By Chip Edwards, President of Allan Edwards, Inc.
Full encirclement steel sleeves have been a popular repair solution for many years and are widely used by pipeline operators. Yet, despite their common acceptance and steady popularity, there is no universal manufacturing specification recognised or enforced by any pipeline industry regulatory body that governs the manufacturing of steel repair sleeves.
As a long-time industry stakeholder throughout its 76 years in business, Allan Edwards observed this gap in recent years and began taking action to standardise and elevate industry practice concerning steel sleeves. Leveraging generations of first-hand experience and trusted expertise, Allan Edwards has adopted a universal steel sleeve specification to ensure a consistent quality baseline is maintained during the manufacturing of all steel sleeves.
A core focus of Allan Edwards is to steer industry advancement while optimising pipeline performance, a focus demonstrated through its full lineup of industry offerings.
A lack of unified standards
While plenty of regulations detail applications for full encirclement sleeves, as well as minimum standards for their installation, there is no formal baseline that sleeve manufacturers must abide by when manufacturing repair sleeves. In short, this means that there is no standardised method for operators to verify the quality of manufactured sleeve material they receive from a sleeve vendor, aside from a visual inspection and any required documentation, such as material test reports (MTRs).
Regulations such as API 1176 dictate the types of defects that repair sleeves can be used to reinforce. Other documents such as ASME B31.8 and ASME PPC-2 recommend welding procedures when installing repair sleeves, as well as minimum wall thicknesses, design pressures, lengths and grade requirements that vary per pipeline anomaly. However, aside from visual inspection, heat number logging and MTR traceability, there is no acceptance (or rejection) standard used to assess the quality of manufactured repair sleeves, nor is there a required set of engineering tests that sleeves must undergo when they are produced (aside from the raw materials’ requirements).
Manufacturing requirements and quality assurance testing have been left to individual sleeve providers to determine – unless operators outline their own unique sleeve manufacturing specifications.
What constitutes a repair sleeve?
Aside from the absence of a universal manufacturing specification, an interesting discussion point has arisen in recent years centering around the definition of a welded repair sleeve. Some operators interpret a full encirclement sleeve exclusively as two pieces of split half pipe. By this definition, steel repair sleeves manufactured from rolled plate would not be considered a repair sleeve. This distinction is marked by the intensive hydrostatic testing and other engineering tests that in-service pipelines – and, by extension, the pre-tested pipe sleeve halves – must undergo to qualify for service. These rigorous testing requirements alone act as somewhat of a manufacturing specification.
Because of the pipe’s stringent testing requirements, some operators prefer split half pipe sleeves to manufactured repair sleeves. Unfortunately, this type of repair sleeve can be expensive for operators, result in substantial waste, and contribute to fit-up problems during installation.
The complications of using split half pipe sleeves
The fundamental issue with constructing sleeves from split pieces of pipe is that the inner diameter (ID) of the 180-degree sleeve half will not fit effectively over the outer diameter (OD) of the same size pipeline. For example, attempting to fit a 24-inch split pipe sleeve over a 24-inch pipeline will result in a fit-up gap because the pipe OD is larger than the ID of the split pipe sleeve. To account for this ID/OD differential, the sleeve halves must each be cut to cover a minimum of 185 degrees of the pipe surface.
Loosely translated, twice the amount of pipe would be needed to complete a single split pipe sleeve repair because, while the overcut section is used, the undercut section must be discarded. This generates significant waste compared to manufactured steel sleeves. Even if a larger-diameter split pipe sleeve was used, it would have to be re-rounded to fit the smaller pipeline – a scenario not feasible in the field.
Fit-up issues are common with split pipe sleeve repairs, as the sleeve halves have not been made to fit together well. In 2021, Allan Edwards commissioned an independent report on the critical importance of sleeve fit-up when reinforcing pipeline defects that highlighted these issues.
Understandably, the blurred regulatory clarity on sleeve manufacturing standards as well as the differing opinions on what constitutes a repair sleeve has led some operators to stay away from steel repair sleeves altogether, whether constructed from split pipe or manufactured from steel plate.
