Peter TuftAS 2885.1 Launch, February 2007 1

AS 2885.1-2007

PENETRATION RESISTANCE

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 2

Why Penetration Resistance?

Incident Causes

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1970 1975 1980 1985 1990 1995 2000 2005

Half decade (year ending)

Nu

mb

er

of

Inci

den

ts

Lightning

External Forces

Earth Movement

Corrosion

Construction

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 3

It really happens

Acknowledgements:Rob Moore & Caltex

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 4

General Requirements

• Penetration resistance is one form of physical protection

• Mandatory in developed areas (T1, T2, S & I); see separate Clause 4.7

• May be used in R1 & R2 areas if required by SMS• Especially near isolated buildings (ie. within

radiation contours)

• From Clauses 4.11.1 & 4.11.2

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 5

Methods

• Calculate using Appendix M• Expected to be usual approach

• Physical testing• Beneficial for some projects in high

consequence areas

• Comparison with previous physical tests• Must be sufficiently similar

• From Clause 4.11.3

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 6

Calculation Objectives

• Determine minimum size of excavator to puncture pipe• For both general purpose and pointed teeth

• Determine likely puncture hole size, and hence failure mode• Rupture if hole ≥ critical defect• Leak if hole < critical defect• No penetration

• Should do calcs even if penetration resistance is not adopted as physical control• Useful reference data for SMS

• From Clause 4.11.3

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 7

Define the Threat

• Equipment type• Usually an excavator

• Equipment size (tonnes)• Penetrator (tooth) type• General purpose (chisel shaped)• Penetration (single sharper point)• “Tiger tooth” (twin sharp points)

• Penetrator dimensions

• From Clause 4.11.3

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 8

Calculation Principles

• No penetration if resistance > force

• RP > B F• RP = force required to penetrate pipe (for

given pipe parameter and tooth dimensions)• F = nominal force applied by machine• B = multi-purpose correction factor

• From Appendix M2

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 9

Pipe Resistance, RP

• Based on extensive APIA-sponsored research

• Excellent correlation between tests, FEA and equation:

RP 0.0007tW (U 410)(L 22.4)W

W 3.14

• Equation M3

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 10

Excavator Force, F

• Also based on APIA-sponsored research• Reasonable correlation between

excavator mass and bucket force:

FBucket 7.5WOP 0.045(WOP )2

• Equation M4

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 11

Factor B

• Multipurpose• Bucket force multiplier, empirical

experience, safety factor• Largely based on Australian field trials

• Range from 0.75 to 1.3• Original research suggested 1.8 to 2.0• Theoretically sound, but not achieved in

practice due to limited reaction force

• May change as further research progresses

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 12

B Values

Circumstances B

Where WT not governed by penetration resistance

<0.75

Adequate resistance to typical excavator, but puncture possible if aggressive

0.75

Reasonable compliance with “No Puncture”

1.0

Where penetration must never occur, in some high consequence areas

≥1.3

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 13

Field Trials

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 14

… in Action

Acknowledgements:Phil Colvin & Alinta

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 15

… and the Results

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 16

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 17

The Design Scenario

• 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 • SMYS = 552 MPa, UTS ≥ 621 MPa

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 18

The Design Problem

• Check penetration resistance for:

Location WTExcavato

rTeeth

Rural roadside

4.8 mm 20 tGen purpose(76 x 13 mm)

Suburban 8.4 mm 30 tTiger

(20 x 12 mm)

• Tooth dimensions from Table M3

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 19

Rural Location

• 4.8 mm WT, 20 t excavator, GP teeth

• RP (pipe resistance) 275 kN

• Fbucket 131 kN

• B (adequate resistance) 0.75• B F 98 kN

• RP >> B F• Resistance >> machine force• No penetration• 4.8 mm WT OK for the identified threat

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 20

Suburban Location

• 8.4 mm WT, 30 t excavator, tiger teeth

• RP (pipe resistance) 181 kN

• Fbucket 184 kN

• B (reasonable ‘No Puncture’) 1.0• B F 184 kN

• RP ≈ B F• Resistance ≈ machine force• No penetration, just• 8.4 mm WT minimum acceptable for the

identified threat

Peter Tuft - Penetration Resistance AS 2885.1 Launch, February 2007 21

Worth 1000 Words …

Penetration Resistance

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Excavator mass, t

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Excavator force - lowExcavator force - nominalExcavator force - maxDozer forceResistance - GP teethResistance - Pen teeth

Peter TuftAS 2885.1 Launch, February 2007 22

Questions?