Pipeline Fittings Quality Assurance Technical Paper

National Energy Board of Canada

Pipeline Fittings Quality Assurance Technical Paper [PDF 604 KB]

DNV-GL

Project No.: PP179886

Date: May 31, 2017

Executive Summary

Recently, pipeline operating company quality assurance measures have identified fittings that did not meet specifications. As a result, on 5 February 2016, the Canadian National Energy Board (the NEB) issued a Safety Advisory and Miscellaneous Order (M0-001-2016) regarding substandard material. On 12 April 2017, the NEB issued a Notice of Intention to Order followed by an amended Safety Advisory SA-2016-01A2 on 12 May 2017. The amended Safety Advisory identifies additional fitting cases where material properties did not meet Company specifications, while the Miscellaneous Order will enable the NEB and Companies to identify any such fittings on existing pipelines, so that fitness for service can be assessed and appropriate mitigation measures can be implemented if required. This paper examines current quality assurance requirements and processes and procedures used to validate pipe and components on pipeline systems and identifies any gaps or shortcomings in the quality assurance specifications that allow pipe or fittings to be manufactured that do not meet the intended material quality requirements.

Microalloyed high strength steels are very sensitive to changes in manufacturing processes such as thermomechanical rolling and heat treating. This sensitivity compounds small deviations in manufacturing processes such as tempering or quenching temperature. To minimize the risk of substandard materials, the initial process qualification often referred to as First Article Inspection^{Footnote 1} forms the basis for all subsequent manufacturing procedures and the Manufacturing Procedure Specification (MPS) when applicable.

Variables such as heat treatment and quenching temperatures, hold times, furnace load configurations, etc. should be sufficiently detailed to allow for quality control monitoring. Initial qualification testing should be rigorous and clearly define the resultant material properties as related to the product specification. Finally, the MPS and Inspection and Test Plan (ITP) should sufficiently describe the process such that production inspection is efficiently and thoroughly conducted. Deviations from the process need to be quickly identified and supplemental testing utilized to define the impact. A robust system of traceability should allow for all materials affected by a process disruption to be identified and segregated to prevent their entry into the supply chain.

In general, standards for fittings lack the detail and rigor associated with line pipe. Enhancements to current industry standards are recommended to close the gaps identified between standards, manufacturing processes and the intended fitting performance.

The failure of components to conform to existing standards and specifications, as investigated in this report, is a direct result of failures to control the manufacturing processes. These failures in processes were not identified by the established ITP protocols, either during production monitoring or subsequent material acceptance lot testing. First Article Inspection and production monitoring is generally conducted for larger mill runs such as major construction projects. Smaller projects generally rely on manufacturers and distributors to provide fittings meeting industry standards with limited or no additional oversight.

Table of Contents

1. 1.0 Scope of work
2. 2.0 Overview of pipeline component production and quality assurance
   1. 2.1 Background on production methods
   2. 2.2 Quality assurance/quality control (QA/QC) overview
   3. 2.3 Relevant standards and regulations
3. 3.0 Pipeline component issues
   1. 3.1 Description of incidents (case studies)
      1. 3.1.1 Published events
      2. 3.1.2 Pipeline Operating Company interviews
4. 4.0 Standards and Regulation gap analysis
5. 5.0 Quality assurance strategies
   1. 5.1 Quality Management Systems (QMS)
   2. 5.2 Development of Manufacturer Procedure Specifications (MPS)
   3. 5.3 Development of Inspection and Test Plans (ITP)
   4. 5.4 Manufacturing Traceability
   5. 5.5 Materials Inspection
   6. 5.6 Raw materials verification
   7. 5.7 Manufacturing Procedure Qualification
   8. 5.8 Inspection and Testing Enhancements
   9. 5.9 Procurement
   10. 5.10 Acceptance and testing
6. 6.0 Conclusion

Appendices

Appendix A – Gap Analysis

List of Tables

1. Table 1. Standards and Regulation Gap Analysis Summary
2. Table 2. Standards and Regulation Quality Assurance Strategies
3. Table 3. Acronyms
4. Table 4. Definitions
5. Table 5. References

1.0 Scope of work

On 20 January 2017, the National Energy Board (NEB) issued a Request for Proposal (RFP) for provision of a Pipeline Materials Quality Assurance Technical Paper (the Paper). The request is to provide the NEB with a technical paper that examines current quality assurance requirements and processes and procedures used to validate pipe and components on pipeline systems and identifies any gaps or shortcomings in the quality assurance specifications that allow pipe or materials to be manufactured that do not meet the intended material quality requirements.

