High Energy Piping Walkdowns in Compliance With ASME B31.1

This paper discusses high energy piping (HEP) system walkdown requirements and guidelines in compliance with the American Society of Mechanical Engineers (ASME) B31.1 Code. Chapter VII states that the Operating Company shall develop and implement a program requiring documentation of piping support readings and recorded piping system displacements. Guidelines for this program are provided in Nonmandatory Appendix V, para. V-7. The Code also requires that the Operating Company shall evaluate the effects of unexpected piping position changes, significant vibrations, and malfunctioning supports on the piping system’s integrity and safety. These requirements and guidelines have been developed for personnel safety and piping system reliability. The HEP system should be maintained to behave as expected in the original design analysis unless a field change is justified by qualified personnel. The walkdown program should be an integral part of an asset integrity management program, including observations, documentation, evaluations, corrective actions, and countermeasures. A thorough HEP system walkdown includes more than documented hanger readings. It should include visual assessments of possible sagging pipe, unusual pipe slopes, building structure damage, lagging/insulation damage, locked spring hangers, piping interferences, damaged spring coils, loose/missing support fasteners, unloaded rigid supports, bent struts, insufficient hydraulic fluid in snubbers, detached Teflon strips on sliding supports, and confirmation that the current supports are consistent with the original design specifications. If accessible, it should be confirmed that there are no gaps in the sliding supports. This paper illustrates that it is now possible to photographically document spring support position indicator readings from distances up to 30 feet (9.1 meters). Photographic documentation provides higher confidence in the position indicator readings and can resolve many visual documentation discrepancies, such as incorrect support readings, readings from opposite position indicator sides, and parallax issues. If accessible, closer inspections may confirm if a spring support is in fact internally bottomed-out or topped-out. Nonmandatory Appendix V provides recommended hot walkdown and cold walkdown forms. These forms provide additional space for applicable notes. Example photographs of many piping system anomalies and associated documentation are provided in this paper. ASME B31.1 requires that significant displacement variations from the expected design displacements shall be considered to assess the piping system’s integrity.

Influence of Smart Spring Support Parameters on Vibration Characteristics of Three Support Shafting

Smart spring support is a kind of active damping device based on piezoelectric material. It can effectively suppress the vibration of a shaft system in an overly critical state by changing the stiffness and damping of the support. The support parameters have a significant impact on the vibration of the system. By studying the influence of the smart spring support parameters on the vibration characteristics of the transmission shaft system, the support parameters can be configured more reasonably so that the vibration of the transmission system can be reduced as much as possible. Based on the finite element method, this paper studies the influence of the stiffness, damping and mass of the smart spring support on the vibration characteristics of the three-support shafting. Firstly, the smart spring shafting test bed is built, and the vibration reduction performance test of the smart spring is carried out to verify the damping effect of the smart spring. Then, the shafting dynamic model is established by the finite element method, and the inherent characteristics of the system are analyzed. Finally, the influence of the stiffness, damping, mass and other parameters of the smart spring support on the dynamic response of the system is studied. The results show that increasing the stiffness of the smart spring support can effectively reduce the vibration amplitude of the system. The damping of the smart spring support has no obvious effect on the vibration of the shafting. The smaller the mass of the smart spring support, the more favorable the system is.

Design and wrench-feasible workspace analysis of a cable-driven hybrid joint

This article proposes a cable-driven hybrid joint (CDHJ), focuses on the effects of external wrench payload and structural parameters on the wrench-feasible workspace for the preliminary design of the mechanism, and further discusses the wrench exertion capability of the mechanism under a certain configuration. This CDHJ has central rigid support with a revolute pair and a central compression spring support. Due to the unilateral property of cables and the flexible compression spring, the kinematic model cannot define the workspace directly; it should be combined with the statics for possible solution, including the spring lateral buckling model based on the elliptic integral solution. Moreover, a global tension index which is to evaluate the wrench-closure property of the global workspace, combined with an index which is to assess the size of the workspace, is proposed to better compare the effects of different external wrench payloads and different structural parameters on the workspace. Simulations were performed and demonstrated the correctness and feasibility of the inverse kinematics and workspace analysis of the joint. Hence, the proposed mechanism has potential use in robotics especially in wheelchair-mounted robotic manipulator joint.

