Metal Expansion Joint
Expansion Joint Engineering Innovation
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Expansion Joint Design
The heart of the expansion joint is the bellows element itself. American BOA is a member of the Expansion Joint Manufacturer's Association and utilizes the equations shown in the EJMA Standards as the basis for their standard and custom bellows designs. In addition, we can perform additional bellows analyses utilizing the equations shown in other codes such as ASME Section VIII, Div. 1, ASME B31.3, or international codes (see below). You will receive free of charge a detailed bellows design calculation for each expansion joint you are interested in. A sample of this analysis is shown below: .

Common Codes Addressed:

· ASME Section VIII, Division 1
· ASME B31.3
· ASME B31.1
· AD Merkblatt, B13
· EN13445 (Chap. 14 for PED compliance)
· Stoomweezen
· If another design code is required, please consult with American BOA

Utilizing this program, we can easily perform all of the analyses noted above utilizing over 35 different materials including:

Austenitic Stainless Steels
Duplex Stainless Steels
Nickel Alloys Copper Alloys
Aluminum Titanium

However, if you require an alloy that is currently not in our database, we will examine the alloy to determine it's welding and ductility properties. If a bellows can be manufactured from the material, we can easily add it to the database to perform your analysis.

In addition to performing analysis on bellows elements, American BOA's Engineering Staff routinely performs calculations on the load restraining hardware normally associated with expansion joints. American BOA uses a combination of 3D modeling software along with finite element analysis (FEA) to determine the correct hardware for your design conditions. The software utilized for solid modeling and FEA work in conjunction with each other to allow the shortest possible time from concept model to production drawing generation. This ensures your customized solution is not only fail safe but produced in a time frame that was previously not possible.

From Model To Analysis
To Production Drawing

American BOA is often requested to aid customers in the proper selection of expansion joints for their particular system. We have the technical expertise to assist customers for the most common applications and the tools in place to aid with selection. By utilizing pipe stress analysis software, American BOA is able to model piping systems to ensure that the expansion joints selected for your system do not result in detrimental loading on vessel nozzles or rotating equipment.


A large contributor to the knowledge base at American BOA has been the capability to perform in-house testing in our state of the art on-site test lab. In addition to utilizing this lab to further our own knowledge of expansion joints, it can be utilized for customer specific expansion joint testing. Some common tests include the following:

High and Low-Frequency fatigue testing, Heat Transfer Testing, Spring Rate Testing,
Bellows Burst Testing, Movement Capability Testing

High Frequency Fatigue with
Thermal Exposure
Spring RateTesting



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