ASME B31G:2009 pdf free download Manual for Determining the Remaining Strength of Corroded Pipelines
1INTRODUCTION
1.1 Scope
This document is intended solely for the purpose ofproviding guidance in the evaluation of metal loss inpressurized pipelines and piping systems. It is applica-ble to all pipelines and piping systems within the scope of the transportation pipeline codes that are part ofASME B31 Code for Pressure Piping, namely: ASME B31.4,Pipeline Transportation Systems for LiquidHydrocarbons and Other Liquids; ASME B31.8,GasTransmission and Distribution Piping Systems; ASMEB31.11,Slurry Transportation Piping Systems; andASME B31.12,Hydrogen Piping and Pipelines, Part PL.Where the term pipeline is used, it may also be read toapply to piping or pipe conforming to the acceptableapplications and within the technical limitations dis-cussed below.
1.2 Acceptable Applications
The application of this document is limited to theevaluation of wall loss in metal pipe within the followinglimitations:
(a) metal loss in pipelines located below ground,above ground, or offshore
(b) metal loss due to external or internal corrosion(c) metal loss produced by grinding where used tocompletely remove mechanical damage, cracks, arcburns, manufacturing defects, or other defects from thepipe surface
(d) metal loss in field bends,induction bends,andelbows
(e) metal loss that incidentally affects longitudinal orhelical electric seam welds or circumferential electricwelds of sound quality and having ductile characteris-
tics,provided workmanship flaws are net presert insufficiently close proximity to interact with the metalloss
(f) metal loss of any depth with respect to the pipewall, except that due consideration shall be given to theaccuracy of measurements and effective corrosion rateswhen the depth of metal loss exceeds 80% of the actualpipe wall dimension
(g) metal loss in new pipe where allowed by the appli-cable code of construction
(h) metal loss in pipe material having ductile fractureinitiation characteristics [see paras.1.7(e) and
(f) unlessusing a Level 3 assessment in accordance with paras.2.2(b) and 2.3
(i) metal loss in pipe operating at temperatures aboveambient within the range of operating temperature rec-ognized by the governing standard, and provided mate-rial strength properties at temperature are considered(j) metal loss in pipe operating at any level of allow-able design hoop stress [see paras. 1.4(a) and (b) foradditional considerations]
(k) metal loss in pipe where internal pressure is theprimary loading [see paras.1.4(c) and (d) for additionalconsiderations]
1.3 Exclusions
This document does not apply to the following:(a) crack-like defects or mechanical surface damagenot completely removed to a smooth contour bygrinding
b) metal loss in indentations or buckles resulting inradial distortion of the pipe wall larger than 6% of thepipe outside diameter, unless a Level 3 assessment isperformed in accordance with para. 2.3
(c) grooving corrosion, selective corrosion, or prefer-ential corrosion affecting pipe seams or girth welds(d) metal loss in fittings other than bends or elbows(e) metal loss affecting material having brittle fractureinitiation characteristics [see paras.1.7(e) and (f)] unlessa Level 3 assessment is performed in accordance withpara.2.4
(f) pipe operating at temperatures outside the rangeof operating temperature recognized by the governingstandard or operating at temperatures in the creep range1.4Additional Considerations
The user is cautioned that additional considerationsmay apply in certain situations, described below.
a) Pipe operating at low hoop stress levels due tointernal pressure (e.g., less than 25% of SMYS) may beperforated by corrosion without inducing structuralmaterial failure.The methods and criteria providedherein 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 sur-face) effectively operates at a greater hoop stress than