Bolt Strength in Sectional Body Construction of Valves

2019 ◽  
Author(s):  
Bhaskar Shitolé
Keyword(s):  
Rigid Bodies ◽  
Bolted Joints ◽  
Terminal Point ◽  
Piping System ◽  
Valve Body ◽  
Section Modulus ◽  
Creep Characteristics ◽  
Body Construction ◽  
Minimum Requirements ◽  
Body Joints

Abstract ASME B16.34-2017 Section 6.4.2 provides requirements for valves with bolted body joints and threaded body joints. The section states that valves with bodies of sectional construction such that bolted or threaded body joints are subject to piping mechanical loads in addition to the pressure rating for which the valve is designed, shall satisfy the following requirements. For bolted joints, the requirement is a simple formula where the product of pressure rating class designation and ratio of area bounded by the effective outside periphery of a gasket or O-ring or other seal-effective periphery and total effective bolt tensile stress area are less than a certain constant. For bolts of strength less than 137.9 MPa, the value of constant reduces as a multiple of 50.76 times the bolt tensile strength in MPa required or provided in a sectional construction. Section 6.4.3 cautions that the minimum requirements of ASME B16.34 may fall short in scenarios due to valve design, special gaskets, high temperature service, creep characteristics etc. This paper reviews and studies this ASME B16.34 requirement which was triggered by failure of a valve with section body construction in the field. Traditionally valves have been considered as rigid bodies when analyzing a piping system for stresses, support loads, terminal point loads and deflections. The rigid modelling assumes the strength of the valve is much higher than an equivalent straight length of pipe. Some computer programs have a provision that permits modeling the valve as a multiple like 3- or 4-times pipe section modulus. This paper compares the strength of piping and valves based on inherent valve body thickness, body sectional bolting provided and strength of the equivalent piping flanges. The paper makes conclusions for the user to be aware of so that pre-emptive actions can be taken when using valves with sectional body construction.

Bolt Strength in Sectional Body Construction of Valves

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Bhaskar Shitolé
Keyword(s):  
Rigid Bodies ◽  
Bolted Joints ◽  
Terminal Point ◽  
Piping System ◽  
Valve Body ◽  
Section Modulus ◽  
Creep Characteristics ◽  
Body Construction ◽  
Minimum Requirements ◽  
Body Joints

Abstract ASME B16.34-2017 Section 6.4.2 provides requirements for valves with bolted body joints and threaded body joints. The section states that valves with bodies of sectional construction such that bolted or threaded body joints are subject to piping mechanical loads in addition to the pressure rating for which the valve is designed, shall satisfy the following requirements. For bolted joints, the requirement is a simple formula where the product of pressure rating class designation and ratio of area bounded by the effective outside periphery of a gasket or O-ring or other seal-effective periphery and total effective bolt tensile stress area are less than a certain constant. For bolts of strength less than 137.9 MPa, the value of constant reduces as a multiple of 50.76 times the bolt tensile strength in MPa required or provided in a sectional construction. Section 6.4.3 cautions that the minimum requirements of ASME B16.34 may fall short in scenarios due to valve design, special gaskets, high temperature service, creep characteristics, etc. This paper reviews and studies this ASME B16.34 requirement, which was triggered by failure of a valve with section body construction in the field. Traditionally, valves have been considered as rigid bodies when analyzing a piping system for stresses, support loads, terminal point loads, and deflections. The rigid modeling assumes that the strength of the valve is much higher than an equivalent straight length of pipe. Some computer programs have a provision that permits modeling the valve as a multiple like three- or four-times pipe section modulus. This paper compares the strength of piping and valves based on inherent valve body thickness, body sectional bolting provided, and strength of the equivalent piping flanges. The paper provides conclusions for the user to be aware of so that pre-emptive actions can be taken when using valves with sectional body construction.

Seismic Analysis of Above Ground Piping in Process Plant

2014 ◽  
Author(s):  
Gaurav P. Bhende
Keyword(s):  
Dynamic Analysis ◽  
Seismic Analysis ◽  
Seismic Effect ◽  
Elastic Behavior ◽  
Piping System ◽  
Process Plant ◽  
Minimum Requirements ◽  
Computer Based ◽  
Design Requirements ◽  
Equivalent Method

The recent natural calamities, especially earthquakes, are making engineering design requirements stringent. The Process Plant Piping is no exception to it. Analyzing the seismic effect by ‘Static Equivalent Method’ is a common practice compared to performing ‘Dynamic Analysis’. This paper starts with the basic reason of earthquake and its effect on the above ground piping system. Further it compares between the results opted based on computer based ‘Spectrum Analysis (Dynamic Analysis) Method’ and ‘Static Equivalent Method’ as per the requirements of ASCE 7. One of the assumptions in Static or Dynamic seismic analysis is — ‘Pipe supports are rigid’. However, in reality the supports, especially structural supports, show elastic behavior based on their material and geometric properties. At the end, this paper compares between the results of seismic analysis performed by considering ‘Supports as rigid’ and ‘Supports as elastic’ and comments on it along with minimum requirements for safe design.

