Round and Rectangular Expansion Joint
Circular and rectangular low-pressure expansion joints are specially designed for circular and rectangular low-pressure pipelines and lines. Some applications such as diesel engine exhaust, gas turbine exhaust, ventilation ducts, and boiler exhaust ducts. You can use various materials in high-temperature or corrosive environments. Each product group has different specifications, but circular expansion joints are usually designed for pressures ranging from full vacuum to 15 psi.
Laminated Bellows Connectors are expansion joints designed to be highly flexible with internal vibration damping for direct installation on vibrating equipment such as engine exhausts, turbochargers, and fan connections. Sizes range from 3″ through 18″ nominal pipe size with fixed, floating, and weld end connections.
Laminated expansion joints are designed for low-pressure applications, such as engine exhaust systems, fan connections, vents, and air conditioning systems. The laminated bellows design enables axial, lateral, and angular movement without using high spring forces in the system. Laminate the board to limit vibration. Laminated joints are ideal for the direct assembly of engine exhaust manifolds, turbochargers, fan inlets, and outlets. Application, but suitable for all pipes and piping. The size range is 6 to 48 inches in diameter.
The maximum pressure (including test pressure) of metal expansion joints with metallic bellows is 15 psi. Inches and full vacuum. They are designed for engine exhaust, fan connections, vents, and other ultra-low pressure applications. The design temperature depends on the design. The structural materials of the standard components: 304 stainless steel bellows, vane ends, and flow bushings; ASTM A-36 angle flanges and carbon steel flanges; and welded ends of ASTM A-53 standard weight carbon steel pipes. Other materials are available, including stainless steel instead of flanges and pipes.
The lateral offset installation illustrated is typical of a Laminated Bellows Expansion Joint installed on an engine exhaust, fan intake, or discharge. The high flexibility and internal damping provided by the laminated construction permits absorption of lateral movement from thermal expansion or mechanical motion. Refer to Column 5 of the Design Data for the maximum lateral offset of each configuration. It is good practice to add Tie Rods to the expansion joint for applications of this type – see Tie Rods below.
Tie rods are available as an option on metal bellows expansion Joints. They react to the pressure thrust in piping and ducting that is not anchored, such as the lateral offset application illustrated above. They may also function as Limit Rods. Limit rods do not react to the pressure thrust in service but are designed to react to the pressure thrust in the event of an anchor failure. Their primary function is to limit the axial extension and compression of the pipe bellows to the rated values. This typically refers to both tie rods and limit rods as Tie Rods. Still, the factory settings are essential – factory settings as Tie Rods do not permit axial extension but limit compression to the rated value of the bellows. Conversely, factory settings as Limit Rods will permit axial extension and compression by the rated travel specified in the Design Data.
Flow liners or internal sleeves are optional features available for all configurations. Liners provide a means of isolating the bellows element from direct contact with the flow and, as a result eliminating flow-induced vibration, minimizing pressure loss, and creating dead air space between the bellows that insulates the bellows. We installed flow liners following the recommendations outlined in the Standards of the Expansion Joint Manufacturers Association (EJMA) summarized as follows.
- 12″ nominal diameter
- Single fixed flange
- Standard bellows material, 304 stainless steel
- Standard Flange Material, A-36 carbon steel
- 3.0″ axial compression, 1.5″ extension
Operating Conditions: Laminated Joints are designed for applications where the pressure, including tests, does not exceed 15 psi. The design temperature varies with the configuration and materials of construction. Consult the purchase specification for the design temperature and the rated travel of the product purchased. Be sure that the system operating conditions and test conditions do not exceed the rated values.
Guides, Supports, Anchors: Guides, support, and anchors are essential to prevent damage. Refer to the installation drawings for the correct location.
Flow Direction: The flow direction can be from either direction for metal bellows that do not include a flow liner. The flow direction for expansion joints with flow liners is from the fixed (welded) end to the free end and indicated on the exterior. Confirm that the joint is oriented correctly.
