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Surface Preparation
Published in Karan Sotoodeh, Coating Application for Piping, Valves and Actuators in Offshore Oil and Gas Industry, 2023
A flange is a component used to connect piping, valves and rotating equipment, such as pumps; a flange connection provides easy access to the piping inside for different purposes such as cleaning, maintenance or inspection, which can be accomplished by unfastening the bolts and nuts.
Shafts and Associated Parts
Published in Ansel C. Ugural, Youngjin Chung, Errol A. Ugural, Mechanical Engineering Design, 2020
Ansel C. Ugural, Youngjin Chung, Errol A. Ugural
Collinear shafts can also be connected by flanged couplings, similar to those shown in Figure 9.16. The flanged portion at the outside diameter serves a safety function by shielding the bolt heads and nuts. The load is taken to be divided equally among the bolts. Rigid couplings are simple in design. They are generally restricted to relatively low-speed applications where good shaft alignment or shaft flexibility can be expected. Keyed couplings are the most widely used rigid couplings (Figure 9.16(a)). They can transmit substantial torques. The coupling halves are attached to the shaft ends by keys. As can be seen in the figure, flange alignment is obtained by fitting a shallow machined projection on one flange face to a female recess cut in the face of the other flange. Another common way to obtain flange alignment is to permit one shaft to act as a pilot and enter the mating flange. Keyed couplings employ standard keys as discussed in Section 9.8.Compression couplings have a split double cone that does not move axially, but is squeezed against the shaft by the wedging of the flanges, as shown in Figure 9.16(b). This kind of coupling transmits torque only by the frictional force between the shaft and the split double cone, eliminating the need for a key and keyway in the coupling.
Joining, Supporting, and Anchoring Reinforced Plastic Pipe
Published in John H. Mallinson, Corrosion-Resistant Plastic Composites in Chemical Plant Design, 2020
This type of flange is commonly made by a matched-steel-die molding process and incorporates a chopped-strand fiberglass reinforcement with special polyester or vinyl ester resins and inert fillers to provide void-free flanges of good physical strength and stable chemical resistance. Tensile strengths of the order of 13,000 psi and flexural strengths of 27,000 psi with a modulus of elasticity at 1.0 × 106 are common in matched-die molding done under extremely high pressure. Compressive strengths of 25,000–35,000 psi are also achieved. The lowest unit costs are obtained with this type of flange. It is sometimes sold with a short length of pipe as a stub end.
Fugitive emissions of volatile organic compounds from the pharmaceutical industry in China based on leak detection and repair monitoring, atmospheric prediction, and health risk assessment
Published in Journal of Environmental Science and Health, Part A, 2023
Fang Zhao, Yao Peng, Lin Huang, Ziwei Li, Weinan Tu, Biao Wu
After monitoring, the repair of a single flange reduced emissions by 47.5 kg, which was the largest emission reduction among all types of components. The repair of open-ended lines achieved the least reduction, of 3.1 kg per piece. Leaks were not identified in three types of components: agitator (shaft seal), pump (shaft seal), and pressure relief equipment. Therefore, these components were not repaired, as shown in Figure 2b). Flanges were the most repaired components. Despite the differences in the effectiveness of leak repair in different components, they all had good repairability and satisfied the production requirements. Flange leaks mainly because of the loosening of bolts and nuts, wearing of gaskets, or seal failures, which can be solved by tightening the bolts and nuts, replacing gaskets, or re-winding thread seal tape. Valve leakage generally refers to the leakage between the valve stem and gland packing, which can usually be eliminated by properly torquing the nut on the gland or gland bolt.[41–43] The main reason for the leakage of open-ended lines is the loose valve end, which can be solved by installing additional valves, blind plates, or pipe plugs, based on the conditions of the valve end or pipeline. A single component emitted 0.32 kg per year after the modification of the equipment and facilities, and a single pump had the highest emission of 1.42 kg per year. Pump leakage is generally due to seal failure and seal face separation, and sometimes results from lower spring pressure or insufficient fluid pressure. Such faults can be repaired by replacing the seal and static and dynamic O-rings and increasing the pressure ratio.
Design and analysis of O-ring polymer gasket for flanged bolted joints in seawater piping using α-FEM
Published in International Journal for Computational Methods in Engineering Science and Mechanics, 2022
Sandeep Kshirsagar, Sundararajan Natarajan
The ASME Boiler and Pressure Vessel code specifies only the general design guidelines for such joints [4]. In order to have leak proof joints, a detailed analysis of the flanged bolted joint assembly with due consideration to various gasket design parameters such as its material and geometry is necessary. Due to the complexity involved, a typical design and subsequent analysis is supported by the finite element method. This has received considerable attention in the literature and some of them are discussed below. Abid and Nash [5] performed a detailed analysis on the influence of gasketed and non-gasketed bolted joints under different operating conditions. The key outcomes of their study are the stress variations in the flanges of pipe joints show flange yielding, flange rotation, effects of joint tightening sequence in response to static and dynamic loading. Hwang and Stallings [6] studied the effects of non-axisymmetric bolt loads using two dimensional finite element models and a detailed three-dimensional modeling in high pressure flanged bolted joints. In their work, the von Mises stress comparisons between the two dimensional and three dimensional FE models show a differences up to 12% at various points due to the non-axisymmetric bolt pretensions. The two dimensional model underestimated the maximum von Mises stress obtained from the three dimensional model by approximately 30%. Sawa et al. [7] using a three dimensional finite element model, studied the effective width of the gasket sealing and the corresponding contact pressure in the flanged bolted joint. Żyliński and Buckkowski [8] used a detailed three dimensional finite element model to compute the working pressure that corresponds to the critical bolt force that may lead to leakage. Jaszak and Adamek [9] determined that assembly torque of nuts required to achieve the desired tightness. Jaszak [10] also performed FE analysis of flanged bolted joints to evaluate the performance of elastic serrated gasket. Aforementioned studies were restricted to bolted joints with stainless steel gaskets. Although, these improved the understanding of the role of various parameters that affects the bolted joints. However, internal and frequent maintenance is still required to avoid any accidents.