Piping anchors

Pipe anchor load The force calculated to resist loading in anchored piping systems, the pipe anchor load is added to the thermal expansion loads of the equipment. 

Currently, qualification methods based on experience are available primarily for seismic design and seismic re-evaluation of equipment [37-39]. Earthquake experience methods are simple and efficient tools to verify the seismic adequacy of selected mechanical, electrical and instriunentation and control equipment classes. Earthquake experience methods are also used to verify the seismic adequacy of piping, anchoring of piping supports and masonry walls, and to check potential seismic interactions. These methods are primarily screening and waUcdown procedures and are summarized in Appendix III. Some of them involve establishing the similarity of candidate items to reference items. Similarity requires both the following basic conditions ... 

The loads at the piping anchor to the equipment nozzle shall be used as the equipment nozzle loads if the equipment and its supports are rigid, or if the equipment nozzle stiffness is modeled in the piping analysis. 

Semi-submersible rigs are often referred to as semis , and are a floating type of rig. Like the jack-up, a semi is self contained. The structure is supported by large pontoons which are ballasted with water to provide the required stability and height. The rig is held in position by anchors and mooring lines or dynamically positioned by thrusters. A large diameter steel pipe ( riser ) is connected to the sea-bed and serves as a conduit for the drill string. The blowout preventer (BOP) is also located at the sea-bed ( sub sea stack ). 

Piping supports, guides, and anchors increase local stresses on the pipe wall at the point of attachment. These stresses derive from continuously acting loads owing to the weight of the piping system carried at these points (pipe, contents, insulation), the pressure in the pipe, and any other loads such... 

In the flexibihty method, a basic anchor is assigned and the entire system is worked in reference to this basic anchor. The pipe is left free to expand from the basic anchor and all the other anchors and restraints are considered as released. The forces and moments are then appHed to the release anchor and restrained points to force those points back to their installed locations. Therefore, finding those forces and moments is required. 

The superheated steam generated in the superheater section is coHected in a header pipe that leads to the plant s high pressure steam turbine. The steam turbine s rotor consists of consecutive sets of large, curved, steel aHoy disks, each of which anchors a row of precision-cast turbine blades, also caHed buckets, which protmde tangentiaHy from the shaft and impart rotation to the shaft when impacted by jets of high pressure steam. Rows of stationary blades are anchored to the steam turbine s outer sheH and are located between the rows of moving rotor blades. 

Thermal-expansion and -contraction loads occur when a piping system is prevented from free thermal expansion or contraction as a result of anchors and restraints or undergoes large, rapid temperature changes or unequal temperature distribution because of an injection of cold liquid striking the wall of a pipe cariying hot gas. 

Thermal displacements. A piping system will undergo dimensional changes with any change in temperature. If it is constrained from free movement by terminals, guides, and anchors, it will be displaced from its unrestrained position. 

Bending or torsional flexibihty may be provided by bends, loops, or offsets by corrugated pipe or expansion joints of the bellows type or by other devices permitting rotational movement. These devices must be anchored or otherwise suitably connected to resist end forces from fluid pressure, frictional resistance to pipe movement, and other causes. 

In the absence of more direc tly applicable data, the flexibility factor k and stress-intensification factor i shown in Table 10-54 may be used in flexibihty calculations in Eq. (10-101). For piping components or attachments (such as valves, strainers, anchor rings, and bands) not covered in the table, suitable stress-intensification factors may be assumed by comparison of their significant geometry with that of the components shown. 

D = outside diameter of pipe, in (mm) y = resultant of total displacement strains, in (mm), to be absorbed by the piping system E = developed length of piping between anchors, ft (m)... 

In calculating the flexibihty of a piping system between anchor points, the system shah be treated as a whole. The significance of all parts of the hne and of all restraints introduced for the purpose of reducing moments and forces on equipment or small branch hnes and also the restraint introduced by support friction shall be recognized. Consider all displacements over the temperature range defined by operating and shutdown conditions. 

The force required to overcome the static friction of the pipe in expanding or contracting on its supports, from installed to operating position. The length of pipe considered should be that located between the anchor and the expansion joint. 

The quencher arm shoiild be anchored to prevent pipe whip. It should also extend to the length (for horizontal vessels) or the height (for vertical vessels) of the vessel to evenly distribute the vapors in the pool. 

Use wrap-around reinforcement at welded support shoes and anchors. Alternatively, all welding of these fittings to the pipe wall may be eliminated by the use of bolted shoes and anchors. 

I xtemal inspection criteria are provided by these standards for foundation and supports, anchor bolts, concrete or steel supports, guy wires, nozzles, sprinklers pipe hangers, . rouiuling coiiiiee(ions, protective coatings, insulation, and external metal surfaces. 

Figure 5.1-5 shows a perspective view of one loop of the system. Note that in this system, kinematic constraints in the form of pipe supports, anchors, and hangers are minimal. Only the pumps are laterally braced by the suppressors. The pumps in this system are supported by hangers from above. 

Figure 13-23. Recommended pulse level for acceptable pipe vibration (assumes adequate pipe support and anchors). (Used by permission Everett, W. S. Hydrocarbon Procession and Petroleum Refiner, V. 43, No. 8, p. 117, 1964. Gulf Publishing Company. All rights reserved.)...

The derrick or mast must also be designed to withstand wind loads. Wind loads are imposed by the wind acting on the outer and inner surfaces of the open structure. When designing for wind loads, the designer must consider that the drill pipe or other tubulars may be out of the hole and stacked in the structure. This means that there will be loads imposed on the structure by the pipe weight (i.e., setback load) in addition to the additional loads imposed by the wind. The horizontal forces due to wind are counteracted by the lattice structure that is firmly secured to the structure s foundation. Additional support to the structure can be accomplished by the guy lines attached to the structure and to a dead man anchor some distance away from it. The dead man anchor is buried in the ground to firmly support the tension loads in the guy line. The guy lines are pretensioned when attached to the dead man anchor. 

Mast setup distance The distance from the centerline of the well to a designated point on the mast structure defined by a manufacturer to assist in the setup of the rig. Maximum rated static hook load The sum of the weight applied at the hook and the traveling equipment for the designated location of the dead line anchor and the specified number of drilling lines without any pipe setback, sucker rod, or wind loadings. 

Figure 6.12 Multiple piping system anchor of guide installation (courtesy of Industrial Hangers Ltd)...

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