Line Pipe Specification and Procurement

Transcription

1 Line Pipe Specification and Procurement John Piper John Piper & Associates Pty Ltd

2 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!

3 Context & Constraints Usage Context Need efficient energy transport Minimum Cost Drives: High strength, thin wall pipe operating at high pressure Constraints X70 X80 Pipe Grades operating safely at 0.8 design factor. Pipelines Designed to AS 2885 Line pipe to API 5L / ISO Supplementary Specifications.

4 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

5 Steel Manufactured-in Integrity 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: Effective Manufacturing Process Design Steel Making, Pipe Making, Coating, Transport & Handling Process Control Inspection and Testing

6 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

7 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

8 Constructability Constructability design-it-in. Length Long pipe length reduces the number of girth welds increases productivity. Handling Robustness 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. 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

9 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.

10 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 Communication

11 Why worry? The Manufacturing Process is complex! Ample opportunity for things to go wrong!

12 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.

13 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

14 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?

15 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.

16 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

17 Manufacture Surveillance & Verification Starts with acceptable historical data Review steelmaker s Test Certificates before production commences Require first day tests on big jobs. Tailor 3 rd 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!!

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

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

20 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.