Shipping Restraints: External restraints are installed at the factory to ensure installation at the correct length and alignment. They are painted yellow and labeled – Shipping bars, remove after installation. Leave these restraints installed until after the metallic expansion joint installation is complete – but they must be removed before pressure testing and operating the system. CAUTION: Shipping restraints may be installed by welding. Protect the bellows element from cutting or grinding during removal.
Tie Rods: Tie rods, limit rods, and control rods are devices that limit the travel of the expansion joint. They are available as an option on Laminated Bellows Expansion Joints. If they are included, be certain that the installation allows the design movement of the expansion joint.
Post Installation Inspection
Round Expansion joints are available in standard designs from 6″ through 48.” Has the capability to manufacture expansion joints with diameters up to 34 feet. Standard end connections are fixed flange, floating flange, angle flange, and weld end. They are available as single joints or universal configurations.
Round Expansion Joints
Round Expansion Joints
Sizes 6″ through 48″ diameter
- Austenitic stainless steel and high nickel alloy bellows
- Wide selection of end fittings
- Designed for maximum flexibility and fatigue life
- Lightweight construction
Round Expansion Joints are designed for lightweight circular ducting used for engine exhaust systems, flue stacks, fan connectors, ventilation ducting, and air handling systems. The bellows are designed to absorb axial, lateral, and angular movements without exerting high spring forces on the system. Standard designs are ideal for engine exhaust manifolds, turbocharger exhaust connectors, fan inlet, and exhaust connectors. You can also adapt the standard designs to special configurations with special flanges, transitions, and elbows. Refer to Laminated Bellows Expansion Joints for sizes 3″ – 18″ for similar expansion joints with high internal damping for applications with vibration or oscillation.
All Round Expansion Joints are designed for maximum pressure (including test pressure) of 15 PSIG and a full vacuum. The design temperature varies with the material used for construction.
The construction materials for standard assemblies are Type 304 stainless steel for the bellows, van stone ends and flow liners, A-36 carbon steel plate flanges and angle flanges, A-53 standard weight carbon steel pipe, etc. A36 fabricated ducting. In addition, optional materials are available, including the substitution of stainless steel for flanges and pipes.
The lower expansion joint in the illustration is a typical application of an expansion joint installed at an engine or fan discharge. The motion for this joint is primarily lateral. Column 4 of the Design Data indicates the rated values for each configuration. If the required motion exceeds the rated value, a Universal Expansion Joint should be considered as described below. For applications of this type, it is good practice to add Tie Rods to the expansion joint – refer to the Tie Rod section below. The rated motions are for conditions resulting from thermal expansion. High-frequency motions such as those caused by excessive engine roll or vibration may cause fatigue of the expansion joint. Consultant the factory for these applications.
Two or more joints are required if the motion exceeds the rated value of a single joint. The Intermediate Anchor is necessary to ensure that each joint absorbs the required motion. It is good practice to design the Intermediate Anchor for loads equal to the spring force at full travel.
Universal Expansion Joints
Universal Expansion Joints are two bellow elements separated by a pipe spool. They are designed primarily for lateral movement. Unlike a single expansion joint that absorbs lateral motion by reshaping the bellows centerline, universal joints absorb lateral motion by angular displacement of the bellows elements. As a result, as the joint length increases, the lateral motion capability increases, and the forces and moments acting on the adjacent equipment decrease. Thus, applying a universal expansion joint is a very effective method of absorbing lateral motions with minimum loading on equipment.
Since most low-pressure piping and ducting are not as rigidly anchored and guided as high-pressure systems, tie rods are recommended for universal expansion joints. Tie Rods react to the pressure thrust, protect the bellows elements from overextension or compression, and control and react to the weight of the center spool. The illustration shows the stops that limit the travel and the center spool support. Longer tied universal expansion joints typically have supports on each rod to guide the center spool. In addition, You can incorporate the expansion joint into pipe runs where the pipe expansion joint extends the length of the run, and the expansion of the run is absorbed within the tie rods and absorbing the expansion of the adjacent run by lateral offset.