Bridging the manufactured repair sleeve gap
Operators need to know that their manufactured repair sleeves are not only installed correctly but tested and manufactured in accordance with strict guidelines. In the past, Allan Edwards catered to multiple customer requirements, varying the sleeve specifications based on customers’ requests. This “tiering out” according to operator mandate often became complicated: certain sleeves would be suitable for one operator but not another.
However, in late 2021, Allan Edwards adopted and began building to a single manufacturing specification with the highest-possible quality standard, meaning virtually all sleeves are suitable and interchangeable to fulfill any order – and all sleeves (apart from very specialised orders) meet or exceed the most stringent operator expectations.
This change allowed Allan Edwards to reduce inefficiencies while maintaining a leaner inventory stock. Allan Edwards repair sleeves now exceed the highest quality assurance standards available.
Allan Edwards’ universal sleeve specification requirements
Facility: Rigorous standards must be upheld within the manufacturing facility, ensuring proper tooling and equipment to support the forming of half sole sleeves.
Incoming inspection: (100 per cent of material received): Heat numbers and MTRs are tracked for both incoming steel plate and backing strips. All incoming plate is tensile tested and Charpy V-notch tested in accordance with ASTM specifications. The Allan Edwards MTR Portal acts as a document storage database where customers can conveniently access all sleeve order documentation through a unique user login.
100% ultrasonic testing: Phased array UT inspection is performed on 100 per cent of incoming plate prior to sleeve formation.
Fabrication: In addition to regularly scheduled maintenance, logging and tagging, all inspection and measurement tools are marked with expiration dates and must be calibrated annually. Backing strips are provided along with the sleeve to prevent the longitudinal weld from burning through to the carrier pipe.
Starting materials: All plate used to form half-sole sleeves is from stock plates which are structural or pressure-vessel quality carbon steel in grades and specified minimum yield strength (SMYS). All tensile strengths, yield strengths and chemical compositions are in alignment with the requirements specified for the ASTM material ordered, and maximum allowable carbon equivalent is calculated according to recommended guidelines.
Forming and dimensional requirements: Half-sole sleeves are formed by rolling or die forming, or both. They are manufactured so that when two halves of the sleeve are placed on the pipe, their total internal circumference equals the outside circumference of the nominal pipe size minus a 1/16 inch gap for welding between the longitudinal edges on either side as per industry standards. Longitudinal edges are beveled to a 30-degree angle.
Final inspection: A final inspection is performed under 500-lux lighting prior to any sleeve departing the yard to ensure no defects are present. All dimensions, including end and side preparation, are measured and verified. Any sleeve that is found to have a defect is rejected.
Marking, shipping and documentation: All sleeves in each bundle are clearly marked with size, wall thickness and grade of plate. Sleeves are stacked and shipped to prevent any distortion in geometry or symmetry of the sleeves that could adversely affect installation. Once the sleeves are ready for shipment, Allan Edwards submits a data package set for each order containing MTRs, non-destructive evaluation (NDE) reports and mechanical testing data. This package is easily accessed through the Customer MTR Portal.
Top-tier manufacturing specifications coupled with a decade of sleeve validation testing
Allan Edwards has recognised and fulfilled a need to standardise sleeve manufacturing through adopting a high-quality manufacturing specification where no benchmark existed. Additionally, in early 2022, it released a comprehensive sleeve testing book, which breaks down the company’s extensive investment in validation testing over the last decade.
The top-tier specification Allan Edwards adheres to – coupled with significant testing data to validate sleeve performance – ensures confidence that Allan Edwards sleeves are a high-quality, long-lasting, and reliable repair method to reinforce pipeline performance. With Allan Edwards sleeves, operators install repair products with full manufacturing transparency and reliable testing data to back their performance.
Allan Edwards’ steel repair sleeves are available in the Oceania region through its agent Tremco Pipeline Equipment. To learn more about how Allan Edwards’ repair sleeves can ensure a safe effective and cost-efficient repair on your pipeline, contact Brett Trembath at firstname.lastname@example.org or call 07 3344 1066.