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U.S. Bellows Designed an Expansion Joint & Duct Work Assembly during a Plant Turnaround

U.S. Bellows Designed a 60" Diameter Universal Expansion Joint & Duct Work Assembly during a Chemical Plant Turnaround

U.S. Bellows designed a universal expansion joint and duct work assembly for a 3rd pass outlet converter to economizer duct work application at a chemical plant in 8 weeks. Expansion joints are used in many economizer ductwork applications near boilers. Plant turnarounds are a vital part of a plant’s maintenance program. They involve a scheduled stoppage of part or all of a plant’s operations. During this time, existing equipment such as expansion joints are removed and replaced with new or upgraded expansion joints. On-time delivery is critical to the plant turnaround schedule in order to limit the amount of time the plant is in shutdown. The total assembly included a universal expansion joint, over 125 feet of custom-built 60” diameter duct work, including elbows, tees, saddles, nozzles, and spring supports. The expansion joints were designed for 0.3 degrees angular movement, 2.875″ lateral, and 3.25″ axial extension. The design conditions were 5 psig at 890 degrees F. The liner, cover, and ducting are fabricated from 304 stainless steel and the bellows are 321 SS. A dye penetrant exam, soap & air test, and spot x-ray on all duct seam welds were performed before shipping. U.S. Bellows has worked extensively on boiler units within the chemical industry and has provided products and designed supports for the unique requirements of economizers including the use of stainless steel and super alloys to support applications such as this involving highly corrosive media.

78” Dia. Universal Expansion Joint Custom-Designed for One of the Oldest Scientific Innovators in the Engineering Industry

78” Dia. Universal Expansion Joint Custom-Designed for One of the Oldest Scientific Innovators in the Engineering Industry

U.S. Bellows, Inc. custom-designed universal expansion joints for one of the oldest scientific innovators in the engineering industry. Large diameter steam pipelines are a part of almost every plant and are associated with innovations in areas like nanotechnology, fuel cells, biomaterials from renewable resources, materials for personal protections (which have been especially important in the time of COVID), emerging video display technologies, and semiconductors. These plants manufacture polymers such as neoprene, nylon, chlorofluorocarbons, synthetic pigments. In this case, the universal expansion joint bellows and liner are fabricated from A240 Gr. 321, the pipe, tie rods, and flanges are fabricated from A240 Gr. 304 stainless steel. They are designed for low pressure (8 PSI) and range from 36” pipe x 60” long up to 78” pipe x 117” long. Per our QC requirements and/or client specifications, the expansion joints were dye-penetrate examined and soap, air bubble tested prior to shipment.

Us bellows universal expansion joint 137373 fab sm
78″ Universal Expansion Joint in Fabrication

Pressure Balanced Tee Universal Expansion Joint for a Boiler Feed Pump Turbine Exhaust

Pressure Balanced Tee Universal Expansion Joint for a Boiler Feed Pump Turbine Exhaust

U.S. Bellows, Inc. custom-designed a pressure balanced tee universal expansion joint for a boiler feed pump turbine exhaust. The expansion joint is 96” diameter and 288” OAL and is designed for 2″ axial movement at 315°F and 15 psig. The bellows, liner, and turning vanes are 304 stainless steel. The remainder of the assembly is fabricated from carbon steel. The expansion joint was dye penetrant examined, and a chemical cleaning of the interior surfaces was performed to remove any oil and grease. U.S. Bellows also conducted a stress analysis and a pneumatic test at 23 psig.

U.S. Bellows Custom-Designed Tied Universal Expansion Joints for Service at a Chemical Plant

U.S. Bellows Custom-Designed Tied Universal Expansion Joints for Service at a Chemical Plant.

Universal expansion joints such as these are used in chemical plants that manufacture petrochemicals (such as ethylene and styrene monomer), polymers, and building products (PVC profiles for windows, doors, and decking). The units range from 26” to 48” in length and 8” to 20” in diameter. The bellows were fabricated from 321 stainless steel, the weld ends, pipe spools, and flanges from 304 stainless steel, and the tie rods and hex nuts from carbon steel. They are designed for temperatures ranging from -150°F to 800°F, operating pressures ranging from 50 to 240 psig, and 0.25” to 2.25” of lateral deflection. The expansion joints were air, soap, and bubble tested, 100% dye-penetrant tested and hydro-tested before shipment. The universal pipe expansion joint consists of two bellows separated by a pipe section or spool. The primary purpose of this arrangement is to have a unit that will accept large amounts of lateral deflection. The amount of lateral deflection they can accept is a function of the amount of angulation each bellows can absorb and the distance between the bellows. For a given bellows element, the amount of lateral deflection capability can be increased or decreased by simply changing the length of the center spool.

Gimbal Expansion Joints for Crude Oil Pipelines in Canada

Gimbal Expansion Joints Fabricated for Crude Oil Pipelines in Canada

U.S. Bellows custom-designed and fabricated universal gimbal expansion joints for 24” diameter crude oil pipelines at a power plant in Canada. The bellows are fabricated from A240 316 stainless steel bellows, the flanges are A105N carbon steel, and the plates are A516 70 carbon steel. The expansion joints are designed for a 10 degrees angular rotation at 285 psig up to 100 degrees F. They are designed for an angular spring rate of 4900 in-lb/dec and vertical offset of 10-1/4”. The units measure 43” x 43” x 110” and 38” x 38” x 79”.

