Project Description

 

 

Round and Rectangular Expansion Joints

Low Pressure Round and Rectangular Expansion Joints have been specifically designed for round and rectangular low pressure duct and piping applications. Applications such as diesel engine exhaust, gas turbine exhaust, ventilation ducting, and boiler exhaust ducting. The designs are highly flexible, and a variety of materials are available for high temperatures or corrosive applications. Specifications vary for each product group but in general round expansion joints are designed for pressures ranging from full vacuum to 15 psig.

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Laminated Bellows Expansion Joints

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 Bellows Expansion Joints

Sizes 3" through 18"
Laminated 3 ply bellows
Austenitic stainless steel and high nickel alloy bellows
Maximum flexibility and extended life

Laminated Bellows Expansion Joints are designed specifically for low pressure applications such as engine exhaust systems, fan connectors, ventilation ducting and air handling systems. The laminated bellows construction permits axial, lateral and angular movements without exerting high spring forces on the system, and the internal damping provided by the laminations limits resonate vibration. Laminated Bellows Expansion Joints are ideal for direct installation on engine exhaust manifolds, turbochargers and fan inlet and exhaust connections. Round Expansion Joints are similar designs with single ply bellows that less suitable for vibration applications but ideal for use throughout the ducting and piping. Sizes range from 6″ through 48″ diameter.

Design Conditions

expansionjoint

Design Features

 

All Laminated Bellows Expansion Joints are designed for a maximum pressure (including test pressure) of 15 psig and a full vacuum. They are intended for applications such as engine exhaust, fan connections, vents and other very low pressure applications. The design temperature varies with the construction. The materials of construction for standard assemblies are: type 304 stainless steel bellows, van stone ends and flow liners; ASTM A-36 carbon steel plate flanges and angle flanges, and ASTM A-53 standard weight carbon steel pipe weld ends. Optional materials are available including the substitution of stainless steel for flanges and pipe.


Applications

The lateral offset installation illustrated is a typical application 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 off-set of each configuration. For applications of this type it is good practice to add Tie Rods to the expansion joint – see Tie Rods below.

 

Laminated Bellows Expansion Joints can also be installed in axial applications as shown in the axial travel illustration. The maximum Axial Compression and Axial Extension for each configuration is given in Columns 3 & 4 of the Design Data. Most applications do not require the amount of rated axial extension. For these applications the expansion joint can be ordered preset if additional travel is needed. As an example a 3" joint (-040-5) rated for 5" compression factory cold sprung 1" (extended 1") can be rated for 5" compression. The allowable axial extension will be reduced from 2.5" to 1.5".
expansionjoint

Axial Travel

 

 



Tie Rods

Tie rods are available as an option on Laminated Bellows Expansion Joints. They react 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 the pressure thrust in service but they are designed to react the 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. This normally refers to both tie rods and limit rods as Tie Rods but the factory settings are important - factory settings as Tie Rods do not permit axial extension but limits compression to the rated value of the bellows. Factory settings as Limit Rods will permit axial extension and compression in accordance with the rated travel specified in the Design Data.

Flow liners or 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 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 follow the recommendations outlined in the Standards of the Expansion Joint Manufacturers Association (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.

 

The minimum thickness of
a stainless flow liner is:
Nominal
Diameter
(NPS)
Minimum
Thickness
(inches)
3”
4”-10”
12”-18”
0.024
0.036
0.048
These values must be increased when:

 

The flow liner length, L, exceeds 18". Multiply the tabulated values by the factor,.
The velocity, V, exceeds 100 ft./sec. Multiply the tabulated values by the factor,.
When the flow is extremely turbulent such as downstream from valves, tees and elbows. Multiply the calculated velocity by 4 to determine if the velocity exceeds 100 ft./sec.
If the liner length exceeds 18" and the velocity exceeds 100 ft./sec., apply both factors.


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 very heavy gauge or a telescoping design should be used.

Flow Liner

If the expansion joint is installed is a vertical run and the flow is upward, drain holes should be added 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. 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 - see illustration.
Connectors designed for axial compression with flow liners must be designed so that the liner does not extent beyond the end of the joint - see illustration.


Ordering Instructions

Refer to the illustrations (2509, 2510 & 2511) above for the configuration required. Refer to the Design Data table for the rated motions, spring rates, lengths and weights.

Example:
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

Installation Procedure

Operating Conditions: Laminated Bellows 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: Laminated Bellows Expansion Joints are light weight construction. Guides, supports and anchors are important to prevent damage. Refer to the installation drawings for the correct location.

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 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 installation of the expansion joint is complete – but they must be removed prior to pressure testing and operating the system. CAUTION: Shipping restraints may be installed by welding. Provide protection for 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

 

1.Inspect the expansion joint for damage with close attention to the bellows element.
2.Is the expansion joint installed at the correct location; are the anchors, guides and supports installed in accordance with the system design?
3.Are the guides and supports free to allow the movement of the expansion joint?
4.Is the flow direction correct if a flow liner is installed?
5.Have the shipping restraints been removed?

 

Round Expansion Joints

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

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
Light weight construction

Round Expansion Joints are specifically designed for light weight 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 ideally suited for engine exhaust manifolds, turbocharger exhaust connectors, and fan inlet and exhaust connectors. The standard designs can also be adapted 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.

Design Conditions

Missing apps.epsAll Round Expansion Joints are designed for a maximum pressure (including test pressure) of 15 psig and a full vacuum. The design temperature varies with the material used for construction.


