Evaluation of Maintenance Intervals for Spring-Operated Relief Valves Using a Risk-Based Inspection Technique

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Robert E. Gross ◽  
Emily M. Mitchell ◽  
Stephen P. Harris
Keyword(s):  
Financial Risk ◽  
Cost Effective ◽  
Process Equipment ◽  
Parameter Estimates ◽  
Savannah River ◽  
Relief Valve ◽  
Equipment Reliability ◽  
Chemical Process Safety ◽  
The Impact ◽  
River Site

The Savannah River Site (SRS) spring-operated relief valve (SORV) maintenance intervals were evaluated using the American Petroleum Institute’s (API) inspection updating approach in API RP 581 for Risk-Based Inspection (RBI) technology. In addition, the impact of extending the inspection schedule was evaluated using Monte Carlo simulation (MCS). The API RP 581 approach is characterized as a Weibull analysis with modified Bayesian updating. Initial Weibull parameter estimates were updated using SRS’s historical proof test records contained in the Center for Chemical Process Safety Process Equipment Reliability Database. The API RP 581 methodology was used to estimate the SORV’s probability of failing on demand and the annual expected risk. An illustration of the inspection costs versus the associated risks is provided. Current practices are reviewed, and recommendations are made for extending maintenance intervals. A cost-effective maintenance frequency balancing both financial risk and inspection cost is demonstrated.

New Insights on the Impact of High Temperature Conditions (176°C) on Carbonate and Sulphate Scale Dissolver Performance

2014 ◽  
Author(s):  
Myles M. Jordan ◽  
Helen Williams ◽  
Sandra Linares-Samaniego ◽  
Dario M. Frigo
Keyword(s):  
Organic Acid ◽  
High Temperatures ◽  
Cost Effective ◽  
Temperature Limit ◽  
Thermal Ageing ◽  
Process Equipment ◽  
Acid Mixture ◽  
Alkaline Ph ◽  
Calcite Dissolution ◽  
The Impact

Abstract Scale-dissolver technology has been developed and applied with varying degrees of success over the past few years to remove carbonate and the more challenging sulphate/sulphide scales from production tubing and process equipment. It can often seem a much safer, more cost-effective remediation approach than physical removal, in particular, in the new generation of HP/HT fields, where any physical well intervention carries high risk, while the high temperatures would normally be beneficial in enhancing scale solubility and dissolution rate. The current paper reports dissolution characterstics of three solvents for calcite, barite, celestite and anhydrite in the temperature range 85°C to 176° to verify their performance up to the very high temperatures of a specific HP/HT development. These solvents included a typical alkaline-pH chelant for sulphate scale, an organic-acid mixture for carbonate scales, and a novel neutral-pH chelant as a less corrosive solvent for carbonate scale removal. In some tests the liquid-to-solid ratiowasvaried to evaluate the impact of excess scale on solvent performance. The performance against BaSO4 of the alkaline-pH chelant unexpectedly declines very significantly at 176°C relative to that observed at 85°C. Thermal instability was ruled out as the cause becausethe solvent showed very limited decline in performance when tested at 85°C after it had been thermally aged at 176°C. Performance at 176°C showed an initial rise followed by a decreasein aqueous barium ions, strongly indicating secondary re-precipitation of a barium-containing species at this temperature. In contrast, dissolution rates of carbonate scale by organic acid were greaterat the higher temperature, as would be expected. The novel neutral chelant showed a decline in calcite dissolution performance during the 176°C test but unlike the alkaline-pH chelant used for sulphate scale, this chelant showed degradation after thermal ageing and re-testing at 85°C. The findings from this paper suggest that there is temperature limit above which effective removal of sulphate scales may not be feasible with the selected solvents due to re-precipitation of a secondary reaction product, while for carbonate removal the current neutral chelants tested have a thermal stability issue at 176°C. These findings need to be considered when evaluating the potential role of chemical remediation in the overall scale-control strategy for HP/HT fields.

scholarly journals Assessing the Impact of Equipment Aging on System Performance Using Simulation Modeling Methods