Us bellows gimbal ej 3d model

3D Modeling was done so that our engineers can check the “fit-up” to confirm the design, perform stress analysis, or other modeling benefits prior to fabrication. We performed hydro tests, completed NDE reports, and supplied Material Test Reports per the client requirements.

Hinged Expansion Joints Custom-Designed for a Process that Produces High-Density Polyethylene (HDPE)

Hinged Expansion Joints Custom-Designed for a Process that Produces High-Density Polyethylene (HDPE)

U.S. Bellows custom designed these hinged expansion joints for a Polyolefin process which produces High-Density Polyethylene (HDPE) resin at a chemical plant. Polyolefins are a family of polyethylene and polypropylene thermoplastics. The job included expansion joints ranging from 12″ to 32″ NPS. The units pictured above have a nominal pipe size of 16″. The bellows and liner were fabricated from 304 stainless steel and the flanges, cover, and hardware from carbon steel. They are designed for an operating temperature of 176°F at 145 psig and 1° of angular movement. The expansion joints were 100% dye penetrant tested, the bellows longitudinal seam welds were 100% X-rayed, PMI examined, and hydro-tested prior to shipment.

Safety Reccomendations

Piping Technology highly recommends that our customers thoroughly understand the uniqueness of pipe expansion joints and their application. The following safety recommendations are paraphrased from the Fifth Edition of The Standards of the Expansion Joint Manufacturers Association, 1980.


Bellows pipe expansion joints are employed in piping systems to absorb differential thermal expansion while containing the system pressure. They are being successfully used in refineries, chemical plants, fossil and nuclear power plants, shipboard applications, heating and cooling systems, pulp and paper plants, and cryogenic plants. Typical service conditions range from pressures of full vacuum to 1,000 psig (70 kg/cm3) and -420F to +1,800 F (-251C to +968 C). Thus, pipe expansion joints must be specified as a highly engineered product. They cannot and should not be purchased and used as commodity items if the pipe expansion joints are to perform their intended function safely and reliably. The system operating requirements, the pipe expansion joint design and manufacturing quality, the installation, test and operating procedures must all be considered for all pipe expansion joint installations.

Unlike most commonly used piping components, a bellows is constructed of relatively thin gauge material in order to provide the flexibility needed to absorb mechanical and thermal movements expected in service. This requires design, manufacturing quality, nondestructive examination, handling, installation and inspection procedures which recognize the unique nature of this product.

In general, the most reliable and safe bellows pipe expansion joint installations have always involved a high degree of understanding between the user and manufacturer. With this basic concept in mind, the following recommendations are given in order to better inform the user of those factors which many years of experience have shown to be essential for the successful installation and performance of piping systems containing bellows pipe expansion joints.

Would you recommend expansion joints become filled with Kao when the expansion joint is utilized in high-temp applications (e.g. reactor overhead lines)?

Yes, we would recommend that the expansion joint is filled with Kao, but it would require a special design or over-sized bellows.

With regards to materials, how do you certify the materials?

We obtain the MTR’s and additionally we perform positive material identification tests in house and if a customer requires additional the additional chemical and physical properties, we can obtain that as well.

Why should I use a double offset expansion joint?

A double offset expansion joint can be used to absorb large amounts of lateral motion with a minimum amount of deflection forces

Why do bellows have corrugations?

Bellows have corrugations (convolutions) in order to be able to absorb the thermal movement of the piping.

Which forming method is better of more quality?

We punch form our bellows. This is an industry accepted forming method.

Where is the insulation pillow located within the expansion joint?

There are a variety of places for the insulation pillow to be placed within the expansion joint. It can be inside the unit or we can fabricate the expansion joint over sized and we can fill the extra space with the insulation pillow for example to reduce the skin temperature of the fabric.

Where is the gasket installed in a fabric expansion joint?

The gasket is a non-porous deformable material that is installed between the belt attachment flange and the fabric belt. The gasket allows a gas tight seal when the back-up bar clamping action is applied.

Where do I install expansion joints in a piping system?

The location of expansion joints in a piping system depends on the design conditions and the piping system configuration. All cases must be evaluated individually.

When are center supports required on expansion joints?

Use a center spool support to support the weight of the spool between the bellows and to stabilize the center spool during operation.

What type of material is normally used in the accumulation barrier?

Kaowool is used. It is a ceramic thermal blanket.

What type of EJ do I use so that I don’t need to design for the pressure thrust force?

Pressure balance type. The major advantage of a pressure balanced joint is its ability to absorb axial movement without imposing additional pressure thrust into the piping system.

What’s the typical spring rate for a 20″ pressure balanced expansion joint?

The spring rate is equal to the spring rate of both flow bellows plus the spring rate of the balancing bellows.

What’s the highest cycle # you can handle?

Fatigue life of any unit has to be calculated. The number of cycles varies according to the design conditions of the expansion joints.