Numerical Analysis of Contraction Geometry Effects on Cavitation Choking in a Piping System

2019 ◽  
Author(s):  
Motohiko Nohmi ◽  
Shusaku Kagawa ◽  
Tomoki Tsuneda ◽  
Wakana Tsuru ◽  
Kazuhiko Yokota
Keyword(s):  
Static Pressure ◽  
Sudden Expansion ◽  
Piping System ◽  
Valve Body ◽  
Line System ◽  
Pipe System ◽  
Flow Fluctuation ◽  
Supply Pipe ◽  
Static Pressure Difference ◽  
Pipe Line

Abstract There is a contraction portion in the water supply pipe line system, and cavitation may occur in the contraction when the flow velocity is increased. Such a situation occurs widely in the throat of the fluid machineries and in the vicinity of the valve body of the valve. In operation of the valve, it is well known that a phenomenon occurs in which the flow rate does not increase even if the static pressure difference upstream and downstream of the valve is increased due to the growth of cavitation in the contraction, which is well known as choking . It is not clear what phenomena occurs when cavitation surge occurs in the pipe system in the situation where choking is occurring in the contraction. In this study, cavitation CFD was performed on pipes those have three different geometry contractions. It was revealed that choking occurred when cavitation occurred in any shape. Also, in the case with the sharp contraction part and the sudden expansion, the flow fluctuation at the upstream of the contraction is much weaker than that at the downstream, but in the contraction with the bent part where the centrifugal force acts on the flow, the flow fluctuation at the upstream was found to be strong.

CFD Simulations and Experiments of Flow Fluctuations Around a Steam Control Valve

2006 ◽  
Vol 129 (1) ◽  
pp. 48-54 ◽  
Author(s):  
Ryo Morita ◽  
Fumio Inada ◽  
Michitsugu Mori ◽  
Kenichi Tezuka ◽  
Yoshinobu Tsujimoto
Keyword(s):  
Three Dimensional ◽  
Control Valve ◽  
Piping System ◽  
Cfd Simulations ◽  
Valve Body ◽  
Side Load ◽  
Flow Fluctuations ◽  
Partial Opening ◽  
Attached Flow ◽  
High Pressure Region

Under certain opening conditions (partial opening) of a steam control valve, the piping system in a power plant occasionally experiences large vibrations. To understand the valve instability that is responsible for such vibrations, detailed experiments and CFD calculations were performed. As a result of these investigations, it was found that under the middle-opening (partial opening) condition, a complex three-dimensional (3D) flow structure (valve-attached flow) sets up in the valve region leading to a high pressure region on a part of the valve body. As this region rotates circumferentially, it causes a cyclic asymmetric side load on the valve body, which is considered to be the cause of the vibrations.

Dynamic Characteristics of Structure With Bolted Joint Considering Some Factors

2004 ◽  
Author(s):  
Shigeru Aoki
Keyword(s):  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Damping Ratio ◽  
Random Excitation ◽  
Pressure Vessels ◽  
Bolted Joints ◽  
Piping System ◽  
Bolted Joint ◽  
Earthquake Excitation ◽  
Applied Torque

Bolted joints are widely used for pressure vessels and piping system. Many studies on strength and stiffness of bolted joint are carried out. However, few studies on the dynamic characteristics of structure with bolted joint are carried out. The dynamic characteristics are important for design of structure subjected to earthquake excitations. In this paper, the effect of bolted joints on dynamic characteristics of structure is examined. First, the damping ratio and the natural frequency of specimens with some types of bolted joints are measured. Those are obtained for some factors, amplitude of excitation, applied torque. Obtained results are compared with those for the specimen without bolted joint. It is found that the damping ratio increases and the natural frequency becomes lower. Next, modeling of the bolted joint is presented. The bolted joint is modeled using additional mass, stiffness and damping elements. Finally, using model of bolted joint, response of the structure with bolted joint subjected to earthquake excitation is examined. Earthquake excitation is modeled as stationary random excitation. Mean square values of the response are obtained. Standard deviation of the acceleration response of the structure with bolted joint are lower than those without bolted joint.