Recently, pipeline operating company quality assurance measures have identified fittings that did not meet specifications. As a result, on 5 February 2016, the NEB issued a Safety Advisory and Miscellaneous Order (M0-001-2016) regarding substandard material. The Order required companies to file with the NEB a report detailing any such fittings in use on the pipeline operating companies’ systems, to identify whether these fittings have been identified as having substandard materials, and plans for mitigation should substandard materials be identified. If a company was unable to determine if the referenced fittings were purchased and installed, then it was to provide a corrective action plan.

As described in the RFP, the issue of some of the fittings not meeting the required material specifications is not considered by the NEB to represent a significant or immediate public safety or environmental risk, because all fittings in service would have passed commissioning hydrotests. Also, the NEB is not aware of reported releases of gas or liquid product as a result of fittings not meeting specifications.

The Scope of Work (SoW) is to prepare a technical paper with the following deliverables:

Section 2 – Overview of Pipeline Component Production and Quality Assurance: An overview of pipeline component production and quality assurance in relation to standards and regulations.

Section 3 – Pipeline Component Issues: An overview of pipeline system pipe and components that have been found to either: not have met specifications or to have failed during testing, commissioning or in-service; including a literature review and an analysis of specific cases (e.g. NEB Safety Advisory 2016-01.

Section 4 – Standards and Regulation Gap Analysis: Identification of gaps in the standards that would have enabled fittings that either failed or did not meet the specifications or standards to be introduced into the supply chain.

Section 5 – Quality assurance strategies: Possible strategies to provide more assurance that pipeline components are produced and installed with the required material properties.

2.0 Overview of pipeline component production and quality assurance

2.1 Background on production methods

Pipeline components for the purpose of this paper refers to manufactured fittings such as elbows, tees, extruded headers, reducers, and caps intended for oil and gas service. Fabricated assemblies which may contain multiple components are excluded. Components are wrought or forged from raw material such as pipe, plate or billets. Components undergo a forming process or shaping process involving hammering, pressing, piercing, extruding, rolling, bending, welding, machining, or a combination of two or more of these operations. Following forming, components are heat treated to provide final design strength and toughness. Heat treatment may include one or more of the following methods:

• Stress relieving where the component is heated to a temperature below the transformation range for a specific period of time and allowed to cool in the furnace or air.
• Normalizing where the component is uniformly heated above the austenitic transformation range, held to achieve uniform temperature throughout the mass of the component, and cooled in air.
• Normalizing and tempering where the component is reheated following normalization to a temperature below the transformation range, held for a specific time, and cooled in the furnace or air.

For pipeline components with grades higher than Canadian Standards Association (CSA) Grade 359 (WPHY^{Footnote 2} 52), quenching and tempering is required to achieve the desired final properties. Quenching and tempering is a process that heats the steel to the fully austenitic range (normalizing) and rapidly quenches the material to achieve a microstructure with high strength and hardness. Toughness of the material is reduced during this process, but addressed by tempering. This increases toughness without having a significant impact on strength. The end result is a steel with a good balance between strength and toughness.

2.2 Quality assurance/quality control (QA/QC) overview

Component manufacturers are required to comply with the requirements of a quality management system such as ISO 9001^{Footnote 3}. In addition, proof tests may be required to verify the adequacy of the manufacturer’s design. Depending on the standards and purchaser requirements specified, additional mandatory testing is conducted to ensure production materials or components conform to the requirements.

Typical pipeline operating company integrity management and quality assurance provisions to ensure fittings conform to the intended design include a combination of company specifications, supplemental production testing requirements, inventory control, and acceptance testing. The main provision continues to be the pre-commissioning (post construction) hydrostatic pressure test. Depending on the intended service, pipeline components are subject to pressure testing at increments of the designed operating pressure. Less common are material and dimensional tests upon receipt of the component to identify substandard materials. Additional risk factors and integrity inspection steps are discussed below.

2.3 Relevant standards and regulations

Industry references that were reviewed for this report and are applicable to the procurement and inspection of line pipe and components include, but are not limited to:

• API Specification 5L, Specification for Line Pipe;
• ASME/ANSI B16.9, Factory-Made Wrought Buttwelding Fittings;
• ASME BPVC-2013, Boiler and Pressure Vessel Code (2015 Edition)
  • Section V-2013, Nondestructive Examination
  • Section VIII, Div. 1-2013, Rules for Construction of Pressure Vessels
  • Section IX-2013, Welding, Brazing, and Fusing Qualifications: Qualification Standard for Welding, Brazing, and Fusing Procedures; Welders; Brazers; and Welding, Brazing, and Fusing Operators.
• ASTM A370-13, Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• ASTM A694, Standard Specification for Carbon and Alloy Steel Forgings for Pipe Flanges, Fittings, Valves and Parts for High-Pressure Transmission Service;
• ASTM A991/A991M-10, Standard Test Method for Conducting Temperature Uniformity Surveys of Furnaces Used to Heat Treat Steel Products
• MSS SP-75 (2014), Specification for High-Test, Wrought Butt-Welding Fittings;
• CSA Z662-15, Oil and gas pipeline systems;
• CSA Z245.1-14, Steel Pipe; and
• CSA Z245.11-13, Steel Fittings