Performance and noise analysis of vibratory feeder using dynamic rubber spring model

In vibratory feeder, material feeding occurs due to the vibration of a trough mounted on helical springs. High vibration amplitude of trough causes the springs to jump and usually results in higher noise level generation and increase in force transmissibility in the support structure of the feeder. Reducing this noise without having significant changes in the dynamics of the feeder unit is a major challenge in the present industries. This paper presents a dynamic rubber spring model for vibratory feeders to reduce the noise level and the force transferred to the support structure of the feeder. Measurement of dynamic parameters such as vibration amplitude and magnitude of force transmitted to support structure, noise level, and conveying speed of particle analyses have been conducted experimentally on vibratory feeder with and without rubber gasket installed at spring support structure. The use of rubber gaskets at spring supports and their implication on force transmissibility and noise level of feeder is established experimentally. The performance analysis of feeder was also conducted using particle conveying speed on trough for different setups of feeder unit. It was found that the introduction of rubber gaskets at spring supports of the feeder increases the system damping, which helps in noise reduction as well as reduced amplitude of vibration and higher acceleration of trough. The increased acceleration leads to higher particle conveying velocity on the feeder trough.

A comparative experimental study on large size center and bi-directional offset spring-bed thrust bearing

The central support tilting thrust bearing is widely used in the motor-generator unit, and the central support tilting thrust bearing performs poorly compared with the offset bearing. In order to improve the performance of the thrust bearing capable of the bidirectional operation, a spring-supported switching tilting thrust bearing was designed, which could run under offset condition at both clockwise and counterclockwise. In order to verify the reliability of the bearing, we designed a true size thrust bearing test bench and measured the performance parameters of the temperature, pressure, oil film thickness, and power loss of the pad. This article introduces in detail the operation mechanism of the bidirectional offset spring-bed tilting thrust bearing. The bidirectional offset spring-bed tilting thrust bearing structure and the central support bearing structure were compared and tested. The test results of the performance difference of large tilting pad bearings with different structures were obtained. According to the experiment, the spring support structure has good adaptability, and the improved bidirectional offset support bearing not only has higher bearing capacity, but also has better performance in all aspects of temperature rise and loss than the central support bearing. The actual size experiment provides the experimental data for the theoretical calculation of large tilting pad bearings, providing a more accurate basis for the bearing performance and safety assessment.

AUSTEMPERING HEAT TREATMENT STUDY OF CAST DUCTILE IRON: ANALYSIS OF MECHANICAL AND MICROSTRUCTURAL PROPERTIES, ACCORDING TO THE A897M STANDARD SPECIFICATIONS FOR AUSTEMPERED DUCTILE IRON CASTINGS

The objective of this work was to develop heat treatment parameters of an austempered cast iron alloy ASTM 897 / A 897M - 1400/1100/1, aiming at the production of a truck spring support. The austempered nodular cast iron, known by the acronym ADI - Austempered Ductile Iron - is a class of nodular cast iron that, after austempered thermal treatment, increases significantly its mechanical properties and tenacity (Machado, 2007). Mechanical and metallographic tests demonstrated the great influence that the level of microshrinkage has on the elongation and mechanical resistance of the material. Generally, tensile tests demonstrate high elongation due to minimal presence of microshrinkage and segregations in the metallic matrix of the material, as well as to the presence of austenite with high carbon retained in the ADI matrix. Analyzes were performed to determine if the mechanical properties required by ASTM 897 / A897M were achieved. Within this standard, four degrees can be obtained. The degree of interest in this study was 1400/1100/1, which is the grade requested by the company, so that the truck spring support can be put into service. Tensile, Charpy and optical microscopy tests were carried out.