Valve Stations Research Articles

Unforeseen Shock Hazards Resulting From Code Compliance: A Case Study at an Above-Ground Pipeline Valve Station

The Code of Federal Regulations (CFR) is a regulatory collection of general and permanent federal agency rules. This case study is specific to two sections pertaining to the control of corrosion and electrical protection of underground pipe lines and valve stations. The transportation of hazardous liquids is covered by 49 CFR 195 and the transportation of natural gasses by 49 CFR 192. Meeting compliance is obtained with the installation of devices and systems that electrically isolate a cathodically protected pipe line and valve stations from nearby grounded structures and equipment. This study focuses on a cathodically protected pipeline isolation system that exposed a worker to a higherthan- expected voltage level and unexpected hazard when work was performed at a valve station after the installation of a required isolation device.

Engineering design highlights of high-efficiency slab casters relocated at Baosteel Zhanjiang

Baosteel Group decided in 2013 to relocate the main segment equipment of the 2 single-strand 2,300 mm slab casters which were shut down at its Luojing Plant to the Zhanjiang Plant and transform them into an upgraded two-strand slab caster. CISDI was contracted to supply the overall design and the main equipment packages. CISDI employed a couple of advanced technologies including online mould width adjustment, top-inserted dummy bar, dual strand tracking and casting at constant speeds to enhance the production capacity of the caster; for sake of Opex saving CISDI also optimized the arrangements of the independent mechanical maintenance shop, utilities of compact design, cooling water valve stations and hydraulic valve stations of compact designs, and open-air cooling water pump station, etc.

Esso pipeline replacement project

Esso recently commissioned (October 2017) a new 350-mm 187-km-long pipeline for carrying crude and condensate from Esso’s Longford Plant (Longford) in Gippsland Victoria, along an existing easement to the Long Island Point facility (LIP) at Hastings, Victoria. This pipeline replaces an existing 700-mm pipeline that was approaching the end of its operational life. Through continued delivery of crude and condensate, this pipeline also ensures that the natural gas which is produced along with these liquids continues to flow to Australian households and businesses. The project included pig launching and receiving facilities at Longford and LIP terminals, 10 main-line valve stations as well as fibre-optic cable for control, leak detection and communications purposes. Early engagement of its contractor partners played a key role in the successful execution of the project. Today’s landscape along the pipeline route significantly differs from that when the original pipeline was installed. Individual needs of the landowners affected by the construction were carefully considered. Significant measures were taken to minimise any impact to the unique flora and fauna of the region. Sensitivities around cultural heritage locations were taken into account while finalising the construction methods. Construction of the pipeline occurred in two summer phases (2015–2016 and 2016–2017) to make efficient use of dry weather and to minimise disturbance to landowners and the environment. The project was completed within budget and ahead of schedule.

OPTIMIZATION OF EQUIPMENT COMPOSITION BASED ON RENEWABLE ENERGY SOURCES IN ELECTRIC SUPPLY SYSTEMS FOR LOW POWER AUTONOMOUS CONSUMERS

The article deals with the methodology of complex foundation and optimal choice of composition and parameters of equipment of hybrid energy complex (EC) based on renewable energy and traditional energy sources. Optimization is made by criteria of energy and economic efficiency. The experimental studies are in numerical simulation of selection process of equipment composition. For estimate calculation with a lack of initial information, simulation is performed in Microsoft Excel. For accurate optimization calculation using detailed initial information, the simulation dynamic model is developed in the environment of MATLAB Simulink. The methodology determines the optimal composition and parameters of the EC equipment based on renewable energy for power supply valve stations in real placement of gas pipeline under construction, that allow us to replace electricity consumed with renewable energy 93,5 % for a year. The economic efficiency of the project is substantiated. The methodology and calculation models can take into account the additional conditions and restrictions, the original data and models of energy converters, which give the flexibility and versatility to the methodology and calculation models. Using the methods and guidelines in the design phase will increase the competitiveness and cost effectiveness of the EC based on renewable energy sources, and optimize the total cost of electric supply low power autonomous consumers.