Risk-Based Inspection Applied to Main Steam and Hot Reheat Piping Systems

2007 ◽  
Author(s):  
Marvin J. Cohn
Keyword(s):  
Cost Effective ◽  
High Energy ◽  
Accurate Estimate ◽  
Terminal Point ◽  
Rational Approach ◽  
Piping System ◽  
Piping Systems ◽  
Risk Areas ◽  
Main Steam ◽  
Life Consumption

Many utilities select critical welds in their main steam (MS) and hot reheat (HRH) piping systems by considering some combination of design-based stresses, terminal point locations, and fitting weldments. The conventional methodology results in frequent inspections of many low risk areas and the neglect of some high risk areas. This paper discusses the use of a risk-based inspection (RBI) strategy to select the most critical inspection locations, determine appropriate reexamination intervals, and recommend the most important corrective actions for the piping systems. The high energy piping life consumption (HEPLC) strategy applies cost effective RBI principles to enhance inspection programs for MS and HRH piping systems. Using a top-down methodology, this strategy is customized to each piping system, considering applicable effects, such as expected damage mechanisms, previous inspection history, operating history, measured weldment wall thicknesses, observed support anomalies, and actual piping thermal displacements. This information can be used to provide more realistic estimates of actual time-dependent multiaxial stresses. Finally, the life consumption estimates are based on realistic weldment performance factors. Risk is defined as the product of probability and consequence. The HEPLC strategy considers a more quantitative probability assessment methodology as compared to most RBI approaches. Piping stress and life consumption evaluations, considering existing field conditions and inspection results, are enhanced to reduce the uncertainty in the quantitative probability of failure value for each particular location and to determine a more accurate estimate for future inspection intervals. Based on the results of many HEPLC projects, the author has determined that most of the risk (regarding failure of the pressure boundary) in MS and HRH piping systems is associated with a few high priority areas that should be examined at appropriate intervals. The author has performed many studies using RBI principles for MS and HRH piping systems over the past 15 years. This life management strategy for MS and HRH critical welds is a rational approach to determine critical weldment locations for examinations and to determine appropriate reexamination intervals as a risk-based evaluation technique. Both consequence of failure (COF) and likelihood of failure (LOF) are considered in this methodology. This paper also provides a few examples of the application of this methodology to MS and HRH piping systems.

A Parametric Study of Hydrodynamic Cavitation Inside Globe Valves

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Zhi-jiang Jin ◽  
Zhi-xin Gao ◽  
Jin-yuan Qian ◽  
Zan Wu ◽  
Bengt Sunden
Keyword(s):  
Large Deviation ◽  
Fluid Velocity ◽  
Economic Loss ◽  
Hydrodynamic Cavitation ◽  
Geometrical Parameters ◽  
Piping System ◽  
Valve Body ◽  
Cavitation Intensity ◽  
Bending Radius ◽  
Globe Valve

Hydrodynamic cavitation that occurs inside valves not only increases the energy consumption burden of the whole piping system but also leads to severe damages to the valve body and the piping system with a large economic loss. In this paper, in order to reduce the hydrodynamic cavitation inside globe valves, effects of valve body geometrical parameters including bending radius, deviation distance, and arc curvature linked to in/export parts on hydrodynamic cavitation are investigated by using a cavitation model. To begin with, the numerical model is compared with similar works to check its accuracy. Then, the cavitation index and the total vapor volume are predicted. The results show that vapor primarily appears around the valve seat and connecting downstream pipes. The hydrodynamic cavitation does not occur under a small inlet velocity, a large bending radius, and a large deviation distance. Cavitation intensity decreases with the increase of the bending radius, the deviation distance, and the arc curvature linked to in/export parts. This indicates that valve geometrical parameters should be chosen as large as possible, while the maximal fluid velocity should be limited. This work is of significance for hydrodynamic cavitation or globe valve design.

scholarly journals Forensic Engineering Investigation Of Sectional Ladder Treestand Failures

2013 ◽  
Vol 30 (2) ◽  
Author(s):  
Jahan Rasty
Keyword(s):  
Structural Strength ◽  
Standard Requirement ◽  
Root Cause ◽  
Section Modulus ◽  
Minimum Requirements ◽  
Cause Of Failure ◽  
Forensic Engineering ◽  
Trade Names ◽  
Testing Standards ◽  
Engineering Investigation