2006 ◽  
Author(s):  
N. K. Gupta
Keyword(s):  
Inductively Coupled Plasma ◽  
Discrete Event ◽  
Radioactive Material ◽  
Savannah River ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Delay Times ◽  
Event Model ◽  
The Impact ◽  
River Site

The radiological Inductively Coupled Plasma Mass Spectrometer (ICP-MS) is used to analyze the radioactive samples collected from different radioactive material processing operations at Savannah River Site (SRS). The expeditious processing of these samples is important for safe and reliable operations at SRS. As the radiological (RAD) ICP-MS machine ages, the experience shows that replacement parts and repairs are difficult to obtain on time for reliable operations after 5 years of service. A discrete event model using commercial software EXTEND was prepared to assess the impact on sample turn around times as the ICP-MS gets older. The model was prepared using the sample statistics from the previous 4 years. Machine utilization rates were calculated for the new machine, 5 year old machine, 10 year old machine, and a 12 year old machine. Computer simulations were run for these periods and the sample delay times calculated. The model was validated against the sample statistics collected from the previous 4 quarters. 90% confidence intervals were calculated for the 10th, 25th, 50th, and 90th quantiles of the samples. The simulation results show that if 50% of the samples are needed on time for efficient site operations, a 10 year old machine could take nearly 50 days longer to process these samples than a 5-year old machine.

scholarly journals Innovative Integration of Decommissioning and Deactivation Program With Soil-Groundwater Clean Up Program Has Positive Results on Budget and Schedule: A Case Study

2007 ◽  
Author(s):  
Bruce G. Schappell ◽  
Gregory G. Rucker
Keyword(s):  
Economies Of Scale ◽  
Cost Savings ◽  
Cost Effective ◽  
Savannah River ◽  
New Approach ◽  
The Common ◽  
Document Generation ◽  
River Site ◽  
Positive Results

An innovative approach to integrate the activities of a decommissioning and deactivation program (D&D) with a soil-groundwater clean up program has had significant positive results saving both money and time at the Department of Energy’s Savannah River Site. The accomplishments that have been achieved by the combining the two programs have been remarkable including significant cost savings, economies of scale for sampling and document generation, and alignment of common objectives. Because of the coordination of both activities area-wide “end states” can be formulated and be consistent with the customers’ cleanup goals and federal regulations. This coordinates and aligns both the environmental clean up and D&D objectives because each must be addressed simultaneously and comprehensively. In this respect, resources from both organizations can be pooled to take advantage of the strengths of each. The new approach allows more efficient use of lean financial resources and optimizes workforce activities to attain the common objectives while being more cost effective, more protective of the environment, and optimizing the use existing resources.

The Impact of Missing and Error-Prone Auxiliary Information on Sparse-Matrix Sub-Population Parameter Estimates

Methodology ◽  
2015 ◽  
Vol 11 (3) ◽  
pp. 89-99 ◽  
Author(s):  
Leslie Rutkowski ◽  
Yan Zhou
Keyword(s):  
Sparse Matrix ◽  
Small Body ◽  
Auxiliary Information ◽  
Poor Quality ◽  
Quality Data ◽  
Estimation Methods ◽  
Parameter Estimates ◽  
Population Parameter ◽  
Conditioning Model ◽  
The Impact

Abstract. Given a consistent interest in comparing achievement across sub-populations in international assessments such as TIMSS, PIRLS, and PISA, it is critical that sub-population achievement is estimated reliably and with sufficient precision. As such, we systematically examine the limitations to current estimation methods used by these programs. Using a simulation study along with empirical results from the 2007 cycle of TIMSS, we show that a combination of missing and misclassified data in the conditioning model induces biases in sub-population achievement estimates, the magnitude and degree to which can be readily explained by data quality. Importantly, estimated biases in sub-population achievement are limited to the conditioning variable with poor-quality data while other sub-population achievement estimates are unaffected. Findings are generally in line with theory on missing and error-prone covariates. The current research adds to a small body of literature that has noted some of the limitations to sub-population estimation.

