Our Updated Sleeve Manufacturing Specification – And How It Benefits Our Customers
Written 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 manufacturing specification governing the fabrication of steel repair sleeves either recognized or enforced by any regulatory body in the pipeline industry.
A Lack of Unified Standards
While plenty of regulations detail usages and 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 fabricating repair sleeves. In short, this means that there is no standardized 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 like 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. Manufacturing requirements and quality assurance testing have been left to individual fabrication shops to determine – unless operators provide their own unique sleeve 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, split half pipe sleeves – must undergo to qualify for service. These rigorous testing requirements alone act as somewhat of a manufacturing spec.
Because of their stringent testing requirements, some operators prefer split half pipe sleeves to manufactured repair sleeves. Unfortunately, this type of repair sleeve can be extremely expensive for operators, results in substantial waste, and contributes to fit-up problems during installation.
The Complications of Using Split Half Pipe Sleeves
The fundamental issue with constructing sleeves from split pieces of half pipe is that the ID of the 180-degree sleeve half will not fit effectively over the OD of the same size pipeline. For example, attempting to fit a 24” half pipe sleeve over a 24” 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, or 370 degrees of the total circumference. Loosely translated, twice the amount of pipe would be needed to complete a single split pipe sleeve repair compared to ordering the exact required amount of manufactured repair 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 possible 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. See our paper on the critical importance of sleeve fit-up when reinforcing pipeline defects.
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 rolled plate.
Bridging the Manufactured Repair Sleeve Gap
Allan Edwards saw a gap that needed to be filled – both to standardize as well as elevate the manufacturing expectations for steel repair sleeves in the oil and gas pipeline industry. 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 different customer requirements, varying the sleeve spec per customer request. 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 nearly all sleeves are suitable and interchangeable to fulfill any order – and all sleeves (apart from very specialized orders) meet or exceed the most stringent operator expectations.
This change allowed us to reduce inefficiencies while maintaining a leaner inventory stock. Allan Edwards repair sleeves now exceed the highest quality assurance standards available. The sleeve specification that we now adhere to covers multiple categories:
Facility: We uphold rigorous standards for our manufacturing facility, ensuring proper tooling and equipment to support the forming of Half-Sole sleeves.
Incoming Inspection: (100% of material received): We track Heat numbers & Mill test reports (MTRs) for both incoming steel plate and backing strips. 100% of incoming plate is tensile tested and Charpy V-notch tested in accordance with ASTM specifications.
100% Ultrasonic Testing: We perform UT inspection on 100% of the plate that arrives in our shop prior to sleeve formation.
Fabrication: In addition to regularly scheduled maintenance, logging & 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 Half-Sole 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 quality carbon steel in the grades and SMYS. All tensile strengths, yield strengths and chemical compositions are in alignment with the percentages specified for the ASTM material ordered, and maximum allowable carbon equivalent is calculated according to recommended PRCI guidelines.
Forming & Dimensional Requirements: Our 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” gap for welding between the longitudinal edges on either side per API STD 1104. Longitudinal edges are beveled to a 30-degree angle.
Final Inspection: A final inspection is performed under a 500-lux light prior to any sleeve departing from our 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 & Documentation: All sleeves in each bundle are clearly marked with size, wall thickness, grade of plate, sleeve serial number and job number. Sleeves are stacked and shipped in such a manner as 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, NDE (Non-Destructive Evaluation) reports and mechanical testing data.
A Top-Tier Manufacturing Spec Coupled with a Decade of Sleeve Validation Testing
Allan Edwards recognized and fulfilled a need to standardize fabrication through adopting a high-quality manufactured sleeve specification where no benchmark existed. Additionally, in early 2022, we released our comprehensive sleeve testing book, which breaks down our extensive investment in validation testing over the last decade. The top-tier specification we adhere to, coupled with the significant testing data validating our sleeve performance, makes us confident that Allan Edwards sleeves are a high-quality, long-lasting, and reliable repair method to restore & reinforce the serviceability of pipelines. With Allan Edwards sleeves, operators install safe, effective, and cost-efficient repair products with full manufacturing transparency and reliable testing data to back their performance.