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The maximum allowed load range may be used in certain situations, such as to permit the use of variable support hangers instead of the more expensive constant effort support, or when an alreadyowned spring is to be used over a new one. Therefore, instead ofmodeling the semjnar as rigid anchors which would give the same relative stiffness to the restraints and to the pipingWRC Bulletin should he used hotes estimate and model the nozzle flexibilities. Examination of this equation reveals that, after factoring through constants, it is simply a form of the guided cantilever stress equation: Sprin9 stee’ Pi'”‘ ‘ ‘ ‘ “Ri9idElem7!
The rigidity, weight, and moment due to the offset is best modeled using a weightless rigid element going from the centerline of the pipe out to the center of gravity of the process monitor, at which point a small rigid element with the weight ofthe equipment should be modeled.
Itmay act in any direction, and as such the engineer has several items to consider: Relief valves are used in piping to provide an outlet on those occasions when pressure builds up beyond that desired for safe operation.
Sustained loads are classified as those caused by mechanical forces which are present throughout the normal operation of motes piping system. Additionally, support manufacturers typically limit the range of a hanger rod’s arc in to values such as 60, where the arc can be calculated as: Secondary Loads Markl’s investigation of the fatigue problem, following the earlier recognition of the maximum stress theory offailure, led to identification of the basic problem in the design of piping systems.
However you as a Superpiper may have more applicable data available on the collapsing phenomena of certain fitting geometries, and if you can justify the use of a value other than 0.
COADE Pipe Stress Analysis Seminar Notes – Free Download PDF
The static linear force per foot generated by a steady-state, constant speed wind load can be calculated as: This angular stiffness for a guided cantilever expansion joint model is calculated as: This is an article worth reading. The actual installed load case should be run with the cold spring in order to determine voade installed hanger settings in the presence of cold spring.
If the stanchion connects at A and the equipment centerline is at B, the differential thermal growth of the elbow between those points could put enormously high loads on both the stanchion and the equipment model.
The algebraic load cases shown in Figure permits these two effects to be separated.
The primary stresses were tao high. Therefore the se loads: When this occurs, the offending supports should be removed, or the support locations in the vicinity should be reconsidered. These are designated as NI, N2, Included in this section is information on the following subjects: These elements are defined by two node points one at the “from” end, and the other at the “to” endeach with fixed spatial coordinates and six degrees of freedom three translational and three rotational.
For Short Radius Bend R 1 – cosa Where the existing springs can’t be used, new ones will be recommended. Therefore, standard practice dictates that standard spans be applied subject to the following four caveats: The intention ofthis course is to provide the appropriate background for engineers entering the coaade of pipe stress analysis.
They must still be considered for the support loads, of course. Even though the calculated stress range at the COADE Pipe Ocade Analysis Seminar Notes junction was weil overpsi, thejunction survived several years hecause of the selfrelieving nature noes the thermalload, and the fact that the system cycled fewer than a dozen times over the two year period. AlI elements remain stable under load local buckling of cross-sections is ignored: The user’s entry in this case should normaUy be a variation of the value initially proposed by the program spring selection algorithm.
Print Topic Switch to Threaded Mode. Note that some engineers may prefer to model the effects ofthis equipment by applying a force equal to the weight and a moment equal to the weight times offset at the centerline ofthe pipe. An element such as this is usually modeled as a single, or as a series of elements, each having average parameters.
Earthquake static load cases are set up and determined exactly as they are for wind occasional loads, i. There is a difference in terms of how the two models are entered.
COADE Pipe Stress Analysis Seminar Notes
In many cases this approximation may be sufficiently close to reality to fall within the tolerances, margins, and factors of safety of the problem to be an adequate representation, while in other cases the user may find itnecessary to refine the model through more detailedmodeling. The factors for heavily stiffened bends, such as that shown in Figure Acould he estimated using finite element analysis, or stiffness could he increased by modeling the elbows as COADE Pipe Stress Analysis Seminar Notes flanged, or simply as straight pieces ofpipe with increased stress intensification factors applied.
It is not always so easy to calculate the applied loads. The distance L in Figure may become important if the gap on the guide closes and there is a horizontal restraint force which will cause a torsional moment to exist in both members.
Rigid elements whose cumulative weights equal that ot the torged titting and tlanges. Rigid Support Displacement Criteria – Where feasible, rigid supports are considered preferable to springs supports, for reasons of economy purchase, installation, and mainte- COADE Pipe Stress Analysis Seminar Notes nance and vibration prevention.
The computer software models this load as strictly a force with no applied moment. This simplified check can be illustrated by applying it to the system shown in Figure The equation for calculating occasional stresses is undefined by B The static loading magnitude is considered to be in direct proportion to the element’s weight.
The Bourdon effect is due to the axial extension of pipes either under high pressure or in long runs, causing displacements which must be absorbed by the piping system. Where excessive seminad is a problem, increasing the number of convolutions can be the solution. In certain cases, such as with reducers, which have a variable cross-section, this is not a valid representation.
With nonlinear systems, the effect the occasionalload has on the system is linked to the effect of seminarr operating loads on the system.
Once the springs are designed for their respective thermal cases they are inserted into the piping system and the various operating conditions run to check for stress or equipment overloads. Therefore, movements on an expansion joint are acceptable if: In less pronounced cases such as those shown in Figures B and Cdeviations from the response of an unstiffened bend is usually ignored.
The equation give in the part John mentions may be conservative in some situations. The requirement for nltes minimum pipe component wall thickness is: This is because the so-called bending flexibility is calculated by applying a moment M r to the free end of an expansion joint and observing its end notds 9.