Regulatory and sustainability initiatives lead to improved polyaminopolyamide epichlorohydrin (PAE) wet-strength resins and paper products

TAPPI Journal ◽  
2018 ◽  
Vol 17 (09) ◽  
pp. 519-532 ◽  
Author(s):  
Mark Crisp ◽  
Richard Riehle
Keyword(s):  
Health And Safety ◽  
Cost Effective ◽  
Worker Safety ◽  
Regulatory Requirements ◽  
Wet Strength ◽  
The Past ◽  
Consumer Safety ◽  
Federal Institute ◽  
Sustainability Initiatives ◽  
The Impact

Polyaminopolyamide-epichlorohydrin (PAE) resins are the predominant commercial products used to manufacture wet-strengthened paper products for grades requiring wet-strength permanence. Since their development in the late 1950s, the first generation (G1) resins have proven to be one of the most cost-effective technologies available to provide wet strength to paper. Throughout the past three decades, regulatory directives and sustainability initiatives from various organizations have driven the development of cleaner and safer PAE resins and paper products. Early efforts in this area focused on improving worker safety and reducing the impact of PAE resins on the environment. These efforts led to the development of resins containing significantly reduced levels of 1,3-dichloro-2-propanol (1,3-DCP) and 3-monochloropropane-1,2-diol (3-MCPD), potentially carcinogenic byproducts formed during the manufacturing process of PAE resins. As the levels of these byproducts decreased, the environmental, health, and safety (EH&S) profile of PAE resins and paper products improved. Recent initiatives from major retailers are focusing on product ingredient transparency and quality, thus encouraging the development of safer product formulations while maintaining performance. PAE resin research over the past 20 years has been directed toward regulatory requirements to improve consumer safety and minimize exposure to potentially carcinogenic materials found in various paper products. One of the best known regulatory requirements is the recommendations of the German Federal Institute for Risk Assessment (BfR), which defines the levels of 1,3-DCP and 3-MCPD that can be extracted by water from various food contact grades of paper. These criteria led to the development of third generation (G3) products that contain very low levels of 1,3-DCP (typically <10 parts per million in the as-received/delivered resin). This paper outlines the PAE resin chemical contributors to adsorbable organic halogens and 3-MCPD in paper and provides recommendations for the use of each PAE resin product generation (G1, G1.5, G2, G2.5, and G3).

Exploring the Benefits of Early Contractor Involvement (ECI) and the Mechanism for Automated 5D BIM Quantification Process in Offsite Modular Construction

2016 ◽  
Author(s):  
Tochukwu Moses ◽  
David Heesom ◽  
David Oloke ◽  
Martin Crouch
Keyword(s):  
Effective Means ◽  
Cost Effective ◽  
Modular Construction ◽  
Automated Quantification ◽  
Building Information ◽  
Project Risks ◽  
Value Add ◽  
The Uk ◽  
The Impact ◽  
Level 2

The UK Construction Industry through its Government Construction Strategy has recently been mandated to implement Level 2 Building Information Modelling (BIM) on public sector projects. This move, along with other initiatives is key to driving a requirement for 25% cost reduction (establishing the most cost-effective means) on. Other key deliverables within the strategy include reduction in overall project time, early contractor involvement, improved sustainability and enhanced product quality. Collaboration and integrated project delivery is central to the level 2 implementation strategy yet the key protocols or standards relative to cost within BIM processes is not well defined. As offsite construction becomes more prolific within the UK construction sector, this construction approach coupled with BIM, particularly 5D automated quantification process, and early contractor involvement provides significant opportunities for the sector to meet government targets. Early contractor involvement is supported by both the industry and the successive Governments as a credible means to avoid and manage project risks, encourage innovation and value add, making cost and project time predictable, and improving outcomes. The contractor is seen as an expert in construction and could be counter intuitive to exclude such valuable expertise from the pre-construction phase especially with the BIM intent of äóÖbuild it twiceäó», once virtually and once physically. In particular when offsite construction is used, the contractoräó»s construction expertise should be leveraged for the virtual build in BIM-designed projects to ensure a fully streamlined process. Building in a layer of automated costing through 5D BIM will bring about a more robust method of quantification and can help to deliver the 25% reduction in overall cost of a project. Using a literature review and a case study, this paper will look into the benefits of Early Contractor Involvement (ECI) and the impact of 5D BIM on the offsite construction process.

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