SS16. Long-Term Results of Deep Vein Valve Reconstructions for Nonhealing C6 Venous Ulcers: An 18-Year Experience

In an era that has seen significant changes in the way we manage nonhealing venous leg ulceration, this study reports the rationale, results, and changing trends of an 18-year experience of deep vein valve reconstruction with evaluation of end points at 2, 5 and 10 years in the management of nonhealing venous leg ulcers in 228 patients. A total of 228 patients (302 limbs) undergoing deep vein reconstructions were followed up for 2 to 18 years (mean, 8 ± 2.3 years). All patients had nonhealing C6 venous leg ulcers of >3 months' duration and were offered deep venous reconstruction as a “last resort” treatment. End-points of the study were freedom from leg ulceration, vein valve patency, and competence assessed serially by physical examination and duplex scanning. Primary refluxive disease was present in 156 patients (209 limbs). External valvuloplasty was performed in 12 limbs (19 valves), and internal valvuloplasty was performed in 181 limbs (324 valves). External supports were used in 16 limbs (16 valves). Multilevel (≥2) reconstructions were performed in 126 limbs. Seventy-two patients had secondary valvular defects involving 93 limbs. Axillary-femoral vein valve transplant was performed for 49 patients (64 limbs) and Maleti Neovalve in five patients (five Limbs) respectively. Saphenofemoral venous transposition was performed in 7 patients (nine limbs), and femoral/popliteal vein ligation was carried out in 11 patients (15 limbs). At 10 years, external valvuloplasty showed ulcer healing in 16% of limbs, with maintenance of competency at only 15.7% of valve stations. Internal valvuloplasty was the most durable valve repair procedure, with actuarial leg ulcer healing rates of 67% and valve station competency of 79%. It was also noted that single-level repairs had significantly lower ulcer healing rates than multilevel repairs (P = .0018). For secondary incompetence, valve transplants had a gradual but increasing deterioration in valve patency and competency at 10 years: 46.8% and 38.3%, respectively, with 36.6% actuarial leg ulcer healing. Although the Maleti Neovalve in our hands performed well initially, all repairs thrombosed by 9 months. Even venous transpositions had no valve competency >2 years. Valvular reconstruction for refluxive disease is effective in healing venous ulcers that defy conservative management and superficial/perforator venous surgery out at 10 years. Furthermore, these procedures are useful for primary but not for secondary incompetence. Multilevel or multivalve reconstructions yield superior results to single-level repairs in medium-term follow-up. Open reconstructions for secondary incompetence may be a waste of time, with increased morbidity.

Cathodic Protection of Pipeline Using Distributed Control System

Distributed control system (DCS) is available in most of the compressor stations of cross-country pipeline systems. Programmable logic controller (PLC) is used in all the intermediate pigging (IP) stations/sectional valve (SV) stations to collect the field data and to control the remote actuated valves. This paper presents how DCS or PLC can be used for cathodic protection of gas pipelines. Virtual instrumentation (VI) software is used here for simulation and real-time implementation purpose. Analog input channels available in DCS/PLC can be used to measure pipe to soil potential (PSP) with the help of half-cell and voltage transducer. Logic blocks available in DCS can be used as low selector switch to select the lowest PSP. Proportional-integral (PI) controller available in DCS/PLC can be used for taking the controlling action. PI controller output varies the firing angle of AC phase controller. Phase controller output is rectified, filtered, and fed to the pipeline as cathodic protection current. Proposed scheme utilizes existing infrastructure to control pipeline corrosion.

Prevention and treatment of venous ulcers in primary chronic venous insufficiency

Prevention and treatment of venous ulcers in primary chronic venous insufficiency

The Pressure's On PRV Stations Curb Insurance Rates

This article discusses a situation in Hillsboro, Oregon, where numerous high‐tech firms were experiencing a gradual reduction in service pressure over time. The city's water department decided the best long‐term solution was to create a separate, higher‐pressure zone in the industrial area. They identified six locations for installation of pressure‐reducing valve (PRV) stations that automatically reduce a higher inlet pressure to a steady, lower downstream pressure, regardless of changing flow rates or varying inlet pressure. The resulting design created a high‐pressure loop that surrounds customers in the designated high‐pressure zone. Safe conditions, continuous flow and installation problems are discussed, along with smooth startup procedures.

Deep venous valve reconstruction for non-healing leg ulcers: techniques and results.