3.0 Pipeline component issues

3.1 Description of incidents (case studies)

3.1.1 Published events

The NEB is aware of instances of pipe and components having substandard material properties installed on pipelines under NEB or another regulatory bodies’ jurisdiction^{Footnote 4}. In the cases examined, the documentation received from the manufacturers indicated that the materials provided met the required specifications. Subsequent testing indicated that some of the pipe and fittings did not meet all the required material specifications. In some instances, the substandard materials were determined to have been a contributing factor to pipeline failure during pressure testing.

Although some of the substandard materials cases described below appeared to have been isolated, the NEB subsequently identified additional cases on pipelines in Canada and the United States (US). The issue of pipe and fittings having substandard material properties entering the supply chain, and subsequently being installed on pipelines, is an industry wide concern.

Canadoil Asia Fitting Case

In December 2010, the NEB was notified of a steel fitting (elbow) that had expanded following a hydrostatic test at a pipeline facility in the US. PHMSA attributed the cause of the elbow expansion to the fitting having a yield strength lower than the specified minimum yield strength. The pipeline operator removed a number of other fittings at the facility for mechanical testing and identified additional fittings with substandard material properties.

The substandard fittings were traced to a manufacturer identified as Canadoil Asia^{Footnote 5} with production originating from Thailand. The fittings were manufactured to the Manufacturers Standard Society (MSS) SP-75 Specification for High-Test, Wrought, Butt-Welding Fittings and were indicated as having met the specified material requirements on the Material Test Report (MTR). However, due to inadequacies in some processes at the manufacturing plant, not all fittings met the specified material requirements.

Ezeflow Fitting Case

In 2013, a pipeline rupture occurred on a sweet natural gas pipeline in Alberta. An estimated 16.5 million cubic meters of natural gas was released. The Transportation Safety Board of Canada (TSB) released its Pipeline Investigation Report on the incident (P13H0107) on 3 November 2015.

Investigations by the TSB, the NEB, as well as the pipeline operator, indicated substandard materials were present in the manufactured elbow where the failure initiated. Fitness for service testing was conducted on the pipeline fittings prior to their installation in 2008, after two fittings failed during the pressure test. Although hardness testing indicated the elbow in question had lower mechanical properties, the operator determined that the elbow was acceptable for use, as the wall thickness would compensate for the lower mechanical properties. Neither the manufacturer nor the pipeline operator physically verified the wall thickness of this specific fitting. The investigation determined that the wall thickness was less than that indicated on the MTR.

Since this incident, the pipeline operating company has increased its manufactured fitting (wall thickness) specifications beyond the manufacturing standards acceptable under the current Canadian Standards Association (CSA) Z662-15 Oil and Gas Pipeline Systems. The fitting manufacturer, Ezeflow, has made improvements to both its manufacturing procedures and its quality assurance (QA) programs. The quality issue appears to be limited to Grade 550 elbows manufactured for a single customer.

In 2008, the US Department of Transportation, Pipeline and Hazardous Materials Safety Administration (PHMSA) observed hydrostatic test failures and excessive expansions on a number of pipelines under construction in the US. Upon investigation, PHMSA attributed the cause of the incidents to the installation of pipe with substandard material properties.

In 2009, PHMSA issued an advisory bulletin (ADB-09-01) warning of the potential for microalloyed high strength line pipe to exhibit inconsistent chemical and mechanical properties, with yield strengths as much as 15 percent below specified requirements. The advisory also warned that in some cases, the pipe materials may successfully pass a hydrostatic test but still present a future concern.

3.1.2 Pipeline Operating Company interviews

DNV GL conducted interviews with representatives of two pipeline operating companies to further understand the issues experienced including details of their subsequent review and analysis.

Operator A:

Operator A identified most of the issues in elbows formed from plate which were related to the material yield strength relative to the specified material grade. The pipeline operating company typically purchases fittings from distributors unless a major project allows for direct procurement from the manufacturer. Heat treatment of all substandard fittings consisted of quenching and tempering. Although the fittings were specified and documented as CSA Grade 483 (WPHY 70), subsequent transverse tensile testing revealed actual strengths with values in the 300s. No axial testing was conducted. Traceability to the plate manufacturer was not maintained, but subsequent chemical composition testing matched mill supplied Certified Mill Test Reports (CMTRs). Hardness testing also revealed large differences from end to end of the fitting. It is the pipeline operating company’s assessment that loss of process control during quenching resulted in non-uniform cooling and variability in material properties from the initial entry of the fitting into the quenching tank to the final immersion.

