Design Method Combining API and ASME Codes for Subsea Equipment for HP/HT Conditions Up to 25,000-psi Pressure and 400°F Temperature
Bibliographic record
Abstract
Summary A current challenge in the offshore industry is the design of subsea equipment for pressures exceeding 15,000 psi and temperatures exceeding 250°F. This combination of pressure and temperature has been fairly accepted as the start of the high-pressure/high-temperature (HP/HT) region. The current American Petroleum Institute (API) standard for designing subsea equipment, API Specification (SPEC) 17D (2011), is limited to a working pressure of 15,000 psi and provides little guidance on temperature conditions exceeding 250°F. This paper demonstrates a design methodology which combines the API and American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) for designing an example subsea pressure containing component for HP/HT conditions greater than 15,000 psi and 250°F. This paper shows the evaluation of a combined load-capacity chart for an API SPEC 17D flange flow-loop [API SPEC 6A (2010), 4 in., 20 ksi) for a design pressure of 20,000 psi and a temperature of 350°F with external tension and bending loads. Both the linear elastic and elastic plastic methods for protection against plastic collapse are used to determine the structural capacity of the flange body. These methods combine the API material and design allowables and ASME design methods. Stress classification and linearization are used for the evaluation of design capacities with linear methods. Modified load-resistance design factors are used both to evaluate design capacities and to account for the difference in ASME and API hydrostatic-test pressures with elastic-plastic methods. The structural capacity is combined with thermal analysis to determine the effects of high temperature on the flange capacity. To assess the cyclic-loading capacity of the flange, stress-based fatigue analysis and fracture-mechanics analysis are also compared. The results obtained are comparable to existing API Technical Report (TR) 6AF1 (1998) charts. This work has been performed to demonstrate both the acceptance of existing methods for HP/HT conditions and to introduce the advanced ASME design methods for designing API SPEC 17D subsea equipment. The methods presented are acceptable for designing equipment up to working pressures of up to 25,000 psi and temperatures up to 400°F.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.021 | 0.005 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".