Tie rods are available as an option on single and universal expansion joints. They react to the pressure thrust in piping and ducting that is not anchored, such as the lateral application for single expansion joints and the universal expansion joint. They may also function as limit rods. Limit rods do not react to the pressure thrust in service but are designed to react to pressure thrust in the event of an anchor failure. Their main function is to limit the axial extension and compression of the bellows to the rated values. Normally refers to both tie rods and limit rods as Tie Rods. Still, the factory settings are important – factory settings as Tie Rods do not permit extension but limit compression to the rated value of the bellows. Factory settings as Limit Rods will permit axial extension and compression per the rated travel specified in the Design Data.
Also known as internal sleeves are optional features that are available for all configurations. Liners provide a means of isolating the bellows element from direct contact with the flow, eliminating flow-induced vibration, minimizing pressure loss, and creating dead air space that provides insulation. Installed flow liners follow the recommendations outlined in the Standards of the Expansion Joint Manufacturers Association, Inc. (EJMA) summarized as follows.
Flow liners are recommended for:
|Gas applications exceeding 4 ft./sec./inch of diameter up to 6" NPS
|Gas applications exceeding 25 ft./sec. Over 6" NPS.
|Liquid applications exceeding 2 ft./sec./inch of diameter up to 6" NPS.
|Liquid applications exceeding 10 ft./sec. Over 6" NPS.
|All applications when flow turbulence is generated within 10 diameters from the expansion joint.
There are special circumstances involving the use of flow liners:
|Standard liners are rigidly attached on the upstream end of the expansion joint and open on the downstream end. If reverse flow conditions exist, the liner thickness must be the weighty gauge or a telescoping design should be used.
|If the expansion joint is installed in a vertical run and the flow is upward, drain. You should add holes at the lowest point of the liner to avoid trapped liquid.
|Unless a special oversize bellows design is used, the flow liner will intrude into the pipe or duct flow path. However, if the expansion joint motion is axial, only this intrusion will be minimal, and the liner inside diameter may be comparable to the adjacent pipe or duct.
|If there is lateral or angular motion, the gap between the liner outside diameter and the bellows inside diameter must be great enough to allow for this movement, as shown in the illustration.
|Expansion joints designed for axial compression with flow liners must be designed so that the liner does not extend beyond the end of the joint shown in the illustration.
- 24″ nominal diameter
- Single fixed flange,
- Standard bellows material, 304 stainless steel
- Standard flange material A-36 carbon steel
- 3.0″ axial compression, 1.5″ axial extension
Operating Conditions: Low-Pressure Round Expansion Joints are designed for applications where the pressure, including tests, does not exceed 15 PSIG. The design temperature varies with the configuration and materials of construction. Consult the purchase specification for the design temperature and the rated travel of the product purchased. Be certain that the system operating conditions and test conditions do not exceed the rated values.
Guides, Supports, Anchors: Low-Pressure Round Expansion Joints are a lightweight construction. Therefore, guides, support, and anchors are important to prevent damage. Refer to the Applications section for the correct locations and design.
Flow Direction: The flow direction can be from either direction for expansion joints that do not include a flow liner. The flow direction for expansion joints with flow liners is from the fixed (welded) end to the free end, as indicated on the exterior. Confirm that the joint is oriented correctly.
Shipping Restraints: External restraints are installed at the factory to ensure installation at the correct length and alignment. They are painted yellow and labeled – Shipping bars, remove after installation. Leave these restraints installed until after the installation of the expansion joint is complete – but You must remove them before pressure testing and use. CAUTION: Shipping restraints may be installed by welding. Protect the bellows element from cutting or grinding during removal.
Tie Rods: Tie rods, limit rods, and control rods are devices that limit the travel of the expansion joint. They are available as an option on expansion joints. If they are included, be certain that the installation allows the design movement of the expansion joint.
Post Installation Inspection
|Inspect the expansion joint for damage with close attention to the bellows element.
|Is the expansion joint installed at the correct location; are the anchors, guides, and supports installed by the system design?
|Are the guides and supports free to allow the movement of the expansion joint?
|Is the flow direction correct if a flow liner is installed?
|Have the shipping restraints been removed?
The Limited Warranty applies to all expansion joints.
