Enhancing the Lifetime of the Pneumatic Cylinder in Automatic Assembly Line Subjected to Repeated Pressure Loading

This study demonstrates the application of parametric accelerated life testing (ALT) as a procedure to identify design deficiencies and correct them in generating a reliable quantitative (RQ) specification. It includes: (1) a system BX lifetime that X% of a product population fails with a parametric ALT scheme, (2) fatigue design, (3) ALTs with alternations, and (4) judgement as to whether the design(s) secures the desired BX lifetime. A (generalized) life–stress model through the linear transport process and a sample size formulation are suggested. A pneumatic cylinder in a machine tool was used as a case study. The cylinder was failing in a flexible manufacturing system. To reproduce the failure and modify the design, a parametric ALT was performed. At the first ALT, the metal seal made of nickel-iron alloy (36% Ni) partially cracked and chipped and had a crisp metal sound. It was modified by changing the seal from a metal to a polymer (silicone rubber). At the second ALT, the piston seal leaked due to seal hardening and wear. The failure modes of the silicone seal in the laboratory tests were similar to those returned from the field. For the third ALT, the seal material was changed from silicone rubber to (thermoset) polyurethane. There were no concerns during the third ALT and the lifetime of the pneumatic cylinder was shown to have a B1 life of 10 years.

Experimental Study for Establishing Metal-to-Metal Seal Evaluation Criteria for Tubular Connections in Thermal and HPHT Applications

Qualification of tubular connections is an important task in well completion design for thermal wells, which experience peak temperatures of 180°C to 350°C, as well as high pressure and high temperature (HPHT) wells, which experience peak temperatures up to 180°C and pressures greater than 70 MPa. Industry protocols (such as ISO/PAS 12835:2013 for thermal wells, and ISO 13679:2019 and API RP 5C5:2017 for HPHT wells) have been developed for the purposes of evaluating the structural integrity and sealability of premium connections. In recognition of the the time and capital expense associated with completing "product line validation" for a connection design per these standards for multiple physical configurations (i.e for combinations of various sizes, weights, and grades), industry is developing a hybrid approach that supplements results from physical qualification tests with numerical simulation, such as Finite Element Analysis (FEA). To facilitate numerical modeling, extensive research work has been performed recently (e.g. Xie, Matthew, and Hamilton (2016) and Xie and Matthew (2017)) to establish a constitutive relationship for evaluating metal-to-metal sealability. It was noted in previous studies that further experimental work is required to better understand connection sealing behavior, especially the effects of surface roughness and thread compounds. This paper presents an experimental study with a series of small-scale metal-to-metal seal tests under various levels of seal contact stress and gas pressures representative of thermal and HPHT operational conditions. These tests incorporated the effects of surface roughness and thread compound. FEA was performed to model the stress conditions in the test specimens. Based on the experimental and analytical study, an updated metal-to-metal seal evaluation criterion with calibrated parameters is proposed for tubular connections used in thermal and HPHT applications.

Three-dimensional loading control of a pneumatic three-universal–prismatic–universal robot

Multidimensional force loading has been widely used in the fields of component and material testing. The pneumatic-driven multidimensional force loading parallel mechanism can meet the requirements of complex force loading. A three-dimensional loading robot based on a pneumatic three-universal–prismatic–universal parallel mechanism is designed to apply time-varying three-dimensional loads on a target. Based on the principle of vector superposition, inverse and forward kinematics are deduced. A second-order mathematical model of a metal seal pneumatic cylinder driven by a flow proportional valve is established. Based on the immersion and invariance technique, the leakage flow in the cylinder is taken as the interference term and estimated. Meanwhile, because of the strong nonlinearity of the actuator, based on suitable disturbance estimation, the control rate of the system is designed through the sliding mode surface, and the stability of the control algorithm is analyzed on the basis of the Lyapunov stability theory. The experimental results show that the immersion and invariance controller exhibits a better control performance than the proportional–integral–differential controller: the steady-state control mean square error is reduced by approximately 21% on average and the dynamic (0.2 Hz) tracking mean square error is approximately 10.35 N.

