Spiral welded pipe for oil & gas: State-of-the-artFor: A Group of Sponsors

Spiral welded pipe offers cost benefits over UOE pipe and is used in utility duties successfully, but,acceptance of this product form for oil and gas applications is markedly varied. Industry requiresbetter information on the technical issues related to specification and production of spiral weldedpipe for oil & gas applications, so that cost savings can be realised wherever possible, withoutcompromising safety.

It is proposed that a global review of the state-of-the-art of spiral welded pipe for oil and gasapplications be undertaken, similar to a successful TWI review of ERW/HFI line pipe. This willcollate experience and concerns worldwide from pipe manufacturers, pipeline installation companiesand operators, producing a single source document to provide guidance on appropriate use ofspiral welded pipe, and identify areas where additional data is required to increase confidence.

PR6161 August 2002

BACKGROUND

Spiral welded pipe offers cost benefits over UOE pipe (estimated at 10-15%) and is used forwater supply and structural applications successfully. In contrast, acceptance of this productform for oil and gas applications is markedly varied. There is a wide range of opinion withsome operators allowing utilisation of spiral pipe for oil & gas pipelines applications in sourservice, however, others will not allow spiral welded pipe even for sweet transmissionpipelines. This has resulted in a restriction on application in certain regions of the world andstrong differences in approach between multinationals.

The opportunity to realise wider application of the cheaper product and associatedcost-savings is therefore restricted through lack of confidence based upon perception andhistoric stance. Differences obviously exist between UOE and spiral welded pipe and it maynot be possible to specify spiral pipe in all applications, but such decisions should be basedupon technical assessment of modern products. Furthermore, if technical concerns areidentified and successfully addressed, the opportunities for wider application of spiral pipewill be increased.

There is significant growth in pipeline projects to satisfy demands for gas on a global scaleranging from $500million to $7billion planned around the world over the next few years (1).Most large projects cover distances typically 200-800km, but there are some proposedprojects between 1500-4200km. Thus, where practical, use of a cheaper pipe product willprovide significant savings. Additionally, many projects in areas of new developments willoften require inclusion of certain levels of material sourcing from within the host country. Inthese cases, UOE pipe may not be available and therefore the project must ensure thatadequate specifications are imposed upon the spiral pipe mill to satisfy fitness-for-purposecriteria.

Therefore, confidence regarding product specification, production and subsequentperformance needs bolstering to provide industry with a viable product choice realising costsavings but without compromising safety. A similar situation existed with ERW/HFI linepipe despite the high quality products achievable today. A recent TWI JIP/GSP successfullyreviewed the global state-of-the-art issues associated with specification of the material,manufacturing process and application for this product form (2). The concerns regardingapplication in sour service are presently being addressed in TWI laboratory studies (3). It isproposed that a similar approach be adopted for spiral welded pipe with independentassessment of the issues affecting widespread use of this product, allowing operators to gainadvantage of the cost savings without impacting upon safety.

BENEFITS

The benefit of wider adoption of spiralwelded pipe for oil & gas service willresult in reduced capital expenditure forpipeline development / replacement. Thespecific savings will depend heavily uponthe project, pipeline length, location etc,but may be about 10-15% of material costfor a typical application.

OBJECTIVES

• Development of an independentstate-of-the-art review of thecurrent experience and concernsinfluencing utilisation of spiralwelded pipe for oil and gas linepipeapplications.

• Identification of necessary datarequired for derivation of the safe

application envelope for spiralwelded pipe including associatedproduction criteria.

APPROACH

The project will involve the collation ofanonymous data from pipe manufacturers,installation contractors and pipelineoperators regarding current manufactureand usage of spiral welded pipe in oil andgas duty. This will include the applicationsand any limitations applied, e.g. only fortransmission networks. In addition,feedback will be sought on the primaryconcerns of contractors and operatorsleading to restriction in application, orindeed, complete avoidance of this productform.

The Sponsor Group is anticipated to beable to provide direct input and to assistwith identification of key individuals in theindustry to maximise the data set.

1. Pipe manufacture and specification

It is recognised that quality control isparamount in the production of seamwelded pipe. In this respect, the followinginformation will be sought from both themanufacturers and the pipeline engineeringand installation contractors:

• Material specification and skelpsourcing

• Manufacturing process and weldingcontrol

• Manufacturer inspection and testingprotocols

• Client specification requirements andmill auditing schemes

2. Pipeline fabrication and installation

Experience of fabrication and installationwill be sought from installation contractorsand operators.

3. Cost savings

Based upon feedback from industry, spiralwelded pipe will be reviewed in terms ofcost comparison with UOE product. Thiswill be on the basis of product cost andpipeline installation costs. Confidentialityof information source will be maintained,with input gathered from across theindustry.

4. Service performance

In order to address concerns over productsuitability, information will be sought frompipe manufacturers, pipeline engineeringcontractors and operators. Service historywill be sought covering both failures andsatisfactory service. Where possible,details of the failures will be obtained toallow considered judgement by TWI.

5. Review and recommendations

The foregoing information will be subjectto detailed review and assessment toidentify the key factors influencingdecisions on pipe product selection. TWIwill highlight the factors which arerestricting further use of spiral weldedpipe. In addition the cost savings whichmay potentially be achieved will behighlighted.

These findings will be discussed with theSponsor Group for consideration of anynecessary additional work needed toaddress the remaining issues. Such aprogramme would be subject to a separateproposal and may include laboratory testsand similar assessments.

REPORTING

During the project a progress statementwill be issued at four months. Feedbackwill be collated verbally and electronicallyfrom the Sponsor Group. A draft finalreport will be produced and discussed at aSponsor Group Meeting at nine months.Any revisions will be issued as a finalreport at the end of the project.

PRICE AND DURATION

The anticipated duration of the project is10 months, although the schedule will bedependent upon the rate of response andsupport from industry.

The price of the study is estimated as £64kIt is proposed that this be distributed overeight sponsors each contributing a singlepayment of £8,000 excluding VAT.

REFERENCES

1. Hart’s E&P, December 2001pp71-72

2. TWI Project Reference 12149:‘ERW/HFI welded line pipe forsour service applications –Phase I’ completed in February2000.

3. TWI Project Reference 12953:‘The Use of ERW/HFI Linepipefor Sour Service Applications -Phase II’