure. The methods and criteria provided herein do not address failure by perforation.
(b) Pipe affected by general corrosion of the pipe wall (i.e., corrosion-caused wall loss over the entire pipe surface) effectively operates at a greater hoop stress
The Effective Area Method evaluates, by iteration, all possible combinations of local metal loss, A, with respect to original material, A0. It requires for input a detailed longitudinal distribution or profile of metal loss. The detailed profile is established by obtaining several measurements oF metal loss or remaining wall thickness throughout the metal loss area. Such measurements may be arranged in a grid pattern, or may follow a “river
bottom” path through the deepest areas of metal loss. Increments of measurement need not he uniform, subject to limitations of application software. If using a grid pattern, the analysis must be repeated along each meridian to establish the governing solution. For a corroded
F profile defined by n measurements of depth of corrosion including the end points at nominally full wall thickness,
literations are required to examine all possible combinations of local metal loss with respect to surrounding remaining material. The local solution resulting in the lowest calculated failure stress shall govern.and external forces; boundary conditions and constraints; ovality, deformations, misalignments, and discontinuities; material stress—strain characteristics; and effects of the flaw on the overall distribution of loads and stresses. A failure criterion should be developed that considers the strain capacity or fracture resistance characteristics of the material. Similar issues should he considered in developing a suitable safety factor as were described for a Level 1 or Level 2 analysis.
3 TABLES OF ALLOWABLE LENGTH OF CORROSION
The Following are applicable to Tables 3-i through
3-I 2M:
(a) Metal loss having a maximum depth of 10% of the nominal pipe wall thickness or less is not limited as to allowable length.
(b) Metal loss having a maximum depth exceeding 80% of the nominal pipe wall thickness shall not be evaluated using the tables of allowable length.