The materials of construction for standard assemblies are Type 304 stainless steel for the bellows, van stone ends and flow liners, and A-36 carbon steel plate flanges and angle flanges, A-53 standard weight carbon steel pipe or A36 fabricated ducting. Optional materials are available including the substitution of stainless steel for flanges and pipe.

 

Applications

The lower expansion joint in the illustration is a typical application of a 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.

The two upper expansion joints shown in the illustration are axial applications in pipe or duct runs. 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. The application of 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 is not as rigidly anchored and guided as high pressure systems, tie rods are recommended for universal expansion joints. Tie Rods react the pressure thrust, protect the bellows elements from over extension or compression, and control and react 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 to supports on each rod to guide the center spool. In addition the expansion joint can be incorporated into pipe runs where the expansion joint extends the length of the run, and the expansion of the run is absorbed within the tie rods as well as absorbing the expansion of the adjacent run by lateral offset.

Tie Rods

Tie rods are available as an option on single and universal expansion joints. They react 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 the pressure thrust in service but they are designed to react 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 but the factory settings are important – factory settings as Tie Rods do not permit extension but limits compression to the rated value of the bellows. Factory settings as Limit Rods will permit axial extension and compression in accordance with the rated travel specified in the Design Data.

Flow liners

or 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; therefore 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.

 

The minimum thickness of
a stainless flow liner is:
Nominal
Diameter
(NPS)
Minimum
Thickness
(inches)
6”-10”
12”-24”
26”-48”
50”-72”
over 72”
0.036
0.048
0.060
0.075
0.090
These values must be increased when:

 

The flow liner length, L, exceeds 18". Multiply the tabulated values by the factor,.
The velocity, V, exceeds 100 ft./sec. Multiply the tabulated values by the factor,.
When the flow is extremely turbulent such as downstream from valves, tees and elbows. Multiply the calculated velocity by 4 to determine if the velocity exceeds 100 ft./sec.
If the liner length exceeds 18" and the velocity exceeds 100 ft./sec., apply both factors.


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 very heavy gauge or a telescoping design should be used.

Flow Liner

If the expansion joint is installed is a vertical run and the flow is upward, drain holes should be added 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. 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 extent beyond the end of the joint shown in the illustration.<


Ordering Instructions

Example:
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

Installation Procedure

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 light weight construction. Guides, supports 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 they must be removed prior to pressure testing and use. CAUTION: Shipping restraints may be installed by welding. Provide protection for 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

 

1.Inspect the expansion joint for damage with close attention to the bellows element.
2.Is the expansion joint installed at the correct location; are the anchors, guides and supports installed in accordance with the system design?
3.Are the guides and supports free to allow the movement of the expansion joint?
4.Is the flow direction correct if a flow liner is installed?
5.Have the shipping restraints been removed?


Warranty

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 Joint with “U” profile
and double miter corners.

Rectangular Expansion Joints

Rectangular Expansion Joints are all metal welded construction designed for very low 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 to 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:

 

Suitable for high temperature service without relying on internal insulation.
All metal all welded construction provides a leak tight design.
They can be designed to any size to meet specific duct or equipment sizes.
Broad selection of materials for high temperature and corrosive service.
Extended life - normal design life is 15 years
Standard and custom bellows convolution profiles and corner designs are available.


Standard Convolution Profiles

The convolution profile can be designed to meet specific requirements; however, the majority of applications can be met with standard designs. 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.

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.

 

LOCORR
LOCORR convolutions are recommended for ducting with dimensions ranging from 2.5 feet through 10 feet of length. The saw-tooth cross section provides high flexibility. They can be used with single or double miter, or camera fold corners.
Material: 0.040″ thick.
Axial Stroke: 0.375″ per convolution
Axial Spring Rate: 279 pounds per inch of stroke per foot of periphery

Standard LOCORR profile.

HYCORR
HYCORR convolutions are recommended for ducting with dimensions greater than 10 feet. The saw- tooth cross section provides high flexibility. They can be used with single or double miter, or camera fold corners.Material: 0.050″ thick.
Axial Stroke: 0.75″ per convolution
Axial Spring Rate: 59 pounds per inch of stroke per foot of periphery.

Standard HYCORR profile.

Standard 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 manufacturing limitations that restrict the depth of the convolutions and as a result have a lower flexibility.

 


End Attachments

The most commonly used end attachments are illustrated below. Bolted angle flanges are the most common which have the benefit of stiffening the duct as well 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.

 

 

Design

Most rectangular expansion joints are used to absorb thermal expansion as axial travel or as 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 they can be used with one of corner designs pictured. The end attachments are generally selected to conform with attachments used in the system or to mate with equipment. The most common end attachments are bolted flanges. The flanges have the added benefit of reinforcing the duct work.

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 stresses, and angular and lateral spring rates associated with the “long side” and “short side” sometimes referred to as the “easy way” and “hard way” and accordingly must be individually analyzed. In addition to these calculations we can perform an analysis on the duct to determine if internal or external stiffeners are required to react 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 and the joint motion is axial; however, limit rods or tie rods are frequently incorporated into the design to prevent over travel.

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 is used to made round corners of rectangular expansion joints.

Although not common because of the added complexity, “race track” or “bath tub” joints are sometimes used. 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 is used to made round corners of rectangular expansion joints.

Custom Assemblies

Bellows are commonly incorporated into assemblies designed specifically for a customer’s application. Our total capability to design products and to fabricate all of the component parts minimizes development time and provides control over production.