The purpose of the present paper was to report clinical and imaging results of a 5 year experience of deep venous valve surgery with evaluation of end-points at 2 year follow up for the management of non-healing venous leg ulcers in 137 patients. Between October 1994 and November 1999, 137 patients (169 limbs) underwent deep vein reconstructions for non-healing venous leg ulcers of clinical, etiological, anatomical, pathological classification (CEAP) C6 class, as a 'last resort' treatment. End-points of the study were post-valve reconstruction, freedom from leg ulceration, vein valve patency and competency at 2 years. Primary refluxive disease was present in 96 patients (118 limbs). External valvuloplasty was performed in 12 limbs (19 valves) and internal valvuloplasty was performed in 90 limbs (144 valves). External supports were used in 16 limbs (16 valves). Multilevel (2-3) reconstructions were performed in 37 limbs. Forty-one patients had secondary valvular defects involving 51 limbs. Axillary-femoral vein or saphenofemoral vein valve transplant was performed for 29 patients (35 limbs) and three patients (three limbs), respectively, saphenofemoral venous transposition was performed in three patients (four limbs), and femoral/popliteal vein ligation was carried out in six patients (nine limbs). Two year results of external valvuloplasty showed ulcer healing in 50% of limbs with maintenance of competency at only 31% of valve stations. Internal valvuloplasty was the most durable valve repair procedure with 2 year leg ulcer healing rates of 67% and valve station competency of 79%. For secondary incompetence, valve transplants had a significant deterioration in valve patency and competence at 2 years: 58% and 47%, respectively, with 55.3% leg ulcer healing. It was also noted that single-level repairs or single valve transplants had lower ulcer healing rates than multilevel repairs or valve transplants with multiple valve stations. In a 2 year follow up, valvular reconstruction for refluxive disease is effective in healing venous ulcers that defy conservative management and superficial/perforator venous surgery. Furthermore, these procedures appear more promising for primary than for secondary incompetence. Multilevel or multivalve reconstructions yield superior results to single-level repairs in medium-term follow up.

Five-Year Experience of Valvular Reconstructions for Nonhealing Leg Ulceration due to Deep Venous Reflux: Lessons Learned

Deep venous reflux is responsible for considerable morbidity in the form of venous leg ulceration and remains a significant health problem. Deep venous reconstructions have been looked upon as controversial in the past. To clarify the role of deep vein valve surgery in venous surgery, we report the lessons learned from clinical and imaging results of a 5-year experience of deep venous valve reconstructions. From 1994 to 1999, 137 patients (169 limbs) underwent deep vein reconstructions for nonhealing venous leg ulcers of CEAP C6 class, as a last resort treatment. End points of the study were leg ulcer healing, and vein valve station patency and competency. All end points were looked at on a follow-up of a minimal 2-year period following the valve reconstructions. External valvuloplasty showed ulcer healing in 50% of limbs with maintenance of competency at only 31% of valve stations. Internal valvuloplasty was the most durable valve repair procedure, with 2-year leg ulcer healing rates of 67% and valve station competency of 79%. For secondary incompetence, valve transplants showed a significant deterioration in valve patency (58%) and competence (47%) at 2 years, with 55.3% leg ulcer healing. Single-level repairs or single valve transplants had much lower ulcer healing rates than multiple-level repairs or valve transplants with multiple valve stations. Important lessons learned from this study are: 1) Valvular reconstruction for refluxive disease is effective in healing venous ulcers that defy conservative management and superficial/perforator venous surgery. 2) These procedures appear more promising for primary than for secondary incompetence. 3) Multiple-level or multiple-valve reconstructions yield superior results to single-level repairs, challenging the gatekeeper concept.

