Analysis of Welding Position and Current on Mechanical Properties of A36 Steel using Shield Metal Arc Welding

Welding is an assembly process that is most often used in the world of construction today. Welding is often used for repairing and maintenance of all tools made of metal, both as a process for filling cracks, temporary joining, or cutting metal parts. This study aims to determine the effect of welding current and position on the tensile strength and Vickers hardness (HV). This study uses ASTM A36 steel plate as base material. The variation of welding currents used are 90A, 110A, and 130A combine with variations in positions 1G, 2G, and 3G. The electrode used in this study is E6013 electrode with a diameter of 3.2 with a butt joint connection. All of processes are performed in room temperature with a strict condition. The results are as follow, the highest Ultimate Tensile Strength is obtained at 90A current and 3G position with a value of 471.93 MPa. For the highest hardness in the Vickers test, it is also obtained at 90A current and 3G position with a value of 242.20 Kgf/mm2.

Flawless Cutting of Tubing and Control Lines by Mechanical Pipe Cutter in Challenging Well Condition Provides an Environmental Friendly Alternative: A Case Study from Brunei

The Electro-Mechanical Pipe Cutter (MPC) is a non-ballistic & non-chemical wireline deployed alternative cutter tool for parting downhole tubular in the process of well abandonment, pipe recovery and retrieving of packer elements. This case study showcases its application in two wells with different challenges in cutting 4.5" tubing viz., (i) with multiple control lines to facilitate fishing operations and (ii) under compression in a highly deviated trajectory. In Well A, Brunei offshore, the position of the tubing and orientation of the control lines were challenging for ballistic option, along with the possibility of scarring the 9-7/8" casing during the cutting operation. Thus, 3-1/8" OD MPC was used for this job to cut near the coupling, ensuring optimum stand off from casing wall aiming to achieve cutting the control lines in tension. Dual cut were designed to allow the room for a safe cut zone. The primary cut was performed near middle of the joint at ∼1985m, with the tubing in tension. The cut was initiated at a very slow feed (0.2 mm/min) and motor rates (4000rpm), which was gradually increased once the cutting was stable. After the accomplishment of the tubing cut, the parameters were again reduced to carefully cutting through control line. The tubing was successfully retrieved with smooth cut without any over pull indicating it to be completely free. The flawless cutting operation was performed in less than one hour with outmost efficiency. In another highly inclined Well B, Brunei offshore, MPC was chosen over ballistic because it was needed to be conveyed by tractor and ballistic shock has potential to damage it during the operation. Also the advantage of MPC to perform multiple cuts in one run, made it a preferred choice. In this well, multiple cuts were performed to weaken the joint connection of the tubing to allow the rig to pull it free. It was to overcome the adversity posed by high inclination and the pipe under compression. Three cuts were performed at ∼2996 m, each 20 cm apart with an OD of nearly 4.609". After completion of the job, the circulation was performed with surface return, indicating successful execution and the tubing was retrieved on surface showing a clean cut. This case study shows the appropriate planning and execution of the mechanical pipe cutter can provide an efficient, environment friendly and safe alternative to cut tubing and control line in the challenging condition especially when an explosive and chemical cutter options are not considered suitable.

Comparative In Vitro Evaluation of the Primary Stability in D3 Synthetic Bone of Two Different Shapes and Pitches of the Implant Threads

Background: Implant primary stability can be affected by several factors related to implant macrogeometry, local anatomy, and surgical techniques. The aim of this research was to study primary stability on polyurethane foam sheets of wide-threaded implant design compared to narrow-threaded implants. Materials and methods: Two different implant designs were positioned on D3 density polyurethane blocks in a standardized environment: the wide-threaded implant and the narrow-threaded implant, for a total of 160 specimens. Moreover, for each group, two different sizes were considered: 3.8mm × 12mm and 4.8mm × 12 mm. The insertion torque (IT) values, the removal strength (RT), and the Periotest analyses were evaluated. Results: A significantly higher IT and RT was reported for wide-threaded implants and two-stage implants (p < 0.01), compared to the narrow-threaded implants. The diameters seemed to provide a significant effect on the primary stability for both implants’ geometry (p < 0.01). A higher mean of the one-stage implant was evident in the Periotest measurements (p < 0.01). Conclusions: Both of the implants showed sufficient stability in polyurethane artificial simulation, while the wide-threaded implant design showed a higher primary stability on alveolar cancellous synthetic bone in vitro. Additionally, the prosthetic joint connection seemed to have a determinant effect on Periotest analysis, and the one-stage implants seemed to provide a high stability of the fixture when positioned in the osteotomy, which could be important for the immediate loading protocol.

Acromial Fracture Associated with Coracoid Fracture Not Belong to Floating Shoulder : A Case Report

Floating shoulder is no osseoligamentous connection between the humeral shoulder joint with the axial skeleton. The osseoligamentous of shoulder joint connection compose a ring, including clavicle,acromion, coracoid, glenoid fossa, surgical or anatomical scapula neck, acromioclavicular ligament and coracolclavicular ligament. This ring is known as superior shoulder suspensory complex (SSSC). The double disruptions of this ring are recognized to create a potentially unstable anatomical situation. Thus, floating shoulder is also characterized as double or more disruptions of SSSC. Surgical reduction and fixation for the displacement of those fractures at one or more sites is recommended in previous reports. We present 2 cases of patients with acromial and coracoid displaced fractures which belong to a type of the double disruptions of SSSC, there were still osseoligamentous connection between the humeral shoulder joint with the axial skeleton. The patient’s shoulder function after nonoperative management was satisfactory.

Long-term outcomes after corrective cartilaginous joint resection based on arthrographic findings of duplicated thumbs

We report greater than 10-year outcomes in duplicated thumbs following corrective cartilaginous resection during the growth period. We have undertaken corrective resection of cartilaginous joint connections based on intraoperative arthrographic findings to reconstruct favourable alignment in six Wassel Type II and IV thumb duplication in six patients. The age at surgery was 13 months (range 10–15), and the average post-surgical follow-up was 134 months (range 120–160). We observed five excellent and one good outcome using the Japanese Society for Surgery of the Hand scoring method. Favourable joint congruency and alignment were preserved, and no growth plate arrest or joint space narrowing was present more than 10 years after surgery. We conclude that corrective resection of the cartilaginous joint based on intraoperative arthrographic findings has long-term reliability for duplicated thumbs, especially those of Wassel Type II and IV, which have a cartilaginous joint connection. Levels of evidence: IV

Experimental study on fatigue performance of Q420qD high-performance steel cross joint in complex environment

The steel structure under the action of alternating load for a long time is prone to fatigue failure and affects the safety of the engineering structure. For steel structures in complex environments such as corrosive media and fires, the remaining fatigue life is more difficult to predict theoretically. To this end, the article carried out fatigue tests on Q420qD high-performance steel cross joints under three different working conditions, established a 95% survival rate $$S{ - }N$$ S - N curves, and analyzed the effects of corrosive media and high fire temperatures on its fatigue performance. And refer to the current specifications to evaluate its fatigue performance. The results show that the fatigue performance of the cross joint connection is reduced under the influence of corrosive medium, and the fatigue performance of the cross joint connection is improved under the high temperature of fire. When the number of cycles is more than 200,000 times, the design curves of EN code, GBJ code, and GB code can better predict the fatigue life of cross joints without treatment, only corrosion treatment, and corrosion and fire treatment, and all have sufficient safety reserve.