Rectangular Expansion Joints
Rectangular Expansion Joints are fabricated to customer-specified dimensions with standard convolution profiles and a variety of corner configurations—materials of construction range from carbon steel to stainless steel and high nickel alloy steels. Metal rectangular expansion joints are leak-tight and typically last 15 years or more.
Rectangular Expansion Joints
Rectangular Expansion Joints are all metal welded construction designed for deficient positive and negative pressure applications such as flue ducts, exhaust systems, ventilation systems, fan connections, and air supply systems. Since these ducts are sized to meet flow requirements and mate with mechanical equipment, rectangular expansion joints are designed to match the duct and equipment sizes. They are manufactured with a variety of convolution profiles, corner designs, and end attachments. Offers standard convolution profiles and corner designs as well as having the capability to manufacture custom designs.
Rectangular Expansion Joints offer many benefits:
Materials can be any sheet material, including Cor-Ten®, austenitic stainless steel alloys 304, 316, 321, 347, and high nickel alloys 600, 625, 800, and 825.
Standard Convolution Profiles
The convolution profile can be designed to meet specific requirements; however, expansion joints can meet most applications with standard designs. Therefore, we offer two standard profiles which are tailored to the lengths of the sides. These profiles are also ideally suited for the most common corner configurations.
The most commonly used corner configurations are pictured below, along with a description of their individual benefits. There are other corner designs, such as rounded corners; however, there are manufacturing limitations that restrict the depth of the convolutions and, as a result, have lower flexibility.
Standard Corner Configurations
The most commonly used end attachments are illustrated below. Bolted Angle flanges are the most common, which benefit from stiffening the duct and ease of installation and removal. As an alternative, the flanges can be welded along the outer edges in place of bolting. Although they are not shown, plate flanges are sometimes used.
Most rectangular expansion joints absorb thermal expansion as axial travel or connectors to isolate fans and other mechanical equipment. As a result, most configurations are single unrestrained joints. There are no standard sizes since the ducts are individually fabricated and designed to accommodate the system design. Although we can fabricate other convolution profiles, the standard LOCORR and HYCORR profiles will accommodate most sizes, and You can use them with one of the corner designs pictured. The end attachments are generally selected to conform with attachments used in the system or mate with equipment. The most common end attachments are bolted flanges. The flanges have the added benefit of reinforcing the ductwork.
We perform a design analysis on all designs in conformance with the method of analysis outlined in the Standards of the Expansion Joint Manufacturers Association, Inc.(EJMA). Rectangular expansion joints have stressed, and angular and lateral spring rates associated with the “long side” and “short side” are sometimes referred to as the “easy way” and “You must individually analyze hard way” and accordingly. In addition to these calculations, we can analyze the duct to determine if internal or external stiffeners must react to the pressure forces.
Rectangular expansion joints are commonly furnished with flow liners to reduce pressure drop and prevent impingement of the flow on the bellows. The material used is frequently the same as the duct material. Most rectangular expansion joints are used in applications where the ducting is supported and anchored. The joint motion is axial; however, limit rods or tie rods are frequently incorporated into the design to prevent overtravel.
Single rectangular metal expansion joints have limited ability to absorb lateral offset or deflection. If lateral offset is a requirement, a universal configuration is recommended or two single joints spaced apart. If the motion is limited to one plane, hinges or slotted hinges are frequently included. Slotted hinges have the benefit of stabilizing the
Expansion joint, limiting the axial travel and supporting the weight of adjacent ducting. The joint pictured is used in the exhaust stack of a ship. The rounded ends are made from round expansion joints cut in half. This is the same technique used to make round corners of rectangular expansion joints.
Although not common because of the added complexity, “race track” or “bathtub” joints are sometimes used. For example, the joint pictured is used in the exhaust stack of a ship. The rounded ends are made from round expansion joints cut in half. This is the same technique used to make round corners of rectangular expansion joints.
Metallic Bellows are commonly incorporated into assemblies designed specifically for a customer’s application. Our total capability to design products and fabricate all parts minimizes development time and provides control over overproduction.