Line Pipe Specification and Procurement

John Piper

John Piper & Associates Pty Ltd john@piperpiper.com.au

Themes 1. The required attributes for line pipe

carrying petroleum products. – What is really needed and why?

2. Technical Procurement Insights – What can go right when buying pipe!

Context & Constraints • Usage Context

– Need efficient energy transport – Minimum Cost – Drives:

• High strength, thin wall pipe operating at high pressure

– X70 – X80 Pipe Grades operating safely at 0.8 design factor.

• Constraints – Pipelines Designed to AS 2885

• Line pipe to API 5L / ISO 3183 + Supplementary Specifications.

1. Required Pipe Attributes • Integrity

– There shall only be one hole in each pipe, centrally located. • Strength

– Strong enough to allow successful field pressure test. • Coatability

– A corrosion resistant coating must be easily applied. • Constructability

– Length – Handling Robustness – Field Bendability – Weldability

• Serviceability – Resistance to Crack initiation – Resistance to a Running Fracture (Brittle and Ductile) – Fatigue Resistance

Manufactured-in Integrity

– Effective Manufacturing Process Design • Steel Making, Pipe Making, Coating, Transport & Handling

– Process Control – Inspection and Testing

• Steel – Consistent composition – Segregation and inclusion Control

• Pipe – No leak or burst

• Coating: – No Corrosion

• Effective Factory coating • Effective Joint Coating

• The key to line pipe integrity is:

Strength • All pipe can operate at actual design pressure with integrity

– I.E. Mill tested to 85% or 90% SMYS. • Field Pressure test is the worst case service requirement. • At 0.8 Df all pipes will be tested above nameplate strength:

– at 100 to 110% yield strength.

• Engineers need certainty, so this is a dilemma. • They must rely on excess strength supplied by the

manufacturer. • The better the manufacturer, the less excess strength! • Fortunately Strain-aging, triaxiality effects and manufacturing

excess allow success. • Use sophisticated simulation software – PipeStrain. • For coated (strain aged) pipe, we now need to know:

– Shape of the stress-strain response – Strength Distribution

Coatability • A forgotten attribute. • Pipe must be:

– Straight – Clean – No oil, grease, paint, salt, lizards,

super-phosphate!! – Free of surface defects – Pits, gouges,

seams, slivers or hackles • Often a mismatch between pipe mill and

coating plant expectations: – Specify

Constructability • Constructability – design-it-in.

– Length • Long pipe length reduces the number of girth welds – increases productivity.

– Handling Robustness

– Weldability • Weld-out is the critical rate determining step in pipeline construction.

– Shape control – roundness and bevel dimensions are critical – CEq critical for pre-heat free cellulosic welds without HACC

• High D/t ratio results in dents, collapsed ends etc

• Inverted dents are rupture sites – Cold Field Bendability

• High D/t makes pipe hard to bend – mandrel machines may be needed.

Servicability – Resistance to Crack initiation.

• Weld quality in HFERW is an issue – Resistance to a Running Brittle Fracture

• DWTT performance is critical – Problem (inverse fracture) in seamless pipe

– Resistance to a Running Ductile Fracture • Ongoing issues with the Battelle 2 Curve methodology.

– Fatigue Resistance • Applicable only to storage

pipelines – Others experience too few

cycles • Largely wall thickness

dependent, but weld shape in SAW pipe can be important.

2. Successful Technical Procurement

• Good Pipeline Design

• Comprehensive Specification

• Capable Mill & Coating Plant

• Comprehensive Technical Agreement.

• Process Validation

When we buy pipe we don’t just buy the pipe we buy the way it is made

Com

munication

Why worry?

The Manufacturing Process is complex! Ample opportunity for things to go wrong!

Good Pipeline Design • Avoid Over-specification

– Eliminates capable mills – Complicates technical negotiation – Adds Cost

• Avoid Under-specification – Project failure? – Increases rework – Compromises pipeline integrity – Adds Cost

• Decide minimum requirements before tendering! – Decide on MAOP, Design factor, Pipe Grade, Location

Class. – Wall thickness, corrosion allowance (Light wall, Heavy

wall, No-penetration pipe. – Fracture control plan.

Comprehensive Specification • Content previously discussed! • Don’t assume API 5L compliance • Remember AS2885 requirements go well

beyond API 5L – Fracture Control – Weldabilty

• Emphasize Sensitive issues E.g. – Length range – Pipe Mass/metre – Surface condition – Dimensional control – weld-out

Capable Pipe Mill

• Prequalify Mills – Else Commercial Imperatives have no answer

• Review each mill for actual capability – Seek performance (historical) data

– The Steel supplier is key – Traceability is critical – Is all the equipment needed

present? – Who is in control – subcontractors?

Capable Coating Plant

• Pre-qualify Coaters – Raw material suppliers are critical – Seek Historical Data

• Plant Capability E.g. – Blasting Capacity – Dew-point control – Inspection availability – Bevel protection

• Handling and transport – Custody Transfer Inspection.

Comprehensive Technical Agreement

• Start with Prequalified Pipe & Steel Mills and Coating plants

• Tailor the Spec to the pipe making method and risk profile of the pipeline.

• Address newly revised AS2885 requirements: – Fracture Control – Field Pressure Test Data

• Require a draft Manufacture Procedure Specification (MPS) on tender response

• A Pre-production meeting is vital – Verifies that the messages have been received

Manufacture Surveillance & Verification

• Starts with acceptable historical data • Review steelmaker’s Test Certificates before

production commences • Require first day tests on big jobs. • Tailor 3rd Party Inspection level to risk profile (both

Manufacturer and Project) • Require a Manufacturer’s Data Record (MDR) on

order completion • At minimum, review TCs before shipment • Extra care if a Type II or Type III Field Pressure

Test – Coated Pipe testing!!

Communication • Key to all activities! • Can be difficult – Long communication lines – language barriers.

Conclusion Achieve Great Line Pipe Procurement through: Careful pipeline design Competent, pre-selected Mills Agreed Specification Strong Communication In-mill Verification

Acknowledgement – I thank the EPCRC which has generously sponsored this

visit to Adelaide and hence the opportunity to present

– I acknowledge the contributions of OneSteel and various

websites that have contributed photos etc. to this presentation. This material is presumed to be in the public domain.