Dead-weight loads

Vacuum Relief and Combined Pressure-Vacuum Relief for Low Pressure Conditions normally used for low pressures such as 1 ounce water to 1.5 psig above atmospheric by special spring or dead weight loading and for vacuum protection such as 0.5 psi below atmospheric. Usually these conditions are encountered in large process, crude oil, ammonia, etc., storage tanks. See later section covering this topic. 

Dead-weight loading (with or without the assistance of levers to reduce the load requirements) of tensile specimens has the advantage of avoiding some of the difficulties already discussed, not the least in allowing accurate determination of the stress if the specimen is uniaxially loaded. The relatively massive machinery usually required for such tests upon specimens of appreciable cross section is sometimes circumvented by the use of a... 

Thermal expansion is a major factor to be considered in the design of piping systems. The reaction load due to pressure drop will normally be negligible. The dead-weight loads can be carried by properly designed supports. 

A much thicker wall will be needed at the column base to withstand the wind and dead weight loads. 

The skirt thickness must be sufficient to withstand the dead-weight loads and bending moments imposed on it by the vessel it will not be under the vessel pressure. 

The skirt thickness should be such that under the worst combination of wind and dead-weight loading the following design criteria are not exceeded ... 

The maximum dead weight load on the skirt will occur when the vessel is full of water. 

When an estimator costs pressure vessels such as reactors and distillation columns, care must be taken to ensure that the wall thickness is adequate. The default method in IPE calculates the wall thickness required based on the ASME Boiler and Pressure Vessel Code Section VIII Division 1 method for the case where the wall thickness is governed by containment of internal pressure (see Chapter 13 for details of this method). If other loads govern the design, then the IPE software can significantly underestimate the vessel cost. This is particularly important for vessels that operate at pressures below 5 bara, where the required wall thickness is likely to be influenced by dead weight loads and bending moments from the vessel supports, and for tall vessels such as distillation columns and large packed-bed reactors, where wind loads may... 

Suppose we apply a constant dead-weight load to a force-measurement system and keep the load applied for several hours. If the output O is monitored over tins period of time, it is often likely that the output value will fluctuate about an expected value for the output. For example, if the load is 100 N, for which the expected output value of the sensing element should be 1 V, it is likely that over time the output wiU assume values such as 1.01, 0.98, 0.99, 0.98, 1.02, etc. This effect is termed as a lack of repeatability. Repeatability is the ability of a system to give the same output for the same input, when this input is repeatedly applied to it. The most common causes for lack of repeatability are random variations in the measurement system elements and their environment. By making reasonable assumptions about the fluctuations of the various inputs, including environment-related ones, it is possible to analytically characterize the fluctuations expected in the output. 

The standard dead weight loading oedometer is the one in general use The alternative is the hydraulic oedometer (Rowe cell) in which the vertical loading and the pore pressures can be independently controlled Reasonable assessments of the magnitudes of foundation settlements can be made if... 

Alex and Janice studied the resistance to crack and craze growth in PC and PMMA in the presence of several surface-active solvents including a component of the universal chemical warfare decontaminant, DS2 (Alex and Janice 1989). A static dead weight-loading apparatus is used for experimentation, and LEFM is used to interpret craze initiation and crack propagation via compact tension specimens. Results reflect relationships based on solubility parameters of the solvents and the polymers. 

Pressure equipment. Pressure devices should be designed to maintain constant pressme on the bond during the entire cure cycle. They must compensate for thickness reduction from adhesive flow-out or thermal expansion of assembly parts. Thus, screw-actuated devices like C clamps and bolted fixtures are not acceptable when constant pressure is important. Spring pressure can often be used to supplement clamps and compensate for thickness variations. Dead-weight loading may be applied in many instances however, this method is sometimes impractical, especially when heat cure is necessary. 

The loadings computed from these equations shall be considered as caused by 67% thermal and 33% dead weight load. 

A stationary block is forced against a rotating ring by a dead-weight load. The bottom part of the ring is immersed in a water-oil emulsion. The presence of the water-oil emulsion is a drawback in this test because the actual wear behavior in an extruder with a polymer melt as the intermediate material between screw and barrel is bound to be substantially different from the wear behavior in the LFW-1 test appa-... 

The test programme specified two serviceabiUty load cases to be apphed to the top rail normal to the plane of the post and rail system (1) a uniform load over an outer bay, and (2) a uniform load over an inner and an outer bay. From a practical standpoint, it was decided to use dead-weight loading and, therefore, the post and rail system was cantilevered horizontally from a rigid steel framework. Three equal point loads were used to simulate uniform loading applied to the outer and iimer bays of the top rail. Deflections at the joints and the centres of the bays of the top rail were recorded with dial gauges. Figure 13.36(a) shows the load case (1) test underway. 

The ultimate load test of the post and rail system used jack rather than dead-weight loads for safety reasons. Hence, upward rather than downward loading was applied to the top rail, as shown in Fig. 13.36(b). However, because the stracture was flexible and the ram extensions of the jacks were... 

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