Operator B:

Operator B identified furnace loading practices that affected normalizing of the fittings which resulted in localized areas of inadequate heat treatment. The stacking of fittings in the furnace, and use of certain steel support racks effectively increased the overall thickness and mass of the material to be heated and hence the hold time in the furnace. A sharp contrast was observed when lighter gauge racks (less mass) were used to load the furnace, and when spacing between the fittings was maintained. In both cases, the manufacturing procedure did not address the relative increase in the fitting localized mass (thickness) relative to furnace hold time. In one case, worn racks had deformed to the point that the contact area was significantly expanded and may not have conformed to the requirements of the original manufacturing procedure qualification tests. Much like welding processes, critical variables such as fitting wall thickness associated with heat treatment should be identified and included in MPS and ITP procedures.

A separate issue identified involved the adequacy of quenching following normalization. In this case the temperature of the quenching medium was not monitored and maintained to assure rapid cooling of the products. Quench tanks did not provide for continual measurement of water temperature or required agitation to ensure consistent cooling rates.

Lot testing incorporating coupons was found to be inadequate to identify substandard materials. Lots, or batches of similarly produced components, were judged to be too large to differentiate between production processes, and the location and number of coupons was found not to be representative of process conditions during heat treatment.

Wall thickness variability was also identified as part of the review but was not considered detrimental. However, specific issues related to the absence of raw material (plate) traceability, material receipt inspection, and comprehensive acceptance testing were the primary drivers for these substandard fittings to enter the supply chain.

4.0 Standards and Regulation gap analysis

A gap analysis was performed to compare selected standards against a list of selected criteria. The criteria were selected based upon DNV GL’s experience with manufacturing and quality assurance processes. The list of criteria is not meant to be all inclusive, but representative of common processes in the order typically employed during manufacturing and testing:

• Fabrication of material
  • Chemistry aim points and limits
  • Carbon equivalent
  • Heat identification
  • Slab or ingot casting requirements, slab identification, and traceability
  • Plate or skelp requirements, testing requirements, identification, and traceability
  • Plate or skelp shipping and handling requirements
  • Heat Treating
  • Forming
  • Welding
  • Hydrotesting
  • Sizing and dimensions
  • Grade requirements
  • Marking requirements
  • Shipping and Handling
• Quality control
  • Product Ordering Requirements
  • Manufacturer Procedure Specifications (MPS)
  • Inspection and Test Plan (ITP)
  • Certified Material Test Report (CMTR)
  • Material receiving and Identification
  • Nondestructive examination (NDE)
  • Defects
  • Retests
  • Final Inspection
• Traceability

The resulting comparison appears in Appendix A below. Operator qualification processes were not considered, nor were procedures related to materials required for sour service applications. Table 1 provides a summary of identified gaps by criteria, standard and associated quality strategy.

CSA Z245.1-14, Steel Pipe and CSA Z662-15, Oil and Gas Pipeline Systems were reviewed to provide a comparison to standards specific to fitting manufacture. In general, standards for fittings lack the detail and rigor associated with line pipe. Enhancements to current industry standards are recommended to close the gaps identified between standards, manufacturing processes and the intended fitting performance. Pipeline operators and/or distributors should consider enhancing product specifications to provide more rigorous traceability, process monitoring and product testing.

Of the fitting standards reviewed, MSS SP-75 was the most comprehensive relative to the selected criteria. However, gaps remain relative to traceability, raw material handling and inspection, chemical composition and lot testing. Emphasis is placed on the control of manufacturing processes by requiring production specific MPS and ITPs, the acceptance and surveillance of which is the responsibility of the purchaser. In practice, this has the potential to cause a gap between the standard and finished goods if the MPS or ITP is incomplete, or is not monitored for conformance during production.

CSA Z245.11-13 Steel Fittings has similar gaps relative to raw materials and raw material verification. The standard makes no reference to establishing manufacturing procedures similar to a MPS for monitoring the various processes involved in the manufacture of fittings. The reporting requirements are less stringent than those within MSS SP-75. The standard requires a Certificate of Compliance with limited mandatory test reporting requirements. Optional reporting requirements are left to the purchaser to include in the purchase order. As discussed below, this creates a low threshold for monitoring and reporting production process parameters of fittings produced for distributor stock or aftermarket resale.

5.0 Quality assurance strategies

The procurement of materials and goods has a significant impact on the overall quality of the finished pipeline. This includes the procurement of line pipe and components such as fittings, valves, flanges, closures, etc. It is essential that contractors, suppliers, and the pipeline operating company achieve alignment on quality.

