powerpoint presentation tuft - as2885 pipe... · • hydrotest. peter tuft - wall thickness as...
TRANSCRIPT
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 2
The Design Problem
• Roma - Brisbane duplication• DN 400, 450 km• Land use ranging from rural to suburban• 15.3 MPa, 10.2 MPa from city gate station• 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 2885.1 Launch, February 2007 3
Definition: Nominal WT, tN
• 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 2885.1 Launch, February 2007 4
Definition: Required WT, tW
• 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 2885.1 Launch, February 2007 5
• Barlow’s rule, unchanged: • Design factor FD ≤ 0.8• Lower values of FD at some locations:
• Road & rail crossings0.72• Pipeline assemblies 0.67• Bridges etc 0.67• Telescoped lines 0.60
• From Clause 5.4.3 & Table 5.4.3
WT for Internal Pressure, tP
tP =PDD
2FDσY
P
σH
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 6
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 2885.1 Launch, February 2007 7
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 2885.1 Launch, February 2007 8
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 3.2.2 (a)(v))
• From Clause 5.4.7
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 9
Putting them all together
• Figure 5.4
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 10
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 2885.1 Launch, February 2007 11
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 2885.1 Launch, February 2007 12
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 2885.1 Launch, February 2007 13
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 2885.1 Launch, February 2007 14
Internal pressure
Location Design Factor
WT, 15.3 MPa
WT, 10.2 MPa
General (R1 to T2) 0.8
Road & rail crossings 0.72
Pipeline assemblies (MLVs etc) 0.67
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 15
Internal pressure
Location Design Factor
WT, 15.3 MPa
WT, 10.2 MPa
General (R1 to T2) 0.8 7.1 4.7
5.2
5.6
Road & rail crossings 0.72 7.8
Pipeline assemblies (MLVs etc) 0.67 8.4
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 16
Penetration Resistance - Rural
• Identified threat • 20 t excavator with general
purpose teeth• Min tP = 7.1 mm
• Previously showed even 4.8 mm WT is OK for the identified threat
• No need to increase WT above tP
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 17
Penetration Resistance - Urban
• Identified threat• 30 t excavator with tiger teeth
• Min tP = 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 2885.1 Launch, February 2007 18
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 2885.1 Launch, February 2007 19
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 2885.1 Launch, February 2007 20
WT for No Rupture - 10.2 MPa
• CDL varies with WT, steel grade and MAOP• Calculate from Clause 4.8.5
• CDL for 10.2 MPa urban line:• 4.7 mm WT CDL = 55 mm• 8.4 mm WT CDL = 150 mm• 11.0 mm WT CDL = 210 mm
• 8.4 mm WT adequate for “No Rupture”• CDL ≥ 145 mm as required
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 21
WT for No Rupture - 15.3 MPa
• CDL for 15.3 MPa rural line:• 7.1 mm WT CDL = 65 mm• 8.4 mm WT CDL = 95 mm• 11.0 mm WT CDL = 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 2885.1 Launch, February 2007 23
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 2885.1 Launch, February 2007 24
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 2885.1 Launch, February 2007 25
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 & calculations in Appendix V
• For the sample design problem:• Pipe with tP based on 0.72 design factor adequate
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 26
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 back after review of fracture control
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 27
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 2885.1 Launch, February 2007 28
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 2885.1 Launch, February 2007 29
Maintainability
• Usual example is provision for future hot tapping
• For the sample design problem:• No special requirements
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 30
Stress Corrosion Cracking
• SCC influenced by hoop stress• Increased WT reduces hoop stress, may reduce
susceptibility to SCC• Heavy wall pipe sometimes specified for this
reason downstream of compressor stations (elevated temperature also promotes SCC)
• For the sample design problem:• No special requirements
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 31
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 2885.1 Launch, February 2007 32
External Pressure
• May be an issue for certain deep water crossings or deep HDDs
• Formulae provided in Clause 5.4.5• For the sample design problem:
• No special requirements
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 33
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 2885.1 Launch, February 2007 34
Allowances
• Clean dry sales gas• No internal corrosion• No erosion
• Good quality external coating plus cathodicprotection• No external corrosion allowance required
• For the sample design problem:• No special requirements
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 35
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 2885.1 Launch, February 2007 36
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 2885.1 Launch, February 2007 37
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 2885.1 Launch, February 2007 38
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 2885.1 Launch, February 2007 39
Remote Rural
7.1In
tern
al
pre
ssu
re
tPtWNo other applicable
componentstN
Nil allowances & tolerance
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 40
Parallel Rural Road
7.1In
tern
al
pre
ssu
re
tPtWNo other applicable
componentstN
Nil allowances & tolerance
Pen
etr
ati
on
re
sist
an
ce
<4.8
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 41
Rural Road Crossing
7.8In
tern
al
pre
ssu
re
tPtWNo other applicable
componentstN
Nil allowances & tolerance
Pen
etr
ati
on
re
sist
an
ce
<4.8
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 42
Suburban General (T1)
tWNo other applicable
componentstN
Nil allowances & tolerance
Pen
etr
ati
on
re
sist
an
ce
8.4
No
Ru
ptu
re
8.4
4.7In
tern
al
pre
ssu
retP
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 43
Suburban Sensitive (S)
tW
No other applicable components
tN
Nil allowances & tolerance
Pen
etr
ati
on
re
sist
an
ce
11.0
No
Ru
ptu
re
8.4
4.7
Inte
rnal
pre
ssu
re
tP
Peter Tuft - Wall Thickness AS 2885.1 Launch, February 2007 44
Station Piping
tWNo other applicable
components
tN
Nil allowances & tolerance
19.2
Inte
rnal
pre
ssu
retP
Grade B, DF = 0.67
21.4
Co
nst
ruct
ab
ilit
y
Sch. 80 stock pipe