Peter Tuft AS Launch, February AS PIPE WALL THICKNESS

Peter Tuft - Wall Thickness AS Launch, February Definition: Nominal WT, t N The “actual” thickness As nominated on purchase order (design) As per mill certificates (operation) Not less than: Required WT plus allowances & tolerances WT for constructability (including rounding to standard sizes) WT for hydrotest From Clause 5.4.1

Peter Tuft - Wall Thickness AS Launch, February Definition: Required WT, t W Minimum WT required for pipe in service Greatest of WT necessary for: Penetration resistance Minimum critical defect length Stress & strain (including vehicle loads) Fracture control Special construction Maintainability (eg. hot tapping) SCC mitigation Fatigue life External pressure Internal pressure From Clause 5.4.2

Peter Tuft - Wall Thickness AS Launch, February Barlow’s rule, unchanged: Design factor F D ≤ 0.8 Lower values of F D at some locations: Road & rail crossings0.72 Pipeline assemblies0.67 Bridges etc0.67 Telescoped lines0.60 From Clause & Table WT for Internal Pressure, t P

Peter Tuft - Wall Thickness AS Launch, February Design Factor Design factor applies ONLY to WT for internal pressure Meaningless to talk about design factor in any other context

Peter Tuft - Wall Thickness AS Launch, February Allowances, G Allowances make provision for loss of thickness Corrosion or erosion Threading, grooving or machining Not commonly required, except corrosion allowance for lines carrying raw well fluids From Clause 5.4.6

Peter Tuft - Wall Thickness AS Launch, February Manufacturing Tolerance, H Does NOT need to be added to Required WT for pipe made from strip or plate (almost all linepipe) Manufacturing tolerances for strip or plate are very small May need to be added for seamless pipe Hole may not be concentric (up to 12.5% WT) Still need to specify tolerance in pipe order Covered by API 5L for almost all cases Special limits on manufacturing tolerance for design factors greater than 0.72 (Clause (a)(v)) From Clause 5.4.7

Peter Tuft - Wall Thickness AS Launch, February Putting them all together Figure 5.4

Peter Tuft - Wall Thickness AS Launch, February Don’t … Calculate WT based on design factor only Order pipe based on design pressure and worry about the rest later Add manufacturing tolerance (unless pipe is seamless) Be over-precise about penetration resistance, critical defect size, etc Calculations for decision support, not hard deterministic outcomes

Peter Tuft - Wall Thickness AS Launch, February The Design Problem Roma - Brisbane duplication DN 400, 450 km Land use ranging from rural to suburban 15.3 & 10.2 MPa Assume X80 pipe Select wall thickness for: Remote rural areas Pipeline parallel to rural roads & highways Road crossings Suburban areas Stations

Peter Tuft - Wall Thickness AS Launch, February Elements of Nominal WT Internal pressure Penetration resistance Minimum critical defect length Stress & strain (including vehicle loads) Fracture control Special construction Maintainability (eg. hot tapping) SCC mitigation Fatigue life External pressure Allowances Manufacturing tolerance Constructability Hydrotest

Peter Tuft - Wall Thickness AS Launch, February Internal pressure Location Design Factor WT, 15.3 MPa WT, 10.2 MPa General (R1 to T2) Road & rail crossings Pipeline assemblies (MLVs etc)

Peter Tuft - Wall Thickness AS Launch, February Penetration Resistance - Rural Identified threat 20 t excavator with general purpose teeth Min t P = 7.1 mm Previously showed even 4.8 mm WT is OK for the identified threat No need to increase WT above t P

Peter Tuft - Wall Thickness AS Launch, February Penetration Resistance - Urban Identified threat 30 t excavator with tiger teeth Min t P = 4.7 mm Backhoe with tiger teeth could penetrate To resist penetration: Require 8.4 mm for reasonable assurance Require 11.0 mm for complete assurance

Peter Tuft - Wall Thickness AS Launch, February No Rupture (Critical Defect Length) Require “No Rupture” in high consequence areas (urban etc) (Clause 4.7.2) Hoop stress ≤ 30% SMYS, or Critical defect length (CDL) ≥ 150% max hole Hole size from identified threat Data in Table M3 95 mm hole size for both points of a tiger tooth on 30 t excavator Required CDL ≥ 150% of maximum hole Must select WT so that CDL ≥ 145 mm

Peter Tuft - Wall Thickness AS Launch, February WT for No Rupture MPa CDL varies with WT, steel grade and MAOP Calculate from Clause CDL for 10.2 MPa urban line: 4.7 mm WTCDL = 55 mm 8.4 mm WTCDL = 150 mm 11.0 mm WTCDL = 210 mm 8.4 mm WT adequate for “No Rupture” CDL ≥ 145 mm as required