The source of the pipe and fittings should be carefully considered during the materials procurement and inspection phase. Pipe and fittings purchased in millrun quantities provide the flexibility to impose project-specific specification requirements that exceed the minimum requirements of the applicable industry specification. Pipe and fittings purchased from distributor’s or manufacturer’s stock can often include materials that meet only the minimum requirements of the applicable industry specification. In addition, they may not have had the benefit of supplemental mill audits and inspections that are common for mill production runs of pipe and fittings. Rigorous mill pre-qualification practices and pre-purchase inspection have proven to mitigate risks associated with stock fittings. Pre-qualification can identify manufacturing facility inadequacies such as worn equipment, inadequate furnace surveying, quench tank mixing, etc. Pre-purchase inspections can also identify geometric, wall thickness, chemistry, and finishing issues prior to individual fittings entering the supply chain.

DNV GL produced a report for PHMSA providing guidance relative to new pipeline construction inclusive of the manufacturing and procurement of line pipe and components.^{Footnote 6}  The following ten strategies adapted from Appendix B of the DNV GL report can be directly applied to the manufacture and procurement of components.

5.1 Quality Management Systems (QMS)

When required by the pipeline operating company, contractors and suppliers should have their own QMS which is aligned with the pipeline operating company’s QMS. Where materials or goods are purchased on behalf of the pipeline operating company by a third party such as a distributor, the pipeline operating company’s QMS should be transferable and adopted by the purchaser. In addition to the QMS, manufacturing processes require additional process documentation, review, and control to facilitate meeting the required quality, schedule, delivery, and overall project objectives including performance specifications and regulatory requirements. This section is applicable to pipe manufacturers, pipe coaters, double jointers, component manufacturers, and other parties who provide materials or products, rather than services.

It is recommended, at minimum, that the pipeline operating company require QMS alignment from suppliers of pressure-carrying pipe and components, as well as the pipeline and facilities construction contractor(s).

5.2 Development of Manufacturer Procedure Specifications (MPS)

When required by the pipeline operating company or referenced standard, the supplier shall provide a manufacturer procedure specification (MPS) detailing manufacturing processes, quality assurance methods, quality control activities inclusive of hold points, and a description of applicable geometrical checks, material testing, and NDT. The MPS should be evaluated prior to the start of production for conformance with customer specifications, industry standards, and the intended service of the product (sour, high temperature, arctic, etc.). Exceptions to the specification taken by the supplier should be carefully considered to assess the likelihood that the final product performance will meet the project criteria.

A pre-production meeting should be held to identify roles and responsibilities of the manufacturer, purchaser and/or surveillance inspectors. Meeting minutes should be retained and any agreed upon changes incorporated into the MPS prior to the start of production. When materials are to be purchased periodically from distributor’s stock the expectation is that the company would have described the QMS requirements to the supplier with enough lead time that the supplier could relay the QMS requirements to the manufacturer and coordinate the preparation of the related audits, inspections, and documentation, if applicable. Distributors and suppliers should keep records of original product specifications, MPS and ITP when required during production (i.e. fittings originally manufactured to MSS SP-75), and any pre-production meeting minutes. Alternative plans for documenting data and information pertaining to material testing, properties and inspection may be necessary if some provisions of the QMS are impractical for components purchased on a less frequent basis or for those having less impact on project risk.

The MPS should clearly identify the suppliers of raw materials, consumables, and component parts, and the quality management practices utilized during the production of these materials. The MPS should also detail the requirements for any documentation provided by raw material, component part, and consumable suppliers in support of the manufacturer’s QMS.

The MPS should detail each step in the manufacturing process and describe the operation in sufficient detail to verify and confirm the process meets industry standards, regulatory requirements, and purchaser specifications. Manufacturing process controls and set points should be specified for monitoring during production. Examples sections within a MPS include but are not limited to:

• Quality control measure options selected to improve the quality;
• Training and competency requirements for personnel performing the activity;
• Inspection requirements;
• Training and competency requirements for the personnel performing the inspection; and
• Applicable records.

The quality plan should reference the documented procedure or specification for the task. Additionally, the personnel performing the task or inspection should be able to understand and competently follow the procedure and quality plan and self-check their work, as applicable. However, self-checking is not a suitable substitute for inspection by other personnel who were not directly involved in the performance of the manufacturing or fabrication task. If quality issues are identified, work should be stopped or the component quarantined and the issue should be communicated to the appropriate personnel. Depending on the project, the personnel performing the activity and the inspection may be employed by the pipeline operating company, contractor, or supplier. Consideration should be given to multiple reviews of tasks or activities, as warranted.