The Purpose Of This Forensic Engineering Investigation Was To Determine The Root-Cause Of Failure Of Three 15-Foot Sectional Ladder Treestands That Caused Injury To Users. All Three Treestands Were Identical In Design And Manufactured By The Same Company Despite Differences In Trade Names. Within A Reason-Able Degree Of Scientific And Engineering Certainty, It Was Concluded That Failure Of The Treestands Was The Result Of Overstressing The Star-Crimped Area Of The Treestands At Adjoining Ladder Sections. Overstressing Was Caused By A Designed Reduction In Section Modulus Of The Rail At Adjoining Ladder Sections. Further, The Load-Bearing Ability Of The Ladder Treestands Was Evaluated In Accordance With Com-Monly Accepted Engineering Principles For Metal Ladder Design (Ansi A14.2-2007). Analysis Revealed That The Structural Strength Of The Rail Section And Testing Standards For The Treestand Industry Are Lack-Ing When Compared To Portable Metal Ladders Designed For Identical Load Ratings. In Fact, The Treestands Failed To Meet The Standard Requirement For A Portable Metal Ladder Rated At 170-Pounds Even When The Treestand Was Tested At ½ Of Its Spanning Length (2-Sections). Comparisons Between The Treestands And Portable Metal Ladder Standards Indicated That The Treestands Failed To Meet Minimum And Generally Accepted Standards For Ladder Design And Suggested The Treestands Do Not Meet Minimum Requirements For Merchantability.

scholarly journals Anti-seismic characteristics of safety valve and its spring failure prediction analysis

2020 ◽  
Vol 306 ◽  
pp. 04004
Author(s):  
Fanrong Meng ◽  
Huibing Zhang ◽  
Ye Dai ◽  
Hanbo Zhang ◽  
Wenqiang Wei ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Dynamic Characteristics ◽  
Nuclear Power ◽  
Safety Valve ◽  
Nuclear Safety ◽  
Working Environment ◽  
Response Analysis ◽  
Piping System ◽  
Valve Body

Safety valve is an important guarantee for nuclear power plant system. Its working environment is harsh, and medium is high-temperature corrosive. It is important to study the dynamic characteristics of nuclear safety valve under unsteady condition to improve the stability and safety of nuclear power plant piping system. Using the finite element method, mass simplification and Rayleigh method, the frequency response analysis of the safety valve and the spring is predicted to predict the seismic capacity under the earthquake load. Based on the verification of the dynamic characteristics of the valve body, the stress and strain analysis of the spring is carried out. To explore the failure condition of the safety valve spring, the lateral deviation linearity of the spring was tested and analyzed by setting up the offset test bench. The results show that the safety valve with the above analysis method can meet the working requirements under the shaking condition. The research results provide an important theoretical basis for the design and analysis of nuclear safety valves.

Life Management of Main Steam and Hot Reheat Piping Systems: Part 2

2006 ◽  
Author(s):  
Marvin J. Cohn
Keyword(s):  
Data Collection ◽  
Fatigue Damage ◽  
Terminal Point ◽  
Piping System ◽  
Material Damage ◽  
Life Management ◽  
Piping Systems ◽  
Creep Fatigue ◽  
Girth Welds ◽  
Main Steam

Since there have been several instances of weldment failures in main steam (MS) and hot reheat (HRH) piping systems, most utilities have developed programs to examine their most critical welds. Many utilities select their MS and HRH critical girth welds for examination by consideration of some combination of the ASME B31.1 Code [1] (Code) highest sustained stresses, highest thermal expansion stresses, terminal point locations, and fitting weldments. This paper suggests the use of an alternative life management methodology to prioritize material damage locations based on realistic stresses and applicable damage mechanisms. This methodology is customized to each piping system, considering applicable affects, such as operating history, measured weldment wall thicknesses, observed support anomalies, actual piping thermal displacements, and more realistic time-dependent multiaxial stresses. The high energy piping life consumption (HEPLC) methodology for MS and HRH critical girth welds may be considered as a rational approach to determine critical weldment locations for examinations and to determine appropriate reexamination intervals as a risk-based evaluation technique. The HEPLC methodology has been implemented over the past 15 years to provide more realistic estimates of actual displacements, stresses, and material damage based on the evaluation of field conditions. This HEPLC methodology can be described as having three basic phases: data collection, evaluation, and recommendations. The data collection phase includes obtaining design and post construction piping and supports information. The effects of current piping loads and anomalies are evaluated for potential creep/fatigue damage at the most critical weldments. The top ranked weldments of the HEPLC study are than selected as the highest priority examination locations. The author has completed many HEPLC studies of MS and HRH piping systems. The previous paper (Part 1) provided examples of data collection results and documentation of observed piping system anomalies. This paper will provide examples of evaluation results and recommendations, including a few case histories that have correctly ranked and predicted locations of significant creep/fatigue damage.

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