Metallic Expansion Joints - Thorburn Flex Inc

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THORBURN FLEXIBLE PIPING SPECIALIST THORBURN EXPANSION JOINTS IN PIPING SYSTEMS In selecting the proper Thorburn metal expansion joint to satisfy system requirements, it is essential that all the operating parameters be fully considered. The following section is presented as a guide for the piping system designer in evaluating the most significant operating requirements and how to apply them in selecting Thorburn metallic bellows expansion joints. Typical Thorburn Metallic Expansion Joint Applications Axial deflection applications Figures 1 through 4 show typical applications of expansion joints to absorb axial pipeline expansion. Note the relative positions of the expansion joints, anchors and guides to achieve proper control of operating conditions. FIGURE 1 Typical tied Single-Flex expansion joint system with beveled ends Lateral deflection applications Figure 5 shows a typical arrangement in which the expansion joint is installed so that the principal pipeline expansion is absorbed as lateral deflection. Figure 6 shows another typical arrangement in which the expansion joint is installed so that the principal pipeline expansion is absorbed as lateral deflection. Thorburn's thrust absorbing tie rods allow the use of intermediate anchors. Where possible, Thorburn's expansion joint should be designed to fill the entire offset leg so that its expansion is absorbed within the tie rods as axial deflection. Any expansion of the offset leg external to the tie rods must be imposed as deflection on the longer pipe legs (this displacement can be minimized by "cold springing" Thorburn's expansion joint). It should be noted that the two horizontal piping legs may lie in any angle in the horizontal plane since lateral deflection can be absorbed in any direction. Rotational deflection applications Figure 7 shows a typical arrangement in which Thorburn's hinged expansion joints are installed in a "Z" type plane so that the pipeline expansion is absorbed as rotational deflection. Note that the thrust absorbing hinges eliminate the need for main anchors and that Thorburn's expansion joint "B" must be capable of absorbing the sum of the rotation of expansion joints "A" and "C". Adequate guiding is necessary to maintain single plane deflection. Just as Thorburn's hinged expansion joints may offer advantages in single plane applications, Thorburn's Gimbal expansion joints (not shown) are designed to offer similar advantages in multi-plane or "angled Z" plane systems. The Gimbal expansion joints are thrust absorbing and usually used in pairs with a Thorburn hinged expansion joint in an arrangement similar to Figure 6. FIGURE 2 FIGURE 3 x 1 1 y FIGURE 4 Page 16
THORBURN FLEXIBLE PIPING SPECIALIST THORBURN EXPANSION JOINTS IN PIPING SYSTEMS FIGURE 5 FIGURE 6 TYPICAL FORCES IN PIPING SYSTEMS FIGURE 7 The following formulas are presented so that the significant forces created in piping sections containing Thorburn metallic expansion joints can be calculated and evaluated. STRAIGHT PIPE SECTIONS (See Fig. 1) F MA❿ = F P + F EJ + F F STRAIGHT PIPE SECTION WITH REDUCER (See Fig. 2) F MA❿ = (F PX - F PY ) + (F EJX - F EJY ) + (F FX - F FY ) CURVED PIPE SECTION (See Fig. 3) In the case of anchors located at pipe bends or elbows, it is necessary to consider the forces imposed by the pipe sections on both sides of the anchor. These forces must be added vectorially. In addition, the effect of centrifugal force due to flow must be considered as follows: F MA(FLOW) = 2AρV 2 g sin FORCES ON INTERMEDIATE PIPE ANCHORS (See Fig. 4) An intermediate anchor is designed to absorb forces due to expansion joint deflection and friction only. It is generally considered good practice to design the immediate anchor to resist the forces on the larger force side. F IA = F EJ + F F LATERAL DEFLECTION (See Fig. 5 and 6) For lateral deflection requirements it is necessary to consider, in addition to the other applicable forces, the lateral force and bending moment imposed on connecting pipe and/or equipment. ROTATIONAL DEFLECTION (see Fig. 7) For rotational deflection requirements it is necessary to consider, in addition to the other applicable forces, the bending moment imposed on the connecting pipe and/or equipment. θ 2 DEFINITIONS OF ACRONYMS F MA = force on main anchor (lbs) F IA = force on intermediate anchor (lbs) F P = force due to pressure (lbs) (bellows effective area x maximum pressure) F EJ = force due to expansion joint deflection (lbs) (axial spring rate x deflection) F F = force due to support and guide friction (lbs) (data available on request) A = bellows effective area (in 2 ) ρ = density of flowing media (lbs/in 3 ) V = velocity of flowing media (in/sec) g = acceleration due to gravity (386 in/sec 2 ) θ = angle of pipe curve (degrees) Note: Deflection forces, bending moments and effective areas are listed in the Expansion Joint Selection Chart (based on ANSI 321 stainless steel at +650ºF). Page 17
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THORBURN'S NON-METALLIC EXPANSION J
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Metallic Expansion Joints - Thorburn Flex Inc

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