Target selection for surgical intervention in severe chronic venous insufficiency: Comparison of duplex scanning and phlebography

Purpose: The goal of this study was to determine whether duplex scanning (DS) alone, compared with ascending phlebography (AP) and descending phlebography (DP), would have been sufficient to guide treatment of severe chronic venous insufficiency (CVI), CEAP Clinical Classes 5 and 6. Methods: Beginning in 1994, patients presenting to the VA Sierra Nevada Vascular Clinic with ulceration due to CVI, CEAP Clinical Classes 5 and 6, were examined with DS, AP, and DP. Phlebography mainly guided surgical interventions. The ability of DS findings to select surgical interventions, with the aims of diversion of reflux from area of trophic skin or reduction of global venous hypertension was compared with phlebography. Of the 33 male patients (age, 29-70 years; average, 55 years) considered for operative interventions between January 1994 and November 1999, 30 were selected for operative treatment. Results: DS was 100% sensitive and specific for detection of complete occlusion of the superficial femoral vein (10/10) and for saphenous incompetence; sensitivity was 95% (19/20); and specificity was 100%. However, DS failed to reveal subtle changes in recanalized femoral veins because of prior thrombophlebitis, which was uncovered by AP in six of 23 patent femoral veins. There were 16 positive findings on AP of residual thrombophlebitis, of which six were not read on DS. Sensitivity was 63%, specificity was 100%, the positive predictive value was 100%, and the negative predictive value was 53%. Reflux grading with DP agreed with DS in 23 of 33 cases or varied by one grade in five of 33 cases: sensitivity, 82%; specificity, 75%; positive predictive value, 96%; and negative predictive value, 37%. Kistner grade 4 reflux involving the superficial femoral and popliteal veins was noted by DP in five of the 33 cases when DS described reflux as “moderate.” Incompetent superficial femoral vein valve stations in the upper third of the vein, which caused primary reflux, were clearly defined by DP in four of 33 cases; valve location was not well defined by DS. Below-knee perforator identification with DS was difficult; this was related to the severity of lipodermatosclerosis and the presence of ulceration. The number of perforators described at operation with subfascial endoscopic perforator surgery (n = 13) averaged 6 ± 2, whereas AP identified an average of 4 ± 2 in supramalleolar area. In four men, two previously undiagnosed caval and two iliac obstructions were detected with AP; one was corrected with Palma bypass grafting. Follow-up at 4 to 60 months (average, 40 months) showed four ulcer recurrences among 30 patients who were operated on. Two patients underwent repeat operations on the basis of repeated phlebographic study and are cured at this time, one patient was healed with conservative therapy, and one patient is lost to follow-up. Conclusions: DS would have been inadequate for identifying surgical targets in CVI, CEAP Clinical Classes 5 and 6. DS overlooked iliac and caval lesions. Potential valveplasty sites, which were only delineated on DP, resulted in four valveplasties in the upper third of the superficial femoral vein for grade 4 reflux. AP localized mid- to upper-leg perforators, but neither AP nor DP detected perforators in the range of 5 to 10 cm above the calcaneus. The net effect of phlebography was a choice for deep interventions in five (17%) of 30 cases, which would not have been possible with DS alone. The identification of iliocaval occlusion influenced the decision, based on prior experience, not to perform distal procedures in three cases. (J Vasc Surg 2000;32:913-20.)

Transcommissural valvuloplasty: Technique and results

Purpose: The purpose of this study was to describe the technique of a variation of closed external venous valve repair (transcommissural valvuloplasty), its complication rate, and duplex scan durability. Methods: The “blind” transcommissural valve repair of the vein was performed by placing transluminal sutures along the valve attachment lines, which simultaneously closed the valve attachment angle and also tightened the valve cusps. A total of 179 successfully repaired valve sites of 141 limbs in 129 patients were followed up 1 to 42 months through clinical observation and with duplex Doppler ultrasound scan. Results: Postoperative complications (< 30 days) occurred in 12 (9%) of 141 limbs: superficial (1) and deep (1) wound infection, large wound hematoma (4), seroma (1), and deep vein thrombosis (5), with associated pulmonary embolus in one patient. Seventy-eight percent (reflux time ≤ 0.5 seconds) and 81% (reflux time ≤ 1.0 seconds) of valve sites were competent. The cumulative competency rate at 30 months was 59% and 63%, respectively. The cumulative ulcer recurrence-free interval was 63% at 30 months (n = 92). The pain score and swelling grade substantially improved. Conclusion: Transcommissural valvuloplasty is a safe procedure with low morbidity. It is relatively rapid and simple to perform, and its competency rates are comparable to those of internal valvuloplasty. Advantages over the internal repair are that venotomy is not required, repair can be extended to small-caliber veins, and multiple valve stations can be repaired in a single stage. (J Vasc Surg 2000;32:969-76.)