Peter Tuft - Wall Thickness AS Launch, February WT for No Rupture MPa CDL for 15.3 MPa rural line: 7.1 mm WTCDL = 65 mm 8.4 mm WTCDL = 95 mm 11.0 mm WTCDL = 145 mm Require 11.0 mm WT for “No Rupture” CDL ≥ 145 mm as required Only needed if line upstream of city gate passes through T1 or sensitive locations

Peter Tuft - Wall Thickness AS Launch, February Stress & Strain Combined stress due to thermal & pressure effects at bends, stations, etc Not relevant to this design problem Covered later in the seminar External loads at road and rail crossings Use API RP 1102 to calculate stresses due to vehicle loads

Peter Tuft - Wall Thickness AS Launch, February Road & Rail Crossings Maximum design factor for API 1102 Includes internal pressure plus vehicle stress 0.72 at designated crossings 0.9 elsewhere (eg. farm vehicles in paddocks) More information on load sources and calculations in Appendix V For the sample design problem: Pipe with t P based on 0.72 design factor adequate

Peter Tuft - Wall Thickness AS Launch, February Fracture Control WT affects fracture initiation Critical defect length Penetration resistance Also affects toughness required for fracture arrest Details covered later in this seminar For the sample design problem: Assume no special requirements But check after fracture control presentation

Peter Tuft - Wall Thickness AS Launch, February Special Construction Covers almost anything where there may be special requirements, such as Above ground or reduced cover Road, rail & water crossings HDDs Tunnels Bridges etc For the sample design problem: No special requirements

Peter Tuft - Wall Thickness AS Launch, February Maintainability Usual example is provision for future hot tapping For the sample design problem: No special requirements

Peter Tuft - Wall Thickness AS Launch, February Stress Corrosion Cracking SCC influenced by hoop stress Increased WT reduces hoop stress, may reduce susceptibility to SCC Hence heavy wall pipe sometimes specified downstream of compressor stations where elevated temperature also promotes SCC For the sample design problem: No special requirements

Peter Tuft - Wall Thickness AS Launch, February Fatigue Fatigue influenced by stress range Discussed in Appendix N Increased WT reduces hoop stress, hence also reduces absolute range of stress due to pressure cycling Fatigue life is long for most ordinary pipelines (>> 100 years) For the sample design problem: No special requirements

Peter Tuft - Wall Thickness AS Launch, February External Pressure May be an issue for certain deep water crossings or deep HDDs Formulae provided in Clause For the sample design problem: No special requirements

Peter Tuft - Wall Thickness AS Launch, February Allowances Clean dry sales gas No internal corrosion No erosion Good quality external coating plus cathodic protection No external corrosion allowance required For the sample design problem: No special requirements

Peter Tuft - Wall Thickness AS Launch, February Manufacturing Tolerance ERW pipe, manufactured from strip No manufacturing tolerance required For the sample design problem: No special requirements for WT But note, X80 pipe and 0.8 DF will require tighter than standard tolerance in linepipe specification

Peter Tuft - Wall Thickness AS Launch, February Constructability May consider extra WT for HDDs etc Outside scope of design problem scenarios No need to round linepipe WT to “standard” sizes ERW pipe ordered in project quantities can be rolled to any desired thickness Station piping ordered in small quantities may need to be rounded up to next standard size For the sample design problem: No special requirements (except at stations)

Peter Tuft - Wall Thickness AS Launch, February Hydrostatic Test May reduce number of test sections by adding short length of heavy wall at bottom of long steep descent For the sample design problem: No special requirements

Peter Tuft - Wall Thickness AS Launch, February Elements of Nominal WT Internal pressure Penetration resistance Minimum critical defect length Stress & strain (including vehicle loads) Fracture control Special construction Maintainability (eg. hot tapping) SCC mitigation Fatigue life External pressure Allowances Manufacturing tolerance Constructability Hydrotest

Peter Tuft - Wall Thickness AS Launch, February Design Problem: Rural ScenarioRemote RuralParallel RoadRoad Crossing Pressure: t P Other req’d components NilNone > 7.1None > 7.8 Required: t W Allowances & tolerance Nil Nominal: t N

Peter Tuft - Wall Thickness AS Launch, February Design Problem: Suburban ScenarioT1 GeneralT1 SensitiveRoad Crossing Pressure: t P Other req’d components Penetration: 8.4 No rupture: 8.4 Penetration: 11.0 No rupture: 8.4 Penetration: 8.4 No rupture: 8.4 Required: t W Allowances & tolerance Nil Nominal: t N

Peter Tuft - Wall Thickness AS Launch, February Design Problem: Stations (rural) Scenario Linepipe (eg. S-bend) Station Pipe Pressure: t P 8.4 (DF = 0.67) 19.2 (Grade B, DF = 0.67) Other req’d components Penetration: 8.4 None > 19.2 Required: t W Allowances & tolerance Nil 21.4 (round up to Sch 80) Nominal: t N

Peter Tuft AS Launch, February Questions?