Premium Anti-Rotation Casing Connector with Metal-to-Metal Seal Optimized for High Fatigue Performance to Meet Market Needs by Reducing OPEX and Risk Exposure

The oil and gas industry continues to face the need to reduce risk exposure and OPEX as a means to compensate for market volatility and lower oil prices. Typical casing connector designs and methods of running casing are becoming less viable as the industry struggles to lower installation costs and reduce HSE concerns. This dilemma leads manufactures to provide practical solutions to reduce the risk exposure while driving costs down by reducing installation time and required rig personnel. This paper outlines how this innovative and fully qualified technology lowers overall risk exposure while reducing OPEX during the installation of casing connectors. A new premium threaded connector named BADGeR™ has been designed and fully qualified and its features have been patented. State of the art verification techniques utilizing finite element analysis were used to fully simulate the combined load conditions during the qualification program that mimic field conditions and meet and exceed industry standard requirements. Special consideration was given to connector make-up and metal-to-metal sealing technology, superior fatigue performance, welding, coating, galling, surface finish, and lubrication. After a lengthy iterative design process, the final design was fully qualified following ISO 13679 / API 5C5 with additional fatigue performance testing. Details of the design features, analysis methodology and results, structural and sealability test results, and fatigue test results are presented. Advantages of this casing connector design relative to traditional industry casing connectors are highlighted. BADGeR includes an innovative hands-free anti-rotation mechanism that significantly reduces rig time and HSE risk exposure. The connector has automatic make-up with gas tight metal-to-metal seal performance that is not impacted by increased tension to the string. The fatigue performance of this connector exceeds the current market offerings. This combination of features incorporated into the connector has gained the attention of the industry and the opportunity to use this technology for critical service wells applications.

Development and Application of 140 MPa Mandrel Casing Head in Ultra-High Pressure Gas Well

In view of the high shut in pressure of gas wells in Kuqa mountain front ultra-high pressure block where the highest shut in pressure of KeS X is 115MPa, the 105MPa casing head currently used can not meet the shut in demanding, so the risk of well control is high. A new 140MPa mandrel casing head was developed. Its sealing structure adopts the form of X Metal sealing at the upper end and rubber seal at the lower end, which has the characteristics of high pressure bearing and reliable sealing performance. The structural design verification of the 140 MPa mandrel casing head was conducted by finite element analysis(FEA) of the structural strength and sealing performance of the key components of the casing head, including casing head body and hanger. Then indoor evaluation tests were carried out on the material, strength and sealing performance of the casing head and hanger, as well as the overall structure, and the 140MPa mandrel casing is completed Finally, the quality control level of 140MPa mandrel casing head product has reached the requirements of ultra-high pressure field working condition through field trial in ultra-high pressure gas well, and it has the conditions for promotion and application in other ultra-high pressure gas wells. The results of and FEA show that the maximum bearing capacity of the mandrel type casing head is 793t, and no yielding occurs under the conditions of bearing capacity of 473t, external pressure of 140MPa and safety factor of 1.35; the maximum internal pressure resistance of the hanger is 212MPa, and no yielding occurs under the conditions of bearing capacity of 200t, internal pressure of 140MPa and safety factor of 1.35. The indoor evaluation test shows that: ① there is no sulfide stress cracking (SSC) and hydrogen induced cracking (HIC) in the casing head body (0Cr18Ni9) and hanger (718); ② there is no leakage in the casing head body under 210MPa clean water and hanger under 140MPa nitrogen; ③ there is no yield in the casing head step and hanger under 673t pressure in the mandrel type casing head. The field test shows that the test pressure of the mandrel type casing head is 117MPa and it is qualified under 280t setting and hanging tonnage. At present, the 140 MPa mandrel casing head has been successfully used in Kuqa mountain for 15 wells, which provides a reliable guarantee for the safety production of ultra-high pressure gas wells. The 140MPa mandrel casing head developed in this paper has the following three innovations: ① adopt the structure without top wire, fix the wear-resistant sleeve by installing the top wire flange during drilling, and avoid the leakage caused by the top wire hole in the later production; ② adopt the form of upper metal seal + lower X-type rubber seal in the sealing structure of hanger, which can not only avoid the metal seal of hanger during the lowering process The seal assembly is damaged and fails, and in case of unqualified pressure test, the metal seal assembly at the upper end of the hanger can be replaced; ③ a limited step is designed at the contact part between the metal seal assembly at the upper end of the mandrel hanger and the casing head body, which can transfer the excess pressure to the casing head body, so as to avoid the failure of the rubber seal and bearing step at the lower part of the hanger.