• Material specifications and requirements;
• Raw material manufacturing requirements;
• Receiving of materials and consumables;
• Material storage and marking requirements;
• Forming, casting, or forging;
• Welding and/or assembly;
• Heat treating;
• Acceptance testing and NDT procedures and reporting;
• Geometrical measurements and reporting;
• Material testing and reporting;
• Repair and re-work procedures;
• Disposition of non-conforming materials;
• Finishing and/or coating;
• Finished material documentation and material tracking; and
• Shipping and handling.

The MPS shall give consideration to the set-up and calibration of NDT equipment and measuring instruments used during the manufacturing process. Set-up and calibration procedures shall be established for all NDT equipment utilized during production. Corresponding personnel qualification requirements shall be listed for each operation. In the event the manufacturer utilizes NDT, measuring instruments, and/or material testing for production control, information, and/or raw material verification, the MPS shall specify the level of inspection and distribution of the results.

5.3 Development of Inspection and Test Plans (ITP)

When required by the pipeline operating company or referenced standard, required tasks for materials manufacturing shall include an ITP developed to establish activities or processes subject to monitoring, documentation review, when witnessing or verification activity is required, when testing of the product is required, or when a hold is required for production to wait for authorization to proceed.

An ITP is integral to establishing a uniform inspection and testing scheme that all parties (inspectors, manufacturers, and auditors) can follow during production. The uniform performance of activities allows for quality events to be measurable.

At a minimum, an ITP is typically developed for each pressure-carrying component of the pipeline system. The ITP should include as appropriate: testing frequency, acceptance criteria, calibration requirements, personnel qualification, reporting, and document retention. Additional information where applicable should include:

• segregation of non-conforming material;
• re-testing provisions, retention of test specimens; and
• supplemental testing of similar materials.

5.4 Manufacturing Traceability

Current industry standards do not require traceability of raw materials such as slabs, plates and welding consumables. Details and additional information concerning the specific material non-conformances listed above is lacking beyond identification of the heat numbers. Thermomechanical plate rolling practices necessary to achieve high strength base materials are not required to be traced to the mother plate. An improvement to the current standards and company specifications would be to include discrete plate tracking. Issues with wall thickness and grade may be resolved during the material receiving process if all plates from a specific mother plate can be identified. Similarly, issues of centerline segregation and variable properties within a given plate, as documented in pipe manufacturing, can be considered a risk in high strength component manufacturing^{Footnote 7}.

Consideration should be given to recording the unique identification of each manufacturing component, raw material and/or consumable. Individual identifiers may be consolidated under a single identifier utilizing an appropriate tracking system. Quality control documentation such as heat treatment data, pressure test data, NDT results, test pieces, and mechanical and metallurgical test results should be traceable to the finished goods.

Control of raw materials, consumables and finished goods throughout the manufacturing process is critical to identifying and segregating non-conforming materials. Additionally, traceability allows for the examination of similar items in the event that non-conformances are discovered.

Examples of items for consideration in a tracking system include but are not limited to pipe joints, fittings, castings, forgings, plate, skelp, welding consumables, heat numbers, lot numbers, and component serial numbers. Manufacturing and testing processes that employ more than one station, equipment operator or multiple discrete pieces of equipment should provide traceability to the finished goods. Examples include welding stations, furnaces, facing machines, assembly lines, tensile testers, and/or inspection stations.

In the case of distributor supplied components, the traceability is further diminished. Distributors provide a valuable service in the overall supply chain. Individual fittings are often necessary on short notice for maintenance projects or smaller projects. In many cases, it is impractical to commission a manufacturing run for small quantities of specific specification. However, obtaining additional manufacturing data for stock distributor fittings would benefit the process of determining the suitability of the material. Industry standards can be improved to include traceable raw material, heat treatment, and testing data for those products not project specific. Additionally, the pipeline operator procurement best practices including a CMTR pre-purchase review, supplemental NDE, and robust mill pre-qualification can benefit the procurement process.

The manufacturing traceability should be maintained after the piping or component is installed. Unique identifiers assigned to pipe and components and tied to geospatial locations and manufacturing traceability records facilitate the future location and assessment of any pipe or component that is related to possible performance deficiencies. The pipeline operator may employ tracking software that integrates with manufacturer systems and maintains product traceability from raw material through installed location.

5.5 Materials Inspection

Material inspection and testing requirements are specified in the MPS and ITP specific to the material being manufactured and the manufacturing process. All necessary witnessing, verification, testing, and documentation review shall be completed and accepted prior to the material or product being classified as finished goods and released to the project. Surveillance should be scheduled and implemented to provide comprehensive inspection of production. Processes that are observed are typically better controlled, and infrequent inspection may result in snap shots that are not representative of full production.

Deviations or upset conditions during the manufacturing process can lead to the introduction of defects in the finished product or the loss of traceability. Expectations for production performance such as pieces per shift, tests completed, product delivered, or repairs should be established to provide for condition monitoring. Deviations from these metrics during the manufacturing process may indicate an upset condition warranting further investigation. Hold points may be established to enable the testing and/or witnessing concurrent with the manufacturing process.

5.6 Raw materials verification

Based on the interviews conducted with the pipeline operating companies, it was identified by one pipeline operator that there is little to no traceability of distributor sourced components relative to the steel or plate mills, unlike the traceability in place for line pipe. MTR reviews and post procurement chemical analysis suggest that lean alloying chemistries may be an issue that when combined with variable heat treatment practices result in substandard material properties.

Other pipeline industry reviews have been conducted and the results documented. Chevron carried out review and testing of various flanges in response to recent incidents^{Footnote 8}. Their analysis identified that chemical composition limits are too permissive in MSS SP-75 and incomplete within ASTM A694. When microalloyed High Strength Low Alloy (HSLA) steel is used, traditional heat treating processes such as quenching and tempering are misapplied. Quality safeguards within industry standards are insufficient to identify all potential issues, and the use of sample coupons and/or testing of starting material may not accurately represent the properties of finished products.

Becht Engineering and Paulin Research Group (Becht) conducted burst tests of welding tees manufactured to ASME B16.9. Their testing indicated that fabrication techniques and acceptance criteria allowed by the standard can result in thinner sections of the tees which do not meet burst test requirements.^{Footnote 9} Becht postulated that it was likely that the current rules are allowing manufacturers searching for an economic advantage to use lower strength material that is easier to form and to use thinner pipe which is also easier to form. This practice may result in insufficient material in the crotch areas and a reduced margin for pressure containment capacity. Becht states that some manufacturers in certain cases are using 87.5 percent of the nominal thickness as a minimum thickness criteria. This practice is generally compliant with B16.9 due to the perceived vagueness of the ‘mathematical analyses’ requirements of paragraph 2.2.

Recommendations were submitted to the B16 committees, however the importance of raw material dimensional properties relative to other component manufacturing processes was not addressed. Case studies referenced above identified instances where elbows exhibited lower than specified wall thickness. Current standards do not provide for traceability to specific mother plates which limits the ability to identify and quarantine substandard plates prior to manufacturing of the component.

5.7 Manufacturing Procedure Qualification

Manufacturing procedures are often developed based on qualification testing. In many cases, trial products are manufactured and tested using a variety of base materials and processes. In this way, each manufacturer develops procedures that are specific to their plants, the installed equipment, and their raw material suppliers. This method results in plant specific processes. In the case of requirements for chemical composition and heat treatment, industry standard guidance in the form of maximum or minimum values are met, but the actual targets are in the manufacturer’s procedure. Deviations from any of the qualification production parameters such as furnace loading, furnace hold times, quench media temperature or agitation can result in substandard products even if the industry standard requirements are met. This effect is compounded if multiple deviations in production parameters occur. Chemical composition may create steels that are sensitive to small deviations in processing such as normalizing or tempering temperatures. Similarly, wall thickness deviations, furnace loading patterns, and furnace rack condition may affect furnace hold times. The cumulative effect of deviations should be addressed in the ITP which monitors specific processes to confirm compliance with the manufacturing procedure. Multiple deviations may trigger supplemental testing or production monitoring.

5.8 Inspection and Testing Enhancements

Pipeline operating companies who have experienced material issues identified inspection and testing improvement opportunities for both manufacturing facilities and distributors. Material testing is generally conducted using coupons which undergo similar forming operations and heat treatment. Coupons often consist of the same raw material (i.e. plate) welded or attached to a production fitting. This may take the form of a welding “run on/run off” tab in the case of formed and welded material. The following items may be considered for inclusion in company specifications and/or commercial agreements to ensure testing is representative of the finished products:

• Increase lot testing frequencies to ensure test results are available for all heat treatment batches.
• Specify locations of test coupons for lot testing including the location within furnace loads.
• Conduct additional furnace uniformity testing to ensure adequate temperature settings and equipment calibration.
• Conduct destructive tests of finished components to verify the accuracy of coupon tests.
• Conduct hardness and metallographic testing to supplement lot testing.
• Restrict the use of retesting and reheat treatments without prior company approval.
• Require charts or records of all heat treatment temperature and hold times in final documentation.
• Mandate traceability to clearly track each fitting from raw material to finished goods.
• Provide for documentation of raw material, process parameters and test results of fittings intended for distributors.
• Apply furnace loading, support and stacking procedures including the use of racks or stands.
• Apply requirements and calculations for heat treatment hold times.
• Apply quench temperature limits, agitation, and process time requirements.
• Apply minimum restrictions on material chemistries for high strength products.

5.9 Procurement

The current industry procurement protocols often rely on a pipeline operating company’s specifications to overcome gaps in industry standards. This creates an uneven playing field where pipeline operators with comprehensive specifications are placed in an uncompetitive position due to higher procurement costs. The opposing risk is that non-conforming materials are not promptly identified and allowed to be placed in operations.  Procurement of fabricated assembles (meter skids) or turn-key constructed facilities (pump stations) may involve an additional party purchasing fittings for inclusion in the assembly.

Based on the interviews conducted with the pipeline operating companies, it was identified by one pipeline operator that components are often procured through distributors based on a listing of pre-qualified manufacturers. The manufacturers are subject to removal should substandard or non-conforming materials be identified during the procurement acceptance and testing process.

Procurement policies and procedures including manufacturer pre-qualification and periodic review should be developed to ensure pipeline operator quality strategies are transferred to all parties in the supply chain.

5.10 Acceptance and testing

One pipeline operating company that was interviewed indicated that a pre- and post-purchase testing process has been initiated for distributor supplied components. MTRs are requested and reviewed against the pipeline operating company chemical specifications prior to issuance of the final purchase order. Prior to delivery to the job site, the pipeline operator visually inspects the component and conducts magnetic particle inspection (MPI) of the pipe ends and any suspect areas. Wall thickness is spot checked in addition to the checks initiated in areas identified by the visual inspection. The pipeline operating company does not allow substitutions of higher yield, lower wall thickness materials in part to avoid weldability issues in the field. The carbon equivalent (CE) value is reviewed at the MTR evaluation stage against pipeline operating company specifications and CSA and API standards.

6.0 Conclusion

Microalloyed high strength steels are very sensitive to changes in manufacturing processes such as thermomechanical rolling and heat treating. This sensitivity compounds small deviations in manufacturing process such as tempering temperature. To minimize the risk of substandard materials, the initial process qualification often referred to as First Article Inspection forms the basis for all subsequent manufacturing procedures and the Manufacturing Procedure Specification (MPS) when applicable.

Chemical composition limits are too permissive in MSS SP-75 and incomplete within ASTM A694. When microalloyed High Strength Low Alloy (HSLA) steel is used, traditional heat treating processes such as quenching and tempering, can be misapplied.

Manufacturers in certain cases are using 87.5 percent of the nominal thickness as a minimum thickness criteria. This practice is generally compliant with B16.9 due to the perceived vagueness of the ‘mathematical analyses’ requirements of paragraph 2.2.

Variables such as heat treatment and quenching temperatures, hold times, furnace load configurations, etc. should be sufficiently detailed to allow for quality control monitoring. Initial qualification testing should be rigorous and clearly define the resultant material properties as related to the product specification. Finally, the MPS and ITP should sufficiently define the process such that production inspection is efficiently and thoroughly conducted. Deviations from the process need to be quickly identified and supplemental testing utilized to define the impact. A robust system of traceability should allow for all materials affected by a process disruption to be identified and segregated to prevent their entry into the supply chain.

The failure of components to conform to standards and specifications, as investigated in this report, is a direct result of failures to control the manufacturing processes. These failures were not identified by the established ITP protocols, either during production monitoring or subsequent material acceptance testing.

Enhancements to current industry standards are recommended to close the gaps identified between standards, manufacturing processes and the intended component performance (See Table 2). Pipeline operators and/or distributors should consider enhancing product specifications to provide more rigorous traceability, process monitoring and product testing.

Appendix A
Gap Analysis

A gap analysis was performed to compare selected standards against a list of criteria. The criteria were:

• Fabrication of material
  • Chemistry aim points and limits
  • Carbon equivalent
  • Heat identification
  • Slab casting requirements, slab identification, and traceability
  • Plate or skelp requirements, testing requirements, identification, and traceability
  • Plate or skelp shipping and handling requirements
  • Heat Treating
  • Forming
  • Welding
  • Hydrotesting
  • Sizing and dimensions
  • Grade requirements
  • Marking requirements
  • Shipping and Handling
• Quality control
  • Product Ordering Requirements
  • Manufacturer Procedure Specifications (MPS)
  • Inspection and Test Plan (ITP)
  • Certified Material Test Report (CMTR)
  • Material receiving and Identification
  • Nondestructive examination (NDE)
  • Defects
  • Retests
  • Final Inspection
• Traceability

The resulting comparison appears in the table below. Pipeline operator qualification was not considered, nor were procedures related to sour service.

The Standards reviewed were as followed:

• CSA Z662-15, Oil and gas pipeline systems
• CSA Z245.1-14, Steel Pipe
• CSA Z245.11-13, Steel Fittings
• MSS SP-75 (2014), High Strength, Wrought, Butt-Welding Fitting

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Date modified:

2021-07-20